Intelligent Energy

Chevron turns a mega-jail into a microgrid

Posting in Design

Thanks to software developed by Lawrence Berkeley National Laboratory, the California's Santa Rita jail can disconnect itself from the grid and function as an island.

Alameda County's Santa Rita Jail in California houses 4,000 inmates, making it the fifth-largest in the country. So, keeping the lights on in a prison with a population of some American towns -- along with security devices, communications and everything else that requires power there -- is well, important.

Chevron Energy Solutions with help from scientists at the Department of Energy's Lawrence Berkeley National Laboratory, has turned the Santa Rita jail into a microgrid that can disconnect from the power grid and independently generate and store its own energy. In other words, the jail can turn into a power island and keep operating even if a natural disaster were to take out the main grid.

The jail's microgrid, which has been operational since the end of the last year, is scheduled to be unveiled today. CES designed, engineered and constructed each phase of the microgrid, which uses software developed by Berkeley Lab scientists that can monitor and manage the jail's electricity and heat requirements.

The microgrid is being called the country's largest CERTS-based microgrid with renewable energy and large-scale energy storage. CERTS or the Consortium for Electric Reliability Technology Solutions is a government organization formed in 1999 to transform the electrical grid into a smart network that can sense and respond automatically to changing flows of power or problems.

A microgrid uses a variety of energy sources to generate power including fossil fuels, solar, wind and even fuel cells. The Santa Rita jail uses them all.

The jail's microgrid also can function when it's connected to the grid, which helps the jail reduce its electricity bill and lower the load on the local power distribution network. If coordinated properly, it would allow utility Pacific Gas & Electric to postpone upgrades on its equipment to increase capacity, saving it loads of money in the process. And energy savings is critical for a one-million-square-foot jail that requires 3 megawatts of electricity all day, every day, according to CES.

The back story

California's energy crisis in 2001 prompted Alameda County to seek stabilize the jail's power sources. Chevron Energy Solutions says it has been a key partner in the design, engineering and construction at each phase of the project.

The plan kicked off that year with the installation of a 1.2 megawatt rooftop solar photovoltaic system and a retrofit helped reduce energy use. In 2005, a 1 MW fuel cell cogeneration plant was installed to provide energy and waste heat recovery.

Multiple energy efficiency and water conservation measures aimed at cutting the jail's peak electrical loads followed. Five small wind turbines were installed in 2010.

Last year, the jail added a 2 MW advanced energy storage system and an automatic disconnect switch. With that addition, the facility evolved into a complete smart grid capable of turning itself into a power island completely removed from the main utility grid.

Photos: Chevron

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Kirsten Korosec

Contributing Editor

Kirsten Korosec has written for Technology Review, Marketing News, The Hill, BNET and Bloomberg News. She holds a degree from Northwestern University's Medill School of Journalism. She is based in Tucson, Arizona. Follow her on Twitter. Disclosure