San Francisco started on the path of transitioning away from petroleum diesel and using cleaner forms of diesel fuel a half-dozen years ago by transitioning to a blend of biodiesel. Currently, most of the municipal fleet uses B20: a blend of 20% biodiesel and 80% petroleum diesel.

The SFFD piloted the use of renewable diesel fuel for our fleet over a period of six months last year. Our fleet ran cleaner and more efficiently, and we are completely supportive of the Mayor’s call to switch to renewable diesel to improve the environment and create a healthier future for our residents.

—San Francisco Fire Chief Joanne Hayes-White

Although renewable diesel is more expensive to produce at this time, it qualifies for valuable credits under Federal and State programs, which allows renewable diesel to be available at or below the price of conventional petroleum diesel, the City said.

Renewable diesel is not the same as biodiesel. Both fuels are produced from numerous bio-feedstock sources, including fats, oils and greases, but the two fuels are produced through different processes. Renewable diesel uses a hydrogenation process, while biodiesel uses an esterification process. According to the California Air Resources Board, the full lifecycle emissions of carbon from renewable diesel produced from sustainable sources are more than 60 percent lower than either petroleum or B20 biodiesel. Chemically, renewable diesel is indistinguishable from petroleum diesel, and testing has shown it to have engine performance that matches or outperforms both petroleum diesel and biodiesel.