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California Jail Installs New Microgrid to Cut Energy Costs

California Jail Installs New Microgrid to Cut Energy Costs

by Derek Gilna

The Santa Rita Jail in Alameda County, California has installed an $11.7 million "microgrid" system to help power the 4,000-bed facility, which is the fifth-largest jail in the nation. Previously, the jail had installed a 9,000-solar panel array that produces 1.2 megawatts of electricity, as well as a 1 megawatt molten carbonate fuel cell, five small wind turbines and a second 1,100-solar panel system.

The Santa Rita Jail and Alameda County partnered with Chevron Energy Solutions to cut utility costs and receive a U.S. Department of Energy grant that enabled the jail to upgrade its power system with the microgrid, which will let the facility remove itself from the state's electrical grid in case of a blackout.

According to Alameda County Sheriff Greg Ahern, the new system will cut the jail's utility bills by charging its 4 megawatt battery storage units at night, when electricity from the grid costs less, and then use some of that stored energy in the afternoon when power prices peak. "It lowers our cost, it gives us a redundancy system in place, and it sends a message to taxpayers that we're doing our best to run the most efficient jail we can," he said.

"One of the things the jail really proves is the plug-and-play nature of this," added Chevron chief project engineer Osama Idrees. "They have the infrastructure to add more batteries, add more solar. It is scalable."

Over the past ten years Alameda County has taken steps to make the Santa Rita Jail's power system more self-sufficient, following lessons learned during California's electrical crisis of 2000-2001 that caused wide-spread blackouts throughout the state. The jail has two emergency diesel generators as an additional backup in case of an extended blackout, which would cycle on when the battery packs run low.

County jails and state prisons are heavily dependent on electricity to power their security cameras and recording systems, electronic doors, perimeter fence alarms, and heating and air conditioning systems. Prisons in California, Indiana and New Mexico have turned to solar power as an alternative source of energy. [See: PLN, March 2012, p.30].

Matt Muniz, energy program manager for the Alameda County General Services Agency, said the microgrid will help tie together all of the jail's previous energy projects and make them more efficient. "Say if we over-produced with the solar, there wasn't any way to store that energy, and we really couldn't project how much solar we'd have, and what our actual loads would be. So this project integrated all those things together."

"The technology for energy sources has been here for years," noted Sheriff Ahern. "But the technology to combine them and store the power has not."

Microgrids have also been touted as a method to reduce demand on the larger power grid during peak electricity usage, according to Chris Marnay, staff scientist at the Lawrence Berkeley National Laboratory. "Micro-grids could free up the grid from all these demands we place on it," he said.

Prior to implementing the microgrid, the Santa Rita Jail had an annual electric bill of about $3 million. The facility's microgrid was funded with a $6.9 million grant from the U.S. Department of Energy, a $2 million grant from the California Energy Commission and $2.5 million from the Pacific Gas and Electric Company.

Sources: San Francisco Chronicle, Contra Costa Times,,

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