Brewing biodiesel from waste oil is becoming a popular trend with municipal agencies for good reason. Biodiesel from grease is better than soy, palm, jatropha or canola-based blends because it doesn't require additional agricultural resources and it takes waste out of the sewage system.

San Francisco has it right, organizing the collection of waste from restaurants and using it to power city vehicles. SF is even considering building its own biodiesel plant. The city hopes to save maintenance fees paid to unclog sewage pipes stuffed with grease.

Waste oil is now approximately 20 percent of the used oil market, and it could clime higher.

According to the Oregon Environmental Council, enough waste oil could be collected for half of the state's biodiesel requirement, which eliminates some of the concerns about planting biofuel cropscausing deforestation.

Incentives should be in place so that this most sustainable of methods can compete with fossil fuels. Biodiesel from waste oil should be taxed less (or not at all) than biodiesel and other fuels because of its extremely light carbon footprint.

There's also millions of gallons of potential biodiesel going down the drain in kitchens across the U.S. each year. Biofuel companies could work with supermarket chains to collect the waste oil from families and offer a small incentive to increase participation.