The National Academy of Sciences (NAS) released a report last month called Hidden Costs of Energy that evaluates the externalities associated with energy production and use in the U.S. Prepared at the request of Congress, it analyzes different energy sectors and develops cost estimates for damages associated with criteria pollution as well as greenhouse gas emissions.
The report includes a number of positive conclusions regarding the benefits of NGVs, which overall perform quite well with respect to the damage assessments. Not surprisingly, CNG powered vehicles scored better than nearly all other technologies with respect to emissions of criteria pollutants. E85 (from corn ethanol) was shown to be no better than or slightly worse than gasoline vehicles. What was surprising is that NAS reports that electric vehicles, and plug-in electric vehicles scored worse than gasoline fueled vehicles in terms of damages associated with emissions of criteria pollutants. In the case of electric and plug-in electric vehicles, the poor showing is due to the fact that the report calculates that the energy use and pollution associated with the production of batteries and electric motors is 20 percent greater than that for conventionally fueled vehicles. In addition, these vehicles rely on stationary source power for their electricity, and much of the nation’s electric power is produced from coal and likely will continue to be for many years. The report notes that cleaner sources of electricity could improve the emission benefits of electric vehicles.
The report’s findings concerning greenhouse gas emissions also were interesting. CNG powered vehicles showed an 11 percent reduction in overall greenhouse gas emissions compared to today’s gasoline vehicles (2005 technology). Projections for 2030, however, indicate that NGVs could reduce greenhouse gas emission by 21 percent compared to gasoline fueled vehicles. In fact, NGVs scored better than nearly all other vehicle technologies in the 2030 forecast, including better than electric and plug-in hybrid vehicles. The report shows electric and plug-in hybrids do provide larger overall reductions of greenhouse gas emission in the earlier years reviewed (i.e., 2005 vehicle technology) than CNG vehicles. However, the report indicates that this will likely change by 2030 due to large improvements in the fuel efficiency of spark-ignited vehicles, including those powered by CNG.
Copies of the NAS report can be purchased at the National Academies Press website.