The National Renewable Energy Laboratory (NREL) has just completed the first year of a study comparing St. Louis transit buses running on B20 biodiesel and ultra-low sulfur diesel (ULSD). Surprisingly the B20 buses actually had slightly lower average mileage than the ULSD fleet, 3.52 vs 3.58 mpg. The new study is the first to examine B20 use on buses equipped with exhaust gas recirculation systems. The EGR helps to reduce NOx emissions. Fifteen identical buses were examined in the study with eight of them using B20 and the rest using ULSD. One notable difference is the mileage on the buses at the start of the test. The B20 fleet had an average of 127,000 miles while the ULSD buses had an average of 107,000. With a differance of only 1.6 percent in the fuel efficiency, that difference might be a part of the reason. The study will continue for another year. Reliability and maintenance were comparable for the two groups. The full report is available at the link.
[Source: National Renewable Energy Laboratory