A big black bus with the words “Powered by Soy Biodiesel” is winding its way through Iowa to promote the fuel made from soybeans. Kirk Leeds of the Iowa Soybean Association says the purpose of the trek is to increase consumer awareness of soy biodiesel.Leeds says soy biodiesel works in any diesel engine and has been used in Europe for 20 years. The fuel’s been available in the U.S. since 1993. Leeds says soy biodiesel helps cut down on the wear and tear in diesel engines, extending equipment life. Nearly half of Iowa’s 60-thousand farmers use soy biodiesel and Leeds says that’s important since farmers use one-third of all the diesel sold in the country. About 300 Iowa gas stations offer “B-2” or some other blend of soy biodiesel. Governor Tom Vilsack has signed a proclamation, declaring this soy biodiesel week in Iowa.Vilsack says it’s important for the Midwest to lead the way so the nation can sever its ties to Middle Eastern oil and develop our own renewable fuels, like soy biodiesel. The West Central Co-op in Ralston, Iowa, is the nation’s largest soy biodiesel plant. About 11 million gallons of soy-diesel is produced in Iowa each year.