UPDATE FROM THE NREL ALTERNATIVE FUEL TRANSIT BUS EVALUATION PROGRAM

The objective of this project, 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 fuel. Final reports from this project were produced in 1996 from data collection and evaluation of 111 transit buses from 8 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, open-loop 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 emission testing newer natural gas engines to study the newer natural gas technology and specifically to measure the new technology LNG buses. This paper presents results to date on the continuation of the program.