A partnership between the city of Millbrae, Calif., and Chevron Energy will bring waste-to-energy capabilities to the agency's Water Pollution Control Plant. Photo: Dick York

The city of Millbrae, Calif., is partnering with San Francisco-based Chevron Energy to construct of facilities at Millbrae's Water Pollution Control Plant that will generate onsite electricity from restaurant kitchen grease and other organic matter.

The upgrades to the plant make it one of the first wastewater treatment plants in the United States to receive and process inedible grease in a comprehensive system specifically designed to control odors, generate reliable power, reduce energy costs, and provide a new municipal revenue stream. The system will create and use a free biofuel-digester gas produced from grease-and increase the amount of “green power” generated by the facility's cogeneration plant by 40%. Because the system will generate electricity onsite, the city will avoid having to purchase about 1.5 million kilowatt-hours from the local utility each year. This lower demand translates to 1.18 million fewer pounds of carbon dioxide emissions annually, equivalent to planting 166 acres of trees.

The upgraded system produce about $264,000 in projected energy savings and revenues from its grease-receiving facility each year. This will effectively pay for the $5.5 million facility improvements, and subsequent maintenance, at no additional cost to ratepayers.