PG&E commissions 182.5MW/730MWh Tesla BESS at Moss Landing


Californian investor-owned utility (IOU) PG&E has commissioned the 182.5MW/730MWh battery energy storage system (BESS) supplied by Tesla at its Moss Landing substation.

The BESS project in Monterey county, known as the Elkhorn Battery, was fully energised and certified for market participation by the California Independent System Operator (CAISO) on 7 April. It was designed, built and will be maintained by both PG&E and Tesla while the project is owned and operated by PG&E.

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Elkhorn comprises 256 Tesla Megapack battery units on 33 concrete slabs with each unit housing batteries and power conversion equipment in a single cabinet. It connects to the 115kv electric transmission system through transformers and switchgears installed as part of the project.

It can discharge 182.5MW of power for up to four hours and will participate in the CAISO wholesale electricity markets as well as ancillary services like operating reserve.

It is not to be confused with Vistra Energy’s 400MW/1,600MW Moss Landing Energy Storage Facility located at the same site, also owned by PG&E. That one is the largest BESS in the world and Vistra recently announced plans to add another 350MW/1,400MWh of storage. It temporarily went offline last year due to a faulty sprinkler system.

Elkhorn brings PG&E’s battery storage connected to California’s electricity grid to 955.5MW, spread across six projects commissioned over 2021 and 2022, with another 1,400MW expected to come online this year. Vistra’s Moss Landing BESS is the largest, followed by LS Power Development’s 200MW Diablo Storage System in Contra Costa County, followed by Elkhorn. The utility is under contract to bring on 3,330MW in total by 2024.

BESS projects like these and others by PG&E’s fellow IOUs SDG&E and SCE are in responsive to a series of directives from the California Public Utilities Commission (CPUC). The most recent was an order to procure 11.5GW of clean energy by the CPUC in mid-2021, with resources required to come online between 2023 and 2026. The state aims to have a carbon-free grid by 2045.

Nearly 3GW of BESS is now connected to CAISO’s grid (which accounts for the majority of the electricity system in the state) and is doing up to 6GWh of load shifting a day, as recently reported last week.

SDG&E also this week announced the completion of a microgrid project in the CPUC’s designated ‘high fire threat district’.

The Romana microgrid facility, one of four planned in the area, will use a 500kW/2000kWh BESS to provide backup power to the Ramona Air Attack Base. The base is home to CAL FIRE and U.S. Forest Service’s aerial firefighting assets including an OV-10A Bronco tactical aircraft and two S-2T airtankers.

It is part of the utility’s efforts to keep essential resources powered during Public Safety Power Shutoffs (PSPS).

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