Combining the need to generate alternative sources of energy with environmentally friendly resources, Chevron Energy Solutions, a unit of Chevron Corp., is working with the City of Millbrae, Calif., to turn restaurant kitchen grease as well as other organic matter contained in a waste treatment plant into electricity. Construction of facilities at Millbrae's Water Pollution Control Plant (WPCP), announced on Sept. 21, will make this facility one of the first wastewater treatment plants in the U.S. to process inedible grease using a comprehensive approach that includes controlling odors, a major concern in wastewater treatment plants, as one of the objectives. The project is expected to be completed by late 2006.
According to Ron Popp, director of public works, Millbrae, this solution will help the facility reduce emissions and lower energy costs. In fact, the cost savings will actually finance both the construction and the necessary maintenance so that utility ratepayers will not see an increase in rates says Popp.
The energy system will create and use a biofuel-digester gas produced from grease. The process uses chopper pumps that reduce grease particle size and moves the grease to anaerobic "digest tanks". Inside the tanks are microbes that digest organic matter from wastewater and produce methane as a byproduct, which is then used to fuel a microturbine. In turn, this increases the facility's amount of "green power" by 40%.
According to Chevron, the city can avoid purchasing 1.5 million kilowatt-hours from the local utilities, thus reducing carbon dioxide emissions by 1,178,000 pounds, which is equivalent to planting 166 acres of trees, according to Chevron.
"The City of Millbrae approached us with a very complex situation, with the goal of upgrading its facilities with more effective technologies while keeping costs under control," says Jim Davis, president of Chevron Energy Solutions. "We love these types of challenges, because they allow us to explore innovative solutions for energy production. In this case, the grease-receiving facility was the key to making this project feasible -- not only will it reduce the WPCP's energy expenses, but it will also open a new revenue stream to help offset the cost of new equipment."
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