ATTACHMENT 4A. Life-Cycle Analysis of Automobile Technologies

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1 ATTACHMENT 4A Life-Cycle Analysis of Automobile Technologies Assessments of new automobile technologies that have the potential to function with higher fuel economies and lower emissions of greenhouse gases (GHGs) have been made by the Energy Laboratory at Massachusetts Institute of Technology (MIT) (Weiss et al., 2000) and by the General Motors Corporation (GM), Argonne National Laboratory, BP, ExxonMobil, and Shell (General Motors et al., 2001 draft). Both studies compared fuels and engines on a total systems basis, that is, on a well-to-wheels (WTW) basis. These assessments provide an indication of areas of promising vehicle and fuel technology and benchmarks for likely increases in fuel economy and reduction of GHG emissions from the light-duty fleet over the next two decades. This attachment provides additional information on the emerging technologies and GHG emissions described in Chapters 3 and 4. MIT s analysis was confined to mid-sized cars with consumer characteristics comparable to a 1996 reference car such as the Toyota Camry. It was assumed that, aided by the introduction of low-sulfur fuels, all technologies would be able to reduce emissions of air pollutants to levels at or below U.S. Federal Tier 2 requirements. Only those fuel and vehicle technologies that could be developed and commercialized by 2020 in economically significant quantities were evaluated. General Motors et al. (2001) focused on the energy use of advanced conventional and unconventional power-train systems that could be expected to be implemented in the time frame in a Chevrolet Silverado full-sized pickup truck. The technologies were assessed on the basis of their potential for improving fuel economy while maintaining the vehicle performance demanded by North American consumers. Vehicle architectures and fuels analyzed in both studies are listed in Table 4A-1. In the MIT study the vehicle lifetimes and driving distances were assumed to be similar for all vehicles. The more advanced technologies were compared to an evolved baseline vehicle, a mid-sized passenger car, comparable in consumer characteristics to the 1996 reference car, in which fuel consumption and GHG emissions had been reduced by about a third by 2020 through continuing evolutionary improvements in the traditional technologies currently being used. Figure 4A-1 summarizes energy use, GHG emissions, and costs for all the new 2020 technologies relative to the 1996 reference car and the evolved 2020 baseline. (The battery-electric car shown is an exception in that it is not comparable to the other vehicles; its range is about one-third lower than the other vehicles.) The bars shown are meant to suggest the range of uncertainty about the results. The uncertainty is estimated to be about plus or minus 30 percent for fuel-cell and battery vehicles, 20 percent for internal combustion (ICE)-engine hybrid electric vehicles (HEVs), and 10 percent for all other vehicle technologies. 4A-1

, 2000) and by the General Motors Corporation (GM), Argonne National Laboratory, BP, ExxonMobil, and Shell (General Motors et al., 2001 draft).

2 MIT concludes that continued evolution of the traditional gasoline car technology could result in 2020 vehicles that reduce energy consumption and GHG emissions by about one-third from comparable vehicles of today and at roughly 5 percent increase in car cost. More advanced technologies for propulsion systems and other vehicle components could yield additional reductions in life-cycle GHG emissions (up to 50 percent lower than the evolved baseline vehicle) at increased purchase and use costs (up to about 20 percent greater that the evolved baseline vehicle). Vehicles with HEV propulsion systems using either ICE or fuel-cell power plants are the most efficient and lowest-emitting technologies assessed. In general, ICE HEVs appear to have advantages over fuel-cell HEVs with respect to life-cycle GHG emissions, energy efficiency and vehicle costs, but the differences are within the uncertainties of MIT s results and depend on the source of fuel energy. If automobile systems with drastically lower GHG emissions are required in the very long run future (perhaps in 30 to 50 years or more), hydrogen and electrical energy are the only identified options for fuels, but only if both are produced from non-fossil sources of primary energy (such as nuclear or solar) or from fossil primary energy with carbon sequestration. The results from the General Motors et al. (2001) study are shown in figures 4A-2 and 4A-3. With regard to fuel use, this study concludes that diesel compression-ignition direct-injection HEVs, gasoline and naphtha fuel-processor fuel-cell HEVs, as well as the two hydrogen fuel-cell HEVs (represented only by the gaseous hydrogen refueling station and fuel-cell HEV in Figure 4A-2) are the lowest energy-consuming pathways. All of the crude-oil based selected pathways have well-to-tank (WTT) energy loss shares of roughly 25 percent or less. A significant fraction of the WTT energy use of ethanol is renewable (over 90 percent for HE100). The ethanol-fueled vehicles yield the lowest GHG emissions per mile. The diesel compression-ignition direct-injection (CIDI) HEV offers a significant reduction of GHG emissions (27 percent) relative to the conventional gasoline spark-ignition vehicle. Considering both total energy use and GHG emissions, the key findings by General Motors et al. (2001), are these: Among all of the crude oil and natural gas pathways studied, the CIDI, hybrid electric vehicle (HEV), the gasoline and naphtha fuel-processor fuel-cell HEV, and the gaseous hydrogen fuel-cell HEV were nearly identical and best in terms of total system energy use. Among these pathways, expected GHG emissions were lowest for the gaseous hydrogen fuel-cell HEV and highest for the diesel CIDI HEV. The gasoline spark-ignited HEV and the diesel CIDI HEV, as well as the conventional CIDI diesel, yield significant total system energy use and GHG emission benefits compared to the conventional gasoline engine. The methanol fuel-processor fuel-cell HEV offers no significant energy use of emissions reduction advantages over the crude oil-based or other natural gas bases fuel cell HEV pathways. Bioethanol-based fuel/vehicle pathways have by far the lowest GHG emissions of the pathways studied. Major technology breakthroughs are required for both the fuel and the vehicle for the ethanol fuel-processor fuel-cell HEV (HE100 FP FC HEV) pathway to reach commercialization. 4A-2

More advanced technologies for propulsion systems and other vehicle components could yield additional reductions in life-cycle GHG emissions (up to 50 percent lower than the evolved baseline vehicle)

3 On a total system basis, the energy use and GHG emissions of compressed natural gas and gasoline spark-ignited (SI) conventional pathways are nearly identical. (Note: the compressed natural gas [CNG] pathway is not shown in Figure 4A-2 or 4A-3). The crude-oil-based diesel vehicle pathways offer slightly lower system GHG emissions and considerably better total system energy use than the naturalgas-based Fischer-Tropsch diesel fuel pathways. Criteria pollutants were not considered. Liquid hydrogen produced in central plants, Fischer-Tropsch naphtha, and electrolysis-based hydrogen fuel cell HEVs have slightly higher total system energy use and the same or higher levels of GHG emissions than gasoline and crude naphtha fuel-processor fuel-cell HEVs and electrolytically generated hydrogen fuel-cell HEVs. TABLE 4A-1. Vehicle Architecture and Fuels Used in the MIT and General Motors et al. Studies MIT (Weiss et al., 2000) General Motors et al. (2001) Conventional (CONV) with spark ignition (SI) gasoline engine (baseline) [GASO SI CONV] 1996 Reference internal combustion engine (ICE) Baseline evolved ICE CONV with SI E85 (85% ethanol and 15% gasoline by volume engine [HE85 SI CONV] Advanced gasoline ICE Gasoline ICE hybrid vehicle (HEV) Diesel ICE hybrid CNG ICE hybrid Gasoline fuel cell (FC) hybrid vehicle Methanol FC hybrid Hydrogen FC hybrid Battery electric CONV with compressor ignition direct injection (CIDI) diesel engine [DIESEL CIDI CONV] Charge-sustaining (CS) parallel hybrid electric vehicle (HEV) with SI E85 engine [HE 85 SI HEV] CS HEV with CIDI diesel [DIESEL CIDI HEV] Gasoline fuel processor (FP) fuel cell vehicle (FCV) [GASO FP FC FCV] Gasoline (naphta) FP fuel cell (FC) HEV [NAP FP FC HEV] Gaseous hydrogen (GH 2 ) refueling station (RS) FC HEV [GH 2 RS FC HEV] Methanol (MeOH) FP FCV [MEOH FP HEV] Ethanol FP FC HEV [HEV 100 FP FC HEV] 4A-3

The crude-oil-based diesel vehicle pathways offer slightly lower system GHG emissions and considerably better total system energy use than the naturalgas-based Fischer-Tropsch diesel fuel pathways.

4 FIGURE 4A-1 Life-Cycle Comparisons of Technologies for Mid-Sized Passenger Vehicles. NOTE: All cars are 2020 technology except for the 1996 Reference car. On the scale, 100 = 2020 evolutionary baseline gasoline ICE car. Bars show estimated uncertainties. SOURCE: Weiss et al., A-4

NOTE: All cars are 2020 technology except for the 1996 Reference car.

5 FIGURE 4A-2 Well-to-wheels Total System Energy Use for Selected Fuel/Vehicle Pathways. SOURCE: General Motors et al., FIGURE 4A-3. Well-to-wheels Greenhouse Gas Emissions for Selected Fuel/Vehicle Pathways. SOURCE: General Motors et al., A-5

6 REFERENCES General Motors Corporation, Argonne National Laboratory, BP, Exxon Mobil and Shell (Draft Final). April 2001 (Draft). Wheel-to-Well Energy Use and Greenhouse Gas Emissions of Advanced Fuel/Vehicle Systems. North American Analysis. Weiss, Malcolm A., John B. Heywood, Elisabeth M. Drake, Andreas Schafer, and Felix F. AuYeung On the Road in 2020: A Life-Cycle Analysis of New Automobile Technologies. Energy Laboratory Report # MIT EL Massachusetts Institute of Technology (MIT). October A-6

, John B. Heywood, Elisabeth M. Drake, Andreas Schafer, and Felix F. AuYeung. 2000.

Well-to-Wheels Energy and Emission Impacts of Vehicle/Fuel Systems Development and Applications of the GREET Model

Well-to-Wheels Energy and Emission Impacts of Vehicle/Fuel Systems Development and Applications of the GREET Model Michael Wang Center for Transportation Research Argonne National Laboratory California