Update From The NRELAhernative Fuel Transit Bus Evaluation Program

The objective” of this proje& which is supported by the U.S. Department of Energy (DOE) through the National Renewable Energy Laboratory (NREL), is to provide a comprehensive comparison of heavy-duty urban transit buses operating on alternative fuels and diesel firel. Final reports from this project were produced in 1996 from data collection and evaluation of 111 transit buses from eight transit sites. With the publication of these final reports, three issues were raised that needed further investigation: 1) the natural gas engines studied were older, openIoop control engines; 2) propane was not included in the original study; and 3) liquefied natural gas (LNG) was found to be in the early stages of deployment in transit applications. In response to these three issues, the project has continued by emissions testing newer natural gas engines (Detroit Diesel Corporation Series 50, Cummins Engine Company L1O-28OG and C8.3-250G) and adding two new data collection sites (GO Boulder in Boulder, CO and Dallas Area Rapid Transit in Dallas, TX) to study the newer natural gas technology and specifically to measure new technology LNG buses. Propane has not been included in this project because there are no original equipment manufacturer (OEM) heavy-duty engines powered by propane available to the transit market. This paper presents results to date on the continuation of the program.