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Environmental Impact of Alternative Fuels and Vehicle Technologies: A Life Cycle Assessment Perspective
Available online at www.sciencedirect.com
ScienceDirect Procedia Environmental Sciences 30 (2015) 205 – 210
International Conference on Environmental Forensics 2015 (iENFORCE2015)
Environmental impact of alternative fuels and vehicle technologies: A Life Cycle Assessment perspective Mohammad Hossein Mohammadi Ashnania,b,c*, Tahere Miremadia, Anwar Joharib and Afshin Danekarc a Research Centre for Science and Technology Policy and Diplomacy, IROST, Tehran, Iran Institute of Hydrogen Economy, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Malaysia c Department of Environmental Sciences, Faculty of Natural Resources Engineering, University of Tehran, Iran
b
Abstract Nowadays a wide range of options of vehicles fuels and technologies are commercially available. Still, the complicated nature of environmental impacts caused by each option makes it a tough decision for the consumer, fleet manager, or policy maker to find the best choice. Even policy makers may run into trouble regarding the relative advantages of cleaner options and their relative effects on fuel and vehicle cycle. In light of these, the present paper is an attempt to evaluate the life cycle environmental impacts of road vehicle fuels and available technologies and compare the cleaner options with each other and the main stream fuel/technologies. A complete fuel life cycle assessment (LCA) on petrol, diesel, compressed natural gas (CNG), electric vehicle (EV), hydrogen fuel cell vehicle (FCV), and biodiesel vehicles was made. Results are shown for climate change, air quality effects and Energy resource depletion impact of the different vehicle technologies. As recommended by the results, none of the options dominated the others regarding all dimensions. Instead of mandating a particular solution, such as electric cars or biofuels, probably successful vehicle and fuel policies include established standards of performance and levies to attenuate emissions and let the market to find the best effective alternative. © 2015 The Authors. Published by Elsevier B.V This is an open access article under the CC BY-NC-ND license © 2015 The Authors. Published by Elsevier B.V. (http://creativecommons.org/licenses/by-nc-nd/4.0/). Research Centre, Faculty of Studies, Peer-review under responsibility of organizing committee of Environmental Peer-review under responsibility of organizing committee of Environmental ForensicsForensics Research Centre, Faculty of Environmental Environmental Studies, Universiti Putra Malaysia. Universiti Putra Malaysia. Keywords: Life cycle assessment; fuels and vehicle options; climate change; energy; air pollution; policy
* Corresponding author. Tel.: E-mail address: [email protected]
1878-0296 © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of organizing committee of Environmental Forensics Research Centre, Faculty of Environmental Studies, Universiti Putra Malaysia. doi:10.1016/j.proenv.2015.10.037
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Mohammad Hossein Mohammadi Ashnani et al. / Procedia Environmental Sciences 30 (2015) 205 – 210
1. Introduction The issue of “sustainability” has never been so important in man’s history; so that it is now important more than other trends such as quality, speed, and production flexibility which were top priorities in the last 25 years. The attention drawn to sustainability is mainly rooted in social awareness of necessity of reaching a balance between human development and conservation of the environment [1]. There are more than enough reasons explaining initiation of transition from the conventional options on the road transport sector toward new options including increase of oil price, the climate change problems, the increasing restrictions on pollutant emissions, the high dependence of road transport sector on oil, economic impact, and geological concerns, etc. Global stability convincingly has never been threatened so persistently like it is by climate change and probably the threat is the most critical challenge in the way of humanity in this century [2, 3]. To realize what was agreed by the participating governments at Cancun 2010 [4], which was to limit the rise in global average temperature to less than 2°C above pre-industrial level, the total carbon dioxide volume that is allowed to be emitted until 2050 should be around 565-886 billion tonnes (Gt) [5, 6] so that two third of this fuel must stay in the ground to meet the goals of Cancun summit. Additionally, fossil fuels are finite and soon there would be no more fossil fuel. Thereby, fossil fuel use should be “sustainable” as without it, our future generations’ development might be constrained. That is, one of the main vital challenges to the mankind is the fast decrease of organic fuel resources extracted from entrails of the earth and also increase of consumption rate of the resources [7]. Increase of world energy consumption led to 12730.4 million tonnes oil equivalent a year by 2.3% in 2013, which means an acceleration over 2012 (+1.8%) [8]. At currently state of the curves of energy consumption and production of energy from oil, reserve depletion would between 34-43 years, and this figure for gas is 37-70 [6, 9-11] and for uranium 235 in the beginning of 50-ies of the current century [7]. To put it another way, the production-consumption balance of energy based on oil, gas, and uranium-235 sources will change from positive to negative [7]. In spite of commonly heard claim that there is enough coal for hundreds of years (reserve depletion time 106-200) [6, 9-11], in absence of oil and gas, the coal deposits would be enough until 2088 [12]. The key drivers behind the growth of energy demand are population growth and increase in income per person. Estimates say that world population reaches 8.7 billion by 2035, which is 1.6 billion increase in energy consumers. Add to this that GDP per person in 2035 is expected to grow by 75%, which is an increase in productivity equal with three-quarters of global GDP growth [13]. Thereby, the issue of energy security will challenge us at national and international levels while a sustainable replacement for fuels and nuclear power is not found [7]. In general, the transport section produces almost a quarter of global energy-rated greenhouse gas emissions. Road transportation covers the largest portion (more than 70%), followed by marine (15%), and aviation (10%). The main portion of road transportation emissions comes from light-duty vehicles and trucks [14-16] (Fig. 1).
Fig. 1. The transport sector as a major contributor to global energy-related CO2 emissions
One main cause of air pollution is transport sector [17-19] so that as recommended by estimates, it caused 3.7 million premature death all around the world in 2012. These deaths were caused by exposure to small particles of 10 microns or less in diameter (PM10), which induces cardiovascular and respiratory disease and cancer. About 88% of these mortalities take place in low-and middle-income countries. The annual cost of air pollution to the developed countries including India and China is around US$3.5 trillion per year in lives lost and ill health [20, 21].
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Given this introduction, it is essential to make a shift towards a more sustainable transport system by cutting fossil fuels consumption through finding new vehicle technologies and alternative fuels. The Life Cycle Assessment (LCA) methodology is of the capacity of being a key management tool to help decision makers to achieve a holistic insight into the entire system associated with single product/service to be introduced. Still, what we usually encountered with in such situations is that the “cleaner energy” will always take place in the future, and thereby, there is always some extent of subjectivity in the analysis, even in the inventory analysis phase of the LCA method, which is supposedly highly quantitative and objective. This study is aimed at assessing the life cycle environmental impact of road vehicle fuels and technologies and comparing the cleaner alternatives with each other and also the mainstream of vehicle fuels/technologies for better transport policies in the future. 2. Methods Different vehicle technologies are usually assessed from different points in their life cycle using life cycle assessment (LCA) method. The method is a “cradle-to-grave” approach of evaluating systems or technologies through compiling a stock of relevant inputs and outputs, assessing the potential environmental impacts associated with known inputs and outputs, and analyzing the results of inventory and impact phases to achieve better informed decisions [22].The main areas of using LCAs is to assess and compare the general environmental load from a variety of competing technologies. The advantage of the approach lies with the fact that, as the analyses is made on a life cycle basis, materials, products or processes with different resource use and emission pathways can be compared. The present study is a streamlined LCA using midpoint model. All the data used in this assessment were collected based on three set questionnaire and the most recent literature reviews and statistics [22-27]. According to reports by International Organization for Standardization (ISO) and the Society for Environmental Toxicology and Chemistry (SETAC), the LCA methodology is comprised of four interrelated stages: Goal and Scope Definition, Life Cycle Inventory Analysis (LCI), Life Cycle Impact Assessment (LCIA) and Interpretation [28-30]. There are two significantly important aspects when it comes to analyzing a new power train/fuel combination in the automotive sector, which are energy efficiency and pollutant emissions. A standard LCA estimates energy and material flows pertinent to all stages of product’s life time (Cradle-to-grave). Additionally, there are two distinguishable life cycles in the automotive life cycle analysis: the vehicle life cycle and fuel life cycle. The former refers to material production, vehicle assembly, distribution, and disposal. The latter, which is also known as well-to-wheels analysis (from energy feedstock recovery, “well”, to energy delivering to the vehicle, “wheels”), can be divided into two key stages: the well-to-tank (energy consumption and emissions to extract raw materials, to transport them, to produce the desired fuel, to distribute the fuel to consumers, and so on); and tank-towheels (energy consumption and emissions caused by using the fuel by vehicle) [22, 31, 32]. What is provided by the goal and scope of definition of an LCA is a description of the product system in terms of the system limitations and a functional unit. The functional unit gives us a way to compare and analyze different goods or services. Within the scope of this paper, it is defined as driving 1km. The vehicles focused in this study are passenger car weigh 1100-1400 kg. A brief description of the vehicle/fuel life cycle is pictured in Fig. 2. Fuel Production
Primary energy
Fuel Distribution Raw Materials
Vehicle
Scrap / Recycle
Landfill
Vehicle Use Maintena
Fixed
Vehicle End-of-life Waste Management
Fig. 2. Automobile/fuel life cycle
The life cycle inventory (LCI) analysis takes into account all required resources and all emissions released by the specific system under investigation and relates them to the defined functional unit [29]. The aim of life cycle impact assessment (LCIA) is to interpret the LCI data through three steps: characterization, normalization, and weighting. The impacts that were taken into account are energy (KJ) and greenhouse gases (GHG) and particulate matter (PM).
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The three functional metrics are used to determine the anticipated categorical impact of the different vehicles on resource depletion (energy efficiency), climate change, and air quality respectively. By fuel we refer to gasoline, diesel, natural gas, biodiesel, electricity, and hydrogen. To compute global warming potential (GWP), the CO 2 equivalent factors from the intergovernmental panel on climate change (IPCC) was used [33]. Based on this procedure, each power train/fuel combination can be used to compare a uniform energy- environmental basis. 3. Results and Discussion To achieve the full life cycle results for the selected technologies, all results of WTW and vehicle production stages were used. LCA analysis results are pictured in Fig. 3-5; where Petr stands for gasoline, Dies stands for diesel, BioD stands for biodiesel, CNG stands for compressed natural gas, EV stands for electric vehicle, and FCV stands for hydrogen fuel cell vehicle. The findings must be taken into account in the context of the limitations of the high level, streamlines nature of the study. In addition, the existence of different parameters led us to spread LCA results, which is shown in the results with error bars. The best energy life cycle value is filled by FCV (power train) H2 (fuel) combination (Fig. 3). Taking into account the simple configuration and light weight of conventional vehicle (CV) and the lowest energy use during the vehicle production stage, CV does result in good performance compared with advance vehicles. 6000
Energy
KJ / KM
5000 4000 Fuel Cycle
3000
Vehicle Cycle
2000 1000 0
Petr
Dise
CNG
BioD
EV
FCV
Fig. 3. Energy resource depletion of different fuel/vehicle technologies
Very high values are obtained with Bio-diesel in fact; it suffers from a very high WTWe. From energy viewpoint, thereby, biofuel options still have to compete with traditional fuels and natural gas. Given their high impact on WTW and vehicle production stages because of combined effect of 1- the high share of fossil in the mix; and 2- the low efficiency of conversion technologies in electricity, EV’s performance is not satisfactory. The TTWe. could be better, but it is constrained by the heavy weight of the battery. Comparing different car technologies indicates that the climate impact is considerably under the effect of vehicle technology, the type of fuel and the feedstock used to generate the fuel (Fig. 4). The best position is filled by the biofuels given their CO2 credit. Results with FCV are satisfactory, which is comparable with those of EV. The contribution of the lithium ion battery to the overall impact is significant. The traditional fuels have higher GHG emission and petrol has the highest GHG emission comparing with other options.
greenhouse gas
gr / KM
400 350 300 250 200
Fuel Cycle
150 100 50 0
Petr
Dise
CNG
BioD
EV
FCV
Fig. 4. The effect of various vehicle technologies on climate change
Vehicle Cycle
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209
particulate matter (PM) gr/KM
As pictured in Fig. 5, electric vehicles with average mix electricity have the highest particular emission on a life cycle basis. The reason is high level of particulates emitted during electricity generation. In addition, diesel and biodiesel life cycle emissions are also larger than other cases because of significant particulate emission generated during vehicle operation. 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0
Fuel Cycle
Petr
Dise
CNG
BioD
EV
Vehicle Cycle
FCV
Fig. 5. Air quality impact of different fuel/vehicle technologies
That is, all other cases are notably similar in life cycle particulate which is mainly because of the majority of life cycle particulate emission of vehicle manufacture. However, all particulate emissions of the other cases are generated while fuel production are located far away from most major cities- in some cases, refinery, fuel processing or vehicle manufacturing plants are located in populated region. 4. Conclusion The key contribution of LCA methods and studies like the present one is helping decision makers to focus better on the important attributes and avoid focusing only on one aspect of fuel cycle or propulsion system or at only one media for environmental burdens. Analysis results regarding both energy efficiency and pollutant emissions lead to notable conclusions: which solution indicates a clear advantage regarding primary sources exploitation, and which one permits reducing pollutant substances in the overall fuel cycle. Still, a reliable solution as to energy aspects might not be as good regarding environmental aspects or vice versa. However, taking into account complicacy of transportation system, modifications to reduce one problem may lead to exacerbation of others. The results also illustrated that all the fuel-efficient technologies, mainly biodiesel, may improve the GHG over the lifetime of the vehicle. On the other hand, conventional biofuels are not free of disadvantages as they are too costly and at the current state they need considerable quantities of fossil resources. These disadvantages may be decreases by technological advances, as pictured in the 2030 forecast. Due to considerable efficiencies of fuel cycle, the FCV can achieve minimum energy consumption – i.e. 20% reduction comparing with CV. LCA analyses results showed that CNG vehicles provide air quality benefits. The study also indicated necessity to focus more on fuel life cycle taking into account that its weight comparing with vehicle life cycle. There are many factors to be concerned with in developing a sustainable transportation system; including the relative roles of public and private transportation, the types of fuels that is available in log-run, geopolitical issues, primary sources deletion, GHG and pollutant emissions of the fuel/vehicle usage, the life cycle energy and emission of the vehicle, available fuel infrastructure, safety, affordability and consumer acceptance of fuels and vehicle and so on. Probably successful vehicle and fuel policies include established standards of performance and levies to attenuate emissions. Instead of mandating a particular solution, such as electric cars or biofuel, it is far better to set overarching policy goals and let the market to find the best cost effective alternative. Effective vehicle emission performance standards compatible with revenue-neutral fuel fees many can be of great reduction of nations’ annual emission – and save a considerable sums of fuel reserves and money. Vehicle effectiveness improvement needs more up-front investment, which results in increase of economic growth and more job opportunities. Additionally, by cutting fuel usage, the improvements leads to higher national security and results in considerable savings to consumers. Through this, the consumer will enjoy more sources to purchase other goods and services, which leads
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to better economic condition. By cutting conventional pollutants, the policies also improve public health. Taking into account the immense change of social and driver goals and availability of technology in the last 50 years, greater changes are expected in the next 30-40 years, which makes is hard to say which fuel/technology will be the winner in 2050 [15, 25]. Acknowledgements We gratefully acknowledge the support and generosity of Research Center for Science and Technology Policy and Diplomacy (MAPSED) Foundation, without which the present study could not have been completed. The authors appreciated the support of Universiti Teknologi Malaysia and Malaysian Min. of Higher Education (GUP grant VOT No. 07H11). References 1. Sobrino FH, Monroy CR, Pérez JLH. Biofuels and fossil fuels: Life Cycle Analysis (LCA) optimisation through productive resources maximisation. Renewable and Sustainable Energy Reviews 2011; 15: 2621-2628. 2. Karl TR, Trenberth KE. Modern global climate change. science 2003; 302: 1719-1723. 3. University of Oxford. Global Challenges – Twelve risks that threaten human civilisation, Future of Humanity Institute, Oxford Martin School & Faculty of Philosophy; 2015. 4. UNFCCC. The Cancun Agreements, United Nations Climate Change Conference: Mexico; 2010. 5. Meinshausen M, Meinshausen N, Hare W, Raper SC, Frieler K, Knutti R, Frame DJ, Allen MR. Greenhouse-gas emission targets for limiting global warming to 2 C. Nature 2009; 458: 1158-1162. 6. IEA. World Energy Outlook 2012, Organisation for Economic Co-operation and Development, : Paris and Washington, DC.; 2012. 7. Zgurovsky M. Sustainable Development Global Simulation: Analysis of Quality and Security of Human Life, INTECH Publisher; 2012. 8. British Petroleum (bp). BP Statistical Review of World Energy, BP London: UK; 2014. 9. Lior N. Energy resources and use: the present situation and possible paths to the future. Energy 2008; 33: 842-857. 10. Shafiee S, Topal E. When will fossil fuel reserves be diminished? Energy policy 2009; 37: 181-189. 11. Singh BR, Singh O. Global trends of fossil fuel reserves and climate change in the 21st century, INTECH Open Access Publisher; 2012. 12. Ecotricity. The End Of Fossil Fuels, in. Britain's leading green energy supplier, 2011. 13. British Petroleum (bp). BP Energy Outlook 2035, BP London, UK; 2014. 14. IEA. co2 emissions from fuel combustion, Organisation for Economic Co-operation and Development, : Paris and Washington, DC.; 2013. 15. Kodjak D, Sanchez FP, Segafredo L. How Vehicle Standards and Fuel Fees Can Cut CO2 and Boost the Economy The International Council on Clean Transportation (icct); 2012. 16. Hester R, Harrison R. Fracking, Royal Society of Chemistry; 2014. 17. Bartolozzi I, Rizzi F, Frey M. Comparison between hydrogen and electric vehicles by life cycle assessment: A case study in Tuscany, Italy. Applied Energy 2013; 101: 103-111. 18. Krzyzanowski M, Kuna-Dibbert B, Schneider J. Health effects of transport-related air pollution, World Health Organization Copenhagen, Denmark; 2005. 19. Colvile R, Hutchinson E, Mindell J. The transport sector as a source of air pollution. Atmospheric environment 2001; 35: 1537-1565. 20. UNEP. Air Pollution: World’s Worst Environmental Health Risk, United Nations Environment Programme; 2014. 21. WHO. Ambient (outdoor) air quality and health, World Health Organization; 2014. 22. Torchio MF, Santarelli MG. Energy, environmental and economic comparison of different powertrain/fuel options using well-to-wheels assessment, energy and external costs–European market analysis. Energy 2010; 35: 4156-4171. 23. Gao L, Winfield ZC. Life cycle assessment of environmental and economic impacts of advanced vehicles. Energies 2012; 5: 605-620. 24. Lane DB. Life Cycle Assessment of Vehicle Fuels and Technologies. London Borough of Camden 2007. 25. MacLean HL, Lave LB. Evaluating automobile fuel/propulsion system technologies. Progr Energ Combust 2003; 29: 1-69. 26. Messagie M, Boureima F-S, Coosemans T, Macharis C, Mierlo JV. A range-based vehicle life cycle assessment incorporating variability in the environmental assessment of different vehicle technologies and fuels. Energies 2014; 7: 1467-1482. 27. Shen W, Han W, Chock D, Chai Q, Zhang A. Well-to-wheels life-cycle analysis of alternative fuels and vehicle technologies in China. Energy Policy 2012; 49: 296-307. 28. Consoli F, Allen D, Boustead II. Guidelines for life cycle assessment: A code of practice. SETAC 1993. 29. ISO. ISO 14040-Environmental management-Life cycle assessment-rinciples and framework. 1997; p:14. 30. Mohammadi Ashnani HM, Johari A, Hashim H, Hasani E. Life Cycle Assessment of Palm Oil Biodiesel Production in Malaysia. Applied Mechanics and Materials 2014; 465: 1080-1086. 31. Hekkert MP, Hendriks FH, Faaij AP, Neelis ML. Natural gas as an alternative to crude oil in automotive fuel chains well-to-wheel analysis and transition strategy development. Energy Policy 2005; 33: 579-594. 32. Svensson AM, Møller-Holst S, Glöckner R, Maurstad O. Well-to-wheel study of passenger vehicles in the Norwegian energy system. Energy 2007; 32: 437-445. 33. Houghton JT. Climate change 1995: The science of climate change: contribution of working group I to the second assessment report of the Intergovernmental Panel on Climate Change, Cambridge University Press; 1996.
ScienceDirect Procedia Environmental Sciences 30 (2015) 205 – 210
International Conference on Environmental Forensics 2015 (iENFORCE2015)
Environmental impact of alternative fuels and vehicle technologies: A Life Cycle Assessment perspective Mohammad Hossein Mohammadi Ashnania,b,c*, Tahere Miremadia, Anwar Joharib and Afshin Danekarc a Research Centre for Science and Technology Policy and Diplomacy, IROST, Tehran, Iran Institute of Hydrogen Economy, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Malaysia c Department of Environmental Sciences, Faculty of Natural Resources Engineering, University of Tehran, Iran
b
Abstract Nowadays a wide range of options of vehicles fuels and technologies are commercially available. Still, the complicated nature of environmental impacts caused by each option makes it a tough decision for the consumer, fleet manager, or policy maker to find the best choice. Even policy makers may run into trouble regarding the relative advantages of cleaner options and their relative effects on fuel and vehicle cycle. In light of these, the present paper is an attempt to evaluate the life cycle environmental impacts of road vehicle fuels and available technologies and compare the cleaner options with each other and the main stream fuel/technologies. A complete fuel life cycle assessment (LCA) on petrol, diesel, compressed natural gas (CNG), electric vehicle (EV), hydrogen fuel cell vehicle (FCV), and biodiesel vehicles was made. Results are shown for climate change, air quality effects and Energy resource depletion impact of the different vehicle technologies. As recommended by the results, none of the options dominated the others regarding all dimensions. Instead of mandating a particular solution, such as electric cars or biofuels, probably successful vehicle and fuel policies include established standards of performance and levies to attenuate emissions and let the market to find the best effective alternative. © 2015 The Authors. Published by Elsevier B.V This is an open access article under the CC BY-NC-ND license © 2015 The Authors. Published by Elsevier B.V. (http://creativecommons.org/licenses/by-nc-nd/4.0/). Research Centre, Faculty of Studies, Peer-review under responsibility of organizing committee of Environmental Peer-review under responsibility of organizing committee of Environmental ForensicsForensics Research Centre, Faculty of Environmental Environmental Studies, Universiti Putra Malaysia. Universiti Putra Malaysia. Keywords: Life cycle assessment; fuels and vehicle options; climate change; energy; air pollution; policy
* Corresponding author. Tel.: E-mail address: [email protected]
1878-0296 © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of organizing committee of Environmental Forensics Research Centre, Faculty of Environmental Studies, Universiti Putra Malaysia. doi:10.1016/j.proenv.2015.10.037
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1. Introduction The issue of “sustainability” has never been so important in man’s history; so that it is now important more than other trends such as quality, speed, and production flexibility which were top priorities in the last 25 years. The attention drawn to sustainability is mainly rooted in social awareness of necessity of reaching a balance between human development and conservation of the environment [1]. There are more than enough reasons explaining initiation of transition from the conventional options on the road transport sector toward new options including increase of oil price, the climate change problems, the increasing restrictions on pollutant emissions, the high dependence of road transport sector on oil, economic impact, and geological concerns, etc. Global stability convincingly has never been threatened so persistently like it is by climate change and probably the threat is the most critical challenge in the way of humanity in this century [2, 3]. To realize what was agreed by the participating governments at Cancun 2010 [4], which was to limit the rise in global average temperature to less than 2°C above pre-industrial level, the total carbon dioxide volume that is allowed to be emitted until 2050 should be around 565-886 billion tonnes (Gt) [5, 6] so that two third of this fuel must stay in the ground to meet the goals of Cancun summit. Additionally, fossil fuels are finite and soon there would be no more fossil fuel. Thereby, fossil fuel use should be “sustainable” as without it, our future generations’ development might be constrained. That is, one of the main vital challenges to the mankind is the fast decrease of organic fuel resources extracted from entrails of the earth and also increase of consumption rate of the resources [7]. Increase of world energy consumption led to 12730.4 million tonnes oil equivalent a year by 2.3% in 2013, which means an acceleration over 2012 (+1.8%) [8]. At currently state of the curves of energy consumption and production of energy from oil, reserve depletion would between 34-43 years, and this figure for gas is 37-70 [6, 9-11] and for uranium 235 in the beginning of 50-ies of the current century [7]. To put it another way, the production-consumption balance of energy based on oil, gas, and uranium-235 sources will change from positive to negative [7]. In spite of commonly heard claim that there is enough coal for hundreds of years (reserve depletion time 106-200) [6, 9-11], in absence of oil and gas, the coal deposits would be enough until 2088 [12]. The key drivers behind the growth of energy demand are population growth and increase in income per person. Estimates say that world population reaches 8.7 billion by 2035, which is 1.6 billion increase in energy consumers. Add to this that GDP per person in 2035 is expected to grow by 75%, which is an increase in productivity equal with three-quarters of global GDP growth [13]. Thereby, the issue of energy security will challenge us at national and international levels while a sustainable replacement for fuels and nuclear power is not found [7]. In general, the transport section produces almost a quarter of global energy-rated greenhouse gas emissions. Road transportation covers the largest portion (more than 70%), followed by marine (15%), and aviation (10%). The main portion of road transportation emissions comes from light-duty vehicles and trucks [14-16] (Fig. 1).
Fig. 1. The transport sector as a major contributor to global energy-related CO2 emissions
One main cause of air pollution is transport sector [17-19] so that as recommended by estimates, it caused 3.7 million premature death all around the world in 2012. These deaths were caused by exposure to small particles of 10 microns or less in diameter (PM10), which induces cardiovascular and respiratory disease and cancer. About 88% of these mortalities take place in low-and middle-income countries. The annual cost of air pollution to the developed countries including India and China is around US$3.5 trillion per year in lives lost and ill health [20, 21].
Mohammad Hossein Mohammadi Ashnani et al. / Procedia Environmental Sciences 30 (2015) 205 – 210
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Given this introduction, it is essential to make a shift towards a more sustainable transport system by cutting fossil fuels consumption through finding new vehicle technologies and alternative fuels. The Life Cycle Assessment (LCA) methodology is of the capacity of being a key management tool to help decision makers to achieve a holistic insight into the entire system associated with single product/service to be introduced. Still, what we usually encountered with in such situations is that the “cleaner energy” will always take place in the future, and thereby, there is always some extent of subjectivity in the analysis, even in the inventory analysis phase of the LCA method, which is supposedly highly quantitative and objective. This study is aimed at assessing the life cycle environmental impact of road vehicle fuels and technologies and comparing the cleaner alternatives with each other and also the mainstream of vehicle fuels/technologies for better transport policies in the future. 2. Methods Different vehicle technologies are usually assessed from different points in their life cycle using life cycle assessment (LCA) method. The method is a “cradle-to-grave” approach of evaluating systems or technologies through compiling a stock of relevant inputs and outputs, assessing the potential environmental impacts associated with known inputs and outputs, and analyzing the results of inventory and impact phases to achieve better informed decisions [22].The main areas of using LCAs is to assess and compare the general environmental load from a variety of competing technologies. The advantage of the approach lies with the fact that, as the analyses is made on a life cycle basis, materials, products or processes with different resource use and emission pathways can be compared. The present study is a streamlined LCA using midpoint model. All the data used in this assessment were collected based on three set questionnaire and the most recent literature reviews and statistics [22-27]. According to reports by International Organization for Standardization (ISO) and the Society for Environmental Toxicology and Chemistry (SETAC), the LCA methodology is comprised of four interrelated stages: Goal and Scope Definition, Life Cycle Inventory Analysis (LCI), Life Cycle Impact Assessment (LCIA) and Interpretation [28-30]. There are two significantly important aspects when it comes to analyzing a new power train/fuel combination in the automotive sector, which are energy efficiency and pollutant emissions. A standard LCA estimates energy and material flows pertinent to all stages of product’s life time (Cradle-to-grave). Additionally, there are two distinguishable life cycles in the automotive life cycle analysis: the vehicle life cycle and fuel life cycle. The former refers to material production, vehicle assembly, distribution, and disposal. The latter, which is also known as well-to-wheels analysis (from energy feedstock recovery, “well”, to energy delivering to the vehicle, “wheels”), can be divided into two key stages: the well-to-tank (energy consumption and emissions to extract raw materials, to transport them, to produce the desired fuel, to distribute the fuel to consumers, and so on); and tank-towheels (energy consumption and emissions caused by using the fuel by vehicle) [22, 31, 32]. What is provided by the goal and scope of definition of an LCA is a description of the product system in terms of the system limitations and a functional unit. The functional unit gives us a way to compare and analyze different goods or services. Within the scope of this paper, it is defined as driving 1km. The vehicles focused in this study are passenger car weigh 1100-1400 kg. A brief description of the vehicle/fuel life cycle is pictured in Fig. 2. Fuel Production
Primary energy
Fuel Distribution Raw Materials
Vehicle
Scrap / Recycle
Landfill
Vehicle Use Maintena
Fixed
Vehicle End-of-life Waste Management
Fig. 2. Automobile/fuel life cycle
The life cycle inventory (LCI) analysis takes into account all required resources and all emissions released by the specific system under investigation and relates them to the defined functional unit [29]. The aim of life cycle impact assessment (LCIA) is to interpret the LCI data through three steps: characterization, normalization, and weighting. The impacts that were taken into account are energy (KJ) and greenhouse gases (GHG) and particulate matter (PM).
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Mohammad Hossein Mohammadi Ashnani et al. / Procedia Environmental Sciences 30 (2015) 205 – 210
The three functional metrics are used to determine the anticipated categorical impact of the different vehicles on resource depletion (energy efficiency), climate change, and air quality respectively. By fuel we refer to gasoline, diesel, natural gas, biodiesel, electricity, and hydrogen. To compute global warming potential (GWP), the CO 2 equivalent factors from the intergovernmental panel on climate change (IPCC) was used [33]. Based on this procedure, each power train/fuel combination can be used to compare a uniform energy- environmental basis. 3. Results and Discussion To achieve the full life cycle results for the selected technologies, all results of WTW and vehicle production stages were used. LCA analysis results are pictured in Fig. 3-5; where Petr stands for gasoline, Dies stands for diesel, BioD stands for biodiesel, CNG stands for compressed natural gas, EV stands for electric vehicle, and FCV stands for hydrogen fuel cell vehicle. The findings must be taken into account in the context of the limitations of the high level, streamlines nature of the study. In addition, the existence of different parameters led us to spread LCA results, which is shown in the results with error bars. The best energy life cycle value is filled by FCV (power train) H2 (fuel) combination (Fig. 3). Taking into account the simple configuration and light weight of conventional vehicle (CV) and the lowest energy use during the vehicle production stage, CV does result in good performance compared with advance vehicles. 6000
Energy
KJ / KM
5000 4000 Fuel Cycle
3000
Vehicle Cycle
2000 1000 0
Petr
Dise
CNG
BioD
EV
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Fig. 3. Energy resource depletion of different fuel/vehicle technologies
Very high values are obtained with Bio-diesel in fact; it suffers from a very high WTWe. From energy viewpoint, thereby, biofuel options still have to compete with traditional fuels and natural gas. Given their high impact on WTW and vehicle production stages because of combined effect of 1- the high share of fossil in the mix; and 2- the low efficiency of conversion technologies in electricity, EV’s performance is not satisfactory. The TTWe. could be better, but it is constrained by the heavy weight of the battery. Comparing different car technologies indicates that the climate impact is considerably under the effect of vehicle technology, the type of fuel and the feedstock used to generate the fuel (Fig. 4). The best position is filled by the biofuels given their CO2 credit. Results with FCV are satisfactory, which is comparable with those of EV. The contribution of the lithium ion battery to the overall impact is significant. The traditional fuels have higher GHG emission and petrol has the highest GHG emission comparing with other options.
greenhouse gas
gr / KM
400 350 300 250 200
Fuel Cycle
150 100 50 0
Petr
Dise
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Fig. 4. The effect of various vehicle technologies on climate change
Vehicle Cycle
Mohammad Hossein Mohammadi Ashnani et al. / Procedia Environmental Sciences 30 (2015) 205 – 210
209
particulate matter (PM) gr/KM
As pictured in Fig. 5, electric vehicles with average mix electricity have the highest particular emission on a life cycle basis. The reason is high level of particulates emitted during electricity generation. In addition, diesel and biodiesel life cycle emissions are also larger than other cases because of significant particulate emission generated during vehicle operation. 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0
Fuel Cycle
Petr
Dise
CNG
BioD
EV
Vehicle Cycle
FCV
Fig. 5. Air quality impact of different fuel/vehicle technologies
That is, all other cases are notably similar in life cycle particulate which is mainly because of the majority of life cycle particulate emission of vehicle manufacture. However, all particulate emissions of the other cases are generated while fuel production are located far away from most major cities- in some cases, refinery, fuel processing or vehicle manufacturing plants are located in populated region. 4. Conclusion The key contribution of LCA methods and studies like the present one is helping decision makers to focus better on the important attributes and avoid focusing only on one aspect of fuel cycle or propulsion system or at only one media for environmental burdens. Analysis results regarding both energy efficiency and pollutant emissions lead to notable conclusions: which solution indicates a clear advantage regarding primary sources exploitation, and which one permits reducing pollutant substances in the overall fuel cycle. Still, a reliable solution as to energy aspects might not be as good regarding environmental aspects or vice versa. However, taking into account complicacy of transportation system, modifications to reduce one problem may lead to exacerbation of others. The results also illustrated that all the fuel-efficient technologies, mainly biodiesel, may improve the GHG over the lifetime of the vehicle. On the other hand, conventional biofuels are not free of disadvantages as they are too costly and at the current state they need considerable quantities of fossil resources. These disadvantages may be decreases by technological advances, as pictured in the 2030 forecast. Due to considerable efficiencies of fuel cycle, the FCV can achieve minimum energy consumption – i.e. 20% reduction comparing with CV. LCA analyses results showed that CNG vehicles provide air quality benefits. The study also indicated necessity to focus more on fuel life cycle taking into account that its weight comparing with vehicle life cycle. There are many factors to be concerned with in developing a sustainable transportation system; including the relative roles of public and private transportation, the types of fuels that is available in log-run, geopolitical issues, primary sources deletion, GHG and pollutant emissions of the fuel/vehicle usage, the life cycle energy and emission of the vehicle, available fuel infrastructure, safety, affordability and consumer acceptance of fuels and vehicle and so on. Probably successful vehicle and fuel policies include established standards of performance and levies to attenuate emissions. Instead of mandating a particular solution, such as electric cars or biofuel, it is far better to set overarching policy goals and let the market to find the best cost effective alternative. Effective vehicle emission performance standards compatible with revenue-neutral fuel fees many can be of great reduction of nations’ annual emission – and save a considerable sums of fuel reserves and money. Vehicle effectiveness improvement needs more up-front investment, which results in increase of economic growth and more job opportunities. Additionally, by cutting fuel usage, the improvements leads to higher national security and results in considerable savings to consumers. Through this, the consumer will enjoy more sources to purchase other goods and services, which leads
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to better economic condition. By cutting conventional pollutants, the policies also improve public health. Taking into account the immense change of social and driver goals and availability of technology in the last 50 years, greater changes are expected in the next 30-40 years, which makes is hard to say which fuel/technology will be the winner in 2050 [15, 25]. Acknowledgements We gratefully acknowledge the support and generosity of Research Center for Science and Technology Policy and Diplomacy (MAPSED) Foundation, without which the present study could not have been completed. The authors appreciated the support of Universiti Teknologi Malaysia and Malaysian Min. of Higher Education (GUP grant VOT No. 07H11). References 1. Sobrino FH, Monroy CR, Pérez JLH. Biofuels and fossil fuels: Life Cycle Analysis (LCA) optimisation through productive resources maximisation. Renewable and Sustainable Energy Reviews 2011; 15: 2621-2628. 2. Karl TR, Trenberth KE. 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