ST. LOUIS -- Public agencies statewide are slowly turning to cleaner-burning biodiesel made largely from soybeans, given increasing pressure to cut tailpipe emissions from their fleets of trucks and tractors, government officials say.

The state's Department of Transportation, for example, has been looking to expand its use of the soybean-bearing alternative fuel with its fleet of about 4,500 diesel-powered pieces of equipment, as essentially directed by the Missouri Legislature.

"We are very supportive of the program," Donnell Rehagen, the transportation department's fleet manager, said Thursday. "It's a good program, and we're talking about renewable fuels. We're glad to be participating, and we're hopeful things will work out well with availability."

The fuel, which can cost anywhere from a nickel to 20 cents a gallon more than traditional diesel, generally is sold in a blend that is 20 percent biodiesel, known as B20.

Proponents say renewable biodiesel burns cleaner than traditional diesel, lessens reliance on foreign oil and cleans the air -- smelling more like French fries than sooty diesel exhaust -- while providing a boost for Missouri's soybean growers.

Other St. Louis-area agencies using biodiesel include Lambert Airport, which uses the bean-based diesel in its snow-removal equipment and fire trucks, and the city of Clayton, which fuels its trucks, fire engines and ambulances with the product.

In use across the state

Elsewhere in Missouri, Columbia is going from a 2 percent blend to B20 this fall, and Jefferson City will start running biodiesel in some of its vehicles. Fort Leonard Wood also uses the fuel. The state transportation department has used biodiesel in its St. Louis district for about the past three years and has seen availability increase noticeably in the past 18 months or so, Rehagen said.

As directed by the legislature, the department will increase its use of the alternative fuel to about 2.5 million gallons by next July, then to 3.5 million gallons -- 75 percent of its overall diesel use -- by the following year.

Today, that department uses only a fraction of that amount, largely in its St. Louis district.

"We have been working on expanding the program as the fuel was readily available throughout the state. The legislation just made us accelerate our plans," Rehagen said.

Metro, the St. Louis area's largest transit agency, used biodiesel for a short time two years ago but no longer puts it into buses. Metro was awaiting results of engine tests on whether there are harmful effects on buses that would void their warranties, said Ray Friem, Metro's senior vice president of transit operations.

Tom Verry, head of outreach and development for the Missouri-based National Biodiesel Board, said more than 50 distributors carry the fuel statewide, with supply now outpacing demand.

That group expects about 20 million gallons of biodiesel to be sold this year, much of it to government fleets and farmers.

Industry officials say an energy bill now pending in Congress could provide a break in the fuel excise tax paid by suppliers to make biodiesel more competitive with petroleum diesel.