How can our cars become less polluting? An assessment of the environmental improvement potential of cars

Transport Policy 17 (2010) 409–419

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Transport Policy journal homepage: www.elsevier.com/locate/tranpol

How can our cars become less polluting? An assessment of the environmental improvement potential of cars$ Guillaume Leduc, Ignazio Mongelli, Andreas Uihlein n, Franc- oise Nemry Institute for Prospective Technological Studies (IPTS), Joint Research Centre, European Commission, Edificio Expo, C/Inca Garcilaso, 3, Sevilla 41092, Spain

a r t i c l e in fo

abstract

Available online 5 May 2010

This paper presents a systematic overview of the environmental impacts of new average diesel and petrol cars from a life cycle perspective. An analysis of different technical and non-technical improvement options that could be achieved at each stage of a car’s life cycle was performed. The consequences of the adoption of these options on the environment were estimated. The results show that some of the options analysed could have a major positive impact on the vehicle efficiency and induce large improvements of the environmental profile of passenger cars. The highest improvements are achievable through more efficient power trains (including hybrid car), and through lightweight cars. For some options, burden shifts from one car life cycle phase to another, or from one environmental problem to another, can occur. The results show that besides the purely technological options, those that imply behavioural changes by the driver may also reduce the environmental burden substantially. & 2010 Elsevier Ltd. All rights reserved.

Keywords: Transport Passenger car Environmental impact Life cycle assessment (LCA) Technical improvement Integrated product policy

1. Introduction and objective In its Communication on Integrated Product Policy (IPP) the European Commission announced that it would seek to identify and stimulate action on products with the greatest potential for environmental improvement (European Commission, 2003). This was scheduled into three phases. After having identified the products with the greatest environmental impact from a life cycle perspective (first phase), the second phase was targeted to determine possible ways to reduce the life-cycle environmental impacts of these products. In the third phase the European Commission would seek to address policy measures for the products that are identified as having the greatest potential for an environmental improvement at least socio-economic cost. The first phase was completed in 2006 with the EIPRO study, which identified the products consumed in the EU having the greatest environmental impact from a life-cycle perspective (Eder and Delgado, 2006). The study showed that groups of products from only three areas of final consumption—food and drink, private transportation, and housing, which account for some 60% of consumption expenditure – are together responsible for 70% to 80% of the

$ The views expressed are purely those of the authors and may not in any circumstance be regarded as stating an official position of the European Commission. n Corresponding author. Tel.: + 34 954 488415; fax: + 34 954 488279. E-mail address: [email protected] (A. Uihlein).

0967-070X/$ - see front matter & 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.tranpol.2010.04.008

environmental impacts of final consumption. Based on these conclusions, three parallel projects were conducted by the JRC-IPTS, dealing with the environmental improvement of products (IMPRO-car, IMPRO-meat, IMPRO-buildings). This paper presents the results and conclusions from the IMPRO-car project, the aims of which were to: (i) estimate and compare the environmental life cycle impacts of passenger cars, (ii) asses the main technically feasible environmental improvement options that could become available on the market within the next two decades. The emphasis was put on measures that would change the inherent characteristics of cars (e.g. engine, car design, and material composition). In addition, some options consisting of a change in the car use pattern were also assessed. There is a wide range of research studies addressing the potential benefits of technical and/or non-technical options with the aim to reduce the environmental impact of passenger cars. It is outside the scope of the present analysis to provide a comprehensive review of this area. However, recent studies such as IEA (2009), EPA (2008), King (2007), AEA (2009), Kobayashi et al. (2009) and Fontaras and Samaras (2009) provide further information about emission reductions achievable with new vehicle technologies and, in some cases, associated costs. The remainder of this paper is structured as follows: the methodology used for the benchmark definition, the life cycle analysis (LCA) and the economic assessment are presented in Section 2. Section 3 presents the results of the LCA for the two reference cases. In Section 4, the environmental improvement potentials and the economic assessment of the

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improvement options are presented. Finally, Section 5 contains the conclusions.

2. Methodology 2.1. Life cycle analysis The environmental impact assessment of the base case passenger cars is performed according to the ISO standard guidelines on Life Cycle Assessment (LCA) (EN ISO 14040, 2006a, 2006b). LCA is a bottom-up modelling approach extensively used to analyse and quantify the environmental impacts attributable to the production, use and end-of-life of a product or service (Guine´e et al., 2002). A LCA study is usually dependent on a combination of different data sets regarding relevant manufacturing processes, and also on assumptions regarding the use phase of the product under study. This section therefore will briefly explain the methodology and document the main data and assumptions underpinning the analysis. For the life cycle impact assessment, this study primarily used the so-called ‘midpoint’ approach for the core indicators of different environmental impacts (Jolliet et al., 2003). The midpoint approach quantifies the environmental impact associated to a product or service in terms of contributions to well defined environmental problems—such as global warming, photochemical pollution and eutrophication. The mid-point indicator is the method used in most of the LCA studies and is conducted through several assessment steps. In a first step, called classification, all the elementary flows or inventory data are assigned to a corresponding impact category or an environmental problem, e.g. CO2 and SO2 emissions attributed to global warming and acidification, respectively. In a second step, called characterisation, all emissions that have been quantified and classified according to a specific impact category are expressed in terms of a reference substance, e.g. the greenhouse gases methane and CO2 expressed in CO2-eq. In a third step, all impact indicator scores are normalised with respect to a reference value specific for each category and to a specific geographic area. In the present study, the impacts are only classified and characterized but not normalised. The midpoint indicators have been calculated using the method developed at the Centrum voor Milieuwetenschappen Leiden also known as CML impact assessment method (Centrum voor Milieuwetenschappen Leiden, 2001). The CML method is freely available and is one of the first LCA midpoint methods which have been developed. Other impact assessment methods are also available, but they are either too specific with respect to an environmental problem (e.g. they assess only cumulative energy requirements), or they quantify ’end point’ indicators arising from an impact category pressures (e.g. human health or damage to ecosystems). End-point impact assessment is beyond the scope of the present study, which aims to quantify the major mid-point environmental impact category pressures known to be relevant for road passenger transport). Consequently, the CML method has been selected as the main impact assessment method, and is complemented with other impact categories, which are considered relevant for this study – in particular, the emission of particulate matter smaller than 2.5 mm, and abiotic depletion excluding the consumption of primary energy resources (such consumption is accounted for as a separate, key impact category). Other adaptations with respect to the CML method include the use of non-zero factors for NOx as a precursor of photochemical pollution and the inclusion of the category ‘solid wastes’ (or ‘bulk waste’) in accordance with the EDIP97 assessment method (Hauschild and Wenzel, 1997, Wenzel et al., 1997).

The following impact categories (midpoint indicators) were considered:

        

Abiotic depletion (excluding primary energy depletion) (AD). Climate change (GWP). Ozone depletion (ODP). Photochemical oxidation (POCP). Acidification (AP). Eutrophication (EP). Particulate matters with a diameter lower than 2.5 mm (PM). Consumption of primary energy resources (PE). Solid waste (BW).

These categories were derived from (Eder and Delgado, 2006), although some amendments were added to better reflect typical environmental pressures associated with cars, and to take into account anticipated data gaps and problems of interpretation. It was decided to exclude energy use under ‘abiotic depletion’ and to explicitly quantify the life cycle primary energy consumption (PE). Despite their relevance, some impact categories were not considered in this study. For instance, human toxicity and ecotoxicity are important when considering cars. However, quantifying the aggregate toxicity associated with the wide range of substances emitted by cars is challenging, particularly owing to the lack of harmonisation in toxicity characterisation across different LCA databases. Indeed, despite improving knowledge, toxicity potentials are still associated with high uncertainty (Huijbregts, 2001). Moreover the emission factors from processes for many of the substances involved are fragmented and also subject to high uncertainty. Thus, human toxicity and ecotoxicity have not been analysed in this study. Land use and noise were also not covered. Land use associated with passenger cars and road infrastructure (roads, motorways, parking) is still increasing in Europe, modifying the landscape and contributing to biodiversity loss. There are however, serious limitations in considering land use as an impact category in the LCA framework, since, so far, no consensus has been reached on appropriate measurement of this impact. The omission of the land use impact category in this study does not entail any bias as the majority of the improvement options analysed is neutral regarding land use intensity. The impact of noise is an another category that was excluded from the present analysis despite the fact that noise produced by cars is far from being negligible. Noise is measured during the standard type approval tests, but data are lacking when considering improvement options and, undertaking a comprehensive assessment, would require the consideration of specific use locations. 2.2. Goal and scope definition Two base car models (one petrol car and one diesel car) were defined by using statistics and data about the automotive market, and more specifically about the new car fleet. Most of the improvement options, especially those that imply technological changes, relate to this car fleet segment. The base case car models are representative of the most commonly purchased cars in the EU today. The average characteristics derived from statistics of new cars sold in Europe with respect to e.g. power, cylinder capacity and weight (Table 1). The base case car models represent benchmarks against which the different improvement options are assessed Section 2.5. The functional unit was defined as a 100 km distance driven and the overall life cycle impacts of the car are normalised to this functional unit. Whilst normalisation allows the effects of

G. Leduc et al. / Transport Policy 17 (2010) 409–419

different mileages between the two base case car models to be ignored for those environmental impacts associated with the usephase of the vehicle (e.g. fuel consumption). However, different mileages between the base cars do influence the normalisation of impacts occurring only once during the lifetime of the vehicle, as for instance those related to the production or end-of-life phases. From a mileage basis, the impacts resulting from the production and disposal of a diesel car with a higher mileage are lower than those of a petrol car with a lower mileage. This distinction between different types of impacts must be kept in mind, while interpreting the results shown in Table 5. The two car models differ in terms of weight and power. They may also differ in terms of comfort and space. For the Life Cycle Assessment of the two reference cases ‘diesel car’ and ‘petrol car’, all the relevant industrial or economic activities directly or indirectly linked to the production, the use and the end-of-life of the product itself (e.g. from cradle-to-grave) should be included. However, lack of data, time and resources necessarily leads to the ’cut-off’ of some system processes from quantification in practice. For example, the energy consumed for manufacturing car components and spare parts is not included in the present analysis due to lack of data. The overall and Table 1 Average characteristics of new cars sold in Europe. Parameter

Unit

Petrol car

Diesel car

Lifespana Emission standard Annual distancea Cylinder capacityb Powerb Weightb Body model

Years – km cm3 kW kg –

12.5 EURO4 16,900 1585 78 1240 Saloon

12.5 EURO4 19,100 1905 83 1463 Saloon

a b

Sources: based on TREMOVE calculations. Sources: data from ACEA, JAMA and KAMA for new cars in the EU-15 in 2004.

Primary energy extraction

411

necessarily stylised structure of the analysed product system is shown in Fig. 1. In this study, five main life cycle steps were identified:

 Production phase (including material production and car assembly).

 Spare parts production (tyres, batteries, lubricants and refrigerants).

 Fuel transformation process upstream to fuel consumption (WTT).

 Fuel consumption for car driving (TTW).  Car disposal and waste treatment (EOL).

2.3. Key assumptions for the reference cases 2.3.1. Production phase For the production phase, data for the extraction and processing of raw materials, and for material production were taken from the Ecoinvent database (Frischknecht et al., 2004)—one of the most complete and updated LCA database available. The only exception refers to the data for the iron and steel production, which have been provided by the International Iron and Steel Institute (IISI). The car’s material composition was defined on the basis of what the existing literature suggests (Schmidt et al., 2004, Schmidt and Butt, 2006). Table 2 lists the material composition of the two base case car models. Due to lack of detailed information, the material composition for diesel and petrol cars was assumed to differ only for their relative content of iron, steel and aluminium, while the content of other non-ferrous metals, plastics and other materials is assumed to be the same. Regarding car manufacturing and assembling, and due to lack of data, the analysis was limited to the environmental impacts associated with the energy consumed during the assembling

Legend

Raw material mining

Freight transport

Fuel production

Material processing

Spare parts manufacturing

Fuel conditioning & transportation

Car assembling

Repairing and maintenance

Fuel distribution

Car drivinggand air conditioning

Washing the car

Car dismantling

WTT

Production

EOL

TTW

Spare parts

not included ithitd in this study

Worn spare parts disposal

Material recycling

Car shredding

Automobile shredder residue (ASR) treatment

Building and repairing infrastructures Fig. 1. Process flow diagram of a car (major life cycle stages).

Landfill of residues

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Table 2 Material composition of the two base case car models (in kg). Material group

Material

Petrol car

Diesel car

Steel

Steel (basic oxygen furnace) Steel (electric arc furnace) Primary aluminium Secondary aluminium Copper Magnesium Platinuma Palladiuma Rhodiuma – – Polypropylenec Polyethylene Polyurethane Acrylonitrile butadiene styrene Pokyamide Polyethylene terephthalate Other plasticsd E.g. textilese Rubber Carbon black Steel Textilesf Zinc oxide Sulphur Additives Lead Polypropylene Sulphuric acid Polyvinyl chloride Transmission fluid Engine coolant Engine oil Petrol/diesel Brake fluid Refrigerant Water Windscreen cleaning agent –

500 242 42 26 9 0.50 0.0010 0.0003 0.0002 40 36 114 37 30 9 6 4 27 23 16 8 4 1.6 0.4 0.4 4 9 0.7 4 0.3 7 12 3 23 1 0.9 2 0.5 1243.3

633 326 43 29 9 0.50 0.0010 0.0003 0.0002 40 36 114 37 30 9 6 4 27 23 16 8 4 1.6 0.4 0.4 4 9 0.7 4 0.3 7 12 3 25 1 0.9 2 0.5 1466.3

Aluminium Other metals

Glass Paintb Plastics

Miscellaneous Tyres

Battery

Fluidsg

Total

a Platinum, rhodium and palladium, as used in converter catalysts, are included in the material composition according to (GHK and BIOIS, 2006). b Paint is assumed to be alkyd paint with a 60% solvent content. c Polyethylene has been assumed to be high density polyethylene. d The plastic category ‘other’ is assumed to correspond to polypropylene which is the most common plastic in car manufacturing. e Other and miscellaneous materials have been excluded for the life cycle inventory. f Textiles are assumed to be mainly polyethylene terephthalate and polypropylene. g All fluids except fuels, refrigerants and lubricants are excluded from the material composition. Their environmental impact is not assessed, but their contribution to the total car’s weight, which entails larger fuel consumption per kilometer, is considered.

phase and with the VOC emissions due to painting operations. Energy used (and fuel mix) for the assembling phase was derived from (Volkswagen AG, 2005). The impacts associated to the energy demanded and consumed for the production and processing of components was not included in this analysis. For paints, the figures according to (European Commission, 2007) were used. 2.3.2. Spare parts production Tyres, batteries, lubricants and refrigerants are considered as spare parts whereas, due to a lack of data, textiles, additives, transmission fluid, engine coolant, brake fluid, water and windscreen cleaning agent were not included. The material composition of the spare parts was derived from (GHK and BIOIS, 2006). The replacement intervals were assumed to be 40,000 km for tyres, 80,000 km for battery and 10,000 km for refrigerants and lubricants.

2.3.3. Well-to-tank (WTT) phase This phase includes crude oil extraction, refinery and distribution of the fuel. Edwards et al. (2006) is the most comprehensive and up-to-date study for the EU providing detailed data on primary energy use and greenhouse gas (GHG) emissions associated with the fuel chain also referred as well-to-tank (WTT). In the cited study, the WTT chain is analysed by looking at each process or step, which is necessary to make the fuel available for the vehicle. For each of these steps/processes, the energy required and the greenhouse gases emitted are quantified. Compared to other data sources, the WTT study was the preferred choice due to its completeness and accuracy. However, the WTT only refers to energy requirements and greenhouse gas emissions. For the other impact categories, the Ecoinvent database was used as a complementary source (Frischknecht et al., 2004). 2.3.4. Tank-to-wheel (TTW) phase The use phase consists of driving the vehicle over total mileages of 211,250 and 238,750 km for the petrol and the diesel car (see Table 1). The fuels considered are unleaded petrol and low sulphur diesel (50 ppm sulphur), produced and distributed in the EU. In order to assess the environmental impacts, real world emissions provided by the ARTEMIS database were used (Transport Research Laboratory, 2000). As the ARTEMIS database provides real world emission data for a few EURO4 vehicles only, type approval emission values were used to cover other regulated pollutants (CO, HC, NOx, PM) as measured under the New European Driving Cycle (NEDC) according to (Vehicle Certification Agency, 2007). To check the consistency between the two data sources used in combination, we compared CO2 emissions and energy use under real world conditions with those measured under the NEDC, which were found to be lower than real world conditions emissions by 14% on average. This finding is confirmed by an extensive literature on the subject (see e.g. Pelkmans and Debal, 2006, Samuel et al., 2005, Soltic et al., 2004) that documents a deviation between the two data sources lying in the range 10–20%. Therefore, to compensate for this deviation, an additional 14% of energy use and CO2 emissions was assumed for the NEDC measurements. To add the Mobile Air-Conditioning (MAC) contribution, it was assumed that the two base case car models are equipped with the most common MAC system, i.e. using HFC-134a as working fluid. Correction factors were applied to the above emission levels to simulate the emissions induced by the air-conditioning system through (1) direct GHG emissions due to refrigerant leakages at the different life cycle stages and (2) indirect emissions of GHG and pollutants resulting from an additional fuel consumption when the AC system is on, depending on driving patterns and climatic conditions (Roujol and Joumard, 2009). In the present study, these emissions are based on updated figures provided by the French Environment and Energy Management Agency ADEME (see e.g. Gagnepain (2006), Barbusse and Gagnepain (2003)). Assuming an average use of an air-conditioning equal to 33% of the annual distance travelled and a 30% urban driving share, the additional fuel consumption due to the use of air-conditioning was estimated to be around 3% over the year. 2.3.5. End-of-life (EOL) phase The EOL scenario assumed for the main basic materials is based on estimates from GHK and BIOIS (2006). We assume 100% landfilling of plastics, paint and glass. All waste treatment processes are accounted as part of the EOL phase. For steel, aluminium, magnesium and lead (only lead components of the battery have been assumed to be recycled), a recycling rate of 95%, 90%, 95% and 92%, has been assumed. For platinum, palladium and

G. Leduc et al. / Transport Policy 17 (2010) 409–419

rhodium embedded in the catalyst, recovery rates of 95%, 97% and 85%, are assumed. In this paper, the use of recycled materials is assessed according to Koltun et al. (2005). This approach generates ‘uncredited’ impacts. This means that the potential benefits due to recycling or recovery are quantified, but they are not subtracted from the overall environmental impacts of the product.

2.4. Cost assessment The assessment of the costs of the different improvements analysed was based on the net present value of the life cycle costs incurred by the new option as compared with the base case, including the four main components: additional investments, fuel cost changes, cost changes in spare parts, and cost changes for waste treatment (Nemry et al., 2008). A 4% discount rate was considered. Retail and transportation margins were added to the manufacturing costs to evaluate the final retail price (excluding taxes). A factor of 1.16 is assumed for the ratio between retail prices and manufacturing costs (Nemry et al., 2008). External costs, i.e. costs due to environmental damage arising from human activity without being paid or compensated for, are taken into account for the cost assessment. The main assumptions concerning the externalities of energy production and consumption were adopted from Labouze et al. (2003), European Commission (2005a, 2005b). The external costs for CO2 emissions were assumed to be 50 Euro/t CO2 (Nemry et al., 2008).

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2.5.1. List of options The list of improvement options considered in the present analysis is derived from the research works carried out by Nemry et al. (2008), Smokers et al. (2006). Based on that, a (nonexhaustive) list of options technically proven and likely to enter the market within the next 30 years was put together. This list is displayed in Table 3 according to the stage of the life cycle in which they could be implemented. However, not all the measures listed in Table 3 were selected for further assessment within this project. A shorter list of options was drawn on the basis of the following criteria: is the option likely to be eligible for IPP? Is the option likely to improve processes that generate significant impacts? Is there evidence that the existing technical potential is already covered by an existing legislation? Are there any reliable data to quantify the environmental impacts? Is the quantification feasible under the methodological approach used in the project? Having addressed these questions, it was concluded that some improvement options do not need or could not be further assessed. However, excluding options from quantification does not mean that the options are not relevant at all. 2.5.2. Description of the selected options The environmental benefits and costs associated with the selected options were quantified and examined with respect to the benchmark of the two base case car models. Some of the options listed in Table 3 have been regrouped and are described in more detail in Table 4.

3. Life cycle assessment results of the reference cases 2.5. Analysis of the improvement options In general, the following questions were addressed: what could be achieved at the various life cycle stages and what would the overall environmental benefit of these various options be? What are the potential trade-offs between the different options and between the different types of environmental benefits? Improvement options for reducing the environmental impact of passenger cars can be broadly classified as follows:

 Options consisting of improving conventional technologies

  

(e.g. new engine and transmission, vehicle weight reduction, reducing aerodynamic drag and rolling resistance); using alternative fuels (e.g. biofuels, CNG, hydrogen) as well as developing technologies for vehicle ‘electrification’ (e.g. hybrid cars). Options consisting of changes in driver behaviour, which can also help reduce the environmental impacts of passenger cars (e.g. eco-driving). Options consisting of infrastructure changes (e.g. dynamic traffic lights, road pavement). Options consisting of more systemic changes such as the shift from private cars to collective transport, the reduction in mobility needs through changes in urban and land use planning of the different human activities.

Despite their significant potential, the third and fourth options are of less relevance as far as an IPP is concerned. The present study then focuses on the first two improvement options that, once identified, will be analysed with regard to their environmental benefits. The two generic vehicles initially defined will be used to simulate the effect of the selected options on their life cycle environmental performance.

This section discusses the overall contribution of the different life cycle stages of the two reference product systems (‘petrol’ and ‘diesel’) with respect to the selected environmental impact categories. The results are presented in Tables 5 and 6. The contribution from the production phase is shown to be the most significant for bulk waste, acidification potential, eutrophication potential, and abiotic depletion. The high contribution of the spare parts production to the abiotic depletion results from lead, which is assigned very high nominal values in the CML characterisation factors. For the other impact categories, the production of spare parts plays only a minor role. The WTT phase shows a high contribution to ozone depletion, acidification, photochemical oxidation, eutrophication and PM. Contributions to greenhouse gas emissions and to primary energy are also significant. The TTW phase makes the largest contribution to greenhouse gas emissions and to primary energy. Its contribution is also relevant for photochemical oxidation and eutrophication. Some of these general patterns are also found for the diesel car (Table 6), although noticeable differences are apparent for the two vehicle types. For instance, the contribution of the TTW phase of the diesel car is much higher for particulates, acidification, eutrophication and photochemical pollution than for the petrol car. In the last three cases, this is due to higher NOx emissions. The difference of impacts between diesel and petrol for the WTT phase has to be considered cautiously as they are very much influenced by the data source used (see Section 2.3.4). When comparing the results for the two base cases, their differences in terms of weight, power, and possibly in terms of comfort have to be kept in mind. The estimated environmental impacts cannot be used to make an accurate comparison regarding the respective environmental performance. However, as far as energy and GHG emissions are concerned, the estimations are in line with (Edwards et al., 2006), namely that diesel

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Table 3 List of improvement options at different life cycle stage. Life cycle phase

Process

Option

Typea

Includedb

Production phase

Raw material mining Material processing Car design and assembly

Improving process Improving process Improving energy efficiency Improving the application of solvents, paints and adhesive Design for better dismantling Material substitution Choosing recycled/renewable/ recyclable/low environmental profile materials Optimising the design and choosing light materials Improving the car body (car body and tyre rolling resistance) Higher MAC efficiency Improving the efficiency of climate control systems Substitute refrigerant Improving process Improving process Improving refinery process Design the process for cleaner fuel production Improving technical equipment for fuel distribution Reducing fuel consumption and Emission control systems for air pollution current engines More efficient power trains Alternative fuels Properly inflate tyres Adapt vehicle speed Driving behaviour Optimise MAC use Increase recovery and recycling of tyres Increase recovery and recycling of batteries Increase recovery and recycling of lubricants Increase recovery and recycling

T T T T T T

n

T

+

T T

+ +

T T T T

nn

T T

n

T T T B B B T T T T

+ + + + + +

WTT

Use phase (TTW)

Primary energy extraction Fuel production

Fuel distribution Car driving

Worn spare parts disposal

EOL

Waste treatment

n n n nn/nnn

+

n

n n

+

nnn nnn nnn

+

a

T: technical, B: behavioural. + : Option included into the assessment, options not included into the assessment; because n not eligible for IPP anr/or better suitable for sectoral regulation (e.g. IPPC), nn not reliable information available for quantification or uncertainties concerning technical potential, nnn no significant impacts expected. b

Table 4 Description of the improvement options covered in the present study. Option

Sub-option

Assumptions

Comments

Car weight reduction

5% Weight reduction

Displacement of conventional ferrous metals with high strength steel Displacement of ferrous materials with aluminium Intensive displacement of ferrous materials with aluminium Intensive substitution of ferrous materials with magnesium It was estimated that improved aerodynamics could reduce fuel consumption by 1.5%. Overall, a total reduction of fuel consumption and CO2 emissions by 4.5% is assumed.

Reduction of the fuel consumption can be attained through the substitution of iron and steel with light materials (components and body structure). Materials like advanced high strength steel, aluminium, magnesium and composites will be used in the short to medium or long term to substitute iron and steel. Reduction of pollutant emissions is expected but was not quantified here.

12% Weight reduction 30% Weight reduction 30% Weight reduction (Mg) Car body and tyres

Improved aerodynamics

Tyres

Air conditioning

MAC improvement (leakages reduction)

Efficient use of the MAC

Power train improvements

Total refrigerant leakages are assumed to be reduced from 70 g HFC-134a/year to 50 g HFC-134a/year in the short term (2010–2015). By increasing the set temperature from 20 to 23 1C, fuel consumption can be reduced by 5% (urban) and 2% (extra urban).

Overall, improvements in power train are assumed to reduce fuel consumption/CO2 emissions by 22.1% and 16.7% for petrol and diesel cars.

We assumed a potential cut of CO2 emissions and fuel consumption by 2.5% due to tyre pressure monitoring system (TPMS) and by 2% due to the use of low rolling resistance tyres (LRRT). Refrigerant leakages concern leakages during operating, loss at servicing, accidents and EOL. No technical improvements with regard to new HFC134-based systems are considered. It is assumed that the automatic regulation is more often used (mode by default) over the year than the manual control, which could partially reduce the expected benefits of this technology. ‘‘Power train’’ refers to improvements in engine and transmission of current petrol/ diesel ICE technologies. The assumptions were calculated from different (possible) combinations of both engine and transmission technologies.

G. Leduc et al. / Transport Policy 17 (2010) 409–419

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Table 4 (continued ) Option

Sub-option

Assumptions

Comments

Tailpipe air emission abatement

Air abatement I Air abatement II

EURO5 emission levels EURO6 emission levels (diesel cars only)

Petrol cars: NOx emissions can be reduced through the use of three-way catalysts; Lean NOx trap (TNT) and Exhaust Gas Recirculation. Diesel cars: diesel particulate filter for PM emissions and new diesel oxidation catalysts for NOx, HC and CO emissions are considered. Diesel hybrid is likely to enter the market in around 2015. Some R&D efforts are still needed. For this reason, it is still difficult to gather large samples of measurements and make a full comparison of both cars. The diesel hybrid car is expected to result in even higher benefits (around 30%) when compared with the current conventional diesel car. Making a full life cycle assessment of biofuels is very challenging. All our assumptions are described in Nemry et al. (2008). Averages over the different technologies (recovery, recycling, landfilling) according to different resins were calculated and applied to the plastic fraction. Thus, plastics are considered as a mix of different types. The singling out of the impacts of recycling or recovering only some of them was not sought. The improvement potentials of speed limits reduction on fuel consumption and air emissions are derived from the ARTEMIS project. Speed dependent hot emission factors covering both air pollutants and fuel consumption are considered. Driving behaviour significantly affects fuel consumption and air emissions of vehicles. We only quantify the potential reduction of eco-driving on fuel consumption (and CO2 emissions) in the long term i.e. about one year after training.

Hybrid cars

Biofuels

An average of 25% fuel savings for petrol hybrid cars is assumed. Potential fuel consumption reduction for hybrid diesel cars is taken from PSA Peugeot Citroen. Average reduction potentials of 45% (urban cycle) and 28% (NEDC) are assumed.

Biodiesel Bioethanol

We assume first generation biofuels with 10% blend.

EOL recycling and recovery

As most of the effort needed to fulfil the EOL Directive concerns plastics, focus was made on this fraction. A scenario, where 50% plastic is mechanically recycled and 50% plastic is recovered was then considered.

Reducing speed limits on motorways

Speed limits on motorways are reduced from 130 to 120 km/h. Fuel consumption reduction is found to be around 6% for petrol cars and 11% for diesel cars (for motorways only).

Driving behaviour

Long term effect of applying eco-driving with the aid of a Gear Shift Indicator (GSI) can reduce fuel consumption by 4.5% (3% from eco-driving lessons and 1.5% from the GSI).

For more details on the underlying assumptions and calculations, see Nemry et al. (2008), Smokers et al. (2006).

Table 5 Life cycle impacts for the reference case petrol car (per 100 km). Impact category

Unit

Production

Spare parts

WTT

TTW

EOL

Total

AD GWP ODP POCP AP EP PM PE BW

g Sb eq kg CO2-eq mg CFC11 eq g C2H4 g SO2 eq g PO4 eq g MJ g

0.07 2.02 0.10 3.30 21.07 2.26 0.43 31.14 157.42

0.08 0.21 0.06 0.85 1.14 0.11 0.07 6.03 7.50

0.00 3.52 3.02 14.29 53.62 4.22 1.36 39.18 102.51

0.00 20.80 0.00 4.27 1.70 0.42 0.00 281.90 0.00

0.00 0.03 0.00 0.01 0.04 0.02 0.00 0.02 135.73

0.15 26.58 3.18 22.72 77.56 7.03 1.86 358.27 403.15

Table 6 Life cycle impacts for the reference case diesel car (per 100 km). Impact category

Unit

Production

Spare parts

WTT

TTW

EOL

Total

AD GWP ODP POCP AP EP PM PE BW

g Sb eq kg CO2-eq mg CFC11 eq g C2H4 g SO2 eq g PO4 eq g MJ g

0.07 1.98 0.09 3.19 19.03 2.05 0.38 28.99 156.76

0.08 0.21 0.06 0.85 1.14 0.11 0.07 6.04 7.51

0.00 3.62 2.74 10.94 36.73 3.58 1.03 40.82 74.58

0.00 19.35 0.00 14.61 11.03 2.85 1.45 255.10 0.00

0.00 0.02 0.00 0.01 0.03 0.01 0.00 0.02 125.70

0.14 25.18 2.89 29.60 67.97 8.61 2.93 330.97 364.55

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cars show slightly lower GHG emissions per kilometer than petrol cars (for the same car performance in terms of acceleration and comfort), in spite of higher emissions at the refinery.

4. Results for the improvement options 4.1. Life cycle assessment results Tables 7 and 8 summarise the results regarding the different options analysed for the petrol car and the diesel car, for the different environmental categories, as a percentage of the reference case. The improvement options analysed are ranked according to the time horizon frame, in which they are assumed to be marketed. All the options show benefits regarding the majority of environmental impact categories. Four of the examined options also lead to a higher impact in at least one impact category. The main potential trade-offs suggested within these results are between energy-related impacts (especially GHG) and waste (in the case of recycling/recovery, hybrid car and weight reduction option). Lightweight cars are undoubtedly beneficial in reducing fuel consumption in the use phase. Depending on the weight reduction option, an increase of the amount of waste and PM emissions associated with the production phase is expected. This is due to the fact that greater amounts of aluminium are used. Production of aluminium leads to higher impact in these impact categories which are not offset due to decreased fuel consumption during the use phase. Hybrid cars are shown to offer higher environmental performance overall. They may also entail particular problems resulting from the batteries used (NiMH). Only for waste, the results are worse compared to the base case. This is due to nickel production which is associated with substantial waste generation. Definitive conclusions are, however, difficult to draw as only very few hybrid car models are currently marketed in Europe. Moreover the assumptions regarding the NiMH battery weight and composition are rather uncertain. Further, investigation would be needed regarding the available recycling technologies and also regarding the detailed characteristics (e.g. material breakdown) of the batteries. Increasing recycling/recovery rates lead to significant reductions of ultimate waste (and landfilling). On the other hand, this is expected to generate very small increases in GHG emissions, acidifying substances and eutrophication. This, however, does not take into account the impacts that are potentially avoided by the substitution of primary fossil energy or raw material outside of the car system. In the case of biofuels, as far as the first generation is concerned, additional eutrophication effects and slight PM emission increases are expected for the petrol car (using ethanol). Acidification is also expected to increase with biodiesel. The increased impacts can mainly be attributed to agricultural production processes for biofuels. Despite the fact that fossil fuel energy is reduced by using biofuels, it has to be stressed that primary energy is generally increased. In addition, the increased use of land entailed by biofuel production is not taken into account here. The various options have similar impacts (compared to the reference) for the diesel car and the petrol car. There are two main exceptions:

 When compared with the respective reference, the environmental benefit expected from air abatement systems is higher for the diesel car. A comparison of the results for these two options illustrates the relevance of a life cycle approach. Although affecting one specific life cycle stage, options can reduce the impacts of other processes. In the case of the power train improvement options, a direct impact on GHG emissions is expected (although not quantified, some tailpipe air emission reductions can also be expected). Indirect positive impacts are also expected for the WTT improvements, associated with lower primary energy requirements for fuel extraction and processing. This is not the case with air abatement options. The results related to the different improvements of the power train (without hybrid), when compared with the hybrid case indicate that the latter would generate greater environmental benefits. The actual gap between both types of power train improvements is, however, somewhat overestimated due to the fact that possible reductions in air pollution from TTW (as a result of fuel saving) were neglected. It should also be noted that the impacts on tailpipe air pollutant emissions – which are likely to be reduced – were not quantified for some options (e.g. weight reduction, MAC, aerodynamics, tyres), mainly due to lack of data. Besides the car efficiency options, those that would rely more on changes in driver behaviour are also shown to have environmental improvement potential. This is the case regarding eco-driving and speed limits. As also noted earlier, parameters like the weight, power and volume of a car all affect the life cycle environmental impacts. These parameters are all subject to consumer decisions when a new car is purchased. 4.2. Results of the cost assessment The results of the cost assessment are displayed in Fig. 2, which shows the avoided environmental impacts monetarised with external costs compared to the direct costs of each improvement option for the petrol and diesel car. Generally, the higher the avoided environmental cost is, the higher the direct cost is. Some options do, however, appear to be more cost-effective than others. The hybrid car is shown to be more costly than the other improvement options. Options that are less reliant on technological changes, such as driving behaviour, are shown to be win–win options (see also speed limits and efficient use of MAC). The option reducing the rolling resistance of tyres is also shown to be a win–win option. We performed a sensitivity analysis for a large range of external cost assumptions (from 10–100 Euro/t CO2) and discount rates (from 1% to 7%). The results of this analysis are not displayed here owing to space constraints. However, the sensitivity analysis has shown that the general conclusions concerning the ranking of the improvement options remain valid. Also, win–win options remain win–win options for the full range of assumptions.

5. Conclusions Different improvement options that could help reduce the life cycle impacts of passenger cars used in the EU were analysed. Two generic car models (petrol and diesel) were defined representing, as far as possible, the ‘average’ car purchased in the EU. Despite the sensitivity of estimates to some factors like the car weight or mileage, the following general conclusions can be unambiguously made:

 The different improvements regarding the power train are shown to have higher potential and relative environmental benefit for the petrol car than for the diesel car.

 Primary energy use and GHG emissions are dominated by the TTW component, followed by the WTT and production phases.

Table 7 Environmental benefits of the improvement options (petrol car) compared to the base case in %. Impact category

2010

2020

Car use efficiency

Weight reduction 5%

Weight reduction 12%

Hybrid MAC improvement car

Higher recycling/ recovery rates

Bioethanol Aerodynamics Tyres Weight reduction 30%

Power train

Air abatement option I

Weight reduction Mg

Driving behaviour

Speed limitation

MAC efficient use

99.2 97.2 97.2 97.8 97.8 98.0 97.8 97.2 97.5

98.4 93.9 93.7 95.7 96.3 96.7 100.8 94.3 103.3

100.0 99.4 100.0 100.0 100.0 100.0 100.0 100.0 100.0

100.0 100.1 100.0 100.0 100.0 99.9 100.0 100.0 77.0

100.0 92.3 100.0 104.5 106.0 115.1 100.0 110.7 100.0

100.0 80.5 79.7 86.6 85.2 87.2 84.3 80.9 94.6

100.0 100.0 100.0 99.9 100.0 100.0 100.0 100.0 100.0

95.6 93.7 84.3 88.8 89.2 91.9 98.1 85.7 101.2

100.0 96.0 95.9 97.3 97.0 97.4 96.8 96.1 98.9

100.0 98.7 98.6 98.4 99.0 99.0 99.0 98.7 99.6

100.0 99.2 99.1 99.4 99.3 99.4 99.3 99.1 99.8

55.1 78.4 77.2 75.0 90.6 83.1 88.0 78.6 104.3

100.0 98.7 98.6 99.1 99.0 99.1 98.9 98.7 99.6

100.0 96.0 96.0 84.8 95.9 84.4 97.3 89.2 97.0 90.6 97.4 91.6 96.8 102.1 96.1 85.7 98.9 108.4

Table 8 Environmental benefits of the improvement options (diesel car) compared to the base case in %. Impact category

AD GWP ODP POCP AP EP PM PE BW

2005

2010

2020

Car use efficiency

Weight reduction 5%

Weight reduction 12%

MAC Higher improvement recycling/ recovery rates

Biodiesel Aerodynamics Tyres Weight reduction 30%

Power train

Air abatement option I

Air abatement option II

Hybrid car

Weight reduction Mg

Driving behaviour

Speed limitation

MAC efficient use

99.2 97.0 97.0 98.6 98.1 98.5 98.9 97.1 97.3

98.3 93.6 93.5 97.3 97.3 97.6 101.3 94.0 104.1

100.0 99.5 100.0 100.0 100.0 100.0 100.0 100.0 100.0

100.0 92.4 100.0 103.9 117.9 186.3 76.1 107.2 100.0

100.0 85.3 84.7 94.0 91.3 93.3 94.3 85.6 96.7

100.0 100.0 100.0 94.5 98.1 96.1 65.8 100.0 100.0

100.0 100.0 100.0 72.7 90.5 80.5 65.8 100.0 100.0

53.0 71.5 69.9 88.9 91.2 87.1 92.0 71.8 103.7

95.3 93.8 83.5 93.0 91.6 94.4 100.7 85.0 102.5

100.0 96.1 95.9 98.4 97.6 98.2 98.5 96.1 99.1

100.0 97.5 97.3 95.8 97.4 96.6 97.1 97.5 99.4

100.0 99.2 99.1 99.6 99.5 99.6 99.7 99.2 99.8

100.0 100.1 100.0 100.0 100.0 99.9 100.0 100.0 77.0

100.0 98.7 98.6 99.5 99.2 99.4 99.5 98.7 99.7

100.0 95.8 96.1 83.9 95.9 83.6 98.4 93.4 97.6 93.2 98.2 94.1 98.5 103.2 96.1 85.0 99.1 110.3

G. Leduc et al. / Transport Policy 17 (2010) 409–419

AD GWP ODP POCP AP EP PM PE BW

2005

417

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G. Leduc et al. / Transport Policy 17 (2010) 409–419

1.60

Hybrid car Petrol car Diesel car

1.40

Weight reduction Mg

Direct costs [Euro/100 km]

1.20 Air abatement option I

1.00

Weight reduction 30 %

0.80 0.60

Higher recycling/ recovery rates

0.40

Air abatement option II

Biofuel Aerodynamics

Weight reduction 12 %

0.20 Weight reduction 5 %

0.00 -0.20 -0.05

Tyres & Driving behaviour

Speed limit 0.00

MAC improvement (HFC-134a)

0.05

Efficient use of MAC

Power train improvement

0.10 0.15 0.20 0.25 Avoided impacts [Euro/100 km]

0.30

0.35

0.40

Fig. 2. Monetised avoided environmental impacts and direct costs of the different improvement options per 100 km.

 The size and breakdown of the other energy-related impacts,



namely photochemical oxidation, eutrophication and particles, differ from one case to the other. For the petrol car, the WTT component dominates, followed by the production phase, whereas, for the diesel car, the TTW component dominates, followed by the WTT component and the production phase. The generation of solid waste is shared between the production, WTT and EOL phases. Abiotic depletion is dominated by production and spare parts (lead). Emissions of ozone depleting substances appear to be entirely dominated by WTT.

This paper, supported by other studies and data sets (see e.g.: King (2007)), indicates that, per 100 km driven, the petrol system is less environmentally friendly with respect to greenhouse gas emissions and primary energy. The diesel car was shown to be less environmental friendly regarding photochemical pollution, eutrophication and particulate matter. A literature review led to the identification of the various improvement options that are, or are expected to be, technically available within the next two decades. The two base case car models were used as benchmarks against which various improvement options were analysed. This led to the conclusions that most of the technically feasible options would result in improved performance across the majority of the environmental impact categories. Some options are expected to generate disadvantages for at least one of the impact categories, with the main potential trade-offs between energy-related impacts (especially GHG) and waste (in the case of recycling/recovery, hybrid cars, the weight reduction option and biofuels). Most of the options have similar impacts (with respect to reference cases) for both the diesel and the petrol car. The two main exceptions concern power trains, where there is higher untapped potential for petrol cars, and air abatement systems, where there is higher potential for diesel cars. Besides the car efficiency options, changes in the driver behaviour are also shown to have environmental improvement potential. This is the case

regarding eco-driving and speed limits. Parameters like the weight, power and volume of a car all affect life cycle environmental impacts, and are subject to consumer decisions when a new car is purchased. In terms of the overall environmental gain, the options with a higher potential can be broadly distinguished from options, where the benefits are of a lower magnitude. The first class is composed of the options where the energy use (and thus CO2 emissions) from TTW (and indirectly from WTT) is substantially reduced. Generally, the higher the avoided environmental cost, the higher the direct cost associated with the option. Some options are, however, more cost-effective than others. The hybrid car is shown to be more costly than the other improvement options, per unit of avoided environmental cost. Options that are less reliant on technological changes, such as driving behaviour, are shown to be win–win options (see also speed limits and efficient use of MAC). The option reducing the rolling resistance of tyres is also shown to be a win–win option. Overall, a majority of the options considered in this project (either qualitatively or quantitatively) are considered in the policy framework which is evolving towards more ambitious targets, especially in relation to the important environmental challenges of global warming and air pollution. A regular assessment of the impact of these policies will be required, with reference to the technological progress that they stimulate. On the other hand, this study did not analyse the potential impact of these different environmental improvement options when applied to the European car fleet. Some options are restricted to the new car fleet, and the effects of these options would gradually increase over time due to the turn-over of the car fleet. Other options, if implemented, could help reduce the impacts of the overall car fleet immediately. For some of these options, however, the actual effect is, highly dependent on consumer choice, and on the possible implementation of policies aimed to change behaviour. Such options could play an important role in influencing the environmental impact associated with transport in the context of increasing mobility.

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