NRC: Car Petroleum Use, GHG Emissions Could Drop 80%

To reach the 2050 goals, vehicles must become dramatically more efficient regardless of how they are powered, according to Transitions to Alternative Vehicles and Fuels. In addition, alternative fuels to petroleum must be readily available, cost-effective and produced with low GHG emissions.  Such a transition will be costly, require several decades and likely require robust governmental support, the report says.

The committee's model calculations, which it admits are "exploratory and highly uncertain," indicate that the benefits of making the transition — such as energy cost savings, improved vehicle technologies and reductions in petroleum use and GHG emissions — exceed the additional costs of the transition over and above what the market is willing to do voluntarily.

Improving the efficiency of conventional vehicles is, up to a point, the most economical and easiest-to-implement approach to saving fuel and lowering emissions, the report says.  This approach includes reducing work the engine must perform — reducing vehicle weight, aerodynamic resistance, rolling resistance and accessories — plus improving the efficiency of the internal combustion engine powertrain.

Improved efficiency alone will not meet the 2050 goals, however.  The average fuel economy of vehicles on the road would have to exceed 180 mpg, which, the report says, is extremely unlikely with current technologies.  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.

The report sees wide consumer acceptance of alternative fuel vehicles as essential if the 2050 goals are to be met, but also foresees numerous hurdles, such as higher prices when compared to gasoline-powered vehicles and limited body styles, potentially getting in the way of this essential consumer acceptance.

Overcoming the barriers to advanced vehicles and fuels will require a rigorous policy framework that is more stringent than the proposed fuel economy standards for 2025.  This policy intervention could include high and increasing fuel economy standards, research and development support, subsidies and public information programs aimed at improving consumers' familiarity with the new fuels and powertrains.  Because of the high level of uncertainty in the pace and scale of technology advances, this framework should be modified as technologies develop and as conditions change, the report says.

According to a report released this week, vehicles sold in 2012 were the most fuel-efficient on record. Fuel economy values increased 16 percent between 2007 and 2012, while CO2 emissions dropped 13 percent, according to the EPA’s annual report on US vehicle fuel efficiency. Between 2011 and 2012 US cars and light trucks saw an increase in average fuel economy to 23.8 mpg — a 1.4 mpg improvement compared to the previous year — representing the largest annual improvements since EPA began reporting on fuel economy, the report said.