With the intent to expand its current yellow-grease recycling program, the city of San Francisco will begin utilizing previously discarded brown grease to produce biodiesel, a project being funded by a $1 million grant received from the California Energy Commission on May 29.

The San Francisco Public Utilities Commission, which runs the city's yellow-grease collection program and will manage the brown grease project, contributed a $1.7 million match to cover labor, equipment and other expenses involved in the construction of a pilot facility. The location of the new pilot plant will be at the public utilities commission's Oceanside Sewage Treatment Plant.

Brown grease, typically disposed of at sewage treatment plants, is identified as the dark substance that remains in grill traps and grease interceptors under restaurant kitchen sinks. According to city officials, San Francisco contains an estimated 2.5 million gallons of brown grease-1 million more gallons than yellow. The current program collects yellow grease from restaurants to fuel city vehicles, buses and fire trucks.

The refined brown grease can be converted into three grades of biodiesel, including high-grade certified biodiesel for vehicles, a lower-grade biofuel source used to run turbines and pumps at sewage treatment plants, and energy for cogeneration (capturing methane gas at the sewage plant to convert into electricity).

Mayor Gavin Newsom said San Francisco's grease recycling program, which was launched in November 2007, has been an enormous success, although the city must continue to raise standards in regard to reducing greenhouse gas emissions and alternative energy exploration. "With this grant, our unique brown-grease-to-biodiesel plant will break new ground for sustainable fuel production in California and serve as a model for the entire state," he said.

Public Utilities Commission General Manager Ed Harrington claimed the project will create a "win-win" situation for ratepayers and the environment. "We will keep more grease out of the sewers and reduce our reliance on outside energy sources for our treatment plants," he said.

The brown grease pilot facility is expected to be completed in December.