aluminium and renewable energy systems – prospects for the

ifeu - Institut für Energie- und Umweltforschung Heidelberg GmbH

Aluminium and Renewable Energy Systems – Prospects for the Sustainable Generation of Electricity and Heat

Final version

commissioned by the International Aluminium Institute

Jan Maurice Bödeker (project management)

Marc Bauer

Dr. Martin Pehnt

Heidelberg, September 2010

Aluminium and Renewable Energy Systems IFEU

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Aluminium and Renewable Energy Systems – Prospects for the Sustainable Generation of Electric-ity and Heat

Executive summary

Renewable energy technologies offer a large market opportunity for aluminium. In the best case scenarios, renewable energy technologies would introduce a market increase of up to 10 % additional aluminium use. This is due to:

the large area of energy collection (e. g. module or collector surface) of renewable energy systems;

the requirement of solar-directed installation (e. g. mounting and frames of solar power plants)

the expected dynamic market development (high expansion targets in many coun-tries).

In other technology areas aluminium has to compete with other materials (e. g. steel and glass for solar thermal power plants). Increasingly, within renewable energy technologies, aluminium is already used to a large extent (e. g. PV and solar collectors).

There has been rapid development in commercially viable renewable energy systems in re-cent years to meet the growing demand for the sustainable generation of electricity and heat in both developed and developing countries. Aluminium plays an important role as one of the key materials in a wide range of renewable energy systems, namely solar thermal collectors, wind turbines, photovoltaic systems, solar cookers and concentrating solar thermal power plants.

This study “Aluminium and Renewable Energy Systems – Prospects for the Sustainable Generation of Electricity and Heat”, commissioned by the International Aluminium Institute (IAI), assesses the present and future use of aluminium in selected renewable energy systems for the years 2020, 2030, and 2050 under different technology development pathways and market conditions. The use of aluminium depends heavily on both the mar-ket growth of the given renewable energy systems as well as the specific use of aluminium in the respective technology. To address this bandwidth three scenarios with two variations (sub-scenarios) were defined in this study. An optimistic SCENARIO HIGH assumes maxi-mum specific aluminium use and optimistic rates of expansion of installed capacities, whereas SCENARIO LOW assumes pessimistic estimates regarding the specific aluminium use and the expansion of renewable energy systems. However, those two scenarios are to be interpreted as the upper and the lower end of the scenario funnel. A more likely outcome is SCENARIO BEST ESTIMATE based on moderate assumptions regarding the growth rate of the renewable energy systems. It is differentiated into three sub-scenarios, which assume a minimum, moderate and maximum specific aluminium use (BEST ESTIMATE Minus, BEST ESTIMATE and BEST ESTIMATE Plus, respectively).

In addition, the energetic and environmental benefits namely generated electricity and heat as well as the CO2 abatement potential of renewable energy systems that use aluminium are projected for the three reference scenarios.


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The specific aluminium (kg per kilowatt) used in the technologies differs significantly (see Figure 1). Particularly PV and CSP use high amounts of aluminium in the Al moderate, and even more in the Al maximum scenario. This is due to rather high shares of aluminium in the components as well as rather low conversion efficiencies (e. g. compared to solar thermal collectors). It has to be noted that in Figure 1 the aluminium use is normalized to one kW heat for solar thermal collectors and one kW electricity for the other technologies.

Figure 1: Specific aluminium use in the various technologies (per kW heat (solar thermal collectors) or kW electricity (others); FP: flat-plate, ET: Evacuated tube)

For solar thermal collectors (flat-plate and evacuated tube collectors), aluminium is mainly used in absorbers, casings and frames. Studies support the trend of increased aluminium use in absorbers. Out of 289 systems analyzed 34% use aluminium absorbers.

The market sales of aluminium could increase if specific aluminium use moved from “Al moderate” with 3.1 kg/m² to “Al maximum” with 4.3 kg/m² (flat-plate) or 0.9 kg/m² to 4.3 kg/m² for evacuated tube technologies. This can be achieved by replacing copper with aluminium in absorbers of flat-plate collectors and steel with aluminium in frames in evacuated tube collec-tors. Additionally, if reflector shields and water tanks are used in evacuated tube collectors then aluminium use would be even higher. This assumption is part of Al maximum.

In SCENARIO BEST ESTIMATE, which assumes a dynamic market growth from 210 million m² installed today to 11 billion m² in 2050 and a moderate specific aluminium use, the total aluminium in use could be 17 million tons (Mt) by 2050. In SCENARIO BEST ESTIMATE Plus which assumes a move from Al moderate to Al maximum, 39 Mt aluminium could be in use in 2050.

With wind turbines, steel is the material predominantly used, with about 85% of the total material input. Aluminium plays a subordinate role and is used in a range from under 0.01% up to about 2.5 % of the total material input. Today, only a low amount of aluminium, esti-mated around 0.1 Mt, is used in wind turbines today, primarily in nacelles and rotors.

In SCENARIO BEST ESTIMATE the total aluminium in use increases to 1.2 Mt aluminium by 2050. The shift from Al moderate to Al maximum concerning aluminium use in SCENARIO BEST ESTIMATE Plus could lead to approximately 7.4 Mt of aluminium in use by 2050. Mar-ket sales of aluminium could be increased by replacing the coverings of the wind turbine na-celle and rotors with aluminium.

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Photovoltaic systems (PV) directly convert solar energy into electricity. According to our re-search, 0.4 Mt of aluminium is used in photovoltaic systems today. Aluminium is predomi-nantly processed in a construction/mounting structure (72% of total aluminium input), fol-lowed by input to panel frames (22%), and aluminium use in inverters (6%).

Analysis shows that between 23 kg/kW (Al minimum) and 59 kg/kW (Al maximum) of alumin-ium are used in photovoltaic systems. In 2050, aluminium use would rise to 19 Mt in SCENARIO BEST ESTIMATE. SCENARIO BEST ESTIMATE Plus with moderate growth and Al maximum of 59 kg/kW would lead to 35 Mt 2050. The full market sales potential of aluminium in photovoltaic systems could unfold if aluminium were used more frequently for mounting structures and frames.

Solar cookers are devices that generate heat for cooking from sun energy. In the absence of detailed expansion scenarios only the overall potential of solar cookers was examined. Aluminium is mainly found in frames and reflectors, but usage varies strongly between 0.1 kg/unit, if no aluminium is used at all (e.g. reflector made of optical polyester and/or wooden frame), and 20 kg/unit if both frame and reflectors are made of aluminium.

Assuming a moderate specific aluminium use and a moderate overall market sales potential of 83 million units, SCENARIO BEST ESTIMATE indicates 0.3 Mt aluminium in use in solar cookers by 2050 if aluminium were used only in reflectors. The SCENARIO BEST ESTIMATE Plus shows a potential of approximately 1.7 Mt by 2050.

Since frames are made from other materials (mainly steel), a replacement potential is given. Nevertheless, even if aluminium use is low compared to other technologies, solar cookers could be a favourable technology on which to focus especially with regard to CDM projects. As there is no clear trend in which directions material inputs will evolve for solar cookers, cheap and light systems which are currently not using aluminium should be further observed in the upcoming years.

Concentrated solar power (CSP) systems use concentrated sunlight to generate electricity or heat. Today, 33’000 tons of aluminium are installed in CSP technologies. Aluminium is mainly used in parts of the power block and the cooling tower, while system frames are mainly made of steel and the absorber system does not use aluminium.

Recently, only small amounts of aluminium have been used. According to SCENARIO BEST ESTIMATE the total aluminium in use increases to 51 Mt by 2050. SCENARIO BEST ESTIMATE Plus indicates a total aluminium use of 105 Mt if specific aluminium use rises from 65 kg/kW to 131 kg/kW (shift from Al moderate to Al maximum). The market sales po-tential of aluminium could be maximized if elevation and collectors, which are today mostly made of glass and steel, were replaced by aluminium.

In 2050 the total aluminium invested in renewable energy systems could amount to 88 Mt in SCENARIO BEST ESTIMATE where specific aluminium use and expansion path are based on moderate assumptions (see Table 1 and Figure 2; for more details see Table 53). SCENARIO BEST ESTIMATE Plus even indicates 188 Mt if specific aluminium use is maxi-mized according to above mentioned aluminium replacement potentials for single renewable energy systems (Al moderate Al maximum).


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Figure 2: Projected cumulative aluminium used in renewable energy systems

Table 1: Study results in brief

Use in renewable energy systems in million tons (Mt)

Global expansion of Renewable Energy Systems

PATH LOW PATH BEST ESTIMATE

PATH HIGH

Cumulative aluminium use in 2050

Al Minimum 4 15

Al Moderate 88

Al Maximum 188 470

Annual use of aluminium in 2031 to 2050

Al Minimum 0.08 0.6

Al Moderate 3.3

Al Maximum 8.8 16.3

In Figure 3, projected annual aluminium sales for all focus renewable energy systems are shown for the SCENARIO BEST ESTIMATE. The total annual aluminium sales increase steadily. From now until the year 2020, approximately 0.5 Mt/a or 1.4 percent of annual alu-minium production could be used in renewable energy systems every year. From 2021 until 2030, total annual aluminium sales for renewable energy systems could increase to around 1.5 Mt or four percent of annual aluminium production and from 2031 until 2050 sales could increase to 3.3 Mt or nearly 9 percent of annual aluminium production.

As Figure 3 shows, in SCENARIO BEST ESTIMATE solar-based technologies (CSP, PV and solar thermal collectors) account for most of the overall potential. Moreover, in SCENARIO BEST ESTIMATE Plus, the rise of aluminium use from Al moderate to Al maximum in CSP, solar thermal collectors and PV systems seems to be very promising.

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Figure 3: Projected annual aluminium use in renewable energy systems in the SCENARIO BEST ESTIMATE

If aluminium use could be further maximized according to SCENARIO BEST ESTIMATE Plus (shift: AL moderate Al maximum), the same installation rates could lead to even higher numbers; e.g. 8.8 Mt/a from 2031-2050 (see Figure 4 and for further details Table 52).

Figure 4: Projected annual aluminium use in renewable energy systems in the SCENARIO BEST ESTIMATE Plus

By 2050 the final energy supply of the selected technologies could amount to around 9’800 TWh electricity and 6’600 TWh heat according to SCENARIO BEST ESTIMATE. In compari-son, total global electricity generation in 2007 was 19’771 TWh. Total CO2 abatement po-tential in SCENARIO BEST ESTIMATE would be around 9’300 Mt in 2050 compared to marginal technologies (gas and coal electricity generation and gas/oil heating systems). As comparison: The annual emitted CO2 emissions in 2007 were approximately 29’000 Mt of CO2.

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In conclusion, renewable energy technologies offer a large market opportunity for alumin-ium. In the best estimate scenario, renewable energy technologies would introduce a market increase of up to 10 % additional aluminium use. This is due to:

the large area of energy collection (e. g. module or collector surface)

the requirement of solar-directed installation (e. g. mounting and frames of solar power plants)

the expected dynamic market development (high expansion targets in many coun-tries).

In many technologies (e.g. PV and solar collectors), aluminium use is increasing, while in others (e. g. for solar thermal power plants) materials such as steel and glass are predomi-nantly used.


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Content

Executive summary ................................................................................................................ 2

1 Introduction ....................................................................................................................... 10

2 Methodological approach ................................................................................................. 12

3 Aluminium in individual renewable energy systems ..................................................... 16 3.1 Solar thermal collectors for hot water generation and process energy ............................ 16 3.1.1 Description of technologies 16 3.1.2 Current market situation for solar thermal collectors 18 3.1.3 Specific aluminium use in solar thermal collectors 23 3.1.4 Technology scenarios for solar thermal collectors 27 3.1.5 Resulting current and future aluminium use in solar collectors 30 3.2 Wind turbines ................................................................................................................... 32 3.2.1 Description of technologies 32 3.2.2 Current market situation for large wind turbine systems 33 3.2.3 Specific aluminium use in wind turbine systems 36 3.2.4 Technology scenarios for wind turbines 42 3.2.5 Resulting current and future aluminium use in wind turbine systems 45 3.2.6 Cables and wind turbines (excursion) 47 3.3 Photovoltaic sytems ......................................................................................................... 48 3.3.1 Description of technologies 48 3.3.2 Current market situation for photovoltaic systems 48 3.3.3 Specific use of aluminium in photovoltaic systems 51 3.3.4 Technology scenarios for photovoltaic systems 55 3.3.5 Resulting current and future aluminium use in photovoltaic sytems 57 3.4 Solar cookers ................................................................................................................... 60 3.4.1 Description of technologies 60 3.4.2 Current market situation for solar cookers 62 3.4.3 Specific aluminium use in solar cookers 64 3.4.4 Technology scenarios for solar cookers 66 3.4.5 Resulting current and future aluminium use in solar cookers 68 3.4.6 Solar community kitchens (excursion) 69 3.5 Concentrating Solar (Thermal) Power (CSP) ................................................................... 71 3.5.1 Description of technologies 71 3.5.2 Current market situation for CSP 74 3.5.3 Specific aluminium use in CSP technologies 76 3.5.4 Technology scenarios for Concentrated Solar Thermal Power 80 3.5.5 Resulting current and future aluminium use in CSP 83 3.6 Cables used in focus REn technologies: excursion ......................................................... 88

4 Overall potential of aluminium ......................................................................................... 91 4.1 Summary of specific aluminium use in renewable energy systems ................................. 91 4.2 Overall use of aluminium in renewable energy systems .................................................. 94

5 Bibliography .................................................................................................................... 100


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6 Annex ............................................................................................................................... 107 6.1 Detailed results ............................................................................................................... 107


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1 Introduction The addition of renewable energy sources to the global energy mix has emerged as one of the most important changes within the energy sector over the last decade. Today, renewable energy sources in the form of wind, solar, hydropower, geothermal, and biomass provide a significant amount of energy, namely electricity and heat. Renewable energy systems have the potential to play an important part in a low carbon future since they generate energy with very low greenhouse gas emissions and global dependence on fossil resources.

With the demand for energy and in particular renewable energy expected to rise in the future, the study “Aluminium and Renewable Energy Systems – Prospects for the sustainable gen-eration of electricity and heat” was commissioned by the International Aluminium Institute. This was done in order to provide information on the present and future potential use of alu-minium in selected renewable energy systems as well as on energetic and environmental benefits, namely generated energy and CO2 reduction potential, for the reference years 2020, 2030, and 2050.

The following renewable energy systems have been focused on:

- solar thermal collectors for hot water generation and process energy - small and large wind turbines - photovoltaic systems - solar cookers - concentrating solar thermal power plants, based on reflector systems for electricity

generation.

Flat-plate collectors Evacuated tube collectors Wind turbines

Photovoltaic systems Solar cookers CSP

Figure 5: Renewable energy systems in focus

In order to identify the potential of aluminium in renewable energy systems, it is necessary to set out a methodological approach, described in chapter 2, that can be applied to renewable energy systems under consideration. In chapter 3 the individual renewable energy systems are analyzed.

Renewable energy systems chapters are structured similarly: the description of the specific technology (chapter x.x.1), an overview of the current market situation (chapter x.x.2), an analysis of the specific aluminium use (chapter x.x.3) as well as the technology specific ex-pansion scenarios (chapter x.x.4). Every specific technology chapter concludes with results on current and future aluminium use for renewable energy systems for reference years and


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energetic and environmental benefits of renewable energy systems using aluminium (chapter x.x.5)1. Chapter 4 summarizes the overall potential of aluminium.

1 Energetic benefits for solar cookers are not calculated.


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2 Methodological approach The total amount of aluminium that is processed in renewable energy systems as well as the CO2 abatement potential of renewable energy technologies that use aluminium as a key component need to be scientifically estimated. Therefore, it is necessary to set out a meth-odological approach that can be applied to all focus technologies in the same way2.

As aluminium’s role today as well as its future market sales potential in the years 2020, 2030 and 2050 needs to be regarded, it is also necessary to gather information on the present and future deployment of technologies. Thus, time is the underlying factor and therefore the total amount of aluminium used and its CO2 abatement potential needs to be calculated sepa-rately for given effective dates, namely for today, 2020, 2030 and 2050.

Methodological steps

Firstly, to estimate the total amount of aluminium used for REn technologies at a given time T, the specific aluminium use for renewable energy systems needs to be calculated. Therefore, the total amount of aluminium in kg and rated power in kW for technologies must be identified. Various life cycle analysis and studies were examined and interviews held with manufacturers and product designers (see Table 3 and Table 4).

It should be noted that this study cannot cover all sub-types of specific technologies. Thus, reference technologies have to be defined for specific renewable energy systems. There will be three reference technology systems for every single specific renewable energy system:

Al minimum: a reference technology with minimum specific aluminium use, according to LCA studies examined and manufacturer’s information.

Al moderate: a reference technology with moderate specific aluminium use.

Al maximum: a reference technology with maximum specific use of aluminium, if aluminium is used to a broader extent (e.g. aluminium replaces competing materials).

Secondly, the global (installed) capacity of the researched renewable energy systems needs to be identified. Thus various renewable energy expansion scenarios for single tech-nologies are investigated in order to determine the installed capacities today and estimated development paths in the future. Out of these examined scenarios, three expansion scenar-ios are defined:

PATH LOW: pessimistic expansion path for researched renewable energy systems.

PATH BEST ESTIMATE: moderate expansion assumed to model a scenario with high prob-ability.

PATH HIGH: optimistic expansion path for researched renewable energy systems.

2 As discussed later, the application of the methodology deviates slightly in regard of solar thermal col-lectors. For an explanation see chapter 3.1.4.


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Thirdly, the total amount of aluminium used in specific renewable energy systems can be derived by multiplying the expected installed capacity and the specific aluminium use:

Total amount of aluminium used in Renewable Energy System

= Global installed capacity * Specific aluminium use

This study will determine total amounts of aluminium by combining these pathways to the scenarios according to Table 2. For example, the total amounts of aluminium for a given time for SCENARIO BEST ESTIMATE will be calculated by multiplying a moderate specific alu-minium use for the reference technology (Al moderate) with minimal moderate installed ca-pacity estimate (= PATH BEST ESTIMATE) for a certain reference year.

Table 2: Scenario definition3

Scenario Specific aluminium use Technology Diffusion scenario

SCENARIO LOW Al minimum PATH LOW

SCENARIO BEST ESTIMATE Minus Al minimum PATH BEST ESTIMATE

SCENARIO BEST ESTIMATE Al moderate PATH BEST ESTIMATE

SCENARIO BEST ESTIMATE Plus Al maximum PATH BEST ESTIMATE

SCENARIO HIGH Al maximum PATH HIGH

Finally, in order to calculate CO2 abatement potential of renewable energy systems in which aluminium is used full load hours for those technologies and a technology-specific substitute factor need to be defined. This substitution factor determines the average CO2 mitigated per kWh of final energy supplied. Technology specific definitions are indicated in the technology chapters.

According to the three paths (LOW, BEST ESTIMATE, HIGH), CO2 abatement potentials for every single renewable energy systems will be calculated for the reference years4.

3 Colors for scenarios will be used throughout the text in order to enhance readability. 4 Explanation on chosen CO2 substitution factors for renewable energy technologies is given in spe-cific technology chapters.


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Table 3: Technology scenarios examined

Scenarios examined

EUROPEAN PHOTOVOLTAIC INDUSTRY ASSOCIATION, EPIA (ed.) (2007): Solar Generation IV – 2007: So-lar electricity for over one billion people and two million jobs by 2020. Amsterdam, The Netherlands.

EUROPEAN WIND ASSOCIATION, EWEA (ed.) (2009): The economics of wind. Brussels, Belgium.

GLOBAL WIND ENERGY COUNCIL, GWEC/GREENPEACE (ed.) (2008): Global Wind Energy Outlook 2008. Brussels, Belgium/Amsterdam, The Netherlands.

GREENPEACE (2009): Sauberer Wüstenstrom: Globaler Ausblick auf die Entwicklung solarthermischer Kraftwerke 2009. Amsterdam, The Netherlands.

GREENPEACE (ed.) (2007): Solar Generation IV – 2007: Solar electricity for over one billion people and two million jobs by 2020. Amsterdam, The Netherlands.

GREENPEACE (ed.) (2008): Energy [r]evolution: a sustainable global energy outlook. Amsterdam, The Netherlands.

IEA (ed.) (2008a): Energy Technology Perspectives 2008 – Scenarios & Strategies to 2050. Paris, France.

MAJOR ECONOMIES FORUM, MEF (ed.) (2009): Technology Action Plan: Solar Energy, Report to the Major Economies Forum on Energy and Climate. Washington D.C., USA.

PETER, S. / LEHMANN, H. (2007): Renewable Energy Outlook: Energy Watch Group Global Renewable Energy Scenarios. Markkleeberg, Germany.

SHELL (ed.) (2008): Shell Energy scenarios to 2050. The Hague. The Netherlands.

UMWELTBUNDESAMT (ed.) (2007): Zukunftsmarkt solarthermische Stromerzeugung. Dessau, Germany.

VIEBAHN, P. (2008): NEEDS - Final report on technical data, costs, and life cycle inventories of solar thermal power plants. Stuttgart, Germany.

WEIß, W. /BERGMANN, I./STELZER, G. (2009): Solar Heat Worldwide: Markets and contribution to the energy supply 2007. Gleisdorf, Austria.

WORLD ECONOMIC FORUM (ed.) (2009): Task Force on Low-Carbon Prosperity: Recommendations Oc-tober 2009. Geneva, Switzerland.


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Table 4: LCAs examined (selection)

LCAs examined

EUROPEAN COMMISSION (ed.) (2009): Environmental and ecological life cycle inventories for present and future power systems in Europe (ECLIPSE): Life Cycle Inventories. Brussels, Belgium.

JUNGBLUTH, N. (2009): Ecoinvent - Teil XII: Photovoltaics. Dübendorf, Switzerland.

NEW ENERGY EXTERNALITIES DEVELOPMENTS FOR SUSTAINABILITY, NEEDS (ed.) (2009): Life Cycle Inventory Database. -,-.

JUNGBLUTH, N. (2007): Ecoinvent -Teil XI: Solarkollektoranlagen. Dübendorf, Switzerland.

BAUER, B. / BAUER, C. (2007): Ecoinvent - Teil XIII: Windkraft. Villingen, Switzerland.

EUROPEAN COMMISSION (ed.) (2009): Environmental and ecological life cycle inventories for present and future power systems in Europe (ECLIPSE): Life Cycle Inventories. Brussels, Belgium.

VESTAS (2006a): Life cycle assessment of electricity produced from onshore sited wind power plants based on Vestas V82

VESTAS (2006b): Life cycle assessment of offshore and onshore wind power plants based on Vestas V90

ELSAM ENGENEERING (2004): Life Cycle Assessment of offshore and onshore sited wind farms. Fredericia, Denmark.

BAUER, B. / BAUER, C. (2007): Ecoinvent - Teil XIII: Windkraft. Villingen, Switzerland.

DONG ENERGY (ed.) (2008): NEEDS - Final report on offshore wind technology. Hamburg, Germany.

ANGERER, G./ERDMANN, L./MARSCHEIDER-WEIDEMANN, F./SCHARP, M./LÜLLMANN, A./ HANDKE, V./ MARWEDE, M. (2009): Rohstoffe für Zukunftstechnologien: Einfluss des branchenspezifischen Roh-stoffbedarfs in rohstoffintensiven Zukunftstechnologien auf die zukünftige Rohstoffnachfrage. Karlsruhe, Germany.

LEHMANN, H./REETZ, T./ROEWER, S./LIEDTKE, C. (2008): Ökologische Chancen und Risiken großtech-nisch angelegter solarthermischer Kraftwerke. Wuppertal, Germany.

VIEBAHN, P. (2004) :SOKRATES-Projekt - Solarthermische Kraftwerkstechnologie für den Schutz des Erdklimas. Stuttgart, Germany.


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3 Aluminium in individual renewable energy systems This study will focus on the following renewable energy systems which are examined in detail in the following chapters:

- solar thermal collectors for hot water generation and process energy (chapter 3.1) - small and large wind turbines (chapter 3.2) - photovoltaic systems (chapter 3.3) - solar cookers (chapter 3.4) - concentrating solar thermal power plants, based on reflector systems for electricity

generation (chapter 3.5).

3.1 Solar thermal collectors for hot water generation and process energy

Solar thermal collectors transform sun rays into thermal energy. The resulting heat is mainly used for hot water generation, space heating, process heat and the generation of electricity. Depending on the desired level of temperature and further criteria (e.g. available space, sea-sonal climate fluctuations), different technologies are employed.

3.1.1 Description of technologies

Unglazed plastic collectors are basic solar plastic absorbers without coping that are assem-bled simply (see Figure 6) and provide low cost heat. Concerning temperature, the range of use is between 20 and 40°Celsius (stagnation temperature: approx. 90°Celsius; maximum temperature to be reached if no heat is conducted by the solar thermal collector). Unglazed plastic collectors are predominantly used for hay drying and public bath heating. For the lat-ter the circulation of the filter is completed by a collector field. For hay drying the air flow is di-rected through the absorber and thereafter into the hay storage facility.

Figure 6: Unglazed solar thermal collector made of plastic (example)

Flat-plate collectors have a glass coping (see Figure 7). They warm up the heat transfer me-dium within a range of use of 30 up to 100°C (stagnation temperature: approx. 200°C). In comparison to unglazed collectors, the higher level of temperature is due to the reduction of convective and radiative heat transfer losses by the glass coping. Flat-plate collectors are used for hot water generation and space heating.


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Figure 7: Example of a flat-plate solar thermal collector5

In evacuated tube collectors the absorber plate is located within an air-evacuated glass tube. Therefore, convective and conductive losses of heat are suppressed (see Figure 8). The temperature of the heat carrying fluid is between 40 and 150°C (stagnation temperature: approx. 300°C). The radiation received in evacuated tube collectors can be exploited to a higher degree compared to flat-plate collectors.

Figure 8: Principle of an evacuated tube collector with heat pipe; view from top6

It must be noted that evacuated tube collectors appear in many different forms: a) systems with or without a reflector shield depending on the absorber characteristics, b) systems with a (manifold) casing or an on-top water tank, and c) mixed variations of a) and b).

Figure 9: Evacuated tube collector with (manifold) casing; without reflector shield and without water tank7

5 Source: Elfsecsolar. 6 Source: Quaschning (2004): Solar thermal water heating: Technology Fundamentals. In: http://www.jxj.com/magsandj/rew/index.html , 02/2004: pp. 95-99.


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Figure 10: Evacuated tube collector with water tank and reflector shield8

3.1.2 Current market situation for solar thermal collectors

Current solar thermal collectors for hot water generation and process heat are unglazed col-lectors, flat plate collectors, and evacuated tube collectors. As shown by Solar Heat World-wide report, which was prepared within the framework of the Solar Heating and Cooling Pro-gramme (SHC) of the International Energy Agency (IEA), at the end of 2007 the solar ther-mal collector capacity in operation worldwide was approximately 147 GWth

9,10. This corre-sponds to about 210 million square meters of collector panels installed. The Renewables Global Status Report supports the overall Solar Heat Worldwide figure of 147 GWth. It further estimates that existing solar hot water and heating capacity has increased by 15 percent in 2008 and has doubled in capacity compared to 200411.

Due to the fact that the Solar Heat Worldwide report fully concentrates on solar thermal col-lectors, including their spatial distribution and technical differences, it illustrates the current market situation in depth. Consequently, its figures are taken as reference for today’s in-stalled solar thermal collector capacity.

Installed capacity by technology

The distribution of worldwide capacity in operation varies widely by collector type: Evacuated tube collectors have the biggest market share, namely 50%, followed by flat plate collectors at 33% and unglazed collectors that have a share of 17%. The total capacity in 2007 is di-vided into 46 GWth glazed flat-plate collectors, 74 GWth evacuated tube collectors and 25 GWth unglazed collectors (see Figure 11)12.

7 Source: Penn Solar Supply. 8 Kingeagle Solar Energy Industry Co., Ltd. 9 Weiß et al. (2009): p. 15. 10 GWth = Gigawatt thermal. 11 Ren21 (2009): p. 13. 12 ibd.


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Figure 11: Installed capacity of solar thermal solar collector types in GW (Source: Solar Heat World-wide 2009)

In 2007 evacuated tube collectors were installed on an area encompassing 106 million square meters. Flat-plate collectors covered 66 million square meters and unglazed collec-tors 36 million square meters (see Figure 12).

Figure 12: Installed capacity of solar thermal solar collector types in million square meters (Source: Solar Heat Worldwide 2009)

Installed capacity by regions

Concerning existing capacity China is the world leader with 67% of existing global capacity (see Figure 13). China is followed by the European Union, which has a 12% share. The German share needs to be highlighted as solar hot water systems set record growth in 2008, with over 200’000 systems installed for an increase of 1.5 GWth in capacity. Spain also saw rapid growth while the rest of Europe, besides Germany, added about 0.5 GWth of new ca-pacity. Among developing countries Brazil, India, Mexico, Morocco, Tunisia, and others saw an acceleration of solar hot water installations13.

13 Ren21 (2009): p. 13.

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Figure 13: Share of solar hot water/heating capacity existing, Top 10 countries, 2007 (Source: Renew-able Energy Policy Network for the 21st century: Renewables Global Status Report (Update): 13)

Growing markets and market sales potentials for solar thermal collector technologies are to be found in China, the European Union, Brazil and India (see Table 5). Besides China being the world leader, concerning existing capacity, it is also the fastest growing market for solar thermal collector systems. There 16 GWth were added in 2007 alone or an existing capacity growth of 19%. The European Union added 1.9 GWth or 12%, Brazil 0.3 GWth or 12% and In-dia 0.2 GWth or 13%. The biggest market in the future will be China according to these fig-ures.

Table 5: Solar Hot Water Installed Capacity existing and added 2007

Additions 2007

in GW

Existing 2007

in GW Growth rate 2007 in %

China 16.0 84.0 19 %

European Union 1.9 15.5 12 %

Turkey 0.7 21.0 3 %

Japan 0.1 4.9 2 %

Israel 0.1 3.5 3 %

Brazil 0.3 2.5 12 %

USA 0.1 1.7 5 %

Australia 0.1 1.2 8 %

India 0.2 1.5 13 %

Others 0.5 3.6 14 %

World total 20.0 126.0 19 %

Although China is the biggest solar thermal collector producer and at the same time biggest market in the world, installations of solar hot water systems per capita are still quite low com-

China67%

European Union12%

Turkey6%

Japan4%

Israel3%

Brazil2%

Others6%


21

pared to other countries, meaning there remains a huge market sales potential in the re-gion14.

The United States is another promising market outside Europe; still small but with a high po-tential for growth. According to the US Solar Energy Industries Association, the US solar thermal collector market grew by 50% in 2008 reaching some 229’000 m² of collector area, or around 160 megawatts thermal (MWth)

15.

Key manufacturers and market actors

Figure 14 shows that annual sales have been growing steadily in recent years. On a global scale the solar thermal market is dominated by China, which had a 75% share of global sales in 2008 and estimated 19’000 megawatts (MW) of annual sales. Germany increased sales from 672 MW to 1’334 MW and had the second highest sales with 5%. The US had 922 MW or 4%, Turkey 3% and Australia 2% with no other country having more than 1%. Although Japan has very high solar PV sales, its sales in solar thermal collector systems are insignifi-cant16.

Figure 14: Annual sales 2000-2008 in MW (Source: ABS Renewable Energy Database)

China has a sophisticated commercial solar thermal collector industry with innumerable fac-tories manufacturing and selling solar systems. The products in China consist mainly of three types: flat-plate and evacuated tube with and without storage tank.

From a global perspective, China is strongly competing with the European solar thermal col-lector industry in the global market. Although Chinese technology is currently of lower quality compared to European technology, it demonstrates a rapid development and is expected

14 Junfeng/ Runqing (2005): pp. 25-27. 15 Solar Energy Industries Association (2009): p. 8. 16 ABS Energy Research (2010).

79 10

1213

15

1820

25

0

5

10

15

20

25

30

2000 2001 2002 2003 2004 2005 2006 2007 2008

in GW


22

that in future Chinese solar-thermal collector systems will be as reliable as the European ones albeit available at lower cost17.

In order to identify key manufacturers, technologies (flat-plate collectors and evacuated tube collectors) need to be distinguished18. At first, flat-plate technology is focused on.

Flat-plate collectors

Among the top solar thermal manufacturers stands Austria’s GREENoneTEC. Annual pro-duction capacity from its eight lines was 1’100’000 m² in 2008. Another key solar thermal manufacturer is TiSUN, also based from Austria. In 2007, TiSUN’s annual production capac-ity reached up to 150’000 m² of collector surface.

While GREENoneTEC and TiSun are specialized in solar thermal technology, a significant market force comes from a group of industrial companies which already supply a range of (renewable) energy solutions, such as condensing boilers, heat pumps and solar PV.

Among the largest of these heating technology companies is Viessmann, one of the world’s largest solar thermal suppliers. Its annual sales of solar thermal collector systems reach 500’000 m².

Bosch Thermotechnology has also expanded its global production capacity for solar collec-tors from 250’000 to 350’000 units annually, equivalent to some 800’000 m² of collector sur-face area.

Schüco International KG from Germany is a leading European building envelope specialist that develops and markets aluminium and steel product solutions. Experience in aluminium fabrication and building integration has been used to construct solar collectors made from an aluminium frame and rear panel. The company has an annual production capacity of some 400’000 solar collectors, equivalent to over 1’000’000 m².

A number of other major players in the solar thermal market are based outside of Europe, among them Turkey’s Ezinc. One of the major manufacturers of solar thermal components, Ezinc solar collector production capacity has reached 400’000 m².

Other major manufacturers are Rheem of Australia, and Solahart, a subsidiary of Rheem, Genersys plc and Solar Twin Ltd of the UK, Spain’s Acciona Energy and Ibersolar Energía, S.A, Enerworks from Canada and Soletrol, based in Brazil, as well as the Israeli firm Nimrod.


It has been estimated that there are approximately 5’000 manufacturers of evacuated tube collectors worldwide, a sector which is dominated by Chinese companies19.

Himin Solar Energy Group is the world’s largest manufacturer of solar thermal products with more than 2 million m² of absorber area annually.

Another Chinese based company, Haining Baoguang Heat Collection Tubes Co., Ltd, has more than 30 automatic production lines. It has the capacity to produce more than 10’000’000 tubes annually.

17 European Commission (2007): p. 4. 18 Appleyard (2009): pp. 4-12. 19 Appleyard (2009): pp. 4-12.


23

Beijing Sunda Solar Energy Technology Co., Ltd. is another Chinese manufacturer of evacu-ated tube solar collectors. Jointly founded by Daimler-Benz Aerospace (DASA) and SUNPU in 1995, Sunda has been active in the European market for over 12 years and established a subsidiary in Germany in 1997. The subsidiary followed the 1996 opening of a manufacturing plant located in Sunhe, Hebei Province, near Beijing which has a production facility of more than 500’000 tubes per year. More than 60% of the company’s products are sold overseas.

Alongside major solar players such as GREENoneTEC and Viessmann Werke, the largest assemblers for evacuated tube collectors in Europe are Germany’s Ritter Solar and King-span Thermomax of the UK.

3.1.3 Specific aluminium use in solar thermal collectors

The current specific use of aluminium is identified for both reference technologies (flat-plate and evacuated tube collectors) separately.


Flat-plate collectors consist primarily of the following key components: absorber, frame, and casing (see Figure 15). In those, different materials can be used. Materials used in absorbers are copper, aluminium and steel. Frames and casings are mostly made of aluminium and steel; to a marginal extent wood is used.

As the reference for flat-plate collectors, a typical product has been chosen20.

Figure 15: Flat-plate collector and main components21

The reference flat-plate collector has a gross area of 3.12 m² and an absorber area of 2.75 m² with an overall weight of 52 kg. A detailed overview of aluminium use is given in Table 6.

The absorber consists of 4.9 kg copper with no aluminium to be found; a 0.2 mm thick cop-per sheet is used22. The frame contains around 6 kg aluminium (1.8 mm thick aluminium sheet). The casing is made of 3.8 kg aluminium (0.5 mm thick aluminium sheet). Aluminium, in frames and casings, is predominantly used because the material is lighter which is prefer-

20 Interview with Mr Cabarrubia, director of production, Soltop Schuppisser AG, 29 April 2010. 21 Source: Skyflair. 22 Figures are rounded throughout the text in order to enhance readability.


24

able for installation23. For the balance of plant (BOP) only the water heat storage is regarded as it is the main component of BOP. According to experts24, the average water heat storage with a 200 liter capacity, an integrated container and a heat exchanger consists of steel (St 37) and chromium-nickel-steel weighing 170 kg. The only component that contains alumin-ium is an aluminium foil for heat containment25.

In total around 9.8 kg overall weight or around 3.1 kg per m² can be found in this reference object. This is the moderate amount of aluminium to be found (Al moderate).

Additional aluminium could be used in the absorber component. Aluminium is likely to re-place copper, if prices for copper increase steadily26. Studies on materials used in absorbers support the trend of increasing aluminium use in absorbers27. Furthermore, in order to have the same conductivity, aluminium needs to be thicker28. Out of 289 systems analyzed 34 per-cent apply aluminium absorbers; 53 percent use copper and 13 percent other materials (e.g. glass, steel etc.) (see Figure 16)29.

In the heat storage, additional aluminium use is not very likely as steel is easier to process, especially for welding, and is cheaper30. Aluminium also corrodes more quickly than steel.

Figure 16: Materials used in flat plate absorbers

In the reference technology 0.2 mm thick copper, totalling 4.9 kg, is used. If aluminium re-places copper in this component, it has to be 0.5 mm thick in order to have the same thermal conductivity characteristics as copper31, resulting in 3.7 kg aluminium per absorber. If alumin-ium is used in an absorber as an alternative material to copper the total weight of aluminium will then be 13.5 kg, which is equal to 4.3 kg/m² (Al maximum) (see Table 6).

If aluminium is only used to a minimal extent (e.g. absorber made of copper, casing and frame made of wood), it is assumed that 0.1 kg aluminium is used per square meter (e.g. screws, bolts etc.) (Al minimum).

23 Interview with Mr Cabarrubia, director of production, Soltop Schuppisser AG, 29 April 2010. 24 Interview with Mr Hoffmann, Jenni Energietechnik, 6 July 2010. 25 Interview with Bernd Sitzmann, Consolar AG, 13. July 2010. 26 ibd. 27 Meyer (2009): pp. 42-44. 28 Interview with Mr Thole, Schüco International, February 2010. 29 Becker (2010): pp. 67 - 83. 30 Interview with Mr Hoffmann, Jenni Energietechnik, 6 July 2010. 31 Personal communication with Mr Thole, Schüco International, February 2010.

Aluminium34%

Copper53%

Others13%


25

Table 6: Use of aluminium in the flat-plate solar thermal collectors: per component (in kg) and in total (in kg per square meter)32

Al minimum Al moderate Al maximum

Absorber - 0.0 kg 3.71 kg

Frame - 5.95 kg 5.95 kg

(Manifold) Casing - 3.8 kg 3.8 kg

Balance of plant - 0.0 kg 0.0 kg

Total in kg - 9.75 kg33 13.46 kg

Total in kg/m²34 0.1kg/m² 3.1 kg/m² 4.3 kg/m²

Evacuated tube solar thermal collectors

A common, market-available evacuated tube collector without a water tank and without a re-flector shield serves as a basic reference system (see Figure 17). Main components are ab-sorber, frame, heat pipes, header pipe and (manifold) casing. To take into account the whole spectrum of this technology, the components water tank and reflector shield are additionally included in analysis for estimates of Al maximum.

The basic reference technology consists of 30 tubes, each with a tube height of 1’800 mm and 47 mm diameter. The total absorber area is 2.4 m², the gross area is 4.36 m². Its overall weight is 94.8 kg.

Absorbers consist mainly of aluminium or copper. In this reference technology, 0.2 mm thick aluminium fins are used, which total 1.3 kg aluminium within the absorbers. Aluminium is used less frequently than copper, but will be used more widely in the future35.

The frame is made of a 1.5 mm thick stainless steel sheet (8.1 kg), but can easily be re-placed by aluminium36. Both aluminium and stainless steel are easily available in local mar-kets and possess good potential for being used in solar water heating. Aluminium however has a distinctive advantage over steel as aluminium is lighter37. The (conservative) estimate for the replacement potential of aluminium is 2.8 kg, if 1.5 mm thick aluminium is used in-stead of a 1.5 mm thick steel sheet.

32 Colors indicate: yellow: moderate amount of aluminium used; green: maximum amount of aluminium used, if aluminium replaces other materials in components; red: minimal amount of aluminium used. 33 Interview with Mr Cabarrubia, director of production, Soltop Schuppisser AG, 29 April 2010. 34 Related to gross area (3.12m²). 35 Bärbel (2008): pp. 68-77. 36 Interview with Mr Roinson, Europe Managing Director, Apricus Solar, 11 June 2010 at Intersolar Fair Munich. 37 Asif, M. (2007): pp. 337-346.


26

Figure 17: Evacuated tube collector: basic reference technology38

The (manifold) casing can be made of steel but here it is made of aluminium (2.6 kg alumin-ium). Header pipe in the reference technology consists of copper (1.4 kg). As aluminium is also used for header pipes the replacement potential for aluminium can be estimated to ac-count for 0.4 kg per header pipe (conservative estimate if aluminium replaces copper, as-suming only equal material thickness).

Heat pipes are made of 0.7 mm thick copper sheet in the reference technology (0.3 kg), but can be replaced by aluminium (0.12 kg).

Systems with water tanks are very common in China and developing countries. According to experts from Chinese manufacturers, water tanks consist of an inner and outer tank and are mostly made of steel to prevent corrosion and because it is cheaper39. In water tanks stainless steel can be replaced by aluminium. But it is recommended to only replace the steel in the outer tank as the inner tank material is permanently in contact with water40. The refer-ence technology is a Sunstar 200 liter water tank made of 1.2 mm thick steel. If aluminium replaces this competing material, 4.2 kg aluminium could be processed, additionally.

If a shield reflector is also used the material might be aluminium. The aluminium use for a reference reflector shield41 is assumed to be 3.9 kg42. It is assumed that the average solar thermal collector needs a reflector that weighs 1.8 kg, resulting in 3.9 kg of extra aluminium use (see Table 7).

38 Source: Apricus. 39 Interview with Ms Qiu, Sales manager, Hejiasun, 11 June 2010 at Intersolar Fair Munich;Interview with Mr Horace, Trade Department, Sangle Solar, 11 June 2010 at Intersolar Fair Munich; Interviwe with Mr Xu, Sales Manager, Sidite Solar Water Heater, 11 June 2010 at Intersolar Fair Munich. 40 Interview with Mr Vasiliadis, Export Department, Nobel Solar Innovations, 11 June2010 at Intersolar Fair Munich. 41 Reference technology Greenonetec VRK 14: Double-ply reflector shield made of 0.3mm thick alu-minium sheet, gross area: 2.57m², 7.47kg aluminium overall. Interview with Mr Kohlenbein, Sales, Greenonetec, 14 June 2010 and Information from Mr Glombitza, Key Account Manager Deutschland, Greenonetec, 15 June 2010. 42 Calculations: 1) Aluminium demand for reflector shield in reference technology Greenonetec VRK 14: AL demand per m²: 0.3 mm*2,7 g/cm³*2 (double-ply) = 1.62 kg/m²; aluminium demand in kg: 1.62 kg/m²*2.57 m² = 4.16 kg. 2) Aluminium demand carried over from VRK 14 to study’s reference tech-nology: 1.62 kg/m² * 4.36 m² (gross area of study’s gross area) = 3.89 kg.


27

Table 7: Use of aluminium in evacuated tube solar thermal collectors: per component (in kg) and in to-tal in kg/m²


Absorber - 1.30 kg 1.30 kg

Frame - 0.0 kg 2.79 kg

(manifold) casing - 2.64 kg 2.64 kg

Header pipe - 0.0 kg 0.42 kg

Balance of

plant

Water tank - 0.0 kg 4.21 kg

Reflector - 0.0 kg 7.06 kg

Heat pipes - 0.0 kg 0.12 kg

Total in kg - 3.94 kg 18.54 kg

Total in kg/m²43 0.1 kg/m² 0.9 kg/m² 4.3 kg/m²

The basic reference technology without a reflector shield and without a water tank contains an overall aluminium specific weight of 3.9 kg of aluminium or 0.9 kg/m² aluminium (Al mod-erate). If the replacement potential of aluminium is fully tapped by utilizing aluminium in the frame, reflector, heat pipe and water tank, 18.5 kg or 4.3 kg/m² of aluminium are processed (Al maximum). If aluminium is only used to a minimal extent it is assumed that 0.1 kg/m² aluminium is used (e.g. screws, bolts etc.) (Al minimum).

To convert the specific aluminium use per m2 into kg/kW, a conversion factor is needed. As figures for specific aluminium use in solar thermal collectors are given in kg/m² and not in kg/kW, figures need to be converted to calculate the global aluminium use for installed tech-nologies. Installed solar thermal systems are measured in terms of collector area (square meters) rather than in terms of installed capacity. In 2004 the International Energy Agency’s Solar Heating and Cooling Programme (IEA SHC) and several major solar thermal trade as-sociations agreed on a conversion factor representing a globally averaged yield factor. Ac-cordingly, the installed capacity [kWth] shall be calculated by multiplying the solar collector area [m²] by the conversion factor 0.7 [kWth/m²]. This factor shall be used for all types of solar thermal collectors.

3.1.4 Technology scenarios for solar thermal collectors

For the determination of the future development of solar thermal collectors, different technol-ogy scenarios were examined (see Figure 18).

43 Related to gross area (4.36 m²).


28

Figure 18: Solar thermal collector scenarios: Installed capacity in GW today, 2020, 2030, 2050

To show the course that the development of solar thermal collectors will take an up-per/maximum and lower/minimum path boundary for expansion scenarios has to be defined, starting at 147 GWth today. PATH LOW is orientated along the lowest figures for the refer-ence years (here: Greenpeace (2008), low scenario). This scenario assumes low progress only (business as usual scenario). PATH HIGH reclines to MEF (2008), high figures for 2020 and 2030 and to Greenpeace (2008), high for reference year 2050). This scenario is based on a best policy approach, assuming dynamically rising energy prices and an increased im-plementation of collectors worldwide. PATH BEST ESTIMATE shows an alternative path of expansion, based on own assumptions:

Between 2004 and 2007 the installed capacity of solar thermal collectors increased by ap-proximately 50%. Thus, an increase of approximately 14.5% per year occurs. The Renew-ables Global Status Report supports this assumption as it states an annual growth rate of 15 % for the years 2007 to 200844.

Assuming that this trend persists, the hypothesis concerning a PATH BEST ESTIMATE is that an annual increase of around 15% will be in effect until 2020. From 2021, as the market for solar thermal collectors will become more saturated, increase will assumingly slow down to an annual rate of 10% until 2030. From 2031 to 2040, the rate drops to an annual rate of 8%, from 2041 until 2050 an annual rate of 5% comes into effect. The three PATHS are out-lined in Figure 19.

44 Ren21 (2009): p. 13.

'0

2'000

4'000

6'000

8'000

10'000

12'000

14'000

today 2020 2030 2040 2050

in GW

Greenpeace (2008), highGreenpeace (2008), lowPeter/Lehmann (2007), highPeter/Lehmann (2007), lowMEF (2009), high

MEF (2009), low

Shell (2008)


29

Figure 19: Solar collector development in PATH LOW, PATH BEST ESTIMATE, PATH HIGH

As for the share of solar collector technologies in the future, market shares are assumed to be constant for all reference years because no clear indication for variation in distribution of market share could be found during analysis.

Table 8: Figures used for calculations

Scenarios Defined specific aluminium use Defined technology expansion PATHs



SCENARIO LOW 0.1 kg/m² 0.1 kg/m² 2020: 360 GW 2030: 640 GW

2050: 1’200 GW

SCENARIO BEST ESTIMATE 3.1 kg/m² 0.9 kg/m² 2020: 852 GW 2030: 2’210 GW 2050: 7’770 GW

SCENARIO HIGH 4.3 kg/m² 4.3 kg/m² 2020: 3’000 GW 2030: 6’000 GW 2050: 13’680 GW

NOTE: As figures for specific aluminium use are given in kg/m² and not in kg/kW, figures need to be converted to calculate the global aluminium use for installed technologies. Therefore, calculation is as following: Step 1: Figure from scenario in GW * 1’000’000 / 0,7 kW/m² = Total area installed. Step 2: Total installed area * market share in percent of sub-technology = Total area installed of sub-technology. Step 3: Total area installed of sub-technology * specific aluminium use in kg/m² = Total amount of AL used for technology

Based on these capacity developments, heat generation and CO2 mitigation by solar collec-tors can be calculated. In order to do this the capacities have to be multiplied with full-load hours. A full-load hour is an hour in which a renewable energy technology produces at full capacity. 850 h/a for solar thermal collectors are assumed as a global average (Source: per-sonal contact information with regard to newest IPPC study; will be published end 2010/beginning 2011).

'0

5'000

10'000

15'000

today 2020 2030 2040 2050

in GW

Path HIGH

Path BEST ESTIMATE

Path LOW


30

Table 9: Heat generated by solar thermal collectors (in TWh, rounded)

in TWh 2020 2030 2050

SCENARIO LOW 300 540 1‘000

SCENARIO BEST ESTIMATE 700 1‘900 6‘600

SCENARIO HIGH 2‘600 5‘100 11‘600

The CO2 abatement potential for solar thermal collectors can be determined by multiplying energy production in TWh with a CO2 substitution factor. According to the German Federal Ministry of Environment, a substitution factor of 0.218 kg CO2/kWh is assumed for Germany where mainly gas and oil and to a lesser extent hard coal and lignite are replaced45. As no global substitution factor exists, it is assumed that the primary energy mix in other countries relies on oil to a broader extent. As oil has a higher CO2 emission factor as gas for example, the substitution factor in this study is assumed to be 0.3 kg CO2/kWh.

Results are shown in Table 10. In SCENARIO HIGH 3’500 Mt would be saved in 2050. Even in SCENARIO BEST ESTIMATE 2’000 Mt would be saved by solar thermal collectors. To compare, in 2007 28’962 Mt of CO2 have been emitted worldwide46.

Table 10: CO2 abatement potential (in million tons, Mt; rounded)

in Mt CO2 2020 2030 2050

SCENARIO LOW 90 160 310

SCENARIO BEST ESTIMATE 220 560 2‘000

SCENARIO HIGH 800 1‘500 3‘500

3.1.5 Resulting current and future aluminium use in solar collectors

Table 11 shows the cumulative mass of aluminium which is used in solar thermal collectors. By 2050, the total global use of aluminium in solar thermal collectors will vary between ap-proximately 0.14 Mt in the SCENARIO LOW, 16.5 Mt in the SCENARIO BEST ESTIMATE and approximately 69.2 Mt in the SCENARIO HIGH. In the latter, the replacement potential of aluminium is fully tapped and technology development takes place according to the PATH HIGH.

Figures shown in Table 12 indicate the annual total aluminium use per decade. Further, alu-minium use as percentage of annual global aluminium production is calculated.

For example, in SCENARIO BEST ESTIMATE, the annual average aluminium use in the decades 2031-2050 is expected to be around 0.6 Mt for evacuated tube and flat-plate collec-tors; equalling 1.6% of annual aluminium production. SCENARIO BEST ESTIMATE Plus shows, that with moderate assumptions on installation rates but with a maximized use of aluminium, even 4.4% could be realized.

45 Federal Ministry of Environment, Germany (2009a): p. 24. 46 IEA (2009): p. 45.


31

Table 11: Total cumulative use of aluminium for solar collectors (in million tons) in Mt 2020 2030 2050


SCENARIO LOW 0.02 0.03 0.06

SCENARIO BEST ESTIMATE Minus 0.04 0.1 0.37

SCENARIO BEST ESTIMATE 1.26 3.26 11.47

SCENARIO BEST ESTIMATE Plus 1.73 4.48 15.75

SCENARIO HIGH 6.1 12.2 27.7


SCENARIO LOW 0.026 0.046 0.086


SCENARIO BEST ESTIMATE 0.55 1.42 5



Total aluminium use

SCENARIO LOW 0.043 0.076 0.143




SCENARIO HIGH 15.21 30.41 69.23

Table 12: Future annual aluminium use (average of decade) in tons and percentage of global annual aluminium production

Annual Al use in

tons Annual Al use as percentage of annual global Al production 1

SCENARIO LOW

2010-2020 2‘500 0.01 %

2021-2030 3‘300 0.01 %

2031-2050 3‘350 0.01 %


2010-2020 8‘200 0.02 %

2021-2030 17‘800 0.05 %

2031-2050 75‘200 0.21 %


2010-2020 150‘000 0.41 %

2021-2030 287‘000 0.79 %

2031-2050 589‘500 1.62 %


2010-2020 357‘000 1.0 %

2021-2030 762‘000 2.1 %

2031-2050 1‘586‘000 4.4 %

SCENARIO HIGH

2010-2020 1‘446‘000 3.97 %

2021-2030 1‘520‘000 4.18 %

2031-2050 1‘941‘000 5.33 % 1 Aluminium production in 2009 was approximately 36.4 million tons (IAI Statistics 2010).


32

3.2 Wind turbines

Energy from wind is an indirect form of solar energy, and thus can be counted as a renew-able energy resource. Wind energy exists as kinetic energy of moved atmospheric air masses and can be converted into a useful form of energy, namely electricity. Wind turbines can be deployed in all climatic areas, on land (onshore) along the coastline, inland or in mountainous territories as well as at sea (offshore).


The most common way to convert wind energy into wind power is to generate electricity with (small and large) wind turbines. Three different technologies exist: large wind turbines (on-shore and offshore) and small wind turbines. Onshore turbines are wind turbines which are located on solid ground. Offshore wind turbines are installed on marine shelves off the coast (see Figure 20).

Figure 20: top left: wind farm Morbach (Germany) with Vestas V80 (2 MW); top right: small wind tur-bine WES WESpe (5 kW); bottom: offshore wind farm Rodsand I (Denmark), operator: E.ON Sverige47

During the last 20 years, technical development of wind turbines has mostly concentrated on constructing progressively larger systems in order to optimally exploit locations with good wind conditions. This goal has spurred on quick technical development. While the average capacity of installed wind turbines was less than 50 kW in 1987, it increased by nearly a fac-tor of forty to 1.9 MW by mid-2008. The largest systems today have a maximum capacity of 6 MW. The yield of such a plant corresponds to the yearly electricity consumption of up to 5’000 households. As the capacity of turbines increased hub heights and rotor diameters did also.

Many systems use intermediary gears which transform the low rotor speed to the required generator speed of 1’500 revolutions per minute. However, losses of about 2% per stage are attributed to the gears. Additionally the gears are themselves a source of noise emissions.

47 Sources: Vestas, Wes-Energy, E.ON.


33

Gearless systems do not face these problems; however they require specially manufactured and very large multi-pole generators48.

Small wind turbines offer additional potential for using wind energy. So far there is no single definition of small wind turbines. The German law on feed-in from renewable energies (EEG) defines the upper limit for small wind turbines at 30 kW of installed capacity. According to DIN regulation49 the limit for small wind turbines is at a rotor area of 200 m2 (plus additional voltage limit). The Federal Wind Energy Association (BWE) refers to two limitations: 200 m2 and 100 kW of installed power. In addition, some building codes and regulations refer to dif-ferent altitude limits which vary from 10 m to 65 m.

Small wind turbines can be distinguished in horizontal and vertical small wind turbines. The terms horizontal and vertical refer to the arrangement of the axis of rotation. Applications for small wind turbines are mainly in developing and emerging countries, in rural areas to supply the network infrastructure or in decentralized solutions to cover the energy demand.

3.2.2 Current market situation for large wind turbine systems

Installed capacity worldwide

As of the end of 2009 the current global installed capacity of wind turbines is 159.9 gigawatts (GW), nearly half of them being located in Europe (76 GW)50. Another 39 GW are installed in Asia which is almost exactly the capacity of the wind power in North America (38 GW). In the Pacific Region there are actually 2 GW. Another 2 GW are installed in Africa, in the Middle East, in Latin America and in the Caribbean. Figure 21 indicates regional shares of the cur-rent global existing capacities in percent. Markets in Europe, Asia and North America con-tribute most to the current capacity installed.

Figure 21: Installed capacity by regions

Since it is important to know where key markets can be found, regional shares of capacities must be broken down to the country level. In Table 13 country shares of the capacity in GW and percentage shares are shown for Top 10 countries.

48 Federal Ministry of Environment, Germany (2009c): p. 64. 49 DIN EN 61400-2:2007. 50 Global Wind Energy Council (2010): Statistics. / Bundesverband Windenergie e.V. (2010): Statistics.

Asia25%

Africa & Middle East

1%

Europe48%

Latin America & Caribbean

1%

North America

24%

Pacific Region

1%


34

Table 13: Share of wind turbine capacity, Top 10 countries, 200951

Country Installed capacity 2009 in GW Share of capacity 2009 in percent

USA 35.2 22.3 %

Germany 25.8 16.3 %

China 25.1 15.9 %

Spain 19.1 12.1 %

India 10.9 6.9 %

Italy 4.9 3.1 %

France 4.5 2.8 %

UK 4.1 2.6 %

Portugal 3.5 2.2 %

Denmark 3.5 2.2 %

Others 21.4 13.6 %

World total 158 100 %

The US is the undisputed world leader with 35 GW capacity installed, followed by Germany (26 GW), China (25 GW) and Spain (19 GW). These countries account for almost two thirds (or 66%) of the capacity in 2009 (see Figure 22). Other countries follow but lag behind in terms of quantity of the capacities compared to the top four countries.

Figure 22: Share of wind turbine installed capacity 2009 (Source: Global Wind Energy Council (2010): Statistics)

In order to identify growing key markets it is worth taking a look at data that provides informa-tion on development meaning newly installed capacities (see Table 14). The countries which had the highest newly installed capacity in 2009 were China (13 GW), the USA (9.9 GW), Spain (2.5 GW), Germany (1.9 GW) and India with 1.3 GW.

According to the data mentioned, one of the future key markets will be China, which is rich in wind resources. Additionally China has chosen wind power as an important alternative

51 Source: Global Wind Energy Council (2010): Statistics.

USA22%Germany

16%

China16%

Spain12%

Rest of Europe

13% India7%

Others14%


35

source in order to rebalance the energy mix, combat global warming and ensure energy se-curity. Supportive measures have been introduced52.

Concerning the US, increasingly high growth rates for wind turbines will persist because of the existence of the production tax credit and the favourable energy policy environment.

Especially the rapid market development since 2000 has contributed to this increased ex-pansion. The capacity increased in the last eleven years from 10 GW in 1998 to 160 GW 2009. 38 GW of this performance was newly installed in 200953.

Table 14: Wind turbines: Added capacity in 2009

Country Added capacity in 2009 Growth rate 2009 in %

China 13.0 GW 34.7 %

USA 9.9 GW 26.5 %

Spain 2.5 GW 6.6 %

Germany 1.9 GW 5.1 %

India 1.3 GW 3.4 %

Rest of the world 9.5 GW 23.7 %

World Total 37.5 GW 100.0 %

The share of offshore wind farms which are installed on high seas in Europe are expected to be about 4 percent in 201054. The vast majority of these facilities were situated in the North Sea and the Baltic Sea. Twenty new projects in the aforementioned regions are being planned. In the future, however, offshore wind power is expected to gain greater importance.


Currently, the largest market share, of manufacturers of wind turbines, is held by the Danish company Vestas with 19.8 percent55 (see Figure 23). Other large manufacturers are GE Wind from the USA (17 percent), Gamesa from Spain (12 percent), Enercon from Germany (ten percent) and the Indian company Suzlon which has a market share of nine percent. A quarter of the entire wind turbine manufacturer market is constituted by five companies, namely Siemens (Denmark), Sinovel and Gold Wind (both from China), Acciona (Spain) and Nordex (Germany). Each of them has a market share between three and seven percent. Nearly 18 percent fall back on smaller manufacturers with market shares below 3.5 percent.

52 Global Wind Energy Council (2008). 53 Global Wind Energy Council (2010): Statistics. / Bundesverband Windenergie e.V. (2010): Statistics. 54 EWEA (2010): p.9. (Note: Figures on global offshore status not found during research.) 55 BTM Consult Aps (2009).


36

Figure 23: Key market actors (Source: BTM Consult Aps (2009): World market update 2009)

The market for small wind turbines is only a niche market which is actually not developed in such a way that detailed market information is available. According to the American Wind Energy Association 19’000 units of small wind energy turbines were sold in 2008; of which the overwhelming majority were sold in the sector of below 10 kW56.

Table 15 below lists key manufacturers of small wind turbines in the German and interna-tional manufacturers of vertical and horizontal wind turbines. Market information on market shares of these different manufacturers is not available.

Table 15: Selected manufacturers of small wind turbines57

Manufacturer Country

Ampair England

Inno Energy Germany

Nakao Intl USA

Partzsch Germany

Ropatec Italia

Sinuswind Germany

TASSA Germany

VENCO Netherlands

WES Energy Germany

winDual Germany

3.2.3 Specific aluminium use in wind turbine systems

Life cycle assessments (LCA) of ten onshore wind turbines with power ranging from 30 kW to 3 MW and the LCAs of five offshore wind turbines with power ranging from 2 MW to 4.5 MW have been analyzed (see Table 17). To get a significant result LCAs of wind turbines of

56 AWEA 2009. 57 Federal Ministry of Environment, Germany (2009b).

Vestas (Denmark)

19%

Suzlon (India)

9%

Siemens (Germany)

7%

GE Wind (USA)18%

Sinovel (China)

5%

Gamesa (Spain)

11% Enercon (Germany)

10% Acciona (Spain)

4%

others 17%


37

manufacturers which are key market players in the wind energy sector have been examined. Data derived from LCA’s provided by Nordex, Vestas and Enercon is supplemented by the wind turbines data from smaller manufacturers and reference turbines from the different LCA’s of reliable and relevant studies.

LCA’s which have been analysed for this report:

- BAUER, B. / BAUER, C. (2007): ECOINVENT - TEIL XIII: WINDKRAFT. VILLINGEN,

SWITZERLAND.

- ELSAM ENGENEERING (2004): Life Cycle Assessment of offshore and onshore sited

wind farms. Fredericia, Denmark.

- DONG ENERGY (ed.) (2008): NEEDS - Final report on offshore wind technology. Ham-

burg, Germany.

- EUROPEAN COMMISSION (ed.) (2009): Environmental and ecological life cycle invento-

ries for present and future power systems in Europe (ECLIPSE): Life Cycle Invento-

ries. Brussels, Belgium.

- VESTAS (2006a): Life cycle assessment of electricity produced from onshore sited

wind power plants based on Vestas V82-1.65 MW turbines. Randers, Denmark.

- VESTAS (2006b): Life cycle assessment of offshore and onshore wind power plants

based on Vestas V90-3 MW turbines. Randers, Denmark.

Large wind turbines

To make a precise statement, wind turbines were subdivided into their component parts. A common wind turbine consists of a foundation (or basement), a tower, a nacelle and a rotor (see Figure 24). Preconditions for a grid connection are (internal and external) cables and a cable station. Because offshore wind farms need additional transformers, transmission infra-structure and cable stations that switch electricity to the adequate grid the specific aluminium use is higher compared to onshore systems.

The foundation that is embedded underground is mostly made of concrete and steel. The main material used for the tower is steel. The nacelle, which consists of a motor that moves the rotor, consists mainly of copper, iron and steel. The rotor, which actually consists of the hub and blades, usually has three blades that consist of fibreglass.


38

Figure 24: Structure of a wind turbine (Source: Government of New South Wales, Australia)

The material which is predominately used in wind turbines is steel (partly high strength steel) with about 85% of the total material input. Cast iron and fibreglass (especially for the blades) are about 5% of the total material input. Aluminium only plays a subordinate role. There is no significant trend in which aluminium parts can be used in a significantly higher amount. “Ma-terial usage is and will continue to be dominated by steel, but opportunities exist for introduc-ing aluminium or other light weight composites, provided strength and fatigue requirements can be met”58.

The covering of the wind turbine nacelle is mostly made of plastic or steel, but could also be made of aluminium which is already the case in the Enercon wind turbines. The nacelle itself is actually produced with cast iron but could also be made of aluminium. Enercon is the trend-setter using aluminium for nacelles. The nacelle casing of Enercon's E-82 wind turbine, winner of European Aluminium award 2008, is no longer made of glass-fibre reinforced plas-tic (GRP) but aluminium. Enercon expects that other European wind turbine manufactures will also replace the GRP nacelles stepwise. Aluminium is used in the E-82 for four reasons: 1) maximum material recyclability, b) minimum fire risk, c) lightning protection is improved as the nacelle has the function of a Faraday cage and d) the nacelle surface helps cool the na-celle components, therefore extending their operational life span.

During the past 20 years, large wind turbine blades have been fabricated from steel, alumin-ium, and composite materials such as wood, fibreglass, and carbon fibers. For a given blade strength and stiffness, the blade should be as light as possible to minimize inertial and gyro-scopic loads, which contribute to blade fatigue. Blades made from steel and aluminium suf-fers from excessive weight and low fatigue life relative to modern composites. Because of these limitations, during the past 10 years almost all blades have been fabricated from com-posite materials, usually fibreglass. Vestas also used aluminium in older models (Vestas V-82) but stopped the use of aluminium in the newer technology (Vestas V-90) in this compo-nent59. The tower consists mainly of steel which is the basic material for the frame and the exterior shell. Only subordinate parts of the tower like the ladder and the lift can be made from aluminium.60

58 US Department of Energy (2001). 59 National Renewable Energy Laboratory (2001): p.5. 60 Interview with Mr Höhl, Nordex area manager South Germany.


39

Results at a glance:

the aluminium use in wind turbines of different manufacturers varies significantly in the different components;

aluminium is used in tower (especially ladder and lift), rotor (frame) and nacelle (base support and nacelle cover);

only one LCA attests aluminium in the foundation;

an additional transmission (cable station and transformer) is needed for offshore elec-tricity generation;

internal and external cables are treated in an ‘excursion’ (at the end of the chapter).

Small wind turbines

The market for small wind turbines is very small. As mentioned above the total sale of small wind turbines was 19’000 units in 2009. However, the market is increasing at the moment and there will be more potential in the future. But with regard to the components of small wind turbines aluminium use is very low. Only some components share a negligible amount of aluminium. The only components which have potential are rotor blades.

Thus, small wind turbines will not be focussed on due to two reasons: 1) Aluminium use in small wind turbines is negligible and therefore aluminium’s potential is expected to be low in the future. 2) No scientific assumption on the market development of small wind turbines in the future can be made. Thus, small wind systems are not included in the calculations.

Resulting specific aluminium use

For calculation of actual and future aluminium use in wind energy systems, three specific aluminium demands were calculated for on- and offshore systems. Results are indicated in Table 16.

Onshore wind turbines

The minimum aluminium use of the analyzed LCA’s was in the Enercon E-112 wind turbine. With its hub height of 124 meters and a capacity of 4.5 GW the turbine represents little alu-minium usage. For onshore electricity generation there is a specific aluminium use of 0.05 kg/kW (Al minimum). Moderate aluminium with 0.26 kg/kW (Al moderate) is to be found in Vestas V-90 wind turbines. The turbine has a capacity of 3 GW and a hub height of 80 me-ters for offshore use and a height of 105 meters for onshore use. The maximum specific aluminium use is given in the reference turbines of the ECLIPSE LCA’s. There it was sup-posed that the whole nacelle casing is made of aluminium so that a high amount of alumin-ium is needed. Al maximum is 3.53 kg/kW.

Offshore wind turbines

To generate electricity with offshore wind an additional transformer and a cable station to transport the electricity through marine cables to the mainland are needed. On land the elec-tricity then gets transmitted in an amount equal to the transmission from onshore wind tur-bines. Because of the additional need of a transformator and a cable station, which are both


40

partly made of aluminium, an additional specific aluminium factor for offshore wind energy is needed.

Al minimum with 0.26 kg/kW is processed in the Enercon E-112 plus additional components (which is evenly used for on- and offshore application). The moderate specific aluminium use per kWh is 1.06 kg for Vestas V-90 offshore turbine plus additional components (Al moder-ate). The reference turbine from ECLIPSE showed maximum aluminium use with 3.93 kg/kW (Al maximum).

Table 16: Specific aluminium use in wind turbines [in kg/kW]

in kg/kW Al minimum Al moderate Al maximum

Onshore 0.05 0.26 3.53

Offshore 0.26 1.06 3.93


41

Table 17: Life cycle assessments (LCA) of wind turbines examined

Offshore Onshore

[unit] ref. turbine

Eclipse Enercon

E-112 Needs ECOinvent Vestas V90

Nordex N43/600

VestasNordex N50/800

Enercon E-66

ref. turbi-ne Eclipse

Enercon E-112

Vestas V82

Vestas V90

Power 2.5 MW 4.5 MW 2 MW 2 MW 3 MW 600 kW 600 kW

800 kW 1.5 MW 2.5 MW 4.5 MW 1.65 MW

3 MW

Hub height m 80 124 60 80 40 35 50 67 80 124 78 105 Tower kg 2 2‘600 Rotor kg 99 43.3 99 99 500 Nacelle kg 8‘820 127 845 204 1‘850 207 127 8‘820 127 Basement kg 1‘550

Aluminium use turbine:

kg 8‘820 226 1‘595 845 1‘950 204 1‘850 207 226 8‘820 226 3‘100 781

Specific alu-minium use

kg/kW 3.53 0.05 0.80 0.42 0.65 0.34 3.08 0.26 0.15 3.53 0.05 1.88 0.26

Transformator kg Cable station kg Transmission per wind farm

kg 1‘220

Transmission per turbine

kg 418.1 1‘220

Total kg 2013.5 3‘170 Specific alu-minium use transmission offshore

kg/kW 0.4 0.21 0.21 0.4

Total specific aluminium use

kg/kW 3.93 0.26 1.01 1.06

Al max. Al min. Al mod. Al MAX. Al MIN. Al

MED.


42

3.2.4 Technology scenarios for wind turbines

Depending on the year of the studies the projected wind capacity for 2010 in some scenarios has already been surpassed by the actual installed capacity in 2009. This applies particularly to the baseline scenarios which project developments under the current state of the art/ busi-ness-as-usual path as they fade out market incentives and technological innovations. The lowest projected wind energy capacity for 2020 is given by Greenpeace (2008), low scenario and projects 346 GW (see Figure 25).

The scenarios that can be classified as moderate are the GWEC (2008) moderate scenario and Peter/Lehmann (2007), high. All precede an installed wind capacity of around 700 GW. Even the scenario of Peter/Lehmann (2007), low is only slightly below the range (550 GW).

Figure 25: Installed capacity of wind turbines (onshore and offshore) in different technology scenarios

For 2030, the projections of the expansion scenarios clearly diverge, depending on the phi-losophy and assumptions of the scenarios. The two reference scenarios of Greenpeace (2008), low (440 GW) and the GWEC (2008), low are below or around 500 GW. A set of scenarios an installed capacity for wind power between 1’000 and 1’600 GW. The GWEC (2008), high scenario and Peter/Lehmann (2007), high represent the highest expansion stages of wind with about 2’500 GW.

In our definition of the scenarios, we set PATH LOW corresponding to the Greenpeace (2008) low scenario (see Table 18 and Figure 26). PATH BEST ESTIMATE corresponds to Peter/Lehmann (2007), low for 202061, and to MEF (2008), low for reference years 2030 and 2050. PATH HIGH corresponds to GWEC (2008), high scenario for 2020 and 2030, then to MEF (2008), high. The installed wind capacity today is 158 GW, according to most recent figures62.

61 Projections of Peter/Lehmann are very reasonable as they are based on actual global wind condi-tions (wind speed and suitable sites for wind turbines), but are only projected until 2020. 62 Global Wind Energy Council (2010).

'0

'500

1'000

1'500

2'000

2'500

3'000

3'500

today 2020 2030 2040 2050

in GWEWEA (2009)

Peter/Lehmann (2007), high

Peter/Lehmann (2007), low

MEF (2008), low

MEF (2008), high

Greenpeace (2008), low

Greenpeace (2008), high

GWEC (2008), low

GWEC (2008), moderate

GWEC (2008), high


43

Table 18: Wind turbine scenarios: PATH LOW, PATH BEST ESTIMATE, PATH HIGH

Figure 26: Development of wind installed capacity in the scenarios PATH LOW, PATH BEST ESTIMATE, PATH HIGH

For market shares of onshore and offshore, it is assumed that offshore wind turbines in-crease more dynamically than onshore wind (see Figure 27). Today, onshore turbines con-tribute to 97%63. But the technology costs have decreased strongly as well as technical de-velopment and investments in offshore technology increased so that offshore electricity gen-eration will become more and more important in the future. By 2020, offshore wind energy will contribute significantly more. It is estimated that around 15% of wind energy generation will come from offshore. After 2020, “offshore wind development even speeds up, so that – in the end – the onshore/offshore ratio is about two-thirds onshore and one third-offshore wind”64. The share of offshore energy could even rise to 40% by 205065.

63 Peter/Lehmann (2007): p.37. 64 ibd. 65 IFEU estimate.

'0

'500

1'000

1'500

2'000

2'500

3'000

3'500

today 2020 2030 2040 2050

in GW

PATH HIGH

PATH BEST ESTIMATE

PATH LOW

in GW today 2020 2030 2050

PATH LOW 158 346 440 526

PATH BEST ESTIMATE 158 550 1‘000 2‘000

PATH HIGH 158 1‘080 2‘375 3‘500


44

Figure 27: Market share onshore (green) and offshore (orange) wind turbines

Based on the defined capacity development electricity generation and CO2 mitigation of wind systems were calculated. Toward this end different studies were evaluated to derive full-load hours66. We assume full-load hours according to Table 19 which will increase in the next 40 years because of higher hub heights and better developed technologies.

Table 19: Expected full load hours today and in future (worldwide average, rounded)

in h/a 2020 2030 2050

Onshore 2’150 2’300 2’400

Offshore 3’600 3’800 4’200

For generation of electricity from wind energy there will be a range of 820 TWh (SCENARIO LOW) and 2’550 TWh (SCENARIO HIGH) for 2020 and a range of 1’640 TWh and 10’920 TWh for the reference year 2050. By comparison the global electricity generation in 2007 was 19’771 TWh67.

Table 20: Energy production (in TWh, rounded)

in TWh 2020 2030 2050

SCENARIO LOW 820 1‘230 1‘640

SCENARIO BEST ESTIMATE 1‘310 2‘790 6‘240

SCENARIO HIGH 2‘550 6‘640 10‘920

66 Sachverständigenrat Umwelt (2010): p. 51. European Wind Association, EWEA (2009): p. 66. 67 IEA (2009): p. 26.

3%

97%

today

15%

85%

2020

33%

67%

2030

40%

60%

2050


45

For CO2 abatement the factor is actually higher than in the electricity mix because wind en-ergy replaces conventionally produced energy from marginal power plants.

The determination of a global substitution factor for wind energy is not possible within this study because it requires detailed energy economic modelling. In the literature there is no globally calculated substitution factor available. We calculate with a substitution factor of 780 g/kWh68, a factor that was derived for Germany based on an analysis of marginal power plants substituted by wind. As a first-order estimate it seems reasonable to use this factor as it constitutes a combination of hard coal based electricity production as well as gas (com-bined cycle and gas turbine electricity production). These three power plant types are, in many countries worldwide, the medium load technologies which can be technically reduced in power with adequate flexibility and are in a position of the marginal cost merit order cross-ing the demand curve (for a detailed explanation of the merit order, see IFEU (2008): Stein-kohle-Kraftwerk Hamburg-Moorburg und seine Alternativen).

The resulting CO2 abatement of wind turbines is about 230 Mt of CO2. In 2020, the abate-ment potential for SCENARIO HIGH increases to about 2’000 Mt CO2. For 2030 and 2050, in SCENARIO HIGH CO2 abatement will be 5’200 Mt and 8’500 Mt respectively (see Table 21).

Table 21: CO2 abatement potential (in million tons, Mt; rounded)

in Mt CO2 2020 2030 2050

SCENARIO LOW 600 1‘000 1’300

SCENARIO BEST ESTIMATE 1’000 2’200 4’900

SCENARIO HIGH 2’000 5’200 8’500

3.2.5 Resulting current and future aluminium use in wind turbine systems

The SCENARIO BEST ESTIMATE projects a total aluminium use in wind energy systems of 0.2 Mt in 2020, 0.5 Mt in 2030, and 1.2 Mt in 2050 (Table 22). SCENARIO HIGH shows a to-tal aluminium use of 12.9 Mt in 2050. Total maximum aluminium use in 2020 and 2030 could be 3.9 Mt and 8.7 Mt, respectively. In 2020 the SCENARIO LOW indicates only negligible amounts of aluminium used.

Table 22: Total use of aluminium in on- and offshore wind (in million tons)

in million tons 2020 2030 2050

Onshore

SCENARIO LOW 0.015 0.015 0.016




SCENARIO HIGH 3.241 5.617 7.413

Offshore

SCENARIO LOW 0.014 0.038 0.055




68 Klobasa et al. (2009): p. 23.


46

SCENARIO HIGH 0.637 3.080 5.502

Total aluminium use






To get an approximation on the amount of aluminium use the annual aluminium use is calcu-lated (see Table 23).

Table 23: Future annual aluminium use (average of decade) in wind energy system and percentage of global annual aluminium production

Annual Al use

in decade in tons

Annual Al use as percent-age of annual Al produc-

tion1

SCENARIO LOW

2010-2020 1‘980 0.005 %

2021-2030 2‘400 0.007 %

2031-2050 2‘350 0.006 %


2010-2020 3‘600 0.01 %

2021-2030 8‘300 0.02 %

2031-2050 9‘200 0.03 %


2010-2020 16‘500 0.05 %

2021-2030 31‘400 0.09 %

2031-2050 31‘800 0.09 %


2010-2020 141‘486 0.4 %

2021-2030 224‘714 0.6 %

2031-2050 256‘6432 0.7 %

SCENARIO HIGH

2010-2020 331‘800 0.09 %

2021-2030 481‘900 0.13 %

2031-2050 404‘800 0.11 % 1 Aluminium production in 2009 was approximately 36.4 million tons (IAI Statistics 2010).

As can be seen from these figures from all scenarios, the highest market potential of alumin-ium is given in decades 2010-2020 and 2021-2030. Afterwards, due to market saturation and lack of optimal locations with wind potentials, aluminium use will resume at the same level or even decrease.


47

For example, in the SCENARIO BEST ESTIMATE aluminium use is highest from 2021-2030 with around 31’400 tons per year. In this decade, annual aluminium use accounts for ap-proximately 0.09 % of annual aluminium production. Compared to the solar collector estimate this figure is relatively low. With equal installation rates but maximized aluminium use (Al moderate Al Maximum) in SCENARIO BEST ESTIMATE Plus, 0.7% of annual aluminium production could be achieved.

3.2.6 Cables and wind turbines (excursion)

Cables are needed to transport the electricity from the turbines to the electricity grid. In future the importance of offshore wind electricity generation will rise to a share of nearly one third of the total wind capacity in the year 2030. Therefore the distances between the place where the electricity is generated (at sea) and the place where the energy is needed will also rise. With regard to aluminium use it is very interesting to closely follow this development. The use of aluminium for external cables is high and is about one third of the total material use of the cables. Therefore the increasing use of cables (especially marine cables) offers a good po-tential for the aluminium industry. The internal cables can also be produced with aluminium. The producers we spoke to mainly use standard NYM cables with 400 volts. These sorts of cables consist primarily of copper with a plastic casing.


48

3.3 Photovoltaic sytems


Photovoltaic systems (PV) directly convert solar energy into electricity. The basic building block of a PV system is the PV cell, which is a semiconductor device that converts solar en-ergy into direct-current (DC) electricity. PV cells are interconnected to form a PV module. The PV modules combined with a set of additional application-dependent system compo-nents (especially inverters and mounting systems), form a PV system. PV systems are highly modular, i.e. modules can be linked together to provide power ranging from a few watts to tens of MW.

The most common technologies used in photovoltaic cells are based on crystalline silicon and thin film methods. Crystalline silicon has dominated photovoltaic production from the be-ginning. It is widely available, has proven reliability and is scientifically well understood due to it being founded on the knowledge and technology originally developed for the microelectron-ics industry. Crystalline silicon module production starts with the melting of purified silicon then different techniques are applied to produce ingots or ribbons with variable degrees of crystal perfection. Afterwards ingots are shaped into bricks and sliced into thin wafers by wire-sawing. In the case of ribbons wafers are cut from the sheet using a laser. Cut wafers and ribbons are processed into solar cells and interconnected in weather-proof packages.

The two main types of crystalline silicon are: single crystalline silicon (sc-Si) and multi-crystalline (mc-Si). Sc-Si is characterized by atomic layers all oriented in the same direction in a single silicon crystal. High purity crystal implies higher cell efficiencies (maximum effi-ciency: approx. 23%). Multi-crystalline silicon is made from small-area clusters of single-crystalline. The clusters are all oriented in different directions, giving the aesthetic effect of non-homogeneous reflection of the wafer. In fact the borders of cluster areas are a semicon-ductor “defect”, leading to poorer electron transmission and therefore lower cell efficiency (maximum efficiency: approx. 15%). Recently ribbon technology has been developed where wafers, in the form of ribbons, are pulled directly from the silicon without the production of the ingot and the need to cut it in wafers.

Thin films are based on a completely different manufacturing approach: instead of producing an ingot and then cutting it into wafers, thin films are obtained by depositing extremely thin layers of photosensitive materials on a low cost backing such as glass, stainless steel or plastic. The first thin film produced historically was amorphous silicon (a-Si) (efficiency approx. 7%). More recently, other thin film technologies have been developed, i.e. Cadmium Telluride (CdTe, maximum efficiency: 11%) and Copper-Indium-Diselenide (CIS, maximum efficiency: 12%).

Emerging PV technologies are comprised of advanced inorganic thin film technologies (e.g. Si, CIS) as well as organic solar cells.

3.3.2 Current market situation for photovoltaic systems

The global PV market has experienced dynamic growth for more than a decade with an av-erage annual growth rate of up to 40%. The installed PV power capacity has grown from 0.1 GW in 1992 to 14 GW in 2008 whereby in 2008 alone 6 GW were installed69.

69 IEA (2010): p. 9.


49

Four countries have an installed PV capacity of one GW or more: Germany (5.3 GW), Spain (3.4 GW), Japan (2.1 GW) and the US (1.2 GW). These countries account for almost 80% of the total global capacity. Other countries (including Australia, China, France, Greece, India, Italy, Korea and Portugal) are gaining momentum due to new policy and economic support schemes (see Figure 28 and Table 24).

Economies like China and India have become global solar forces in the past decade and will remain important key players in the future. The potential of PV for widespread electricity generation is substantial in Latin America and Africa. These world regions may become very important markets in the mid- to long-term. In Brazil, a leading country in the use of PV for ru-ral electrification70, the market is currently dominated by multinationals with no national manufacturers. However, with the support of the government, the Brazilian Centre for Devel-opment of Solar PV Energy (CB-Solar), created in 2004, has developed a pilot plant to manufacture cost effective PV modules and silicon solar cells at scale71.

Figure 28: Market share of installed capacity

Table 24: Solar PV: Existing and added capacity, 2007

Additions 2008 in GW Existing 2008 in GW Growth rate 2008 in %

Germany 1.5 5.4 27 %

Spain 2.6 3.3 78%

Japan 0.24 1.97 12 %

USA 0.25 0.73 34 %

Other EU 0.4 0.75 53 %

South Korea 0.25 0.35 71 %

Others 0.2 0.45 44 %

As for a technology distribution crystalline modules (sc-Si and mc-Si) represent approxi-mately 87 % of the global annual market today (see Figure 29). Thin films currently account for approximately 12 % of global PV module sales (amorphous (a-Si) and micromorph silicon

70 IEA (2010): p. 15. 71 IEA (2010): p. 16.

Germany36%

China1%

Spain23%

Japan15%USA

8%

South Korea

2%

Others 15%


50

(a-Si/μc-Si), ii) Cadmium-Telluride (CdTe), and iii) Copper-Indium-Diselenide (CIS). Emerg-ing technologies are about to enter the market via niche applications (1%)72. In the future, thin film technology application will increase as prices for silicium rise.

Figure 29: Market shares of PV technologies

Table 25: Key manufacturers of PV systems73

Company Country Production in MW

Suntech China 704

Sharp Japan 595

Q-Cells Germany 551

JA Solar Holdings China 520

Mitsubishi Heavy Japan 421

Kyocera Japan 400

Trina Solar China 399

SunPower Philippines 397

Gintech Taiwan 368

Motech Taiwan 296

Ningbo Solar Electric China 260

Sanyo Japan 260

E-Ton Solar Taiwan 220

Schott Solar Germany 218

Neo Solar Taiwan 201

Bosch Germany 200

Canadian Solar China 200

SolarWorld Germany 200

China Sunergy China 194

First Solar USA 143

72 IEA (2010): p. 7. 73 Compiled from Hirshman (2010): pp. 176-199; Hirshman (2009): pp. 170-206.

Emerging technologies

1%

Thin film technologies

12%

Crystalline technologies

87%


51

3.3.3 Specific use of aluminium in photovoltaic systems

Aluminium is found in three main components of a solar PV system: inverter, panel and mounting structure. A PV inverter is an electrical inverter that is made to change the direct current (DC) electricity into alternating current (AC). Here the casing is made of aluminium.

Figure 30: PV inverter with aluminium casing (top), slanted roof mounting structure (bottom left), panel frame made of aluminium74

For the panel aluminium can be used to achieve enhanced cell performance via a back sur-face field formation. Therefore a so called metallization paste, which can contain aluminium e.g., is attached to the backside of the panel to reduce stress and the bowing of thin film75. Most of the aluminium is used in the frame of the panel. The advantage of aluminium is that it is lighter than other metals which are very important for construction/mounting. 78% of PV analyzed, from 772 modules made by 166 producers, used aluminium for the panel frame, 15% were frameless panels, and only one percent used other materials (e.g. glass, synthet-ics)76 (see Figure 31).

74 Sources: Comel, Cool Power, Jiangyin Lutong Industrial Co., Ltd. 75 Carroll et al. (without year): p. 1. 76 Own analysis; Source: Photon, February 2010: pp. 14-47.


52

Figure 31: PV panel frame materials used

It is necessary to have a faultless roof for panels to be mounted on slanted roofs. The mount-ing system uses wood, aluminium or steel that is directly attaches to the roof. Panels can also be integrated into a slanted roof. First the roof tiles are removed in the area foreseen for the solar laminates and then steel profiles are screwed into the tile slats. Different aluminium profiles can be used to make a frame for the laminate. Rubber is attached to these profiles and the laminates are placed within these frames and connected to the electric system. All edges are sealed with rubber or silicone. Steel sheets are mounted in gap between roof tiles and solar laminates77.

Flat roof mounted PV systems use gravel for the foundation. Insulating mats, aluminium pro-files and smaller components are the main parts of the mounting system. First any sand or gravel is cleaned from the roof. A mat made from recycled plastic is attached for the protec-tion of the roof and then foundation is made with loose gravel and placed on the plastic sheet. Aluminium profiles are mounted and the panels fixed to this foundation.

When panels are mounted to a façade they are placed together on an aluminium profile which is attached to the façade. If available the modules are attached to the construction steel in the wall78.

In order to determine the current use of aluminium in grid-connected photovoltaic systems different small scale plants of 3 kWp capacity have been examined79. The plants differ ac-cording to the cell type (single and multicrystalline silicon, ribbon-silicon, thin film cells with CdTe and CIS), and the place of installation (slanted roof, flat roof and façade) (see above for explanation of different cell types). Slanted roof and façade systems are further distin-guished according to the kind of installation (building integrated i.e. frameless laminate or mounted i.e. framed panel). Figures for the above mentioned systems were analyzed by ex-amining different LCA studies, especially the detailed Ecoinvent LCA on photovoltaics.

As for ground mounted systems, which were not part of the Ecoinvent LCA, the literature does not supply data. According to the German monitoring report on ground mounted PV fields, mounting constructions are mainly made of metal; only 10 % of surveyed 159 PV

77 Jungbluth (2009): p. 90. 78 Jungbluth (2009): p. 90. 79 Jungbluth. (2009): p. 90.

Aluminium78%

Frameless15%

Others1%

n/a6%


53

fields are made of wood80. Ground mounting facilities primarily use a rammed post construc-tion technique with profiles to hold PV panels on top of posts.81 (see Figure 32). Ramming post are not made from aluminium but from steel because steel does not distort when hitting obstacles in the ground8283.

Figure 32: Ground-mounted PV field with rammed post construction84

The results for specific demands of aluminium in the components are given in Table 26. Ac-cording to our data, aluminium is used predominantly in construction (72% of total aluminium input), followed by the input of aluminium to panel frames (22%), and finally aluminium in in-verters (6%). Profiles for mounting are mainly made of aluminium due to its lighter weight. Furthermore aluminium is recyclable and profile geometries are easier to meet system re-quirements. Although material input for construction/mounting structures could have been saved these savings were compensated by the increase in material prices. In Germany, be-tween 2005 and 2007 material input for construction was reduced by 50 kg/kWp while at the same time costs increased from 130 Euro/kWp to 180 Euro/kWp, thus cheaper materials might come into the market. PV systems can also be built with materials (e.g. wood) but ma-terial characteristics for wood (influence of weathering) are not as high when compared to aluminium, even if treated with preservatives. Therefore there is no clear trend that might in-dicate an increase or decrease of aluminium use in PV technologies.

80 Federal Ministry of Environment, Germany (2007). 81 Federal Ministry of Environment, Germany (2007): p. 23. 82 Interview with Mr Heim, Mounting Sytems, 7 July 2010. 83 Interview with Mr. Grützner, Schletter, 12 July 2010. 84 Source: Solarenergie-Förderverein e.V.


54

Table 26: Specific aluminium use in photovoltaic systems

Slanted roof panel Slanted roof laminate Flat roof panel Facade Ground mounted

crystalline Thin film crystalline Thin film crystalline crystalline framed modu-

le85

frameless module86

sc-Simc-Si

a-Si CIS sc-Simc-Si

ribbon-Si

a-Si CIS CdTe sc-Si mc-Si sc-Simc-Si/

Inverter 3.4 3.4 3.4 3.4 3.4 3.4 3.4 3.4 3.4 3.4 3.4 3.4 3.4 3.4 3.4 3.4

Construction 60.9 64.5 131.1 79.6 - - - - - 75.0 54.0 57.3 56.6 60.0 90.087 90.0

PV pa-nel/laminate

17.0 43.2 45.4 - - - - - 0.5 17.0 18.1 17.0 18.1 22.0 0.5

Total use of aluminium in kg per unit

81.2 67.9 177.6 128.

4 - - - - - 78.9 74.4 78.7 76.9 81.4 115.4 93.9

Total use of aluminium in kg /kW

27.1 22.6 59.2 42.8 - - - - - 26.3 24.8 26.2 25.6 27.1 38.5 31.3

85 Average weight of 22 kg other PV panels has been considered. 86 Figure of frameless CdTe thin film laminate has been considered. 87 According to Bächler (2007) 120kg/kW of aluminium and steel are used in ground-mounted PV fields. As aluminium is lighter than steel 30 kg alumi-num/kW is assumed, resulting in 90kg /3kWp (Source: Bächler (2007)).


55

As neither figures for crystalline and thin film technologies nor figures for different construc-tion types vary considerably, specific aluminium use is evenly analyzed for all sub-technologies.

The minimum specific aluminium use to be found is 23 kg/kW (Al minimum). Al maximum is 59 kg/kW and Al moderate is set to be the average of all other technologies, being 32 kg/kW.

Table 27: Total use of aluminium in kg/kW

kg/kW

Al minimum 23

Al moderate88 32

Al maximum 59

3.3.4 Technology scenarios for photovoltaic systems

The technology scenarios for the future development of photovoltaic systems show a wide range of assumed development pathways (see Figure 33).

Figure 33: Technology scenarios for PV

In our analysis we assume for the SCENARIO BEST ESTIMATE that there will be growth rates of 20 % until 2020, 10 % from 2020 until 2030 and 5 % until 205089. For SCENARIO LOW a very pessimistic path is followed. Thus, the lowest projected installed capacity for 2020 is given by EPIA (2008), reference scenario and projects 33 GW. Greenpeace (2008), low scenario projects 86 GW in 2030 and 153 GW in 2050. SCENARIO HIGH follows Greenpeace (2008), high in 2020 with 269 GW, EPIA (2006), reference scenario with 1’272 GW in 2030 and MEF (2008) projections with 3’200 GW in 2050.

88 Average of AL minimum and AL maximum. 89 Frankl (2004): p. 45.

'0

'500

1'000

1'500

2'000

2'500

3'000

3'500

today 2020 2030 2040 2050

in GWPeter/Lehmann (2007), high


MEF (2008)



EPIA (2006), reference

EPIA (2006), moderate

EPIA (2006), IEA reference

IEA (2008a), ACT Map

IEA (2008a), Blue Map


56

The installed capacity today is set to 14 GW according to the newest report published by IEA90.

Table 28: Study PATHs: installed capacity in GW

in GW today 2020 2030 2050 PATH LOW 14 33 86 153 PATH BEST ESTIMATE 14 87 225 597 PATH HIGH 14 269 1‘272 3‘200

Figure 34: Study PATHs

The produced electricity per year is based on 1’000 full-load hours on a global scale for 2010, which is a rather conservative estimate. Due to more efficient PV technologies full load hours will increase by 5% until 2050 (see Table 29).

Table 29: Expectations of full load hours today and in future (worldwide average, rounded)

in h/a 2020 2030 2050

Photovoltaic systems 1’050 1’150 1’200

Consequently, electricity generation from photovoltaic systems will be between 21 TWh (SCENARIO LOW) and 170 TWh (SCENARIO HIGH) for 2020 and between 100 TWh and 2’300 TWh for 2050. In comparison the global electricity generation in 2007 was 19’771 TWh.

90 IEA (2010): p. 9.

'0

'500

1'000

1'500

2'000

2'500

3'000

today 2020 2030 2040 2050

in GW

PATH HIGH

PATH BEST ESTIMATE

PATH LOW


57

Table 30: Energy production (in TWh, rounded)

in TWh 2020 2030 2050


SCENARIO BEST ESTIMATE 90 260 720


For the calculation of the CO2 abatement potential, as described in chapter 3.2.4, a global substitution factor is required. However it seems reasonable to use – as a conservative esti-mate – the factor derived for German conditions based on an analysis of power plant opera-tion and marginal power plants (600 g CO2/kWh)91. Due to the production characteristics (peak in noonday), a higher share of gas power plants is substituted compared to wind power.

Today, the resulting CO2 abatement is about 8 Mt of CO2. In 2020 the abatement potential for SCENARIO BEST ESTIMATE increases to about 55 Mt CO2. In 2030 and 2050 CO2 abate-ment will be 156 Mt and 430 Mt respectively (see Table 31). In spite of the higher substitution factor and higher full load hours compared to solar thermal collectors the lower projected in-stalled capacities photovoltaic systems lead to a lower CO2 abatement potential.

Table 31: CO2 abatement potential (in million tons, rounded)

in Mt CO2 2020 2030 2050



SCENARIO HIGH 170 880 2‘300

3.3.5 Resulting current and future aluminium use in photovoltaic sytems

Using the scenario assumptions defined above, the SCENARIO BEST ESTIMATE projects a total aluminium use in PV systems of 3 Mt in 2020, 7 Mt in 2030, and 19 Mt in 2050. SCENARIO LOW indicates a total aluminium use of 1 Mt in 2020 and 4 Mt in 2050 (Table 32). SCENARIO HIGH shows a total aluminium use of 16 Mt in 2030. Total maximum alu-minium use in 2020 and 2030 will be 75 Mt and 189 Mt.

Especially when compared to the technologies examined so far the latter figure is very high. This has to do with the optimistic technology diffusion assumptions of the circumstances that constitute this scenario.

If installation rates are assumed to be as in Scenario Best Estimate and aluminium use is as-sumed to be Al maximum, aluminium use could be almost doubled in the reference years (Scenario Best Estimate Scenario Best Estimate Plus).

91 CO2 abatement factor is set to 0.6 kg CO2/kWh, which is slightly higher than 0.591 kg CO2/kWh mentioned by German Federal Ministry of Environment (Federal Ministry of Environment, Germany (2009): p. 24).


58

Table 32: Quantification on future total use of aluminium for reference years

in million tons (Mt) 2020 2030 2050

SCENARIO LOW 1 2 4

SCENARIO BEST ESTIMATE Minus 2 5 14


SCENARIO BEST ESTIMATE Plus 5 13 35

SCENARIO HIGH 16 75 189

To get an approximation on the size of development of the annual aluminium market for PV systems, the total aluminium use per decade is calculated (see Table 33). As seen in these figures from all scenarios the biggest market sales potential of aluminium is given in decades 2021-2030 and 2031-2050. For example, in the SCENARIO BEST ESTIMATE aluminium use is highest in 2031-2050 with almost 0.6 Mt per year. In this decade, annual aluminium use accounts for approximately 1.6 % of annual aluminium production. If aluminium were to be used to a broad extent annual aluminium use could even be 4.7 % in 2050 (Al moderate Al maximum as in SCENARIO BEST ESTIMATE Plus).

Table 33: Total and annual aluminium use (in tons and as percentage of annual global aluminium pro-duction)

Annual Al use in decade in

tons

Annual Al use as percentage of an-nual Al production92 (rounded)

SCENARIO LOW

2010-2020 44‘000 0.12

2021-2030 122‘000 0.33

2031-2050 77‘000 0.21


2010-2020 150‘000 0.4

2021-2030 360‘000 1.0

2031-2050 500‘000 1.4


2010-2020 233‘000 0.64

2021-2030 442‘000 1.21

2031-2050 595‘000 1.63


2010-2020 466‘640 1.3

2021-2030 1.280‘000 3.5

2031-2050 1‘700‘000 4.7

SCENARIO HIGH

2010-2020 1‘505‘000 4.13

92 Annual production: 36,400,000 tons (Source: IAI 2010).


59

2021-2030 5‘918‘000 16.26

2031-2050 5‘688‘000 15.63


60

3.4 Solar cookers

Solar cookers are devices that concentrate solar radiation in a focal point where a dark con-tainer absorbs heat from sun rays in order to heat the container’s content. Solar cookers are qualified for boiling water, warming up food, frying, baking or roasting.


There are different types of solar cookers (see Figure 35): Box cookers are insulated boxes that capture both direct and diffused solar radiation. Mirrors are laterally attached to allow more sunlight to enter through the glass top. Therefore a frequent manual re-positioning fac-ing the sun is not needed. Depending on the design and the temperature of the surrounding air, temperatures of over 100 °C can be reached (no frying or roasting is possible). The box cookers must be closed during cooking, which makes stirring or adding of ingredients impos-sible. Therefore, the solar box cooker can be used only for basic cooking (for example to prepare rice or lentils). Box cookers consist of two boxes. The outer box is made out of wood, plastic or metal and the inner box is made out of aluminium sheets93.

Figure 35: Example of solar cookers: box cooker (top left), panel cooker (top right), panel cooker with aluminium panels (bottom)94

Panel solar cookers consist mainly of reflecting panels which are made from cardboard with aluminium foil adhered to it or cardboard that already contains an aluminium coating (e.g.

93 Interdepartementale Plattform zur Förderung der erneuerbaren Energien und der Energieeffizienz in der internationalen Zusammenarbeit (without year): p. 6. 94 Sources: Applied Solar, Ecofriend.org, SolarcookeratCantinaWest.


61

used Tetra-Pak wrapping)95 though some are made of aluminium sheet. The focus of the panels is the pan so to prevent the pan from losing its heat, the pan is put in a transparent and heat resistant plastic bag that have a limited lifetime. As with the box cooker, the heat is lost when the bag is opened which prevents any intervention in the cooking process for stir-ring or adding of ingredients. Temperatures can reach just over 100 degree Celsius.

Solar parabolic cookers have a reflecting surface in the form of a parabolic dish, which con-centrates the solar rays at a focal point at which the black coated cooking pot is placed. High temperatures, well over 150 degrees Celsius, can be reached when the cooker is well posi-tioned towards the sun. The cooker needs to be repositioned towards the at least every 15 minutes. In contrast with the solar cooking box however, cooking times can be similar to tra-ditional stoves. Solar parabolic cookers consist of a galvanized steel or metal frame, with a wooden frame being use in rare cases96. Reflector panels are attached to the frame and con-sist of aluminium or steel. Additionally an extra ceramic layer exists to prevent weathering. These solar cookers weigh 20 kg or more with a steel frame or around 12 kg with an alumin-ium frame97.

Figure 36: Solar parabolic cookers98

(Automatic) solar parabolic cookers or so called Scheffler solar kitchens are bigger consisting of one or more solar dishes (each 2 to 16 square meters). The concentrating reflectors track the movement of the sun, reflecting the light of the sun and concentrating it on a fixed posi-tion. In some configurations the reflected and concentrated sunlight enters a nearby kitchen directly to strike a cooking pot or frying surface. In other configurations, the concentrated sunlight is used first to create steam which is transported by pipes to a nearby kitchen. These solar kitchens reach very high temperatures. This technology is very cost-intensive and is primarily installed in India. The structure of the reflector is made from steel or aluminium and

95 ibd. 96 Interdepartementale Plattform zur Förderung der erneuerbaren Energien und der Energieeffizienz in der internationalen Zusammenarbeit (without year): p. 12. 97 Source: Sun and Ice 2010 pricelist. 98 Source: EG Solar.


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is flexible. Fixed, non-mobile devices are equipped with glass mirrors while mobile devices are equipped with aluminium sheets99.

Figure 37: Solar community kitchen100

3.4.2 Current market situation for solar cookers

Exact global figures for solar cookers in use today are not available in the literature. Several small scale projects exist worldwide which list the dissemination of solar cookers for their project. In order to get an approximate first overview of global capacity it is therefore neces-sary to look at sales figures from main manufacturers (see Table 34).

Table 34: Sales101

99 Interdepartementale Plattform zur Förderung der erneuerbaren Energien und der Energieeffizienz in der internationalen Zusammenarbeit (without year): p. 13. 100 Source: Indiamart. 101 Interdepartementale Plattform zur Förderung der erneuerbaren Energien und der Energieeffizienz in der internationalen Zusammenarbeit (without year): p. 49.

Company Name of so-lar cooker model

price remarks

Integrated Lo-gistics Sotu-tions, S.A. de C.V. (ILS), Mexiko

Hot Pot USA: 99$US

Hot Pot is sold mainly in Mexico, but is ex-ported to US and Europe. Several thousands of solar cookers have been produced.

SunFire, South Africa

SunFire14, SunFire10

South Africa 2000R, 1500R

Sales around 500 a year.

Solar Oven So-ciety, USA

SPORT USA: 125$US -

Sun Oven In-ternational, USA

Global Sun

USA: 279$US Thousands of solar cookers have been sold.


63

Estimates for China show that 1.4 million have been sold so far103. Figures for China, how-ever, must be regarded carefully and as very uncertain, e.g. manufacturer Yangcheng esti-mates having sold 1.8 million units alone.

India as well produces very high figures of 75’000104 and 100’000105 solar cookers sold every year. Another figure estimates 500’000 units that have been sold in India106.

The Deutsche Gesellschaft für technische Zusammenarbeit estimates that 900‘000 solar cookers have been sold worldwide until 2002, most of them in Asia (95 percent)107108.

102 Interview with Mr Michelbauer, EG Solar, 21 June 2010. 103 Xiaofu (2009). 104 Mahalingam (2006).. 105 Maithani (2009). 106 Gadhia (2009). 107 Interview with Ms Feldmann, HERA - Poverty-oriented basic energy services, GTZ, 16 March 2010. 108 GTZ (2002).

Solar cookers international, USA

Cookit USA: 25$US

SCI is the umbrella organization for solar cook-ing. It sells different solar cookers, and pro-duces the simplest of all cookers, Cookit.

Müller Solar-technik, Germany

Kundu Kaar, Zèbre, Primerose

Germany Kundu Kaar 80€, Zèbre 140€, Primerose 285€

Small manufacturer from Germany which has been in business for five years. Sales are around several hundred a year.

Alsol, Spanien Alsol 14 Spain: 260€ Target 2009 was 800 solar cookers. Sun Co SA, Portugal

SunCook Europe: ca. 300€ Model made fully out of plastic. Sucessful dis-tribution via idCook, France.

Yancheng Sangli Solar Energy, China

Butterfly 1050$ US for 10 pieces in export; in China: 65$US.

Sales mainly in China. The model Butterfly is rather heavy because it is manufactured from steel (50 kg). Producer estimates having sold 1.8 million units since 1983 and 80,000 units per year.

Fair Fabricators, India

- India: 50 $US Producer estimates: sold 100,000 units in last 20 years.

Rohitas Elect-ronics, India

Tulsi cooker USA: 307$US The only solar cooker on the market with elec-trical backup. On the market for 25 years. An-nual sales of 5,000 solar cookers.

unknown, Chi-na

Ico-GE Spain: 85€ Discount model with poor quality.

EG Solar e.V., Germany

SK14, SK11 298 - 378€

Inventor of SK 14 model. Sold 50,000 units within the last 20 years.102

Sun and Ice GmbH, Germany

Premium11, Premium14

Germany: 239€ (1,1m), 279€ (1,4m)

Commercial branch of EG Solar. Has sold 14,000 solar cookers within the last five years.


64

3.4.3 Specific aluminium use in solar cookers

Solar parabolic cookers usually come with a steel or aluminium metal pedestal frame. The reflecting material of the solar cooker can be made from a plain full material (most common is aluminium) or a plain material with an additional reflecting layer. These materials show dif-ferent reflectance characteristics.

Table 35: Reflectance of different materials used for solar cookers

Reflecting materials Reflectance

Clear/transparent glass 94%

Common glas 80%

Polished plain aluminium 84%

Coated foils/film 80-75%

Although clear/transparent glass proves to be the most effective material, it is difficult to ob-tain in developing countries109. Common glass (thickness: 2 mm) is more widespread and does not lose effectiveness when maintained regularly. Although, in order to get an optimal focal point, assembling of small glass facets is necessary because glass cannot be bent. Even today it is difficult to form glass into the desired shape with the degree of accuracy re-quired. For instance it is preferred that the curve of parabolic reflectors be accurate to within one tenth of a degree. Unfortunately this degree of accuracy is currently not available110 es-pecially not in developing countries.

Furthermore glass facets are fragile, showing shorter life times111. Today this technique is still in use, mainly in China, which has the advantages of good friction resistance, slick surface, reasonable price and a moderate four to five year life-span112. It is, however, vulnerable to erosion, desquamate, metamorphose, and cost time and labour for replacing the slick sur-face. Aluminium film, with characteristics of high reflectance and easy replacement and a life-time of only 2-3 years, was used for the recently produced commercialized solar cookers.

Coated foils/films are spanned and adhered firmly onto a metal frame. Weathering of the glue is one disadvantage, another one is the blinding of the foil113. Solar cookers using syn-thetic reflecting layers like (optical polyester; example solutions from idCook, France114) show good intensity and rigidity, and are very light, which can meet the demand of the general

109 Tyroller (2004): p. 23. 110 United States Patent 4238265: Method of manufacturing a glass parabolic-cylindrical solar collec-tor. 111 Garg et al. (2000): p. 306. 112 Interview with Mr Veit, EG Solar at Intersolar, 12 June 2010. 113 Tyroller (2004): p. 24. 114 e.g. idCook solar cookers consist only of a negligible amount of aluminium per square meter; Total weight: 6.5kg; about one 1g/m² aluminium (Source: Interview with Mr Basilhet, idCook, at Intersolar, 12 June 2010).


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transportation; plus they are very cheap115. The disadvantage of this solar cooker is less re-sistance and that cleaning causes abrasion and subsequently loss in reflectivity116.

Metals cannot be polished in order to be reflective enough for solar cooking. One exception though is anodized aluminium. Aluminium solar cookers show good shape maintenance but their disadvantage is that they become blind in proximity to salt water. This kind is the most widely used especially for the economically moderate price, easy shaping, and simple tech-nique117. Polished aluminium is easy to deal with and assemble. Improper cleaning of the surface leads to scratches and consequently to a reduction of reflective effectiveness118. Alanod, a German manufacturer for aluminium sheets produces a variety of aluminium grades. It does market one product line specifically for solar applications with reflectivity grades of 85-95%119. Aluminium products that are expected to last for extended periods of time must be covered with a protective coating.

Currently there are two types of material for reflection layers in use glass mirror and alumin-ium film. The latter is prone to weathering. Full-material solar cookers do not necessarily need reflecting material, especially when made of aluminium which shows high reflecting characteristics.

For this study a full material solar parabolic cooker was chosen as the reference technology because this technology is regarded as a common market available technology120. Addition-ally its costs are moderate, and net power, cooking temperatures and life span characteris-tics are adequate due to its nano-ceramical protection layer. Finally these solar cookers have the advantage to being easily manufactured on-site.

With this reference solar cooker the following specific aluminium use is assumed. 20 kg of aluminium can be found in a model in which the whole apparatus (frame, reflector) is made of aluminium (Al maximum)121. Al moderate is estimated with a share of 3 kg of aluminium per solar cooker unit, whereas aluminium is used in reflectors122. It consists of reflector sheets made from highly reflective aluminium (anodised, hard, high reflecting aluminium sheet, 0.5 mm thick). These reflectors are fixed to a parabolic shaped metal frame. Al mini-mum is estimated to be 0.1 kg per unit if nearly no aluminium is used at all123.

Table 36: Aluminium use in solar cookers


Total 0.1 kg 3 kg 20 kg

115 Interview with Mr Basilhet, idCook, at Intersolar, 12 June 2010. 116 Interview with Mr Michelbauer, EG Solar, 21 June 2010. 117 Interview with Mr Michelbauer, EG Solar, 21 June 2010; Interview with Mr Veit, EG Solar at Interso-lar, 12 June 2010, Interview with Mr Basilhet, idCook, at Intersolar, 12 June 2010. 118 Tyroller (2004): p. 24. 119 Reflective 85, MIRO Reflective 90, MIRO high reflective 95. 120 Interview with Mr Michelbauer, EG Solar, 21 June 2010; Interview with Mr Veit, EG Solar at Interso-lar, 12 June 2010, Interviwe with Mr Basilhet, idCook, at Intersolar, 12 June 2010. 121 Model SK 14 (full equipment) from EG Solar, EG Solar 2010. 122 Sun and Ice SK 14 model; Interview with Mr Michelbauer, EG Solar, 21 June 2010. 123 idCook Cook up 200 made mainly of optical polyester and wood; Interview with Mr Basilhet, id-Cook, at Intersolar, 12 June 2010.


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3.4.4 Technology scenarios for solar cookers

As opposed to the other renewable energy technologies focused on and due to the fact that no expansion scenario is available for the reference years 2020, 2030 and 2050, only the overall potential of solar cookers that can reasonably be installed in the future will be focused on hereafter. Solar Cookers International has compiled a list of twenty countries with the highest potential for solar cooking. Criteria for this ranking include annual average sunlight, cooking fuel scarcity and population size. Of the estimated 500 million people who have abundant sunshine and suffer from fuel scarcity, 85 % of them live in a few countries124.

Table 37: Focus countries for solar cookers

For an estimation on the overall market potential of solar cookers, it has to be assessed how many people could use solar cookers instead of other systems:

In developing countries, especially in rural areas, 2.5 billion people rely on biomass, such as wood, charcoal, agricultural waste and animal dung to meet their energy needs for cook-ing125. In the absence of new policies the number of people relying on biomass will increase to over 2.6 billion by 2015 and to 2.7 billion by 2030 because of population growth126. Two complementary approaches can improve this situation: 1) promoting more efficient and sus-tainable use of traditional biomass, 2) encouraging people to switch to modern cooking fuels and technologies. Halving the number of households using traditional biomass for cooking by 2015 – a recommendation of the United Nations Millennium Project – would involve 1.3 bil-lion people switching to other fuels or cooking systems.

Experts estimate that solar cookers could be used by 1 billion people worldwide127. Other ex-perts say that the economical potential of solar cookers worldwide is at least 167 million solar cookers128. The latter estimate seems to be reasonable, but approximations of 1 billion peo-ple or more seem to be unreasonably high therefore an own estimate was calculated129:

According to other sources 500 million people have abundant sunshine and suffer from fuel scarcity, a prerequisite for switching to solar cooker technology. It is assumed that one solar cooker serves 6 people. Consequently, the market potential consists of around 83 million so-

124 Blum (2009): p. 1. 125 GTZ (2007): preface. 126 Note: About 1.3 million people – mostly women and children – die prematurely every year because of exposure to indoor air pollution from biomass. 127 Interview with Mr Michelbauer, EG Solar, 21 June 2010. 128 Lardy (2006). 129 Calculation on the basis of Seifert (1999): Proposals for a Global Solar Cooker Programme.

Focus countries for solar cookers

India China Pakistan

Ethiopia Nigeria Uganda

Sudan Afghanistan Tanzania

South Africa Niger Somalia

Brazil Kenya Nepal

Mozambique Burkina Faso Madagascar

Malawi Zimbabwe


67

lar cooker units. It is assumed that an average of 1’000 solar cookers are produced annually in one workshop, and 2’000 workshops/manufacturers exist.

Therefore two million solar cookers could be produced every year and it would take approxi-mately 42 years (approximately: year 2050) to equip all the above mentioned 500 million people with solar cookers. Subsequently 83 million units are considered to be PATH BEST ESTIMATE, 167 million units mark PATH HIGH and PATH LOW is set to 10 million solar cooker units by default.

The primary energy that is used for cooking varies strongly from region to region. A consid-eration of a regional specific primary energy mix could not be undertaken within the scope of this study. In order to obtain an estimate on CO2 abatement potential of solar cookers world-wide small scale projects and especially CDM projects have been examined. CO2 abatement potentials for a single cooker per year are listed in Table 38.

According to the projects examined, annual CO2 savings are within a span of 0.8 t (Solar Cooker CO2 abatement potential Minimum) to 3.7 t (Solar Cooker CO2 abatement potential Maximum) of CO2 per solar cooker per year. This corresponds well to the assumptions of other experts130. Solar Cooker CO2 abetment potential moderate is the average of CO2 abatement potential of a solar cooker per year in examined projects, namely 2.5 t.

Table 38: Solar cooker projects and annual CO2 abatement potential per solar cooker in tons

Project Annual CO2 abatement poten-tial per solar cooker in tons

CDM Solar Cooker Project, Indonesia (Aceh)131 3.5

Federal Intertrade Pengyang Solar Cooker Project, China132 2.1

Ningxia Federal Solar Cooker Project, China133 2.1

Federal Intertrade Hong-Ru River Solar Cooker Project, China134

2.1

Federal Intertrade Haiyuan Solar Cooker Project135 2.0

Project in Chad136 3.7

Project in Nepal137 3.3

South Africa solar cooker project138 0.8

Average 2.5

CO2 abatement potential for solar cookers in Mt for the three different PATHs is shown in Ta-ble 39.

130 Personal information of Mr Seifert, EG Solar. 131 UNFCCC CDM project. 132 UNFCCC CDM project. 133 UNFCCC CDM project. 134 UNFCCC CDM project. 135 UNFCCC CDM project. 136 Krämer (without year): p. 8. 137 Shrestha (without year): p. 2. 138 Hancock et al. (2006): p. 21.


68

Table 39: CO2 abatement potential for solar cookers in million tons (Mt)

CO2 abatement potential for solar cookers

in million tons (Mt)

SCENARIO LOW 8

SCENARIO BEST ESTIMATE 208

SCENARIO HIGH 618

3.4.5 Resulting current and future aluminium use in solar cookers

Based on these assumptions, the SCENARIO BEST ESTIMATE leads to an overall specific aluminium use of 249’000 t until 2050. Compared to the above mentioned technologies, fig-ures even in SCENARIO HIGH are rather low. Nevertheless, especially with regard to CDM projects, solar cookers could be a favourable technology for aluminium use.

Especially noteworthy is that moving from Al moderate to Al maximum increases market po-tential by five times (see SCENARIO BEST ESTIMATE Plus).

Table 40: Overall aluminium use in solar cookers

in t Overall aluminium use in solar cookers

SCENARIO LOW 1

SCENARIO BEST ESTIMATE Minus 8‘300

SCENARIO BEST ESTIMATE 249‘000

SCENARIO BEST ESTIMATE Plus 1‘660‘000

SCENARIO HIGH 3‘340‘000


69

3.4.6 Solar community kitchens (excursion)

The basic idea of this technology is that the concentrating reflectors track the movement of the sun, reflecting the light of the sun and concentrating it on a fixed position. In some con-figurations the reflected and concentrated sunlight enters a nearby kitchen directly to strike a cooking pot or frying surface. In other configurations, the concentrated sunlight is used first to create steam which is transported by pipes to a nearby kitchen.

Figure 38: Scheffler community kitchen139

This technology is also well known as Scheffler solar kitchen technology and is named after German Wolfgang Scheffler who built the first well-functioning Scheffler-Reflector) in 1986 in Kenya. Since then the technology has been continuously improved. For a number of years mainly 8 m² size reflectors were constructed for canteen kitchens. After 2000 mostly 10 m² and 16 m² Scheffler-Reflectors were installed140.

It is difficult to approximate how many Scheffler Reflectors exist since there is no central reg-istration and many workshops work independently. In 2004 there were about 750 reflectors in 21 countries, which corresponds to about 200 solar kitchens, including 12 solar steam kitch-

139 Source: Barli.org. 140 Information from Solare Brücke website; see: http://www.solare-bruecke.org/English/scheffler_e-Dateien/scheffler_e.htm; last accessed: 20 July 2010.


70

ens with 10 to 106 reflectors per installation. In 2006 it was estimated that around 950 Schef-fler Reflectors were installed worldwide141.

Estimation on installed capacity of solar community kitchens

According to experts there are today 2’300 solar reflectors with an average size of 10 m² and 16 m² worldwide. Half of the 2’300 solar reflectors have 10 m² (=11’500 m² installed capacity) and the other half have a 16 m² reflector (= 18’400 m² installed capacity)142. Most of the solar community kitchens are found in India143 Including the world’s largest solar kitchen set up in Taleti, India. The food is cooked in 200-400 liters cooking pots, producing an average of 20’000 meals a day and up to 38’500 meals per day during periods of peak solar radiation maximum.

Current use of aluminium in solar community kitchens

Reflectors are primarily made from reflecting glass and for the mounting structure steel is used144. Aluminium is to be found in aluminium profiles which bear the reflectors. Therefore, flat and E-profiles made of AlMgSi alloy are used. An estimated 20 kg of aluminium is used for an 8 m² reflector145, resulting in 2.5 kg per square meter. As almost 30’000 m² of solar kitchens exist, 75 tons of aluminium are currently processed in those systems.

Future perspective of aluminium use in solar community kitchens

During our research no scientific reliable figure on future perspectives could be found. While one expert estimates a slight increase in installed capacity, another expert argues that bigger solar community kitchens based on solar reflectors have the potential to be replaced by CSP technologies (e.g. parabolic trough systems) because the generation of heat will be cheaper146. If parabolic trough technology should gain momentum to serve as a provider of heat for community kitchens, then aluminium use for this technology would increase147.

141 Information from Solare Brücke website; see: http://www.solare-bruecke.org/English/scheffler_e-Dateien/scheffler_e.htm; last accessed: 20 July 2010. 142 Interview with Ms Hoedt, assistant of Wolfgang Scheffler, 1 July 2010. 143 Interview with Mr Veit, EG Solar at Intersolar, 12 June 2010. 144 Information from Solare Brücke website; see: http://www.solare-bruecke.org/English/scheffler_e-Dateien/scheffler_e.htm; last accessed: 20 July 2010. 145 Interview with Ms Hoedt, assistant of Wolfgang Scheffler, 1 July 2010; own calculations. 146 Interview with Mr Michelbauer, EG Solar, 21 June 2010. 147 Interview with Mr Michelbauer, EG Solar, 21 June 2010.


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3.5 Concentrating Solar (Thermal) Power (CSP)

Concentrated solar power (CSP) or solar thermal power plants use concentrated sunlight to generate electricity or heat by using high temperatures. CSP power generation is generally divided into four types: solar fields, solar towers, solar dishes and concentrating photovoltaic.


Solar fields are the most common type to generate CSP, but all types of CSP have the same principle for generating electricity (see Figure 39): Solar radiation gets concentrated by a concentrator (e.g. troughs, a central receiver or a dish-sterling) to heat a transfer fluid (e.g. oil, molten salt, water or air). The heat then can be channelled to and stored in a thermal storage system (molten salt, PCM148, concrete) or can be directly converted to electricity. The advantage of these technologies is the possibility that, especially in combination with storage systems, electricity is available when the sun does not shine. Within this combination storage of 7.5 hours for solar fields and 16 hours for solar towers is possible and currently being practice. Another usage of this technology is co-generation for cooling or desalination.

Figure 39: Concentrating Solar Power technologies (top left: solar field Andasol I, Spain; top right: so-lar tower Solar Two, USA; bottom left: Stirling Energy Systems Concentrator Dish; bottom right: SolFocus 1100 system)149

148 PCM = Phase Change Materials. 149 Sources: Estelasolar, Global-greenhouse-warming.com, Solarcentral.org, Worldofphotovoltaics.com.

Solar field Solar tower

Solar dish Concentrated PV


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Solar fields

Sun rays are collected in a trough and passed to a receiver in the middle of the mirror. Nor-mally there are two different types of troughs: parabolic troughs and Fresnel reflectors.

The parabolic troughs concentrate sunbeams directly through an absorber which is filled with thermo oil that is needed to generate steam. This steam can be used to generate electricity with the use of a conventional steam turbine and a generator. The plants can be equipped with a tracking mechanism to use the maximum sunlight at any given time. The efficiency of these plants is above 20%. Parabolic troughs are the oldest method of CSP, with the first troughs being used in the SEGS (“solar electricity generation systems) which were built in California during the 1980’s.

Fresnel collectors consist of several flat mirrors that direct sunlight indirectly through a sec-ondary concentrator to the absorber, which is filled with water that evaporates and thereby generates electricity via a steam turbine. The flat mirrors have only one axis which reduces the production costs in comparison to parabolic troughs. The disadvantage of Fresnel collec-tors is that the efficiency is lower so therefore Fresnel collectors need a bigger field area to produce the same electricity as parabolic troughs.

In summary the lower efficiencies get compensated through the lower production costs. Fresnel troughs are beneficial in unsettled regions where land use only plays a minor part (e.g. desert regions). In comparison parabolic troughs are advantageous in regions where land use has a significant influence on the living standards. Another advantage of Fresnel collectors is that the collectors are suitable to spent shadow under their construction area. This is an opportunity for usage on agricultural areas to protect plants from direct solar radia-tion.

Solar tower

A solar tower consists of a central receiver located at the top of a tower. Independently oper-ating heliostats (mirrors) build a field around the tower and concentrate the solar radiation to the receiver that usually consists of a ceramic membrane. With this technology temperatures of over 1’000 degrees Celsius can be reached. The energy transportation and storage (through steam, molten salt, air, etc.) is much easier and the energy efficiency is higher than in solar fields because the concentration and energy conversion is fixed in one point. Actu-ally, energy from solar towers can be stored over a period of 15 hours. That is two times higher than the storage possibilities of solar fields (about 7.5 hours)150.

150 Estella (2009): p. 23.


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Figure 40: Types of CSP technologies151

Solar dishes (or stirling dishes)

Solar dishes consist of one big parabolic trough that concentrates the solar radiation to one point in the middle of the dish. There, an engine (stirling motor) converts heat to electricity or heat of different dishes can be transported into a central power engine where a stirling en-gine generates electricity. Normally solar dishes have a capacity of 5 to 50 kW.152 But dishes beyond 100 kW are planned or are under construction.

Because of the low capacities of solar dishes, in comparison to other CSP technologies, and a feasible possibility to store the energy there is no mass market. Only a few demonstration systems are actually running. Therefore, solar dishes are practical for a decentralized use in regions where no grid connection is possible or an additional use through an insufficient grid is needed.

Concentrating Photovoltaics (CPV)

The principle of Concentrating Photovoltaic systems is different than other technologies men-tioned in this chapter. While solar fields, dishes and towers use the concentrated sun radia-tion to generate heat, CPV tries to avoid thermo dynamical processes. The sun radiation gets concentrated (mostly through Fresnel lines) but the concentrated radiation gets immediately directed through PV cells behind the lenses. In comparison to normal PV cells the radiation has a much higher concentration (between 10 and 2’000 times153) and is therefore more ef-

151 Source: Greenpeace (2009): p. 16. 152 Viehbahn (2008): p. 10. 153 According to Pihl (2009): p. 17.


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fective. CPV systems use triple junction PV cells, normally operate between 5 and 100 kV and can work with an efficiency of 40%.

3.5.2 Current market situation for CSP

The idea of using solar energy in large power plants is not new. At the beginning of the 20th Century a solar field was built in Shuman (Egypt) with a capacity of 55 kilowatts. But because of low energy prices and high costs for power generation development stagnated a long time.

In the 1980’s a total of nine power plants (SEGS = “solar electricity generation systems”) were built in California (USA) which have a total capacity of 354 MW. The two biggest solar thermal power plants in Europe (Andasol I-II) are located in southern Spain and feature a ca-pacity of 50 MW each. Another identical solar field (Andasol III) with the same capacity is al-ready under construction. Despite the fact that the technique was already well known the large increase of solar thermal power plants in the market only took place during the last five years. Today a total of 516 MW are installed worldwide (2009)154.

Installed capacity worldwide

In comparison to other renewable energy technologies (wind, PV, solar thermal power, bio-mass) concentrated solar power (CSP) is still a niche technology. The installed capacity is 516 MW worldwide. Divided into technologies, parabolic troughs prevail with an installed ca-pacity of 468 MW (90.2% of the total installed capacity in 2009 and 15,798 GWh produced electricity). Solar towers had a capacity of 44 MW (8.5 % of the total capacity) in 2009. Fres-nel troughs only had a capacity of 4 MW (0.8 % of the total capacity and 10 GWh produced electricity). Solar dishes only worked in demonstration projects with a total capacity of 0.24 MW (3 GWh produced electricity)155.

Also interesting is the capacity that is planned or under construction. Here the capacities vary significantly from the already installed capacities. A total capacity of 9’658 is planned or un-der construction. The share is 4’449 MW (46%) of parabolic troughs, 3’026 MW (31%) for so-lar towers, 483 MW (5%) of Fresnel troughs and 1’700 MW (18 %) of solar dishes156 (see Table 41).

Table 41: Installed and planned capacity and electricity generation of CSP technologies

Technology Installed capacity in 2009 (in MW)

Produced electric-ity in 2009 (in GWh)

Planned capacity or un-der construction (in GW)

Parabolic troughs 468 15’798 4’449

Fresnel troughs 4 10 483

Solar towers 44 83 3’026

Solar dishes 0.24 3 1’700

154 Greenpeace (2009): p. 16. 155 Greenpeace (2009): p. 16. 156 Greenpeace (2009): p. 16.


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Installed capacity by regions

For CSP technologies it is necessary to have constant high solar radiation. Therefore most of the regions of the world are not qualified. Only the regions which lie in the sun belt of the world (20 and 40 degrees latitude north and south) are suitable for CSP technologies. There the solar radiation is much higher than in the rest of the world; a significant condition to make CSP technologies profitable. Regarding Europe, only a few regions can fulfil these conditions namely parts of the Mediterranean area of Europe especially in southern Spain. One third of the planned capacity and capacity under construction worldwide is being realized in Spain157. Excellent conditions are also found in Africa, especially Northern Africa, in Australia, in the Southern United States and in parts of the middle of South America.


Solar fields

The Solar Energy Generating Systems (SEGS) were produced by Luz II Ltd. (which is actu-ally a subsidiary of BrightSource Energy) in the 1980’s. The operating company of the SEGS is FPL Energy (a subsidiary of the FLP Group). The SEGS receivers were built by the Ger-man company Schott AG. The SEGS are the biggest currently installed CSP plants with a to-tal capacity of about 354 MW158.

The Andasol Concentrating Solar Power plants (Andasol I+II in operation; Andasol III under construction) are located in Granada in Southern Spain and were developed and produced by the German company Solar Millenium. About 75% of the plants are in possession of the Spanish construction company Grupo Cobra (a subsidiary of Grupo ACS). The other 25% are in possession of Solar Millenium. Flagsol GmbH, a subsidiary of Solar Millenium, is re-sponsible for the operation of the plants. Each of the three identical plants has a capacity of 50 MW159.

Another big concentrating solar power field in Boulder City (Nevada, USA) is under construc-tion. Solargenix is the prime contractor of this 64 MW plant. In Israel a 150 MW facility (with the option of an expansion to 500 MW) is operated by the company Solel160.

A power plant using Fresnel technology has been near Sidney, Australia, since 2004. The University of New South Wales has developed this technology which has a total capacity of 15 MWth and runs in co-generation with a coal plant to generate steam.

Two other Fresnel based power plants are located in Sevilla (Spain, 176 kW, PSE) and in Karlsruhe (Germany, 1.4 MW, Novatec Biosol). The former is used for the cooling system of the local university. The latter is used to produce solar steam for a coal plant.

157 Fraunhofer ISI, ITZ (2009): p. 155. 158 For more information: www.flp.com 159 For more information: http://www.solarmillennium.de/ 160 For more information: http://thefraserdomain.typepad.com/energy/2005/09/about_parabolic.html


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Solar towers

In Sevilla (Spain) a tower was built in 2007 with a capacity of 11 MW. In 2009 the plant was complemented by a second tower with a capacity of an additional 11 MW. The two towers (called PS10 and PS20) are operated by the Spanish company Abengoa and are part of big solar park of different CSP technologies with a total capacity of 302 MW.

CESA-1 and SSPS-CRS are two solar towers located on a test field in Almería (Spain) that use Fresnel technology. They have a capacity of 7 MW and 1.2 MW. In the United States “Solar Two” is the biggest current running solar tower. It is located in California and has a capacity of 10 MW. In Jülich (Germany) the first German demonstration and development of a solar tower was started in 2006 and has been running in test mode since 2009 with an ap-proximate capacity of 1,5 MW161.

Solar dishes

As mentioned earlier, there is no market for solar dishes. Only some test projects generate solar energy but these systems do not run on a commercial basis. With regard to the future, interesting projects are being planned at the moment, e. g. Stirling Energy Systems (SES) plans in cooperation with the Sandia National Laboratories a solar field of over 70,000 dish engine units in San Diego. In 2014 the field should have a capacity of 750 MW and supply about 562,500 households with energy162.

3.5.3 Specific aluminium use in CSP technologies

Concerning CSP technologies, aluminium use today and in future for those technologies has to be considered with great care. Depending on the future development with a variety of dif-ferent factors (e.g. investments in R&D, grid connection developments, national and interna-tional policy and many more) aluminium might play a significant role. On the other hand, aluminium could also play a subordinate role if development moves into other directions.

The optimal location for CSP technologies is in regions where the sun radiation during the year is high. These regions are mostly in deserts and dry areas in the sun belt of the world. But most of the suitable regions have no or only a slightly developed infrastructure where production and transportation of CSP components for power plants are difficult to handle. Component materials (reflector systems and supporting structure) have special requirements for an efficient usage in CSP technologies:

low costs corrosion resistance (sand storms in desert regions and salt deposit in coastal re-

gions) mechanical resistance (periodical washing) high solar reflectivity low weight (transportation) high stiffness (of frames to carry the reflectors) a simplified assembly line (less developed infrastructure)

161 For more information: Solarinstitut Jülich (http://www.fh-aachen.de/index.php?id=378) 162 For more information: http://www.sandia.gov/LabNews/100507.html


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To give detailed information about current and future aluminium use life cycle assessments (LCA) of the current technologies on the market and those technologies that have a potential to play a significant role in future have been examined. The analysis was completed with ex-pert interviews of different component manufacturers and plant operators of CSP technolo-gies. LCA’s and studies which were used to analyze CSP technologies are:

- ANGERER, G./ERDMANN, L./MARSCHEIDER-WEIDEMANN, F./SCHARP, M./LÜLLMANN, A./

HANDKE, V./ MARWEDE, M. (2009): Rohstoffe für Zukunftstechnologien: Einfluss des

branchenspezifischen Rohstoffbedarfs in rohstoffintensiven Zukunftstechnologien auf

die zukünftige Rohstoffnachfrage. Karlsruhe, Germany.

- EUROPEAN COMMISSION (ed.) (2009): Environmental and ecological life cycle invento-

ries for present and future power systems in Europe (ECLIPSE): Life Cycle Invento-

ries. Brussels, Belgium.

- HYDRO (2009): Seeing the Light. The use of Aluminium Support Structures in Con-

centrated Solar Power Energy Generating Facilities. Oslo, Norway.

- JUNGBLUTH, N. (2007): Ecoinvent -Teil XI: Solarkollektoranlagen. Dübendorf,

Switzerland.

- LEHMANN, H./REETZ, T./ROEWER, S./LIEDTKE, C. (2008): Ökologische Chancen und

Risiken großtechnisch angelegter solarthermischer Kraftwerke. Wuppertal, Germany.

- VIEBAHN, P. (2004): SOKRATES-Projekt - Solarthermische Kraftwerkstechnologie für

den Schutz des Erdklimas. Stuttgart, Germany.

Parabolic troughs

The parabolic troughs which are used in most operating solar fields are silver-based mirrors made of special flat glass (mostly with iron content) (see Figure 40). This guarantees good reflection characteristics and a long durability.

Some companies though have fields where aluminium parabolic mirrors are tested. In com-parison to glass mirrors, aluminium mirrors have the same surface reflectivity and are lighter. While glass mirrors have an average weight of 11 kg per square meter163 aluminium troughs have only an average weight of 7 kg per square meter which is about 35 per cent lower than glass collectors. Especially when transportation costs are (only areas of the Sun Belt are suitable for CSP technologies), the lower weight can play a significant role in the decision as to which material will be used in the future.

The system frames can be made of steel and aluminium, respectively. Some companies have developed aluminium frames which are already used in solar fields. The use of alumin-ium in frames for parabolic dishes varies widely because of different requirements. For the frames of a 64 MW solar field in the USA (Nevada Solar 1) 3’402 tons of aluminium were re-quired. The same amount was used for three 50 MW solar fields in Spain. Other require-ments for aluminium frames have been found for a solar field in Florida, USA. Because of the high possibility of hurricanes in this region, the frames must have a stronger design to with-

163 Data from FLABEG technical sheet of parabolic collectors.


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stand hurricane force winds. Therefore, a total of 8’165 tons of aluminium were used for this 75 MW field.

The absorber systems are made of stainless steel with selective coating. The envelopes consist of Borosilicate anti-reflective glass. The absorber system does not use aluminium and there is no research on using aluminium for these systems164.

Aluminium is used in parts of the power block and the cooling tower. The LCA of NEEDS showed a total of 950 kg of Aluminium in a power block for a 50 MW solar field (Andasol I) and a total of 624 kg for a parabolic solar field of 5 MW. The SOKRATES LCAs even showed a total of 1’500 kg of Aluminium used in the generators (both for parabolic and Fresnel tech-nologies). The same LCAs also showed an aluminium share of 600 kg in the cooling tower. Particularly the cooling fins are made of aluminium.165

Figure 41: Parabolic collector at Andasol I166

The attention is on the collectors and the elevation. Other components (cooling tower, heat pipes, generator, pre- and reheater) of solar fields only use aluminium in small amounts where no significant potential could be identified.

Today’s minimum aluminium use (Al minimum) is given when collectors are made of glass and the elevation is made of steel. The aluminium only exists in small amounts 0.0008 kg/kW (see Table 42). The maximum aluminium (Al maximum) amount is given when both elevation and collectors are made of aluminium (possibility of a solar field completely proc-essed with aluminium). Then a specific factor of 53.9 (worldwide average) kg aluminium per kW for the elevation (truss systems) and a factor of 76.7 kg/kW for the collectors build the basis for calculation. Summed up the result is a total specific factor of 130.6 kg aluminium per installed kW.

For Al moderate, we assume 65.3 tons per MW (average of Al minimum and Al maximum) of the aluminium use when solar fields are partly made of aluminium (either elevation or col-lectors).

164 Expert interview with Florian Höcht, Schott Solar 165 Expert interview with Barbara Fricke, research associate at Solarinstitut Jülich (SIJ), Germany. 166 Source: SolarMillenium.


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Table 42: Specific aluminium use in solar fields today [in kg/kW]

kg/kW Al minimum Al moderate Al maximum

Collector - - X 53.9

Elevation/Frame - X - 76.7

Specific aluminium use in tons per MW

0.0008 65.3 130.6

Fresnel collectors

Common like parabolic mirrors Fresnel collectors are currently made of flat-glass with a silver mirror. Steel evaluation constructions are used to fix the (single-axis) mirrors into the sun. In comparison with parabolic mirrors, the main advantage of these systems is their simple de-sign that makes the components easier to produce with less material input (see Figure 42).

According to NEEDS a total amount of 285 tons of glass and 1’234 tons steel167 (and other materials which are not important in regard of a possible substitution with aluminium) are used for elevation and collectors by a solar field with a capacity of 5 MW168 . That implies a specific material input per installed MW of 247 tons steel and 57 tons of glass. All in all, a 5 MW solar field uses a total of 2’209 kg aluminium in components like cooling rips of the cool-ing tower. In summary, aluminium currently plays a minor role for Fresnel technologies.

Figure 42: Linear Fresnel collector at test plant Almeria169

Solar towers

The aluminium use in solar towers plays a subordinate role. The heliostat mirrors (which are composed of several small mirror modules) are made of iron and glass170. These materials 167 1’234 tons steel = 161 tons reinforcing steel + 555 tons converted steel + 519 tons rolling sheet (calculation with precise value) 168 Viebahn (2008): p. 88. 169 Source: Fraunhofer ISE.

or


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guarantee good reflection characteristics and are used in all heliostat fields on the market. The tracking systems which align the mirrors into sun beams are made of steel. The tower is made of concrete and steel frames. Finally, the aluminium used in solar towers is in the sub per mill range. Components which are made or partly made of aluminium are the cooling fins of the heat exchanger (80% of the aluminium use) and electrical components (20%)171.

Figure 43: Heliostats at Solar tower Jülich172

3.5.4 Technology scenarios for Concentrated Solar Thermal Power

The various market scenarios for CSP technologies differ significantly depending, amongst others, on the year of the studies. The lowest projected CSP capacity for 2020 is given by the two baseline scenarios of Greenpeace (Greenpeace Energy [R]evolution baseline sce-nario and Greenpeace: Sauberer Strom aus den Wüsten – reference scenario) and projects 8 and 7.4 GW. The projected capacities go up to 14 till 40 GW (Viehbahn and Pe-ter/Lehmann scenarios) (see Figure 44). Ambitious scenarios project capacities up to 84.3 GW of installed capacity of CSP technologies for 2020.

The newest report (Energy Technology perspectives) launched in July 2010 from the IEA projects a capacity of 147 GW for 2020 which is nearly two times higher than the highest pro-jected capacity of the other scenarios. This capacity corresponds with 1’500 newly installed 100 MW plants in the next ten years which, according to market experience, planned projects and duration of planning, is not realistic.

For 2030 the projections of the expansion scenarios also clearly diverge. The two reference scenarios of Greenpeace (12 and 12.8 GW) are almost under the actual planned CSP pro-jects. A set of scenarios (Viehbahn (2008), optimistic, IEA (2010b), MEF (2010), industry, Pe-ter/Lehmann (2007), high, Greenpeace (2008), moderate and ambitious) project an installed capacity for CSP of 200 GW and beyond. The Greenpeace ambitious scenario and the IEA (2010b) forecast the highest capacities of about 340 GW.

For 2050 the trends vary from 17 and 18 GW (Greenpeace baseline scenarios) to 1’524 GW (Greenpeace (2008), ambitious). A range of scenarios lies in the middle of these projections,

170 Expert interview with Barbara Fricke, research associate at Solarinstitut Jülich (SIJ), Germany. 171 ibd. 172 Source: Solarturm Jülich.


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between 800 GW (MEF (2010), industry, Greenpeace (2008), moderate) and 1’100 (IEA (2010b)).

In our SCENARIO BEST ESTIMATE, the capacity will rise to 30 GW in 2020 and 140 GW in 2030. The capacity of Concentrating Solar Power will be at 800 GW which is over forty times higher than in the SCENARIO LOW (see Figure 45 and Table 43).

The SCENARIO LOW projects a capacity of 8 GW of Concentrating Solar Power technolo-gies for 2020. For 2030 the capacity will rise to 13 GW. In 2050 the cumulated installed ca-pacity will be at 18 GW in SCENARIO LOW.

The SCENARIO HIGH projects a capacity 85 GW for 2020, 340 GW in 2030 and 1’500 GW for 2050. It projects a capacity that is 1’100 higher than SCENARIO BEST and 1’480 higher than in the SCENARIO LOW.

Figure 44: Technology scenarios for CSP technologies

Table 43: Chosen scenarios of future CSP developments in GW

in GW today 2020 2030 2050

SCENARIO LOW 0.5 8 13 18

SCENARIO BEST ESTIMATE 0.5 30 140 800

SCENARIO HIGH 0.5 85 340 1‘500

'0

'200

'400

'600

'800

1'000

1'200

1'400

1'600

2010 2020 2030 2040 2050

in GWPeter/Lehmann (2007), high


MEF (2009), moderate

MEF (2009), industry



Greenpeace (2009), reference

Greenpeace (2009), moderate

Greenpeace (2009), ambitious

UBA (2007), projection A

UBA (2007), projection B

Viehbahn (2008), very optimistic

Viehbahn (2008), optimistic-realisticViehbahn (2008), pessimistic

IEA (2010b)


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Figure 45: Scenarios for CSP technologies

To determine the electricity generation of CSP technologies and the CO2 abatement potential of these technologies a definition of the full load hours of these technologies is required. The problem here is that the solar radiation varies significantly in the different world regions. Addi-tionally only some regions are suitable for use. Another problem is the storage possibility. Depending on the future development of storage technologies the full load hours can be ex-tended. Full load hours also depend on the different technologies themselves. Today the so-lar fields Andasol I+II (parabolic dishes) run with average of 3’820 full load hours173. Higher full-load hours can be achieved with storage e.g., like in the Jordan/Aqaba Solar Water Pro-ject. But in such systems, with given solar areas, lower overall capacities can be achieved. To avoid calculation problems it is assumed that plants only run peak load during sun radia-tion.

To calculate the produced electricity and later the CO2 abatement potential it is assumed that the full load hours of today will not rise to a great extend as climatic prerequisites remain the same. The current operating concentrating solar power plants are well suited in the Sun Belt with full load hours of about 3’600.

173 Viebahn (2008): p. 8.

'0

'200

'400

'600

'800

1'000

1'200

1'400

1'600

today 2020 2030 2040 2050

in GW

IFEU HIGH

IFEU BEST ESTIMATE

IFEU LOW


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With the assumptions of 3’600 full load hours today and in future, CSP technologies actually generate about 2 TWhel per year. The electricity generation will rise to 29 TWh in the SCENARIO LOW, to 108 TWh in the SCENARIO BEST ESTIMATE and to 306 TWh in the SCENARIO HIGH in 2020. The produced electricity in 2030 will be between 47 TWh and 1’224 TWh, depending on the scenario chosen. In 2050 the electricity generation will be 65 TWh in the SCENARIO LOW about 2’880 TWh in the SCENARIO BEST ESTIMATE and about 5’400 TWh in the SCENARIO HIGH. In comparison, global electricity generation in 2007 was 19’771 TWh.

Table 44: Generation of electricity in TWh

On the basis of the yearly produced electricity of CSP technologies, CO2 abatement potential can be calculated thus. As a result it is necessary to define a CO2 abatement factor and sub-stitution factor. As no global substitution factor is available, we assume for a first-order esti-mate the same substitution factor as for PV (600 g CO2/kWh)174. Results are shown in Table 45. The CO2 abatement of CSP technologies in SCENARIO HIGH in 2050 (3’240 Mt) is nearly as high as CO2 abatement by solar thermal collectors.

Table 45: CO2 abatement potential of CSP technologies

in Mt CO2 2020 2030 2050




3.5.5 Resulting current and future aluminium use in CSP

As already mentioned above, solar fields do not use aluminium for the main components of the plants. Glass collectors are used for the collectors and steel is the main material used for the truss systems in all CSP technologies. But there are companies which already build alu-minium truss systems for solar fields. According to expert interviews, R&D trends and other indicators there is a high potential for aluminium to not only substitute steel and glass, but to play a significant role in future CSP technologies, especially in the collector design. There-fore, for the calculation of the overall aluminium use, assumptions have to be made with re-spect to the share of aluminium in the different components. The total specific aluminium use per MW includes a fix factor of aluminium used in the components where no potential is as-sumed (0.0008 t/MW):

174 CO2 abatement factor for PV is set to 600 gCO2/kWh, which is slightly higher than 591 gCO2/kWh mentioned by German Federal Ministry of Environment (FEDERAL MINISTRY OF ENVIRONMENT, GERMANY 2009: Erneuerbare Energien in Zahlen: page 24).

in TWh 2020 2030 2050





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Table 46: Assumptions of the market shares of significant components of solar fields in the different scenarios in 2020, 2030, 2050 (in %)

2020 2030 2050

Scenario LOW BEST

E. HIGH LOW

BEST E.

HIGH LOW BEST

E. HIGH

Collector 0% 10% 20% 0% 20% 50% 0% 30% 100%

Elevation 0% 40% 50% 0% 60% 70% 0% 60% 100%

Total specific aluminium use (kg/kW)

0.0008 36.1 49.1 0.0008 56.8 80.6 0.0008 62.2 130.6

The resulting aluminium use in the SCENARIO LOW (with the assumption of an aluminium market share of 0% both of elevation and collectors and a low expansion scenario of CSP technologies) is negligible. In SCENARIO BEST ESTIMATE aluminium use will be at 1.1 Mt in 2020 with the assumption of a market share of 10% of aluminium for the collectors and 40% of the truss systems and a moderate development of CSP technologies (see Table 47). In 2030 a market share of 20% for collectors and 60% for elevation can be assumed. Summed up with a moderate CSP scenario, the aluminium use will be around 8 Mt. An alu-minium use of about 50.8 Mt is shown until 2050 with the assumptions of a market share of 30% for collectors and 60% for elevation. If the same moderate installation rates are as-sumed but specific aluminium use is varied, Al maximum leads to 104’500’000 t in Scenario Best Estimate Plus and Al minimum leads to 640 tons in Scenario Best Estimate Minus.

Significantly higher are the amounts of aluminium in SCENARIO HIGH that reflects a sce-nario where aluminium will be employed up to 100% in the different components. In this sce-nario an aluminium use of 4.2 Mt in 2020 and of 27.4 Mt in 2030 is possible. An optimal mar-ket development resulting in a market share of 100% both of collectors and truss systems would lead to a aluminium use of as much as 196 Mt in 2050.

Table 47: Total aluminium use in CSP technologies

in t 2020 2030 2050



SCENARIO BEST ESTIMATE 1‘100‘000 8‘000‘000 50‘8000‘000

SCENARIO BEST ESTIMATE Plus 1'500‘000 11'300‘000 104'500‘000

SCENARIO HIGH 4‘200‘000 27‘400‘000 196‘000‘000

In SCENARIO BEST ESTIMATE an annual aluminium use of 0.3 per cent of the annual aluminium production in the first decade between 2010 and 2020 is to be found (see Table 51). Aluminium use rises to an annual 1.9 per cent in the next decade. The years from 2031 until 2050 show a considerate share on the total production of 5.7 per cent. In SCENARIO HIGH, the annual aluminium use in CSP technologies is at 1.2 per cent of the total produc-tion in the first decade. In the next decade between 2021 and 2030 the annual aluminium


85

share on the total worldwide aluminium production rises to 6.4 per cent. With the assump-tions of a total market share of 100 per cent aluminium, both in elevation and collectors, in the year 2050, CSP technologies can reach an annual 23.1 per cent (nearly one fourth) of the total aluminium production.

Table 48: Future total and annual aluminium use per decades in tons and as percentage of annual global aluminium production

Annual Al use (Mt) Annual Al use as percent-age of annual Al produc-

tion1 SCENARIO LOW

2010-2020 0.0000006 -

2021-2030 0.0000004 -

2031-2050 0.0000002 -


2010-2020 0.00000240 -

2021-2030 0.00001 -

2031-2050 0.00003 -


2010-2020 0.11 0.3

2021-2030 0.69 1.9

2031-2050 2.09 5.7


2010-2020 0.15 0.4

2021-2030 1.13 3.1

2031-2050 5.22 14.4

SCENARIO HIGH

2010-2020 0.42 1.2

2021-2030 2.32 6.4

2031-2050 8.425 23.1

1 Annual production: 36’400’000 tons (Source: IAI 2010).

Fresnel- and Central Receiver technologies (excursion)

Whereas parabolic troughs have been operating for over 25 years und generate electricity under commercial circumstances, Fresnel troughs and central receivers are still in the devel-opment stage. Because data is lacking, detailed information about future aluminium use can only be made for parabolic troughs. However, assumptions of many market actors indicate that these technologies might have a bigger market share in future. Therefore, it is necessary to outline a perspective on how aluminium use will change when those technologies will have a market potential.


86

The basis of the following analysis is the NEEDS LCA’s of the different technologies and fo-cused on the fields and elevation175. Parabolic troughs, Fresnel systems and central receiv-ers have different collector designs with a different amount of material input. Aluminium de-mands vary significantly for each of these technologies. For example, the amount of alumin-ium used to build heliostats (for central receivers) is about half the amount which is used in the example parabolic field of the LCA. The specific aluminium use of the central receiver, however, is one third of the one of the solar field (designed with parabolic troughs).

To compare the different technologies among each other, it is necessary to normalize the material inputs of the different components (elevation and collector) to one MW to make pre-cise statements. With this information, quotients can be calculated to compare Fresnel-troughs and central receivers with the parabolic reference technology. Results attest to the fact mentioned above that Fresnel troughs are much lighter than parabolic troughs. The glass amount for collectors which is used for Fresnel technology is only 43 per cent of the amount used for a parabolic field to get the same capacity (proportion Fresnel/parabolic of 0.43). The difference between the amounts of steel used for elevation also varies. For Fres-nel troughs only around 75% of the steel amount of parabolic troughs is used.

The proportions of central receivers (in regard of parabolic troughs) go into a different direc-tion. The amount of glass which is used for heliostats to get 1 MW capacity is 59% higher than for parabolic troughs and the amount of steel for the elevation is 86% higher.

Table 49: Comparison of material inputs in Parabolic, Fresnel and Central receiver technologies

Name Andasol Novatec SolarTres Proportion

Type Parabolic Fresnel Heliostat Fres-

nel/Parabolic Central Recei-ver/Parabolic

Capacity 46 MW 5 MW 15 MW

Collector design glass glass glass

Weight in kg 6’148’846 285’234 3’180’904

kg/MW 133’671 57’047 212’060 0.43 1.59

Elevation steel steel steel

Weight in kg 15’168’192 1’234’928 9’204’250

kg/MW 329’743 246’986 613’617 0.75 1.86

Concerning the substitution of steel and glass by aluminium, it is assumed that Fresnel-troughs and heliostats materials could be replaced by aluminium as aluminium has almost the same reflectance.

In summary, if Fresnel troughs would be the most common future CSP technology the alu-minium use for CSP would decrease in a significant way because the aluminium input for col-lectors (25% less material demand as in parabolic trough system) and elevation (53% less material demand) would be much less than for parabolic troughs. On the other hand, if cen-tral receivers would replace parabolic troughs in future the aluminium use would be higher (plus 59% for collectors and 86% for elevation).

175 Viebahn (2008): p. 88.


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Aluminium use in storage systems (excursion)

The biggest problem of renewable energies now and in future will be the possibility to store the produced energy. This is especially evident for the fluctuating energies - wind and solar power. An additional problem is valid for CSP technologies. To use CSP for base load elec-tricity generation it makes it necessary to store the produced electricity over the day period when the sun does not shine. Over the whole year sun radiation is also not available every day. Therefore, energy has to be saved (at least to balance daily fluctuations).

Possible storage systems are:

molten salt concrete phase Change Material storage (PCM) pressurized Water – ruths and hot water storage.

In regard of aluminium, Phase Change Material storage systems include aluminium. This storage possibility has a great future potential in comparison with the other storage types176. To store 1 MWhth (in a system of 600 MWth and a storage time of 16 h), an aluminium input of around 3 tons is necessary.177

176 Compare with Viebahn (2008): 50. 177 Viebahn (2008): p. 87.


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3.6 Cables used in focus REn technologies: excursion

Cables are essential to transmit generated electricity from its place of generation to the place where electricity is transformed. The requirements concerning the technical and electrical properties of those cables can vary depending on the type of electricity generation. The dis-tance between generation and transformation is one of the key points for the decision how to transmit electricity. In future the need to transport electricity over long distances will increase in a way that much effort will be necessary to overcome the associated challenges.

Large CSP power plants (like Desertec) are currently being planned or under construction in Europe, the Middle East and in North Africa (EUMENA). In the long term the aim is to cover big parts of the European energy demand with electricity produced in the MENA (Middle East & North Africa). Also, offshore wind parks in the seas around Europe, especially in the North, are under development.

Fluctuation of renewable energies, especially wind and solar energy, makes it necessary to transport electricity over long distances to balance variations. The regional distance between production and demand is therefore an important factor. Offshore wind energy is available in the seas of Northern and Western Europe. Concentrating solar power can only be produced in the Mediterranean regions of Southern Europe.

Additionally, offshore wind energy needs to improved technology to transport electricity over long distances. The existing European grid system is unsuitable for these challenges.. AC cables have high transmission losses so that they are unsuitable for high distances. Another reason why electricity transportation over long distances will get more important is that the centers (conurbations; big cities) where most of the electricity is needed are not suitable to produce energy in vast amounts.

HVDC (High Voltage Direct Current) cables are used currently as they are the best option to transport electricity over long distances without high performance losses (approx. 10 per cent at a distance of 3’000 km). HVDC are cables with a voltage of over 100 kV. Currently used cables for energy transportation are cables with about 800 kV which can transport an electric load of 10 GW over distances of about 3’000 km178.

In comparison to conventional AC high voltage lines HVDC need an AC/DC converter in-stead of a common transformer to change the AC voltage into DC. This makes HVDC lines very expensive so they are not economically beneficial until a distance of about 600 kilome-ters for overhead lines and about 50 kilometers for submarine cables179.

Currently, a total of about 75,000 MW (divided into 92 different projects) are transmitted through HVDC lines all over the world180. The overwhelming majority of these cables have voltages between 100 kV and 500 kV. The current stage of market and future development assume a wide range future distribution of 800 kV HVDC lines.

178 Viebahn (2008): p. 87. 179 ABB (2010). 180 May (2005): p. 31.


89

Figure 46: HVDC cables (submarine in front; overhead in back)181

To make future assumptions of the potential of aluminium use for HVDC lines, a line with a voltage of 800 kV has been analyzed. Overhead cables and submarine cables use different materials because of special requirements they need to fulfill. While both cables have to re-sist corrosion, overhead lines must to be resistant against air impacts or desert influences like sand storms and submarine cables must to be resistant against water and the influences of salt water. Thus the structure of the cables more specifically the coat has to be different.

The main material used for overhead cables is reinforcing steel with 150 tons used for a one kilometer long cable. Chromium steel has an amount of 12.8 tons per kilometer. Aluminium is the second most important material in HVDC overhead cables with a total amount of 34.8 tons. Other materials are concrete and ceramic tiles with a total amount of 4.2 tons182. Sub-marine cables have a completely different structure and use different materials. The main materials are chromium steel, copper and lead. Differing figures for aluminium use in subma-rine cables are shown in Table 50.

Table 50: Specific aluminium use for HVDC cables

Material Unit Material unit/km Material unit/km

HVDC Overhead HVDC Submarine

Reinforcing steel kg 150‘000 -

Concrete m3 163 -

Aluminium kg 34‘800 1/1‘100/2‘200183

Ceramic tiles kg 4‘000 -

Chromium steel kg 12‘800 192’000

Copper kg - 152’000

Lead kg - 136’000

Paper kg - 48’000

Polybutadiene kg - 8’000

181 Source: ABB. 182 May (2005): p. 110. 183 Source: Prysmian Cables and Systems (2010), own assumptions.


90

Polypropylene kg - 18’400

Potential of aluminium use in HVDC cables in future

The aluminium use for one kilometer of overhead cable is around 35 tons. Projected to a ca-ble transmission line with a distance of 3’000 kilometers, the total amount of aluminium for one EU-MENA electricity transmission line is 105’000 tons.

With regard to the future installed capacity for wind and CSP approximately 10 of those transmission systems, with an average length of 3’000 kilometers, could be installed in the next 40 years in the EU-MENA region (see Figure 46)184. This would correspond to a total aluminium use, for HVDC overhead cables, of approximately 1’050’000 tons (approx. 1 Mt).

Assuming an additional 1’100 kilometers of submarine cables will be installed among Medi-terranean neighboring countries185, aluminium sales for HVDC submarine cables that con-nect Europe and Africa (e.g. DESERTEC) could be 1.1 tons if only marginal amounts of alu-minium are used. (e.g. aluminium foil), 1’210 tons if moderate amounts of aluminium are used (e.g. aluminium water barrier) or 2’420 tons if the maximum amount of aluminium is used (e.g. strengthened aluminium water barrier).

Figure 47: Trans-Mediterranean Interconnection for Concentrating Solar Power186

184 Own assumptions. 185 Trieb (2006): page15; own assumptions. 186 Source: DLR.


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4 Overall potential of aluminium

4.1 Summary of specific aluminium use in renewable energy systems


Currently it is estimated that 0.3 Mt of aluminium are used in solar thermal collectors, mainly in absorbers, casings and frames. Studies support the trend of increasing aluminium use in absorbers. Out of 289 systems analyzed, 34% use aluminium absorbers with increasing ten-dency. In evacuated tube solar thermal collector frames, steel could be replaced by alumin-ium. While both aluminium and steel are readily available in local markets, aluminium has a distinctive advantage as it is lighter than steel.

Systems with water tanks are very common in China and developing countries. They are primarily made of steel to prevent corrosion and because of the lower prices. In water tanks, stainless steel can be replaced by aluminium, but it is recommended to only replace steel in the outer tank as the inner tank is permanently in contact with water. If a reflector shield is used, it could be made of aluminium due to its good reflectance characteristics. A reflector shield enhances energy yield of absorbers significantly, therefore, a very high market poten-tial for aluminium can be found. If this substitution potential was realized, the specific use of aluminium could be increased from 3.1 kg/m² to 4.3 kg/m² (flat-plate) or 0.9 kg/m² to 4.3 kg/m² (evacuated tube).

Wind turbines

The material predominantly used in wind turbines is steel which accounts for about 85% of the total material input, with aluminium only playing a subordinate role. It is estimated that around 0.1 Mt of aluminium are processed in wind turbines today, primarily in nacelles and rotors.

While material usage is and will continue to be dominated by steel, the wind turbine nacelle and rotor casings are potential components where aluminium use could be increased.


Aluminium in PV systems is used predominantly in construction/mounting structures (72% of total aluminium input), followed panel frames (22%), and lastly inverters (6%). Our review shows that between 23 kg/kW and 59 kg/kW of aluminium are used. The advantage of alu-minium is that it is lighter than other metals, which is very important for construction/mounting structures. Profiles for mounting are primarily made of aluminium due to its lighter weight. Furthermore aluminium is recyclable and makes it easier for profile geometries to meet sys-tem requirements.

The full market sales potential of aluminium in photovoltaic systems would unfold if alumin-ium were used more often for mounting and frames. There is no clear trend that might indi-cate an increase or decrease of aluminium use for PV technologies. But market development for panels without frames and wooden frames as well as developments in mounting materials should be looked at closely in future.


92

Solar cookers

Usage of aluminium in solar parabolic cookers varies widely. Solar parabolic cookers consist of a frame and a reflector. Either no aluminium is used at all (e.g. reflector made of optical polyester and/or wooden frame) or all components are made of aluminium. Usage varies widely between 0.1 kg/unit if no aluminium is used (e.g. reflector made of optical polyester and/or wooden frame) and 20 kg/unit if both components are made of aluminium. Solar community kitchen reflectors are usually made of steel and reflecting glass. For the mounting structure steel is used intensively while aluminium is found in the profiles which bear the re-flectors.

Even if aluminium use potential is low, when compared to other technologies, solar cookers could be a favourable technology on which to focus, especially with regard to CDM projects. Since there is no clear trend in which direction material inputs will evolve for solar cookers, cheap and light systems which don’t currently use aluminium should be further observed in the upcoming years.

CSP

Concentrated solar power (CSP) based on parabolic troughs are silver-based mirrors made of special flat glass. The system frames can be made of steel and aluminium, respectively. Some companies have developed aluminium frames which are already used in solar fields. The use of aluminium for parabolic troughs varies widely because of different build require-ments (e.g. to withstand storms). The absorber systems are made of stainless steel with se-lective coatings and the envelopes consist of Borosilicate anti-reflective glass. Aluminium is used in parts of the power block and the cooling tower. Specifically the cooling fins are made of aluminium.

Minimum aluminium use is given when collectors are made of glass and the elevation is made of steel. The maximum aluminium amount is given when both elevation and collectors are made of aluminium. In that case the specific aluminium use could increase to 131 kg/kW in an optimistic scenario.

If Fresnel troughs were the most common future CSP technology, the aluminium use for CSP would decrease significantly compared to parabolic troughs because the aluminium input for collectors and elevation would be much less than for parabolic troughs. On the other hand, if central receivers would replace parabolic troughs as alternative CSP technology the alumin-ium use would be higher.

All technologies

Comparing the aluminium use of the various technologies, Figure 48 demonstrates that par-ticularly PV and CSP have high specific amounts of aluminium in Al moderate, and even more in Al maximum scenario. This is due to a rather high percentage of aluminium in the components as well as (e. g. compared to solar collectors) rather low conversion efficiencies. If aluminium use moved from Al moderate to Al maximum, especially in PV and CSP sys-tems, total as well as annual aluminium sales could be maximized substantially. Possible fu-ture trends and maximization options of aluminium use are summarized in Table 51. It must be noted that in Figure 48, the use is normalized to a kW heat for collectors or electricity for the other technologies.


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Figure 48: Specific aluminium use in the various technologies (per kW heat (solar thermal collectors) or kW electricity (others); FP: flat-plate, ET: Evacuated tube)

Table 51: Summary of future trends regarding specific aluminium use in renewable energy systems

Component Remarks


Flat-plate Absorber

market is dominated by copper, but increase in aluminium use in recent years

aluminium needs to be thicker than copper to have same conductivity

Evacuated tube

Frame steel replacement possible advantage of aluminium as it is lighter

Reflector shield high market potential aluminium increases absorber efficiency

Header pipes &Heat pipes

copper replacement possible, but low replace-ment potential

Water tanks if water storage tanks are used, replacement of

steel at least in outer tank is possible

Wind turbines

Nacelle

aluminium in covering of nacelle possible (e.g. Enercon turbine)

no significant difference between on- and off-shore wind turbine replacement potential

Rotor cast iron and glass fibres could be replaced increased use of light weight composites

PV - Frame

profiles and frames are mostly made of alumin-ium

advantage of aluminium: combination of stiffness

0

20

40

60

80

100

120

140

Solar collector

FP

Solar collector

ET

Wind Onshore

Wind Offshore

PV CSP

Sp

ecif

ic a

lum

iniu

m u

se (

kg/k

W)

Al maximum

Al moderate

Al minimum


94

and light weight characteristics

Mounting no clear trend developments in frame and mounting materials

should be closely monitored

Solar cookers

either solar cooker consists of 100% aluminium or not at all

developments concerning cheap and light sys-tems not using aluminium should be monitored carefully

CSP Parabolic troughs

Elevation & Collector

huge potential if elevation and collectors are made of aluminium instead of glass and steel

Fresnel

aluminium used in components like cooling rips of the cooling

replacement potential in troughs where alumin-ium replaces steel

4.2 Overall use of aluminium in renewable energy systems

To calculate the overall market sales potential of aluminium in renewable energy systems the specific aluminium use as shown above was linked to the various technologies installation scenarios.

We define three scenarios and two variations (sub-scenarios): In SCENARIO BEST ESTIMATE, the specific aluminium use and technology scenario are based on moderate as-sumptions. As this scenario is the most likely reference scenario, it is further differentiated by assuming moderate installation rates and maximum specific aluminium use (SCENARIO BEST ESTIMATE Plus) as well as moderate installation rates and minimum specific alumin-ium use (SCENARIO BEST ESTIMATE Minus). A pessimistic estimate regarding the specific aluminium use and the expansion of renewable energy systems constitutes SCENARIO LOW, while the optimistic SCENARIO HIGH assumes a high specific aluminium use and op-timistic rates of expansion. The two latter scenarios, however, are to be interpreted as the upper and the lower end of the scenario funnel and are not considered to be very likely.

In 2020, total aluminium use for all renewable energy systems would be around 6 Mt in SCENARIO BEST ESTIMATE (see Figure 49 and Table 53), increasing to 20 Mt in 2030 and 88 Mt in 2050. If moderate installations were assumed and moderate use of aluminium was optimized from Al moderate to Al maximum (SCENARIO BEST ESTIMNATE Plus), market sales could reach 188 Mt in 2050.

If aluminium market sales potential and rates of installations are assumed to be pessimistic, significantly lower amounts of 4 Mt are projected for the SCENARIO LOW in 2050, whereas in the SCENARIO HIGH 470 Mt are projected for the year 2050 if installed capacities de-velop optimistically and aluminium replacement potential is fully tapped (very optimistic as-sumptions).


95

Figure 49: Total aluminium invested in renewable energy systems in the different scenarios

In Figure 50 annual aluminium sales in renewable energy systems are shown for the SCENARIO BEST ESTIMATE, in which the total annual aluminium use increases steadily. From today until the year 2020, approximately 0.5 Mt or 1.4 percent of annual aluminium production would be used in renewable energy systems every year. Between 2021 until 2030, total annual aluminium use for renewable energy systems will increase to around 1.5 Mt or four percent of annual aluminium production and from 2031 until 2050 to 3.3 Mt or nearly 9 percent of annual aluminium production187.

It is clear that solar-based technologies (CSP, PV and solar thermal collectors) are most sig-nificant to the overall potential. Concerning solar cookers only an overall potential until 2050 has been estimated due to a lack of scenario information. Until 2050 approximately 0.3 Mt would be processed, meaning that annual aluminium use is low (less than 0.1% of annual aluminium production).

187 IAI Statistics (2010).

0

100

200

300

400

500

2020 2030 2040 2050

Mt Aluminium

SCENARIO HIGH




SCENARIO LOW


96

Figure 50: Projected annual aluminium use in renewable energy systems in the SCENARIO BEST ESTIMATE188

In Figure 51 and Figure 52 annual aluminium sales for the two variations (sub-scenarios), which assume the same moderate installation rates as in SCENARIO BEST ESTIMATE with a shift from Al moderate to Al maximum, are indicated. As shown in SCENARIO BEST ESTIMATE Plus, the rise of aluminium use from Al moderate to Al maximum in solar-driven technologies seems to be very promising. Here, aluminium sales could be more than dou-bled in CSP and solar thermal collectors and could be almost tripled in PV technologies.

Figure 51: Projected annual aluminium use in renewable energy systems in the SCENARIO BEST ESTIMATE Plus

188 Due to very low figures solar cookers have been exempted.

0

5

10

15

20

0,0

1,0

2,0

3,0

4,0

5,0

6,0

7,0

8,0

9,0

today-2020 2021-2030 2031-2050


Mt/a


Wind turbines


CSP

0

5

10

15

20

0,0

1,0

2,0

3,0

4,0

5,0

6,0

7,0

8,0

9,0

today-2020 2021-2030 2031-2050


Mt/a


Wind turbines


CSP


97

If aluminium use decreased from Al moderate to Al minimum as assumed in SCENARIO BEST ESTIMATE Minus, only PV systems would show a noteworthy aluminium market sales potential.

Figure 52: Projected annual aluminium use in renewable energy systems in the SCENARIO BEST ESTIMATE Minus

Figure 53 and Figure 54 show results for SCENARIO HIGH and SCENARIO LOW. As men-tioned earlier, these scenarios are to be interpreted as the upper and the lower end of the scenario funnel and are not to be considered very likely.

Figure 53: Projected annual aluminium use in renewable energy systems in the SCENARIO HIGH

0

5

10

15

20

0,0

1,0

2,0

3,0

4,0

5,0

6,0

7,0

8,0

9,0

today-2020 2021-2030 2031-2050


Mt/a


Wind turbines


CSP

0

5

10

15

20

0,0

1,0

2,0

3,0

4,0

5,0

6,0

7,0

8,0

9,0

today-2020 2021-2030 2031-2050


Mt/a


Wind turbines


CSP


98

Figure 54: Projected annual aluminium use in renewable energy systems in the SCENARIO LOW

With the projected market expansion of renewable energy systems, considerable amounts of electricity and heat can be generated. For example, in the SCENARIO BEST ESTIMATE to-tal electricity produced in 2050 is projected to supply 50% of current global electricity. Other renewable energy sources such as hydropower, biomass and geothermal will complement this generation. In SCENARIO LOW and HIGH these shares are 20% and are around 100% of 2008 electricity consumption. Taking into consideration the rising electricity demand and the generation of electricity in other renewable electricity systems, the latter scenario would imply a move toward a 100% renewable electricity system and thus represents the upper boundary of a probable development. Please note that the focus of this calculation is to de-termine aluminium market sales potentials for individual technologies and not the creation of a synchronized set of global energy scenarios.

Correspondingly, in 2020 renewable energy systems in SCENARIO BEST ESTIMATE would help abate 1’300 Mt of CO2 emissions compared to marginal technologies (gas and coal electricity generation and gas/oil heating systems) (see Figure 55 and Table 55 for more de-tails). In comparison, the annual emitted CO2 emissions in 2007 was 28’962 Mt of CO2. In 2030 3’200 Mt of CO2 would be abated and in 2050 7’300 Mt would be saved with renewable energy systems. Complemented by other renewable technologies and efficiency measures, significant carbon savings could be achieved when compared to the current levels. Projec-tions in the two other scenarios vary from 1’800 Mt (SCENARIO LOW) to 18’200 Mt (SCENARIO HIGH) for 2050.

0

5

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15

20

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1,0

2,0

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4,0

5,0

6,0

7,0

8,0

9,0

today-2020 2021-2030 2031-2050


Mt/a


Wind turbines


CSP


99

Figure 55: Projected CO2 abatement potential in SCENARIO BEST ESTIMATE compared to marginal technologies (gas and coal electricity generation and gas/oil heating systems)

0

50

100

150

200

250

today-2020 2021-2030 2031-2050

Mt CO2/a


Wind turbines

PV

Solar cookers

CSP


100

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107

6 Annex

6.1 Detailed results

Table 52: Projected annual aluminium use for all Renewable Energy Systems (million tons, Mt)

Annual Al use in Mt

Annual Al use as percentage of an-nual Al production189 (rounded)

SCENARIO LOW

2010-2020 0.05 0.12

2021-2030 0.13 0.33

2031-2050 0.08 0.21


2010-2020 0.17 0.5

2021-2030 0.39 1.1

2031-2050 0.59 1.6


2010-2020 0.51 1.4

2021-2030 1.45 4.0

2031-2050 3.31 9.1


2010-2020 1.11 3.1

2021-2030 3.40 9.3

2031-2050 8.76 24.1

SCENARIO HIGH

2010-2020 3.70 10.2

2021-2030 10.24 28.1

2031-2050 16.26 44.7

189 Aluminium production: 36.4 million tons.


108

Table 53: Projected total aluminium use (million tons, Mt)

in million tons (Mt) 2020 2030 2050 Solar thermal collectors






Wind turbines






PV SCENARIO LOW 1 2 4





Solar cookers190

SCENARIO LOW - - 0.000001

SCENARIO BEST ESTIMATE Minus 0.0083

SCENARIO BEST ESTIMATE - - 0.25

SCENARIO BEST ESTIMATE Plus 1.66

SCENARIO HIGH - - 3.34

CSP SCENARIO LOW 0.000006 0.00001 0.00001


SCENARIO BEST ESTIMATE 1.1 8 50.8

SCENARIO BEST ESTIMATE Plus 1.5 11.3 105

SCENARIO HIGH 4.2 27.4 196

TOTAL (rounded)

SCENARIO LOW 1 2 4





190 An overall potential is indicated because no scenario exists.


109

Table 54: Projected electricity and heat generation of the selected systems in 2020, 2030, 2050 in TWh

in TWh 2020 2030 2050

HEAT

TWhthermal

Solar ther-mal collectors


SCENARIO BEST ESTIMATE 700 1,900 6‘600

SCENARIO HIGH 2‘600 5‘100 11‘600

Electricity

TWhel.

Wind turbines

SCENARIO LOW 820 1‘230 1‘640


SCENARIO HIGH 2‘550 6‘640 10‘920

PV




CSP




Total (rounded)



SCENARIO HIGH 3‘140 9‘330 20‘200


110

Table 55: Projected CO2 abatement potential of renewable energy systems in million tons (Mt) com-pared to marginal technologies (gas and coal electricity generation and gas/oil heating systems)

in million tons (Mt) 2020 2030 2050 Solar thermal collectors


SCENARIO BEST ESTIMATE 220 560 2,000


Wind turbines SCENARIO LOW 600 1‘000 1’300

SCENARIO BEST ESTIMATE 1’000 2’200 4’900

SCENARIO HIGH 2’000 5’200 8’500

PV SCENARIO LOW 21 60 100



Solar cookers191

SCENARIO LOW - - 8

SCENARIO BEST ESTIMATE - - 208

SCENARIO HIGH - - 618

CSP SCENARIO LOW 20 30 40



TOTAL (rounded)

SCENARIO LOW 700 1‘300 1‘800


SCENARIO HIGH 3‘200 8‘300 18‘200

191 An overall potential is indicated because no scenario exists.

aluminium and renewable energy systems – prospects for the

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