On a paved expanse next to an electrical substation in Escondido, 30 miles north of downtown San Diego, sits a row of huge silver boxes. The site resembles a barracks, but instead of soldiers, the 24 containers house racks of battery packs.
This is the largest lithium-ion battery in the world, according to its developers. When the local grid needs more power, these batteries deliver, almost instantaneously. They hold up to 30 megawatts fully charged – roughly equivalent to powering 20,000 homes – and can sustain that level for up to four hours.
AES Energy Storage built the system in less than six months for utility San Diego Gas & Electric (SDG&E) in response to a four-month blowout at southern California’s Aliso Canyon natural gas storage facility. The rupture in October 2015 leaked more gas into the atmosphere than any other spill in US history.
After the leak was finally plugged in February 2016, utilities needed a fast-response energy source to deploy quickly in the densely populated areas around Los Angeles and San Diego. They wanted to prevent blackouts during periods of high demand, especially when customers crank up the air-conditioning on hot summer days.
Traditional grid solutions didn’t make sense. Gas peaker plants – which can be turned on quickly to meet demand – can take years to gain permission and be built, and they burn fossil fuels. You can’t drop a hydroelectric dam in the middle of a city. Solar power doesn’t help much in the evening, when summer demand is highest.
Instead, utilities Southern California Edison and SDG&E chose something relatively new: grid-scale batteries. What followed was the Escondido battery plus several others totalling about 100MW. The project became a major test case for the grid storage industry’s ability to make the grid more efficient and clean.
“To go from something that we thought of as kind of the future technology to, all of a sudden, it coming to the rescue so quickly – yeah, I think that’s a huge success story,” said John Zahurancik, president of AES Energy Storage.
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