| Summary of WTW petroleum energy use and GHG emissions for combined
CD and CS operations relative to baseline gasoline ICEV. Single markers indicate conventional hybrids. Click to enlarge. |
Researchers at Argonne National Laboratory have published results of a well-to-wheels (WTW) lifecycle analysis of petroleum energy use and greenhouse gas emissions of plug-in hybrid electric vehicles employing gasoline, diesel, E85 and hydrogen (fuel cell) fuels, with an all-electric range between 10 to 40 miles.
Compared to an internal combustion vehicle fueled with gasoline, PHEVs that employed petroleum fuels (gasoline and diesel) offered a 40-60% reduction in petroleum energy use and a 30-60% reduction in GHG emissions. PHEVs fueled by E85 offered a 70-90% reduction in petroleum energy use and a 40-80% reduction in GHG emissions. PHEVs equipped with hydrogen fuel cells offered a more than 90% reduction in petroleum energy use and a 10-100% reduction in GHG emissions.
The spread of WTW GHG emissions among the different fuel
production technologies and grid generation mixes was wider than the spread of petroleum
energy use, mainly due to the diverse fuel production technologies and feedstock sources for the
fuels considered in this analysis.
The PHEVs offered reductions in petroleum energy use as compared with regular hybrid electric vehicles (HEVs). More petroleum energy savings were realized as the AER increased,
except when the marginal grid mix was dominated by oil-fired power generation. Similarly,
more GHG emissions reductions were realized at higher AERs, except when the marginal grid
generation mix was dominated by oil or coal. Electricity from renewable sources realized the
largest reductions in petroleum energy use and GHG emissions for all PHEVs as the AER
increased. The PHEVs that employ biomass-based fuels (e.g., biomass-E85 and -hydrogen) may
not realize GHG emissions benefits over regular HEVs if the marginal generation mix is
dominated by fossil sources.
—Elgowainy et al. (ANL/ESD/09-2)
The Argonne team expanded the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model and incorporated the fuel economy and electricity use of alternative fuel/vehicle systems simulated by the Powertrain System Analysis Toolkit (PSAT). WTW results were separately calculated for the blended charge-depleting (CD) and charge-sustaining (CS) modes of PHEV operation and then combined by using a weighting factor that represented the CD vehicle-miles-traveled (VMT) share.
Based on PSAT (Powertrain System Analysis Toolkit) simulations of the blended charge depleting (CD) operation, grid electricity accounted for a share of the vehicle’s total energy use ranging from 6% for a PHEV 10 to 24% for a PHEV 40 based on CD vehicle miles traveled (VMT) shares of 23% and 63%, respectively.
For a carbon-intensive generation mix, such as that of Illinois…PHEVs produce more WTW GHG emissions compared with regular HEVs for most fuels. Such implication becomes more pronounced as the AER increases from 10 mi to 40 mi, especially for E85 and hydrogen fuels, which highlights the significance of the electricity generation mix for charging PHEVs.
—Elgowainy et al. (ANL/ESD/09-2)
Resources
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A. Elgowainy, A. Burnham, M. Wang, J. Molburg, and A. Rousseau (2009)Well-to-Wheels Energy Use and Greenhouse Gas Emissions Analysis of Plug-in Hybrid Electric Vehicles (ANL/ESD/09-2)
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A. Elgowainy, A. Burnham, M. Wang, J. Molburg, and A. Rousseau (2009) Well-to-Wheels Energy Use and Greenhouse Gas Emissions Analysis of Plug-in Hybrid Electric Vehicles (SAE 2009-01-1309)