Pumps dispense vegetable oil-based fuel

The station opened Wednesday, making the alternative fuel available to the public. A similar station had opened in Sparks, Nev., on Tuesday.

While biodiesel avoids the release of carbon monoxide and the small particles released by burning traditional diesel, it doesn't cut down on smog-causing nitrogen oxide.

The fuel is made from either recycled vegetable oil from restaurants, or from soybean oil. The San Francisco operation offers fuel that is 100 percent biodiesel, but a 20 percent biodiesel-80 percent petroleum diesel is available at other biodiesel facilities.

Diesel engines can use the fuel without any modification, and it contributes to the life of the engine by increasing lubrication so moving parts won't break down as easily, said Robert Skinner, a spokesman for World Energy Alternatives, the company providing the biodiesel to the San Francisco station.

But biodiesel has some drawbacks. It's more expensive than regular diesel, selling for about $3.15 a gallon in San Francisco and for about $1.62 a gallon in Sparks. It also causes a slight drop in fuel economy.

The fuel is used primarily by fleets of vehicles such as school buses, Skinner said.