Moss Landing Power Plant is Home to the World’s Largest Lithium-Ion Battery Energy Storage System

Monterey Bay’s three iconic smokestacks from an old power plant stand as landmarks at its midpoint but now serve as one of the world’s largest battery energy storage systems.

Vistra Energy’s natural gas-fueled Moss Landing power plant has served California with electricity since 1950.

Battery Storage

Moss Landing Power Plant in California is home to one of the world’s most extensive utility-scale battery storage facilities, recently adding 350MW/1400MWh phase for their battery energy storage system (BESS), expanding capacity up to 750 megawatts/3,000 megawatt hours and fulfilling their 15-year resource adequacy contract with Pacific Gas & Electric Company.

This project includes 256 Tesla Megapack batteries on 33 concrete slabs. They sit beneath transformers and switchgear that connect the energy stored in these batteries to PG&E’s 115kV transmission lines at Moss Landing; all equipment is seismically certified. Project manager Alan Prior notes that “there’s a lot of redundancy” within the facility. If one component goes down or becomes damaged, other elements usually work; even hidden behind visible batteries and transformers lie approximately five feet of infrastructure.

Moss Landing BESS remains operational, yet after it overheated recently, it led to targeted sprinkler deployment and fire service involvement – marking only its second overheating incident since starting operations in 2015. A maintenance check caused an emergency shutdown, which then led to overheated batteries which then overheated.

Overheating of battery systems is a potential concern, but it should be stressed that overheating episodes are relatively rare. They’re designed to withstand brief attacks of overheating while protecting batteries from damage, and Moss Landing facility’s cabinets are insulated with foam insulation to minimize the chances of overheating.

Overheating was caused by batteries being too close together, not environmental temperature fluctuations. According to the local fire district fire chief, overheating occurred within minutes, and they responded swiftly when necessary.

Morgan considers Moss Landing BESS to be “remarkable,” noting its revitalization of an idled power plant site, enhancements of grid stability, filling reliability gaps caused by intermittent renewables such as solar or wind energy sources, emission-free electricity production that supports California sustainability goals and mandates as well as community benefits.

Battery Racks

Vistra’s Moss Landing power plant houses one of the world’s largest battery energy storage systems: with an unprecedented 400 MW/1 200 MWh capacity, Vistra’s phase one facility at Moss Landing can power approximately 225,000 homes during California’s peak pricing periods – and capture excess solar output that’s stored until nightfall when demand peaks.

The initial phase was completed in December 2020, while an addition of 100 megawatts came online in August 2021. Together, these facilities can store 750 megawatts. Constructed as resource adequacy contracts with PG&E, these storage facilities may be called upon during peak energy demand periods in summer for callback purposes.

Visitors arriving at this site are met by an expansive sea of battery racks – energy storage systems located within three buildings that once contained turbines – taking advantage of power transformers and underground cable systems at the site, supplied by LG Energy Solutions with four-hour discharge duration batteries for energy storage purposes.

Solar power charges the batteries during the day and releases them at night, providing backup power during grid outages or blackouts. IBEW Local 234 Business Manager Lamont Adams reports that when combined with other renewable resources such as geothermal, this system helps California meet its carbon-free goals.

This year, an additional battery will be added at this site, bringing its total storage capacity up to 398 megawatts. A more significant addition may come online by 2023 – Adams notes that the state needs hundreds of megawatts of storage to meet its clean energy targets.

The success of this system has prompted others to follow suit: the 400-megawatt Elkhorn Battery Storage Project was inaugurated this month in Contra Costa County; construction is underway for a 60 MW Coso battery system in Inyo County, and NextEra Blythe will become fully functional later in 2018.

Future vision: Tesla-powered battery technology will become part of electric vehicles and the power distribution system. PG&E recently inaugurated an 182.5-megawatt Tesla battery storage facility at Moss Landing; further plans include turning Morro Bay Power Plant into a 600-megawatt facility by 2024.

Battery Cabinets

Moss Landing power plant has been an iconic feature on Monterey Bay for 40 years. Yet, its twin smokestacks have recently earned international acclaim as one of the most extensive lithium-ion battery storage facilities worldwide. Lamont Adams of Local 234 remarks: “It’s quite spectacular” as one of these world-class lithium-ion energy storage systems at 400 megawatts (MW).

Moss Landing dwarfs any competing US system, even the latest 250MW project in San Diego, which came online last year. Moss Landing’s immense capacity results from ongoing transformation efforts at this old fossil fuel plant into an international leader for clean and renewable energy production – and Local 234 members are instrumental in driving that change forward.

At the core of it all lie massive batteries: They fill old turbine halls of decommissioned plants like an electric labyrinth. Each cabinet holds thousands of lithium-ion cells that resemble household AA batteries in size and store enough energy for hours to power a quarter million homes for power outages.

Each cabinet is fitted with a layer of steel designed to act as a fire barrier. At the same time, batteries themselves are kept cool with liquid cooling – both measures should protect them from overheating – However, neither of these measures is failproof: just five months after Moss Landing BESS went live in 2021, an overheating incident caused several battery modules to smoke, prompting Vistra to temporarily close phase one storage facility as they searched for causes and solutions.

But, despite all of the smoke, this was not a severe problem. Most likely, it was simply due to an air handling unit misfiring and activating a water system designed to spray batteries with cool water to prevent them from overheating. A few weeks later, however, another smokey incident at the battery site caused more delays for the project.

The Labyrinth of Electric Potential

Large battery systems that store energy for an entire power grid resemble batteries found at home: each lithium-ion cell is slightly bigger than an AA cell; many laptops require six, while Tesla electric vehicles need nearly 5,000. At Moss Landing BESS facility, these cells fit neatly into racks approximately the size of a coat closet stacked and aligned in rows inside what was once an old turbine facility at a former natural gas-powered electricity plant; it is now the world’s largest.

Engineers from Chile’s premier power transmission company recently visited Vistra Zero’s facility for a three-hour tour that provided insight into its general layout, battery types and type designs, transformer design, cooling/temperature monitoring processes, fire protection measures, and disposal/recycling procedures. “It’s an extraordinary place,” noted John Burke, Vice President of Global Operations of Vistra Zero, offering solar PV generation and battery storage technology.

At Moss Landing Power Plant in Monterey County, which began operating commercially in 1950, this battery storage facility was completed within 16 months at a budget of just over $150 million and on schedule. Vistra reports that each cabinet contains 22 individual battery modules; the facility can deliver 400 megawatts and 1,600 megawatt-hours – enough power for 300,000 homes!

Vistra intends to expand its facility if the market and economic conditions permit. Physical space at the site supports up to 1,500 megawatts and 6,000 megawatt-hours, and their existing infrastructure can connect directly to PG&E’s grid. Vistra CEO Curt Morgan called it an exciting opportunity: “Working closely with California state authorities and PG&E allows us to deliver energy directly to California residents,” as Vistra stated last week.