Grease to generate power

There will be a new life for San Mateo County restaurant grease that would normally end up clogging a pipe or filling a landfill.

Construction started Wednesday on new facilities at the Water Pollution Control Plant in Millbrae which will turn the grease into usable energy.

For Millbrae, this means lower energy and operating costs, greater power reliability, a free biofuel source and a new revenue source. The new system will also offer a more efficient disposal of grease, converting it into methane instead of letting it sit in a landfill while lowering the air emissions produced.

Millbrae teamed up with Chevron Energy Solutions to upgrade the facilities into a treatment plant with the ability to receive and process restaurant kitchen grease and other organic matter into a biofuel called methane.

"What other project can you think of that takes everyday grease ... and turns it into energy?" Jim Davis said, president of Chevron Energy Solutions.

There is a three-step process involved. First, grease is collected each night from restaurants then brought to the plant in trucks. The new facilities will allow grease to be drooped off 24 hours a day.

Then the grease will be stored in a new 12,000 gallon tank where it is mixed to produce methane. Finally, the methane is used to fuel the new 250 kilowatt microturbine cogeneration system, which produces power for operating the plant.

Currently, the plant uses a 75 kilowatt internal combustion electrical generator fueled by methane.

This process creates a 40 to 50 percent increase in natural gas at the plant which directly generates a 40 to 50 percent increase in using electricity more efficiently according to environmental engineer Greg Chung.

This process of using otherwise wasted energy while generating electricity is known as cogeneration.

"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. ... In this case, the grease-recieving facility was the key to making this project feasible; not only will it reduce the [Water Pollution Control Plant's] energy expenses, but it will also open up a new revenue stream to help offset the cost of new equipment," Davis said.

Since the plant will generate electricity on site, the city will not have to pay for the energy used. Millbrae anticipates receiving about $200,000 annually in rebates for the excess energy. The city will also receive revenue from the disposal fees grease hauling companies will have to pay. These savings will be put towards the $5.5 million cost of the new facilities.

The facility could be used by companies from the Peninsula through San Francisco that would otherwise have to go to the East Bay or the Central Valley to dispose of the grease, said City Manager Ralph Jaeck.

The process of turning grease into an energy source is also being utilized in Redwood City. Kennedy Jenks Consultants studied the plant in Redwood City to determine gas production. Millbrae will be producing more gas and energy than the Redwood City plant though, because the Redwood City plant receives more waste water.

Heather Murtagh can be reached by e-mail: heather@smdailyjournal.com or by phone: (650) 344-5200 ext. 105. What do you think of this story? Send a letter to the editor: letters@smdailyjournal.com.