Vistra finished Phase II expansion of its Moss Landing Energy Storage Facility in California, the company announced Thursday, adding 100 MW/400 MWh to the world’s largest battery facility.

The facility is now storing power and supporting the California grid, when needed, with a total capacity of 400 MW/1,600 MWh.

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“This facility provides a solution California desperately needs and this expansion was able to come online at the right time – as the summer heat intensifies and demand for electricity is at its highest,” Vistra CEO Curt Morgan said in a statement. “The state’s laudable immense buildout of intermittent renewable power has both lowered emissions and presented a reliability challenge… Our Moss Landing battery system helps to fill that reliability gap, storing the excess daytime power so it doesn’t go to waste and then releasing it to the grid when it’s needed most.”

The expansion, which began in Sept. 2020, finished ahead of schedule, despite the impact of the COVID-19 pandemic. The lithium-ion battery system is co-located on the site of the existing Moss Landing Power Lant in Monterey County.

Morgan said the site is capable of support expansion up to 1,500 MW/6,000 MWh.

“California leads the country in the transition away from fossil fuels and the Moss Landing Energy Storage Facility stands as a model for how batteries can support intermittent renewables to help create a reliable grid of the future,” Morgan said.

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