evaluation of carbon capture and storage
TRANSCRIPT
Energy Economics 1
‘Evaluation of Carbon Capture and Storage (CCS): Potentials & Problems’
Participant:
Ahmed Hussein, 173666
Lecturer: Prof. Dr. Anke Weidlich
23 January 2015
Hochschule Offenburg
Badstraße 24, 77652 Offenburg
Department: Mechanical- and Process-Engineering
Study course: Energy Conversion and Management
January 12, 2012 [CCS: Potentials and Problems]
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Abstract
The Carbon dioxide emissions and its direct effect on the global warming has been
the main topic in almost all of the discussions related to the climate change in the last
couple of decades.
Carbon capture and storage (CCS) or Carbon capture and sequestration, is a new
and innovative technology that covers a broad range of methodologies which have
been developed to allow an adequate capture, transportation and safe storage for the
CO2 emissions into a safe geological storages. Instead of dissipating CO2 into the
atmosphere, this technology has been adopted as the leading solution for reducing
the greenhouse effect and its negative impact on the environment.
Some newly developed technologies could help to spread out the commercial
deployment of CCS technologies into industries and lead to cost reductions for CO2
capture technologies and monitoring stored CO2 techniques.
With the fact that CCS will always require additional energy and as an attempt to
employ such a new technology, it is very important to predict and compromise in both
short and long runs to understand how actually this new technology will be beneficial
based on different prospects and diverse aspects. For example, power plants
operators will require to see an appropriate value to invest such technology while on
the other hand the environmentalists will call for legislated laws for mitigating the
contribution of fossil fuel emissions to global warming.
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Contents
Abstract ............................................................................................................... 1
List of figures ..................................................................................................... 3
List of tables ...................................................................................................... 3
1 Introduction .................................................................................................. 4
2 Basics ............................................................................................................ 5
2.1 General ..................................................................................................................... 5
2.2 Scrubbing technologies ...................................................................................... 6
2.2.1 Post combustion capture .............................................................................. 6
2.2.2 Pre-combustion capture................................................................................ 7
2.2.3 Oxy-fuel combustion...................................................................................... 8
2.3 Transportation ........................................................................................................ 9
2.4 Sequestration (storage) ..................................................................................... 10
2.4.1 Geological storage ....................................................................................... 10
2.4.2 Ocean storage .............................................................................................. 11
2.4.3 Mineral storage ............................................................................................ 12
3 CCS potentials........................................................................................... 13
4 CCS problems ........................................................................................... 14
5 Conclusion ................................................................................................. 16
6 List of references ...................................................................................... 17
January 12, 2012 [CCS: Potentials and Problems]
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List of figures
Figure 1: CCS ........................................................................................................................ 5
Figure 2: A schematic of post-combustion capture for coal emissions ................................. 6
Figure 3: Simplified model of a post- combustion capture unit ............................................ 7
Figure 4: A schematic of oxy-fuel combustion capture......................................................... 8
Figure 5: CO2 transportation .................................................................................................. 9
Figure 6: A schematic for geological storage of CO2 .......................................................... 10
Figure 7: A schematic for ocean CO2 storage ...................................................................... 11
Figure 8: A schematic for mineral CO2 storage................................................................... 12
Figure 9: A schematic for CO2 leakage to the fresh water wells ................................... 15
List of tables
Table 1: Comparison of power stations with and without CO2 capture .............................. 14
January 12, 2012 [CCS: Potentials and Problems]
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1 Introduction
The following report shall discuss the CCS evaluation in order to identify the
potentials and problems that may accompany this technology when considered
technically feasible in industry. With a rapid spreading technologies of CCS, a
possible key advances for CO2 sequestration technology are expected to arise in the
next 50 years from an eventual adoption of CCS as a standrad procedure for all large
stationary fossil fuel installations. This; for sure, will include a gradual improvement
(replacement) for current power plants involving new technologies like ion transfer
membranes to produce pure oxygen which is then to be used in Oxy-fuel combustion
processes resulting in significant reduction in flue gases by 75% as well as consistent
pure product of CO2 ready for direct sequestration.
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2 Basics
2.1 General
Capturing and compressing CO2 requires much energy and would increase the fuel
needs of a coal-fired plant with CCS by 25%-40%.
At large point sources, such as large fossil fuel or biomass energy facilities and other
industries with large amounts of CO2 emissions, CCS can be applied.
Figure 1: CCS
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2.2 Scrubbing technologies
2.2.1 Post combustion capture
As the main technology used in fossil-fuel burning power plants, the CO2
emissions are directly captured from the flue gases at power stations or other large
point sources.
Figure 2: A schematic of post-combustion capture for coal emissions
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2.2.2 Pre-combustion capture
By using gasifiers, the fossil fuel used in the utility is partialy oxidized. The flue
gases produced (CO and H2O) are then transformed to CO2 and H2 by the mean of
water-gas shift reactions. CO2 is then ready for transportation and storage, while the
H2 can be used in industry as fuel. This technology is widely used in fertilizer,
chemical, gaseous fuel (H2, CH4), and power production.
Figure 3: Simplified model of a pre- combustion capture unit
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2.2.3 Oxy-fuel combustion
A pure oxygen is used for the whole combustion process resulting in high
temperature combustions. Not only the usage of pure oxygen will result in
significant reductions in flue gases (75% reduction), but also will provide pure
combustion products of CO2 and H2O and an overall sufficient emission control.
Figure 4: A schematic of oxy-fuel combustion capture
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2.3 Transportation
Although the COA conveyor belt system or ships are usually the conventional
ways for transport, transportation of CO2 through pipelines remains the cheapest way
of transmission. The transfered CO2 quantities are then stored in either geological,
ocean or mineral storages or used in EOR (Enhanced Oil Recovery) activities.
Figure 5: CO2 transportation
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2.4 Sequestration (storage)
2.4.1 Geological storage
It is the option that suggests injecting the CO2 in high pressures and
temperatures directly into underground geological formations. In oil or gas fields,
saline formations and saline-filled basalt formations are the best choice for
storing CO2. Using geochemical trapping mechanisms should be used to prevent
leaking of CO2 back to the surface.
Figure 6: A schematic for geological storage of CO2
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2.4.2 Ocean storage
Carbon dioxide is fed and stored deep down in ocean water in two ways:
CO2 is injected into high depths (1000-3000 m) under the seawater level
through pipelines or specially equipped ships which is then forming upward-
plumes and hence the CO2 is dissolved in seawater.
CO2 is injected into very high depths (more than 3000 m) where such
depths could cause the injected CO2 to liquify at lower densities than
seawater forming a lake of accumulated CO2 in the sea floor.
Figure 7: A schematic for ocean CO2 storage
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2.4.3 Mineral storage
CO2 is forced at this case to react with metal oxides in order to form stable
carbonates. This reactions require a suitable conditions as well as a lot of
energy for the conduct of the chemical reactions.
Figure 8: A schematic for mineral CO2 storage
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3 CCS potentials
Scrubbing CO2 from ambient air as a geoengineering technique, would
directly affect the international endeavors for reducing the greenhouse
effect on global warming.
CCS could reduce the emissions of CO2 to the atmosphere by 80-90% if
applied to modern conventional power plants.
The IPCC (Intergovernmental Panel of Climate Change) which is a scientific
intergovernmental trend established in 1988 by the UN, estimates that the
economic potential of CCS could be between 10% and 55% of the total
carbon mitigation effort until 2100.
In long term estimations and as a result of the world’s gradually growing
care for the environment, some successful research done by (RD&D) trends
suggested that electricity generation from coal-fired power plants in 2025
employing CCS will cost less than those that do not employ CCS
technologies.
Plenty of storage capacities worldwide should not pop out problems about
where to store the captured CO2. NETL (National Energy Technology
Laboratory) reported that Northern America has enough storage capacities
at its current rate of production for more than 900 years worth of CO2.
Captured CO2 would be very effective when utilized in EOR (Enhanced Oil
Recovery) technologies and in other productive industries like fire
extinguishing systems, production of stable carbonates, limestone and other
CO2 based industries.
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4 CCS problems
The process of CCS consumes energy, which means an increase in the fuel
needed by e.g. coal-fired power plant would increase by 25-40%.
CCS technologies would reflect on the cost of energy supply by 21-91%.
Therefore, the cost of energy entring homes will be endangered.
% LHV $/kW c/kWh $/t CO2
Low heating value percentage US dollars per kilo watt Cents per kilo watt hour US dollars per ton of CO2
More geographical restrictions and limitations would be enforced on newly
built power plants to be close to CO2 storage locations and on the other
hand putting extra expenses for CO2 transportation and mobilization on
existing power plants which located far from CO2 storages.
Possibilities of CO2 infiltration from storages will always remain an
encountered threat.
CO2 storage in oceans with a risk of CO2 leakages would end up to an
environmental catastrophe which may kill the living organisms in seawater
by a phenomenon called ocean acidification.
Table 1: Comparison of power stations with and without CO2 capture
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CO2 storage into underground geological formations may lead to CO2
infiltrations to the underground clustered water sources which result in
poisoning the fresh underground water which is considered in many
countries as supplementary resources for drinking water.
Mineral storage of CO2 would cost a conventional power plant 60-180%
more energy than other power plant without CCS technology.
Figure 9: A schematic for CO2 leakage to the fresh water wells
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5 Conclusion
Although CCS technologies would seem to be commercially feasible at many cases,
careful study for environmental impacts which could be done by employment of CCS
technologies is always essential. As the problems and potentials stated by this report
have seemed to be sort of equiponderant, a strong uncertainity would glow in the
horizon to urge decision makers to carefully stand on the net benefit behind
employing such technology. Compromise and smart decision making will always
have the key role in such conditions.
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6 List of references
1. "IPCC Special Report Carbon Dioxide Capture and Storage Summary for Policymakers"
2. NETL 2007 Carbon Sequestration Atlas, 2007 ALSTOM, 2006.
3. ALSTOM signs exclusive license agreement for carbon capture technology, 31 May 2006.
4. Department of Energy, 2008. Fact sheet: DOE to demonstrate cutting-edge carbon capture and
sequestration technology at multiple FutureGen clean coal projects.
5. http://en.wikipedia.org/wiki/Carbon_capture_and_storage