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Thursday, Sep 28, 2023

Energy County may expand use of landfill generators

Last summer, San Diego County was being swamped by the high price of electricity.

This summer, using more “swamp gas” may be part of the solution.

Each of San Diego County’s 10 landfills produce methane, also known as swamp gas. By law, the county is required to collect it and burn it off.

Now the county is eyeing a small project which would use some of that methane to generate power. The proposal would install a turbine generator on the gas control system at the inactive Jamacha landfill, similar to what is being done elsewhere in the county.

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The electric generator could be up and running as early as June, said county Supervisor Dianne Jacob.

Supervisors voted unanimously Feb. 12 to look into the $525,000 project. The money would come from the county’s Solid Waste Management budget, she said.

The cost covers installing the microturbines at Jamacha, along with the infrastructure to transfer the electricity into the local grid. The revenue generated from the project would recoup the capital outlay within five to six years, Jacob said.

Jacob also pointed out the county could get up to $75,000 in state money for the project. Assembly Bill 970, the Electricity Peak Load Efficiency Grant Program, offers incentives for developing renewable energy development to augment peak electricity supply. The bill, approved in 2000, provides $50 million for the California Energy Commission to distribute as grants.

Jacob added with power shortages on the rise and electric costs soaring, such a project is not only cost-effective, it’s vital. In the past month, Californians have just come out of 32 consecutive days of “Stage 3” alerts, meaning the level of energy surplus in the state had dwindled below the 1 & #733; percent mark, she said.

Now, the county is expected to use twice as much energy over the summer as it did in the winter, she said.

Jacob noted the Jamacha turbine is expected to produce only 300 kilowatts of electricity per hour, or enough power for about 300 San Diego homes. That’s small compared to a full-size power plant, which produces enough energy to power 500,000 homes or more.

Combined with other “peaker” plants, it would provide enough electricity to get San Diego over the hump when reserves are low and energy use climbs, she said.

Bill Polick, spokesman for the county’s Department of Public Works, said methane from the landfill is already collected, only to be burned off. Now the heat would be used to turn a turbine to generate electricity, which could then be sold, Polick said.

The turbines could last a very long time, theoretically forever, so long as they are properly maintained and worn-out parts are replaced. As for the fuel supply, landfills tend to produce methane over a long period of time. An extremely conservative estimate is that the landfill is good for 20 years of fuel, but it could be much higher, he said.

Currently, only the Jamacha landfill is being considered. Two other landfills have their methane already committed to other generators which use it to create electricity, while the remaining sites don’t produce enough of the gas to make energy generation feasible, Jacob said.

Ron Kole, spokesman for the Metropolitan Wastewater Department, said at the North City Water Reclamation Plant and the Metro Biosolids Center, methane gas collected from the county’s landfills is used to generate electricity that powers the plant. The excess electricity is then sold back into the grid, he said.

The Point Loma sewage treatment plant also uses methane gas to generate electricity. At the Point Loma facility, the gas comes from the sewage itself, which releases methane during the digestion process, Kole said.


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