Validating the role of AFVs in voluntary mobile source emission reduction211 programs

摘要

Late in 1997, EPA announced new allowances for voluntary emission control211u001eprograms. As a result, the US Department of Energy's (DOE) Clean Cities and other 211u001emetro areas that have made an ongoing commitment to increasing participation by 211u001ealternative fuel vehicles (AFVs) in local fleets have the opportunity to estimate 211u001ethe magnitude and obtain emission reduction credit for following through on that 211u001ecommitment. Unexpectedly large reductions in key ozone precursor emissions in key 211u001elocations and times of the day can be achieved per vehicle-mile by selecting 211u001especific light duty AFV offerings from original equipment manufacturers (OEMs) in 211u001elieu of their gasoline-fueled counterparts. Additional benefit accrues from the 211u001efact that evaporative emissions of non-methane hydrocarbons (generated in the 211u001ecase of CNG, LNG, and LPG by closed fuel-system AFV technology) can be 211u001eessentially negligible. Upstream emissions from fuel storage and distribution 211u001ewith the airshed of interest are also reduced. This paper provides a 211u001ejustification and outlines a method for including AFVs in the mix of strategies 211u001eto achieve local and regional improvements in ozone air quality, and for 211u001equantifying emission reduction credits. At the time of submission of this paper, 211u001ethe method was still under review by the US EPA Office of Mobile Sources, pending 211u001emutually satisfactory resolution of several of its key points. Some of these 211u001eissues are discussed in the paper.