Nationwide and State-by-State Emission Benefits of a Gasoline Sulfur Limit

摘要

EPA recently completed its study of the need, cost-effectiveness, and technological feasibility of Tier 2 standards, and will soon propose Tier 2 standards for cars and light trucks. As a part of its Tier 2 Study and the upcoming Tier 2 notice of proposed rulemaking (NPRM), EPA is also studying the effects of gasoline fuel sulfur on exhaust emissions from advanced technology vehicles, and has indicated it will implement some kind of sulfur limit in gasoline as well. Both the American Automobile Manufacturers Association (AAMA) and the American Petroleum Institute (API) have forwarded proposals for reducing sulfur in gasoline. This analysis examines these proposals and examines the emission data on the effect of sulfur on advanced technology and current vehicles. An advanced MOBILE5 model was created to incorporate a number of recent improvements in emission factor methodology and to include the effects of sulfur on exhaust emissions for different vehicle technologies. Finally, the model was used with activity data obtained from EPA to determine nationwide, and state-by-state emission reductions of HC, CO, NOx, and PM for the two proposals. The results of the analysis indicates that the emission reductions from the AAMA proposal exceed the API proposal and that low sulfur fuel appears to be essential to achieve the fall emissions benefit from advanced national LEV vehicles (NLEVs) and Tier 2 vehicles.