SAN FRANCISCO - The city of San Francisco has fallen well short of its 2007 stated mandate to switch its 1,500 diesel-powered vehicles to a 20-percent biodiesel blend, according to the San Francisco Examiner newspaper. Tighter storage tank regulations have hindered the effort.

Muni is the largest transit system in the Bay Area and seventh largest in the nation, serving more than 200 million customers a year. About half of Muni's 507 diesel and hybrid buses now run on B20 - a blend of 80 percent regular diesel and 20 percent biodiesel. But for the past year or so, the rest have been running on a blend of less than 1 percent biodiesel, the newspaper reported. The Examiner cited a memo sent to Mayor Gavin Newsom in early December from San Francisco Municipal Transportation Agency Executive Director Nathaniel Ford. In the memo, Ford said about 50 percent of those vehicles on 1-percent biodiesel will be converted back to B20 this month after an underground fuel tank upgrade is completed. The rest of the vehicles, however, will remain running on the lower level for the near future. 

The memo attributed the drop in Muni's biodiesel use to stricter state regulations on biodiesel storage in underground tanks. Those regulations were imposed by the State Water Resources Control Board to protect water quality. The stricter regulations prompted the Department of Public Health to require the San Francisco Municipal Transportation Agency to reduce the biodiesel at two of its three diesel tanks. 

Of the diesel-engine vehicles operated by other city departments, only 40 percent are now using B20. The remaining vehicles use B5, a 5 percent blend. This includes vehicles operated by the Department of Pubic Works, the San Francisco Public Utilities Commission, the Fire Department and other city agencies, the newspaper reported.