WASHINGTON, D.C. – More than 600 fleets now use biodiesel, according to the U.S. Department of Energy as published on the Web site www.chronotype.com/. Last fall, Minnesota became the first state to require biodiesel to be blended into all diesel fuel using soybean-based oil. While the mandate was temporarily waived on two occasions because of quality and production issues, fewer problems are now being reported. According to the National Biodiesel Board, biodiesel is available at more than 600 retail fueling stations in the United States and from more than 1,500 petroleum distributors.