Search Results

A conversion to light-duty diesel vehicles is considered one pathway for reducing transportation greenhouse gas emissions in the United States. However, expanding diesel's market share could have significant public health consequences. This paper evaluates the environmental tradeoffs of diesel passenger vehicles, and suggests that a rapid conversion to light-duty diesel vehicles could yield carbon emission savings within the decade of up to 4 percent versus the base case. While significant reductions in criteria emissions appears technologically possible, it will likely require that diesels incorporate two exhaust control systems and utilize reformulated diesel fuel or alternative fuels. Finally, we suggest that diesel manufacturers must address other evolving public health concerns, including emissions of ultrafine particles and toxics, before expanding the market share of the diesel powerplant.

Fuel cell vehicles (FCVs) powered by hydrogen are the cleanest, simplest technology for automotive applications; however, concerns over the cost and availability of hydrogen fueling infrastructure are driving the development of FCVs powered by liquid fuels-including methanol, ethanol, and gasoline. This paper suggests that there are important energy and environmental trade-offs associated with liquid-fueled FCVs: some designs may offer small or no improvement over other high-efficiency vehicles, and significant benefits will only accrue through a shift to renewable energy sources. Given that public-interest goals will continue to be the motivating force behind FCV development, it is critical to maintain a focus on the energy and environmental implications of fuel choices.