From: innovations.harvard.edu
Published February 10, 2009 08:58 AM

Gookiest cooking grease to be converted to fuel

San Francisco will become the first city in the country to convert large batches of "brown grease" - the smelly, mucky mess left over from foods cooked in oil - into biodiesel and other fuels under a program set to start by the end of the year.

The $1.2 million pilot program, which is being funded by state and federal grants, will go toward building a grease recycling plant near the city's Oceanside treatment plant. The program will allow the city to collect about 10,000 gallons a week of dirty grease, which can be converted into roughly 500 gallons of fuel.

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"At home, when you're making eggs and it burns and you get that brown stuff and you scrape it off, that's what brown grease in essence is," Mayor Gavin Newsom said at a news conference Wednesday. "But it also becomes commercial-grade biodiesel. This is the good stuff, environmentally speaking."

About 10 million gallons of brown grease are produced in San Francisco every year, most of it safely collected and treated in the city's sewer system like any other waste material. Grease that isn't treated usually gets dumped down the drain, where it can cause major clogs to city pipes - at a cost of about $3.5 million a year, say city officials.

Not only is that a waste of money, but it's a waste of a potential natural resource, said Ed Harrington, general manager of the San Francisco Public Utilities Commission.

"It's being treated through the wastewater system like any other solid now. That doesn't take advantage of the fact that there's energy in it," Harrington said.

San Francisco has been recycling "yellow grease" - oil that's been used for "clean" cooking like frying potatoes - since 2007. Programs that convert used cooking oil into biodiesel are becoming increasingly common in the United States, but so far no one has created a large-scale system for converting brown grease into fuel, said Karri Ving, the biofuel program coordinator for the Public Utilities Commission.

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