Financing the Infrastructure to Support Alternative Fuel Vehicles: How Much Investment is Needed and How Will It Be Funded?

APPENDIX B: COMPARISON OF GHG EMISSIONS FROM AFVS

While natural gas is a fossil fuel, compared with vehicles that rely on diesel and gasoline, natural gas vehicles produce lower levels of some types of emissions. Vehicles powered by CNG emit approximately 6 – 11 percent less lifecycle GHG emissions compared to gasoline-powered vehicles.¹⁹¹

Lifecycle emissions of PEVs vary drastically depending on how the electricity used for charging is generated: PEVs produce fewer lifecycle GHG emissions using electricity from power plants using relatively cleaner fuels (e.g., nuclear, renewable, and hydroelectric power plants), than they do when they rely on fossil fuel plants (e.g., coal, oil, or natural gas). Depending on the mix of fuels used to produce electricity, typical estimates suggest that BEVs could reduce GHG emissions by 20 – 50 percent and PHEVs could reduce GHG emissions by 20 – 60 percent, compared to gasoline vehicles.¹⁹²

Hydrogen can be produced from many different energy resources, and its lifecycle GHG emissions vary widely depending on how it is produced. Hydrogen fuel cell vehicles reduce GHG emissions by 30 – 55 percent with hydrogen produced using SMR (natural gas feedstock) and up to 95 percent using hydrogen produced from renewable feedstocks.¹⁹³

Ethanol releases GHGs when it is used to power vehicles, but unlike the fossil carbon released by petroleum-based fuels, much of the CO2 released in the combustion on ethanol is offset by the CO2 that was captured by the crops grown to produce ethanol. Corn-based ethanol can reduce lifecycle GHG emissions by up to 52 percent compared to gasoline. The use of cellulosic ethanol, which is produced from plants that are less reliant on petroleum-based fertilizers, could reduce GHG emissions by as much as 86 percent.¹⁹⁴