Petroleum use, greenhouse gas emissions of U.S. automobiles could drop 80 percent by 2050

says.  All the vehicles considered are and will continue to be several thousand dollars more expensive than today’s conventional vehicles.  Additionally, particularly in the early years, the report predicts that alternative vehicles will likely be limited to a few body styles and sizes; some will rely on fuels that are not readily available or have restricted travel range; and others may require bulky energy storage that will limit their cargo and passenger capacity.  Wide consumer acceptance is essential, however, and large numbers of alternative vehicles must be purchased long before 2050 if the on-road fleet is to meet desired performance goals.  Strong policies and technology advances are critical in overcoming this challenge.

The report identified several scenarios that could meet the more demanding 2050 greenhouse gas goal.  Each combines highly efficient vehicles with at least one of three alternative power sources — biofuel, electricity, or hydrogen.  Natural gas vehicles were considered, but their greenhouse gas emissions are too high for the 2050 goal.  However, if the costs of these vehicles can be reduced and appropriate refueling infrastructure created, they have great potential for reducing petroleum consumption.

While corn-grain ethanol and biodiesel are the only biofuels to have been produced in commercial quantities in the United States to date, the study committee found much greater potential in biofuels made from lignocellulosic biomass — which includes crop residues like wheat straw, switchgrass, whole trees, and wood waste.  This “drop-in” fuel is designed to be a direct replacement for gasoline and could lead to large reductions in both petroleum use and greenhouse gas emissions; it can also be introduced without major changes in fuel delivery infrastructure or vehicles.  The report finds that sufficient lignocellulosic biomass could be produced by 2050 to meet the goal of an 80 percent reduction in petroleum use when combined with highly efficient vehicles.

Vehicles powered by electricity will not emit any greenhouse gases, but the production of electricity and the additional load on the electric power grid are factors that must be considered.  To the extent that fossil resources are used to generate electricity, the report says that the successful implementation of carbon capture and storage will be essential.  These vehicles also rely on batteries, which are projected to drop steeply in price.  However, the report says that limited range and long recharge times are likely to limit the use of all-electric vehicles mainly to local driving.  Advanced battery technologies under