From fryers to fuel

Pub date January 23, 2008
WriterRachel Stern
SectionGreen CitySectionNews & Opinion


GREEN CITY At Ar Roi Thai in Nob Hill, about 75 gallons of oil are left over every month from the creation of the restaurant’s deep-fried cuisine, according to manager Theresa Shotiveyaratana. But instead of dumping it, the business donates its gunk to the newly established SFGreasecycle, which converts it into biodiesel that is now used to power San Francisco city vehicles such as Muni buses and fire engines.

As of Dec. 31, 2007, the city completed a yearlong project proposed in Mayor Gavin Newsom’s Biodiesel Initiative, which called for all 1,600 municipal vehicles to run exclusively on B20, a mixture of 20 percent pure biodiesel and 80 percent traditional petroleum diesel. The blend is compatible with most modern-day diesel engines and reduces carbon monoxide emissions by 12 percent and the particulate matter found in smog by 20 percent.

But most of that biodiesel hasn’t been generated locally: the city is halfway through its three-year master fuel contract with San Francisco Petroleum, which gets the stuff from soybean oil produced in the Midwest.

"It’s really not enough that a city looks at using biofuels to offset fossil fuels," said Karri Ving, the San Francisco Public Utilities Commission’s biofuels coordinator and one of SFGreasecycle’s three staff members. "We don’t want to go from one environmentally disastrous fuel to another. We want less shipping miles from the middle of the country."

That’s where SFGreasecycle, a $1.3 million program put into action by the SFPUC last month, comes in. It picks up used fats, oils, and grease (known in the program as FOG) at no charge from wherever people are willing to spare them. The list currently comprises mostly eateries, from chains like Baja Fresh and locals like Ar Roi, but also households, high schools, a synagogue, and museums such as the de Young.

About 170 restaurants have signed up so far, allowing the organization to collect an average of 5,000 gallons of so-called yellow grease — or what comes straight from the frying pan — per month. Furthermore, its efforts are a way of keeping congealed grease out of sewer pipes, which costs the city roughly $3.5 million in cleanup efforts per year, according to the SFPUC.

Ving said the organization has even loftier goals in mind. By the beginning of 2010 it aims to collect 100,000 gallons of grease per month. That’s about 20 percent of the five to six million gallons of diesel that the Department of the Environment estimates the municipal fleet burns per year.

Mark Westlund, the spokesperson for the Department of the Environment, said using the grease as a replacement for the imported fuel is a real possibility as they have "an almost one-to-one conversion rate."

SFGreasecycle uses four biodiesel treatment plants in the Bay Area to convert the grease to usable fuel. And sticking with its zero-waste goals, it donates the small amount of unusable, low-quality grease to the plants, which convert it into methane, which in turn powers these facilities.

Eric Bowen, chair of the city’s Biodiesel Access Task Force, shares Ving’s sentiment that "not all biodiesel is created equal," he told us. The task force is working with the Board of Supervisors to expand the local sources of biodiesel when the fuel contract expires in 18 months and to look into building a production facility in the city, where none currently exist.

The United States Department of Energy estimates that biodiesel contains roughly 8 percent less energy per gallon than petroleum diesel, although that translates into only about a 1 percent difference in mileage and performance.

Bowen said using biodiesel is a win-win situation since it acts as a natural solvent to clean fuel filters. And "the improved lubricity extends the vehicle life," he said. But before they use biodiesel for the first time, diesel tanks must be cleaned out, which the Fire Department found costs $2,000 to $3,000 per tank.

SFGreasecycle also complements the city’s Climate Action Plan, which aims to reduce greenhouse gas emissions to 20 percent below 1990 levels by 2012. "The goal is not just to make San Francisco sustainable," Ving told us, "but to develop a program that can be implemented by other municipalities."

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