Life Cycle AssessmentAudi looks one step ahead

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Life cycle assessment – the concept

Times change. Raw materials are becoming scarcer, emissions are on the increase and many cultures in various parts of the world are undergoing major changes. Against this backdrop, careful use of resources is gaining in importance all the time.

Audi is helping to make this change – true to the technical leadership implied in its classic motto 'Vorsprung durch Technik'. Modern technolo-gies, new materials and highly efficient components are available to optimise vehicle design. For Audi, as a pioneer in vehicle development, progress in the careful use of non-renewable resources is a task that involves every area of its activities.

Life cycle assessments (LCA) are important procedures that can help to reduce the motor vehicle's impact on the environment. Audi not only assesses the vehicle while it is in use, which mainly concerns its fuel consumption, but the entire life cycle from production to recycling. Audi looks one step ahead.

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Life cycle assessment – what's involved

Assessment of a vehicle’s complete life cycle as a major contribution to more sustainable treatment of the environment.

The life cycle assessment analyses the effects of a product on the environment during its entire existence, from production to its period of use and its end-of-life recycling. It is a quantitative evaluation of ecological aspects such as the emission of greenhouse gases (including carbon dioxide [CO2]), energy consumption, acidification or 'summer smog'. Audi compiles its life cycle assessments according to the procedure laid down in the international ISO 14040 series of standards.

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• Development phase: assessment of materials and semi-fi nished product manufacturing chains• Production phase: assessment of components and complete vehicles• Use phase: assessment of fuel/electricity (including production)• Recycling phase: assessment of process chains of valuable materials

Stages in motor-vehicle life cycle assessment

InputEnergy Raw materials

OutputEmissionsWaste

* abhängig von

Production components (depending on manu-

facturing concept)Recycling

Use

Materials and production

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Life cycle assessment – the boundaries

Before a life cycle assessment is compiled, its boundaries must be defined by deciding which processes should be examined. The available means, the time framework and data availability all have to be taken into account. Audi has laid down broad limits for its complete-vehicle life cycle assessments.

The examination starts with the manner in which raw materials are obtained, and how individual components are manufactured. Even during the first new-model development stages the engineering teams have to take decisions that have major effects on in-house production and the entire supply chain.

Audi's experts assume for assessment purposes that vehicles will cover a distance of 200,000 kilometres. They not only take into account the emissions caused when the vehicle is being driven, but also those that occur when the fuel is produced. Recycling at the end of the vehicle's life and the use of secondary raw materials are also included in the life cycle assessment.

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Supply → pipelineTransport → refiningprovision of fuel

System boundaries of vehicle LCA

Recovery of energy and raw materials

Raw material extraction

Manufacture

= product system

Production Use Recycling

Semi-finished product manufacture

Component manufacture

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Life cycle assessment – effect categories

The result of the inventory analysis is converted into effect indicators and these in turn are grouped into effect categories which describe the principal environmental problem-areas: the 'greenhouse effect' (global warming potential), eutrophication of water and soil, 'summer smog', acidification and damage to the ozone layer. When evaluating the greenhouse effect, which is a major indicator, the Audi LCA specialists list the effects resulting from all gases that influence the climate. The gases are included in the LCA according to their effect in relation to CO2, but the importance of other effect categories as well as the greenhouse potential is not disregarded.

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Effect of substances on the environment

Global warming potential

CO2

CH4

SO2

NOx

HC

R11

Estimated effectInventory analysis

Extraction of raw materials

Production

Manufacture

Utilisation / transport

Recovery / Recycling

Effect indicators

Eutrophication

Photochemical smog

Acidification

Ozone breakdown

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Life cycle assessment – questions

The central factor that has to be considered in Audi life cycle assessments is the effect that possible optimisation will have in the various phases of a vehicle's life.

For example, the use of lightweight materials usually leads to additional effort or complexity in component manufacturing. On the other hand, the vehicle weighs less and therefore consumes less fuel in the subsequent operating phase. For Audi, environmentally acceptable lightweight construction means that the savings during vehicle operation must be greater than the additional effort and expense caused in the production phase.

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Additional environmental burden caused

by manufacture of lightweight materials

Reduced environmental burden during vehicle

operation as a result of lightweight construction

Environmentally acceptable lightweight construction

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Life cycle assessment – the influencing factors

LCA is a tool that enables Audi to evaluate the effects of strategic decisions when new vehicle concepts are being developed. This concerns in-house processes and also those used by outside suppliers.

Even a single modification can have a negative effect on one of the phases in the life cycle, but if the drawbacks are more than compensated for in another phase, the balance is then positive. In practice this means that the extra effort and expense involved in using lightweight materials is made good by reduced consumption in the vehicle's use phase, so that there is an advantage below the line compared with a conventional concept.

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•Materials•Component concepts • Degree of weight saving•Production • Processes • Energy sources • Electricity mix

•Weight of vehicle•Power unit • Type of fuel • Drivetrain efficiency•Production of fuel type • Processes • Energy sources • Electricity mix

•Recovery of valuable materials

Recycling

Additional burden by lightweight design

Break-even

0 km 200.000 km

Gre

enh

ouse

gas

es [

in t

CO

2 e

qu

ival

ent]

Depreciation distance

LCA of different vehicle concepts

Influencing factors (examples)

Materials and production Use

Net reduction of green-house gases

Conventional construction Environmentally acceptable lightweight construction

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Lightweight construction – choice of materials

The choice of materials has a decisive effect on the CO2 emissions that occur in component manufacturing. The range is wide, in view of the many different manufacturing and recycling methods involved. Due to the production process and the nature of the energy source, primary aluminium gives rise to higher emissions than occur in the production of primary steel. If on the other hand recycled aluminium can be used, the effort and expense are at a lower level, comparable with recycled steel. At Audi the recycling process starts in the production phase, when trimmings from the presses are collected and returned for recovery.

Production recycling makes a significant reduction in CO2 emissions possible.

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Greenhouse gas emissions for various materials [kg CO2 eq. / kg component weight]

= Process-dependent scatter

*Carbon fibre reinforced polymer

• The scatter bandwidths for the various materials result from the different manufacturing and recycling processes that can be used.

Steel

0 5 15 25 3510 20 30 40 45

Aluminium

Magnesium

CFRP*

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Lightweight construction – component concepts

If a vehicle's use phase is considered in isolation, then lightweight materials are extremely attractive. The chart shows the potential weight saving for components with identical functions if a modern lightweight material is used instead of conventional steel.

Aluminium is about two-thirds lighter than steel, but metal of slightly heavier gauge has to be used for a vehicle body. An aluminium body built according to the Audi Space Frame (ASF) principle weighs about 40 percent less than a comparable steel body.

Magnesium is about a third lighter than aluminium. At the moment it is mainly used in the form of castings.

Carbon fibre reinforced polymer (CFRP) – a composite material containing about 50 percent woven carbon fibre in a resin matrix – is even lighter than magnesium, but offers a similar overall weight saving. Its production is still extremely intensive in terms of energy consumption.

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Lightweight potential of components (identical functions)

Weight-saving potential, depending on material and manufacturing processes (compared with steel):

~ 40 % for aluminium~ 55 % for magnesium~ 55 % for CFRP

Steel

0 %

MagnesiumAluminium CFRP

100 %

50 %

25 %

75 %

0 %

100 % ~ 40 % ~ 55 % ~ 55 %

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Lightweight construction – secondary effects

The weight reduction that Audi achieves by using lightweight materials permits welcome secondary effects in other areas of the vehicle.

Lower body weight initiates a downward turn in the weight spiral, which permits chassis and drivetrain components to be downsized, for instance by reducing the size of the brakes. Weight-saving potential is possible in every technical area. In the life cycle assessment these savings help to compensate for the additional effort and expense incurred in the manu-facture of lightweight materials.

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Reversing the weight spiral

Lightweight construction is the starting point for a reversal of the weight spiral.

Lightweight body construction

A smaller fuel tank

Downsizing ofengine

Secondary effects,e.g. transmission

Detailed lightweight construction in all areas

Secondary effects,e.g. chassis, brakes

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Audi A6 – the life cycle assessment

Audi has compiled a detailed LCA for the new A6. For comparison, the engineers chose the top-selling model from previous generation, the A6 3.0 TDI with automatic transmission.

A notable achievement on the new model is reversal of the weight spiral: the new Audi A6 3.0 TDI quattro is 80 kilograms lighter. This is due to more intensive weight-saving measures applied to the body, engine, drivetrain and chassis. The chart shows all the areas that contributed signifi cantly to this reduction.

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MMI 3G system integration

Use of high-end steelgrades in the bodyshell,including form-hardenedgrades and tailored blanks

Aluminium rear shelf

Aluminium boot lid

Lightweightforged wheels

Aluminium doors

Aluminium fender

quattro drivetrain optimisedfor weight saving

Lightweight compositebrake discs

Neodymium speakers

Aluminium module cross-member

Cast aluminium suspension strut domes

Aluminium bonnet

Aluminium bumper system

Aluminium pipes

Aluminium axle components

Engines and transmissions optimised for weight saving – adoption of

lightweight materials for functional integration

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Audi A6 – materials

The materials used for the product have a significant influence on the LCA. According to the material classification in VDA directive 231–106, the proportion of lightweight metals in the new Audi A6 3.0 TDI is about 19 percent of the car's curb weight, three percentage points more than in the previous model. By contrast, the proportion of steel and other ferrous metals went down by 5 percent. Audi has extensively replaced steel with aluminium.

Previous Audi A6 New Audi A6

1. Steel / iron

2. Light metals

3. Non-ferrous metals +4. Special-purpose metals

5. Polymers + 6. Process polymers

7. Other materials + 8. Electrics / electronics

9. Fuels and auxillary means

55 % 50 %

6 %4 % 5 %5 %

17 %

4 %

19 %

16 %

3%

16 %

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Audi A6 – the results of the life cycle assessment

The new Audi A6 contains a higher proportion of light metals than the previous model, and in most cases more energy is consumed in their production. Despite this, the break-even point is reached before the fi rst 5,000 kilometres have been driven, and from this point on the new car's much lower fuel consumption makes the balance more positive with every successive kilometre.

Although the previous model emitted scarcely 53 metric tons of CO2 equivalents during its complete life cycle, the new Audi A6 has distinctly less impact on the environment: 46 t of CO2 equivalents. In other words, Audi has succeeded in reducing greenhouse gas emissions by 7 metric tons of CO2 equivalents or 13.2 percent. In all other relevant eff ect categories too, the new model records better results than its predecessor.

Reduction of all examined eff ect categories

Global warming potential -13 %

Photochemical ozone creation potential -4 %

Acidification potential -3 %

Ozone depletion potential -0,5 %

Eutrophication potential -3 %

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The additional burden caused by more intensive lightweight construction and drivetrain optimisation is written off during the first 5,000 kilometres.

Use

Distance covered [km]

RecyclingMaterials and production

[kg

of C

O2 e

quiv

alen

ts]

Fuel consumption:

Audi A6 3.0 TDI quattro tiptronic (previous model) 7.1 l / 100 km

Audi A6 3.0 TDI quattro S tronic(new model)6.0 l / 100 km

10.000

0

30.000

50.000

20.000

40.000

Audi A6 3.0 TDI quattro tiptronic (previous model)Audi A6 3.0 TDI quattro S tronic

60.000

0

40

.00

0

80

.00

0

12

0.0

00

16

0.0

00

20

.00

0

60

.00

0

10

0.0

00

14

0.0

00

18

0.0

00

20

0.0

00

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Life cycle assessment – electromobility

Electrically propelled vehicles such as future e-tron models from Audi have a highly efficient drivetrain and cause no local emissions. Of course, responsibility does not end at the electric power socket. In the use phase, the complete 'well-to-tank' CO2 emissions caused by the generation and supply of electric power have to be included in the LCA.

As the chart shows, there are immense differences between the various regions of the world, depending on the local electricity mix. In China most electricity comes from coal-fired power stations with intensive CO2 emissions, whereas in Norway clean hydroelectric power predominates, and emissions of CO2 equivalents (in grams per kWh) there are lower than in China by a factor of 25.

The chart on page 28 shows the effect of the electricity mix on the operation of a compact-class electric car. In China its emissions of greenhouse gases total 171 grams per kilometre, in Norway a mere 7 grams. For this reason Audi plans for its future e-tron models to be operated exclusively on electricity generated by ecological means. With its e-gas project, Audi will be playing an active part in the development of regenerative electricity production.

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A similar picture is revealed if the production and recycling phases are added to the use phase. An electric car has a much better overall balance than a conventional vehicle powered by a petrol engine in Norway, whereas in China the balance is worse. The chart on page 29 also shows that the production of a conventional car accounts for about 20 percent of total emissions, and that this proportion is higher for an electric vehicle because production of the batteries consumes a large amount of energy.

Greenhouse gas emissions caused by

electric power generation / well-to-tank

(selected countries)

Coal

Nuclear power

Hydroelectric

Others

*Electricity mix of EU 25-Members (2007)

g CO2 eq. / kWhChina

1140 gEU 25*560 g

Norway46 g

23 %

77 %77 %

39 %

19 %

32 %

10 %

1 %

99 %

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Assumption: battery-electric vehicle, compact classconsumption: 15 kWh / 100km

Greenhouse gas emissions from electric vehicles in relation to the electricity mix

200

150

100

50

0

Greenhouse gas emissions g CO2 eq. / km

84

EU

7

Norway

171

China

29

~ 75 %

Greenhouse gas emissions balance in relation to electricity mix

than reference vehicle with internal combustion engine

Internal combustion engine

Electrically propelled

► Electricity mix as in China

► Electricity mix as in Europe

► Electricity mix as in Norway

Better Poorer

Assumption: compact class car, distance 200,000 km, consumption: internal combustion engine: 5.5 l fuel / 100 kmelectric drive: 15 kWh / 100 km

Materials and production

Use (well-to-wheel)

Recycling

~ 20 %

~ 25 %

~ 45 %

~ 90 %

< 1 %

~ 2 %

~ 1 %

~ 5 %

~ 80 %

~ 55 %

~ 5 %

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Life cycle assessment – conclusionThe public today tends to judge cars to a large extent by their fuel consumption. Here too, Audi looks one step ahead. Its life cycle assessments analyse effects on the environment for the vehicle's entire lifetime. The use of sustainable materials and manufacturing processes can greatly reduce these effects.

The LCA that Audi has compiled for its new A6 shows on the one hand that the new saloon model is superior to its predecessor in all environmentally relevant criteria. In addition it is sound evidence that the lightweight design measures Audi has adopted quickly pay for themselves during the use phase, despite the higher energy consumption they entail. The weight advantage soon makes itself felt as a worthwhile reduction in CO2 emissions – an admirable example of environmentally acceptable light-weight design as Audi understands it.

Although electric vehicles are locally emission-free, a 'well-to-tank' assessment is essential if their potential environmental benefit is to be correctly estimated. Considerable differences occur according to the regional electricity mix. No ecological benefit is obtained unless renewable energy is used. Audi is now helping to develop it.

Impressum:

AUDI AGTotal Vehicle Development andProduct Communications85045 IngolstadtTel: +49 841 89-32100Fax +49 841 89-32817Status: 05 / 2011