Life Cycle Assessment of Hydrogen Fuel Cell and Gasoline Vehicles

Life Cycle Assessment of Hydrogen Fuel Cell and Gasoline Vehicles

CHAPTER ELEVEN Life Cycle Assessment of Hydrogen Fuel Cell and Gasoline Vehicles Mohammed M. Hussain* and Ibrahim Dincer1** National Research Council...

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CHAPTER ELEVEN

Life Cycle Assessment of Hydrogen Fuel Cell and Gasoline Vehicles Mohammed M. Hussain* and Ibrahim Dincer1** National Research Council – Institute of Fuel Cell Innovation, Vancouver, British Columbia, Canada Faculty of Engineering and Applied Science, Institute of Technology (UOIT), University of Ontario, Oshawa, Ontario, Canada

*

**

Contents 1. Introduction 2. Methodology 3. Scope 4. Limitations 5. Results and Discussion 6. Concluding Remarks References

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1. INTRODUCTION The transportation sector is a significant contributor to major environmental concerns such as global warming, greenhouse gas (GHG) emissions, and climate change. According to the US Environmental Protection Agency (EPA) estimates, in 2006, approximately 28% of total US GHG emissions came from the transportation sector [1]. The technology which provides a potential solution to major environmental con­ cerns arising from the transportation sector is often referred to as polymer electrolyte membrane (PEM) fuel cell. PEM fuel cell-powered vehicles using hydrogen have many advantages, such as energy efficient and environmentally benign operation, compatible with renewable energy sources and carriers of future energy security, economic growth, and sustainable development. However, to validly assess an emerging technology like PEM fuel cell-powered vehicle, the methodology must consider the total system over its entire life cycle. The life cycle of a vehicle technology must include all the steps required to produce a fuel, to manufacture a vehicle, and to operate and maintain the vehicle throughout its lifetime including disposal and recycling at the end. A typical life cycle of a vehicle is shown in Fig. 11.1. Utilizing a life cycle approach is essential in better understanding the relative importance of one technology over other [2]. On the other hand, without a life cycle 1

Corresponding author: [email protected]

Electric and Hybrid Vehicles ISBN 978-0-444-53565-8, DOI: 10.1016/B978-0-444-53565-8.00011-7

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Inputs for each stage:

Materials and energy

Primary energy sources Manufacturing

Raw material acquisition

Fuel production

Use Fuel distribution

Recycling or disposal

System boundary Outputs for each stage: Desired products, energy released, Atmospheric emissions, waterborne, and solid wastes

Figure 11.1 Typical life cycle stages of a vehicle.

approach, false conclusions can be drawn [3]. Therefore, many North American and European companies have incorporated life cycle-based methodologies into their busi­ ness and decision making processes. One such approach which assesses or evaluates the technologies over their entire life cycle is often referred to as life cycle assessment (LCA). LCA is a “cradle-to-grave” approach, which sets a systematic procedure for compiling and examining the inputs and outputs of materials and energy and associated environmental impacts of a product or technology along its entire life cycle [4,5]. According to the International Organization for Standardization (ISO), an LCA involves four major steps, as illustrated in Fig. 11.2. The first major step of an LCA is to define the goal and scope of an investigated system or product, wherein the intended application of the study, the data sources, and the system boundaries are described and the criteria for selecting input and output flows or processes are specified. The second major step is referred to as the “inventory analysis,” which involves collection of data and calculation or quantification of relevant inputs and outputs over the entire life cycle stages of an investigated system. Typically, data collection follows a process chain, involving extraction, conversion, transport, produc­ tion, use and disposal or recycling. Then, the potential impacts of all the relevant input

Life Cycle Assessment of Hydrogen Fuel Cell and Gasoline Vehicles

Goal and scope definition

Inventory analysis

Impact analysis

Improvement analysis (Interpretation)

Figure 11.2 Steps involved in an LCA [4].

and output flows considered in the inventory analysis are determined in the third major step of an LCA, which is referred to as the “impact analysis.” Finally, in the last step of an LCA, the findings from the inventory and impact analyses are combined to draw conclusions and to provide future directions for improving the design and performance of the investigated system [6]. Numerous LCA studies on hydrogen fuel cell technology in relation to conventional and other alternative transport solutions have been reported in the literature, mainly focusing on different stages of vehicle life cycle with different fuel options and variable degrees of details and impacts [7–19]. Weiss et al. [8] assessed the technologies for new passenger cars that will be developed and commercialized by the year 2020. It was reported that their quantitative results are subject to the uncertainties due to projections into the future and those uncertainties are larger for rapidly developing technologies, such as fuel cells and new batteries. In another assessment from Weiss et al. [11], it was concluded that hydrogen is the only promising fuel option for automobile systems with much lower GHG emissions only if it is produced from nonfossil sources of primary energy (such as nuclear, wind, or solar) or from fossil primary energy with carbon sequestration. Colella et al. [14] conducted an LCA to estimate the net change in emissions and energy use from an instantaneous change to a hydrogen fuel cell vehicle (HFCV) fleet. Granovskii et al. [15] also conducted life cycle analysis of hydrogen fuel cell and gasoline vehicles using a first principle methodology. Similarly, Zamel and Li [16,17] performed life cycle studies of hydrogen fuel cell and internal combustion engine gasoline vehicles in Canada and the United States, with fuel cycle calculations carried out using GREET [20] and vehicle cycle data obtained from the published literature. General Motors (GM) also conducted two well-to-wheels (WTW) analysis [18,19], one based in North

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America and the other in Europe. A total of 88 fuel supply pathways including 14 hydrogen-based pathways were examined in the GM’s European WTW analysis. The objective of this chapter is to present an LCA of HFCV which includes not only the operation stage of the vehicle on the road but also the manufacture and distribution of both the vehicle and the fuel during the vehicle’s entire lifetime and to compare it with the conventional gasoline internal combustion engine vehicle (ICEV).

2. METHODOLOGY The LCA of a vehicle technology is the comprehensive evaluation of all the major steps required to make up the life cycle of a vehicle and is shown in Fig. 11.3. It can be classified into two major cycles, referred to as the “fuel cycle” and the “vehicle cycle”. The “fuel cycle” involves the following stages: • Feedstock production: Energy consumption and GHG emissions during the production of primary energy sources (natural gas and crude oil) are quantified in this stage. • Feedstock transport: The primary energy sources for hydrogen and gasoline have to be transported to the refineries and reforming plants. Energy consumption and GHG emissions during the transport of primary energy sources are counted in this stage. • Fuel production: Energy consumption and GHG emissions during processing of primary energy sources (refining crude oil for gasoline and reforming natural gas for hydrogen) are quantified in this stage.

System boundary

Fuel production

Fuel distribution

Fuel use

Feedstock transport

Feedstock production

Vehicle disposal

Vehicle material production

Vehicle use

Common stage

Fuel cycle Figure 11.3 Vehicle life cycle stages described in Section 2.

Vehicle assembly

Vehicle distribution Vehicle cycle

Life Cycle Assessment of Hydrogen Fuel Cell and Gasoline Vehicles

• Fuel distribution: Energy consumption and GHG emissions during distribution of hydrogen and gasoline to the tanks of the vehicles are counted in this stage. Typically, distribution of gasoline follows a supply chain: from refineries to terminals by ship or pipeline, transfer to road tankers, to service stations, and finally to vehicle tank. Similarly, natural gas is transported through pipeline or road tankers to decentralized refueling stations, where hydrogen is produced through steam reforming. On the other hand, the “vehicle cycle” consists of the following stages: • Vehicle material production: Energy use and GHG emissions from vehicle materials production are counted in this stage. Typically, vehicle incorporates nearly 890 kg of ferrous metals, 100 kg of different types of plastics, roughly 80 kg of aluminum, and about 200 kg of other materials [8]. And for PEM fuel cell-powered automobile, we need the materials for fuel cell components such as polymer membrane, platinum as catalyst, graphite, etc. • Vehicle assembly: The energy required and GHG emissions for transport of vehicles during assembly are quantified here. Because of the complex supply chain in the automobile industry and the associated difficulty in estimating vehicle assembly energy requirements, assembly energy is typically estimated as a linear function of vehicle mass [21]. • Vehicle distribution: The energy needed and GHG emissions during the transport of a vehicle from the assembly line to the dealership are counted in this stage. • Vehicle use: It coincides with the fuel use stage of the “fuel cycle.” It includes energy consumption and GHG emissions during maintenance and repair over the lifetime, which is typically assumed to be 300,000 km [13]. • Vehicle disposal: After a vehicle’s life, the vehicle is shredded. The disposal energy is the sum of energy needed to move the bulk from the dismantler to a shredder and the shredding energy [22]. The assessment of energy consumption and GHG emissions during the life cycle stages of fuel and vehicle cycles is based on various sources reported in the published literature. The analyses of different stages of both cycles (fuel and vehicle) are then combined to obtain the total life cycle energy consumption and GHG emissions of a vehicle.

3. SCOPE In this chapter, the following fuel and vehicle technologies are assessed based on

the methodology described in the above section.

Fuels considered:

• Hydrogen from natural gas reforming in hydrogen refueling stations • Gasoline from crude oil

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Vehicle technologies considered: • PEM fuel cell-powered vehicle using hydrogen as fuel • Spark ignition internal combustion (IC) engine-powered vehicle using gasoline as fuel

4. LIMITATIONS The assessment presented in this chapter is based on various data sources pub­ lished in the open literature, and like any other assessment or analysis has some limitations. The major boundaries and assumptions considered in the present assessment are stated below: • The boundaries of the physical system are such that secondary energy and environmental effects are not quantified. For instance, energy consumption and GHG emissions during the operation of a steam reforming plant of natural gas are quantified, but the energy and emissions involved in making the steel, concrete or other elements embodied in the plant itself are not counted. • Data used for assessment is from mid-size family passenger cars (average vehicle weight is 1,300 kg). • Data used is based on North American experience. • Other production methods (e.g., electrolysis, nuclear, hydro, etc.) of hydrogen are not considered in the present assessment: only large-scale production methods are considered. For instance, hydrogen is mostly produced via steam reforming of natural gas at present; similarly, gasoline is mostly produced via crude oil refining.

5. RESULTS AND DISCUSSION We begin the assessment from fuel cycles, which include recovery of the raw material for each (such as natural gas for hydrogen or crude oil for gasoline) through conversion to the final fuel (such as hydrogen or gasoline) and delivery into the tank of the passenger car. The two characteristics of the fuel cycles assessed in the present study include the following: • Total energy consumed originating from raw materials or other energy sources • Total GHG emitted from raw materials or other sources The GHG emissions assessed in the present study are CO2 and CH4. N2O is neglected since its greenhouse contribution for each of the fuel cycles accounts for less than 1% of the other gas emissions [23,24]. The energy consumption and GHG emissions during fuel cycles for hydrogen and gasoline are listed in Table 11.1. Figs. 11.4 and 11.5 show the comparison of energy consumption and GHG emissions during the fuel cycles of hydrogen and gasoline, respectively. It can be seen from the figures that both energy consumption and GHG

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Life Cycle Assessment of Hydrogen Fuel Cell and Gasoline Vehicles

Table 11.1 Energy consumption and GHG emissions during fuel cycles [8,25,26]

Feedstock production Feedstock transport Fuel production Fuel distribution Total

Energy consumption (MJ/GJ)

GHG emissions (kg CO2/GJ)

Hydrogen

Gasoline

Hydrogen

Gasoline

50.0 80.0 530.0 110.0 770.0

62.40 8.20 135.00 15.00 220.60

23.52 1.23 99.00 8.25 132.00

3.40 0.60 12.00 0.70 16.70

Energy consumption (MJ/GJ)

900.00 800.00

Gasoline

700.00

Hydrogen

600.00 500.00 400.00 300.00 200.00 100.00 l ta

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To

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n tio uc od Fu

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pr el Fu

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Fe e

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to

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k

pr

tra

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ns

uc

po

tio

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0.00

Figure 11.4 Energy consumption during fuel cycles of hydrogen and gasoline [8,25,26].

emissions during the fuel cycle of hydrogen are higher when compared to the gasoline fuel cycle. Fuel production stage of hydrogen cycle is the major contributor to the total energy consumption and GHG emissions. The other significant contribution comes from the fuel distribution stage which includes the primary energy in the form of the electric power used for compressing hydrogen. Table 11.2 lists the energy consumption and GHG emissions during vehicle cycle of HFCV and ICEV. The comparison of energy consumption and GHG emissions during the vehicle cycle of HFCV and ICEV is shown in Figs. 11.6 and 11.7, respectively. The greatest contributor to energy consumption and GHG emissions for the ICEV is the vehicle use stage (coincides with fuel use stage). The energy consumption of ICEV is

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GHG emissions (kg CO2/GJ)

160.00 140.00 Gas oline 120.00

Hy drogen

100.00 80.00 60.00 40.00 20.00 l ta

io ut rib

Fu

el

di

st

To

n

n tio uc pr od el

Fu

st ed Fe

Fe e

ds

to

ck

oc

k

tra

pr od

ns

uc

po

tio

rt

n

0.00

Figure 11.5 GHG emissions during fuel cycles of hydrogen and gasoline [8,25,26].

Table 11.2 Energy consumption and GHG emissions during vehicle cycles [8,13]

Vehicle Vehicle Vehicle Vehicle Vehicle Total

materials production assembly distribution use disposal

Energy consumption (MJ)

GHG emissions (kg CO2)

HFCV

ICEV

HFCV

ICEV

54,600.0 24,300.0 2,100.0 195,000.0 300.0 276,300.0

49,800.0 25,500.0 2,100.0 819,000.0 300.0 896,700.0

3,630.0 1,650.0 110.0 0.0 0.0 5,390.0

3520.0 1,760.0 110.0 5,903.3 0.0 64,423.3

about 3 times higher than that of HFCV. Moreover, GHG emissions during the vehicle cycle of HFCV are around 8% of the GHG emissions of the ICEV, which clearly indicates the environmental friendliness of HFCV. Figs. 11.8 and 11.9 show the comparison of life cycle energy consumption and life cycle GHG emissions of the two vehicle technologies considered in the present assessment. Although the fuel cycle energy consumption of HFCV is about 3.5 times higher than that of ICEV, the overall life cycle energy consumption of HFCV is about 2.3 times less than that of ICEV. This is due to high efficiency of HFCV as compared to ICEV during the vehicle use stage of the vehicle cycle. Similarly, the

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Life Cycle Assessment of Hydrogen Fuel Cell and Gasoline Vehicles

1,000,000

Energy consumption (MJ)

900,000 800,000

ICEV

700,000

HFCV

600,000 500,000 400,000 300,000 200,000 100,000

sp

l ta

os

us e hi

cl

Ve

e

hi

di

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To

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hi

hi

cl

cl

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m

as

at

se

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m

ia

bl

ls

y

0

Figure 11.6 Energy consumption during vehicle cycles of HFCV and ICEV [8,13].

70,000

GHGs emissions (kg CO2)

60,000

ICEV HFCV

50,000 40,000 30,000 20,000 10,000

al

di

To t

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0

Figure 11.7 GHG emissions during vehicle cycles of HFCV and ICEV [8,13].

GHG emissions of HCFV is 8.5 times higher than that of ICEV during the fuel cycle; however, the overall life cycle GHG emissions of an HFCV are about 2.6 times lower than that of ICEV, which is due to zero GHG emissions during the vehicle use stage of the vehicle cycle.

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Life cycle energy consumption (MJ)

1,000,000 900,000 800,000 700,000 600,000 500,000 400,000 300,000 200,000 100,000 0 ICEV

HFCV

Figure 11.8 Life cycle energy consumption of vehicle technologies.

70,000

GHG emissions (kg CO2)

60,000

50,000 40,000 30,000 20,000 10,000 0 ICEV

HFCV

Figure 11.9 Life cycle GHG emissions of vehicle technologies.

6. CONCLUDING REMARKS An LCA of HFCV and ICEV has been presented in this chapter. An LCA is a technique to assess the energy and associated environmental impact of a system or product. The assessment presented in this chapter is based on various sources available in the published literature. The characteristics of the vehicles (HFCV and ICEV) assessed are energy consumption and GHG emissions during their entire life cycles. It is found that the energy consumption and GHG emissions during the fuel cycle of hydrogen are higher than the fuel cycle of gasoline, and fuel production stage of the hydrogen fuel cycle is the major contributor to the total energy consumption and GHG emissions.

Life Cycle Assessment of Hydrogen Fuel Cell and Gasoline Vehicles

However, during the vehicle cycle, the energy consumption and GHG emissions of ICEV are higher than that of HFCV, and the greatest contributor to the energy consumption and GHG emissions is the vehicle use stage of the ICEV. Moreover, it is found that the overall life cycle energy consumption of HFCV is about 2.3 times less than that of ICEV and overall GHG emissions of HFCV are about 2.6 times lower than that of ICEV.

REFERENCES 1. EPA, Inventory of US Greenhouse Gas Emission and Sinks: 1990–2006, Office of Global Warming, Washington, D.C., 2008. 2. M. Pehnt, Int. J. Life Cycle Ass. 8 (2003) 283. 3. I. Pembina, Life-cycle Value Assessment (LCVA) of Fuel Supply Options for Fuel Cell Vehicles in Canada, Calgary, Canada, 2002. 4. ISO 14040, Environmental Management – Life Cycle Assessment – Principles and Framework, International Organisation for Standardisation, Geneva, Switzerland, 1997. 5. M. Pehnt, Int. J. Hydrogen Energy 26 (2001) 91. 6. M. Pehnt, Handbook of Fuel Cells – Fundamentals, Technology and Applications, John Wiley and Sons, Ltd, Chichester, UK, 2003. 7. M. Singh, R. Cuenca, J. Formento, L. Gaines, B. Marr, D. Santini, et al., Total Energy Cycle Assessment of Electric and Conventional Vehicles: An Energy and Environmental Analysis, Argonne National Laboratory, ANL/ES/RP-96387, Springfield, VA 22161, 1998. 8. M.A. Weiss, J.B. Heywood, A. Schafer, F.F. AuYeung, On the Road in 2020, MIT EL 00-003, Energy Laboratory, Massachusetts Institute of Technology, Cambridge, 2000. 9. A. Bauen, D. Hart, J. Power Sources 86 (2000) 482. 10. C. Handley, N.P. Brandon, R. van der Vorst, J. Power Sources 106 (2002) 344. 11. M.A. Weiss, J.B. Heywood, A. Schafer, V.K. Natarajan, Comparative Assessment of Fuel Cell Cars, MIT LFEE 2003-001, Laboratory of Energy and the Environment, Massachusetts Institute of Technology, Cambridge, 2003. 12. H.L. MacLean, L.B. Lave, Environ. Sci. Technol. 37 (2003) 5445. 13. B. Sorensen, Total Life-Cycle Assessment of PEM Fuel Cell Car, Energy and Environment Group, Roskilde University, Denmark, 2004. 14. W.G. Collela, M.Z. Jacobson, D.M. Golden, J. Power Sources 150 (2005) 150. 15. M. Granovskii, I. Dincer, M. Rosen, Int. J. Hydrogen Energy 31 (2005) 337. 16. N. Zamel, X. Li, J. Power Sources 155 (2006) 297. 17. N. Zamel, X. Li, J. Power Sources 162 (2006) 1241. 18. General Motors, Argonne National Laboratories, BP, ExxonMobil, and Shell, GM Well-to-Wheel Energy Use and Greenhouse Gas Emissions of Advanced Fuel/Vehicle Systems – North American Analysis, General Motors, Argonne, USA, 2001. 19. General Motors, L-B-Systemtechnik GmbH, BP, ExxonMobil, and Total-FinaElf, GM Well-toWheel Energy Use and Greenhouse Gas Emissions of Advanced Fuel/Vehicle Systems – European Analysis, General Motors, Ottobrun, Germany, 2002. 20. M. Wang, GREET 1.5 – Transportation Fuel-Cycle Model, vol. 1: Methodology, Development, Use and Results, Center for Transportation Research, Argonne National Laboratory, Argonne, USA, 1999. 21. Automotive Engineering, Life Cycle Analysis: Getting the Total Picture on Vehicle Engineering Alter­ natives, SAE International, Troy MI 48084 USA, 1996. 22. Automotive Engineering, Progress in Recycling Specific Materials from Automobiles, SAE Interna­ tional, Troy MI 48084 USA, 1997. 23. M. Wang, H.S. Huang, A Full Fuel Cycle Analysis of Energy and Emissions Impacts of Transportation Fuel Produced from Natural Gas, Report ANL/EDSs-40, prepared by Argonne National Laboratory, The Center for Transportation Research, Energy Systems Division for US DOE, 1999. 24. Energy Information Administration (EIA), US DOE, Emissions of Greenhouse Gases in the United States 1996, DOE/EIA-0573(96), 1997.

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25. IEA (International Energy Agency), Automotive Fuels for the Future: The Search for Alternatives, IEA-AFIS, Paris, 1999. 26. P.L. Spath, M.K. Mann, Life Cycle Assessment of Hydrogen Production Via Natural Gas Steam Reforming, NREL (National Renewable Energy Laboratory), Colorado, NREL/TP-570-27637, 2001.