The city of San Francisco this month launched the first city-wide project in the U.S. to collect brown grease for conversion into biodiesel and other fuels.
Though programs to turn yellow cooking oil into biofuel are increasingly popular, this project makes full use of the "brown grease" that is currently discarded as waste. Brown grease is the mix of used oils and food scrapings that flow down the sink drain during dishwashing, food preparation, and daily cleaning.
In commercial kitchens, before brown grease has a chance to enter the sewer pipes, it is captured in a mechanism called a "grease trap." Putting this previous waste-only product to use, San Francisco will refine brown grease collected from restaurants and residents and create multiple types of alternative energy.
The pilot project is a joint public-private collaboration between the San Francisco Public Utilities Commission (SFPUC), BlackGold Biofuels, and URS.
The brown grease biodiesel plant will be constructed at the award-winning Oceanside Treatment Plant next to the San Francisco Zoo. It will be the first of its kind combining a sewage treatment plant with this new technology to generate three different types of alternative energy sources:
- High-grade, road-worthy certified biodiesel for vehicles;
- Lower grade boiler fuel for running sewage treatment plant equipment
- Converted methane to run the treatment plant
The program is an extension of the SFPUC’s existing SFGreasecycle program that since 2007 has been collecting used cooking oil for free and recycling it into biodiesel.
The state and federal grant-funded project also could save the city $3.5 million annually in sewer clean up. The SFPUC estimates that grease blockages in San Francisco sewers account for 50% of all sewer emergencies.
In addition, sewage treatment plants account for 3% of the nation’s electrical consumption because they run 24 hours a day, seven days a week.
"Thanks to these collective grants, our cutting-edge brown-grease-to-biodiesel plant will break new ground toward accessible, sustainable energy and serve as a model for the entire state and the country," said Mayor Gavin Newsom.
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