The Tesla/PG&E energy storage will be used to store wind and solar power during offpeak hours, similar to Vistra’s 300 MW/1,200 MWh, battery energy storage at the same site. Nearby, Dynegy is also going to deploy a 300MW / 1,200MWh energy storage unit on PG&E’s power transmission grid.
“Combined, this is going to be the largest battery facility in the world, so it's a big boost to our community and our country," said Monterey County Supervisor John Phillips. The Monterey County Planning Commission last week gave the greenlightfor the PG&E/Tesla energy storage project.
Some 268 Tesla Megapack lithium-ion batteries will be interlinked to form the 730 MW energy storage facility and then grid-connected at a PG&E substation. Each Megapack comes from the factory fully-assembled with up to 3 MWhs of storage and 1.5 MW of inverter capacity, building on Powerpack's engineering with an AC interface and 60% increase in energy density to safe cost.
To reach over 1.1 GWh capacity, Tesla will eventually deploy 449 Megapacks at the Moss Landing site.
Megapacks replace peaking plants
PG&E pointed out that Megapack can help reduce the need for fossil-fuelled peaking power plants. Placed at the end of the so-called merit order, these power units are only fired up at times of peak power demand when the local grid operator cannot meet demand.
"They cost millions of dollars per day to operate and are some of the least efficient and dirtiest plants on the grid," Tesla stated. By using Megapacks, instead Tesla said it can deploy an emissions-free 250 MW, 1 GWh power plant in less than three months on a three-acre footprint – four times faster than a traditional fossil fuel power plant of that size. The units can also be DC-connected directly to solar, creating seamless renewable energy plants.
Together – the PG&E energy storage, the Dynergy unit and Vistra’s energy storage and a 75 MW unit by Hummingbird Energy Storage – will have enough installed capacity to replace three gas-fired peakload power plants, the California Public Utilities Commission confirmed.