Moss Landing Power Plant
| Company type | Power generation facility |
|---|---|
| Industry | Energy |
| Founded | 1949 |
| Headquarters | Moss Landing , United States |
Area served | California |
Key people | Vistra Corp (owner of Vistra Energy Storage Facility), PG&E (owner of Elkhorn Battery Facility) |
| Products | Electricity generation, battery energy storage |
| Owner | Vistra Corp, Pacific Gas & Electric (PG&E) |
The Moss Landing Power Plant is a facility located in Moss Landing, California near the center of Monterey Bay, generating electricity primarily from natural gas and incorporating substantial battery energy storage. As of , its battery storage system ranks among the largest globally, offering 630 MW of power capacity and 2,500 MWh of energy storage. This setup enables the plant to store surplus electricity—mainly produced by California’s solar installations during daylight hours—for deployment during periods of high demand, such as evenings.
This battery storage is divided between two sites: the Vistra Energy Storage Facility, managed and owned by Vistra Corp, headquartered in Irving, Texas, and the Elkhorn Battery Facility, owned by California utility PG&E and utilizing Tesla battery technology.
The plant is easily recognizable by its two 500-foot tall stacks, which serve as notable regional landmarks. It currently operates two combined cycle units with a total net capacity near 1,020 MW. Prior to retiring its two supercritical steam units in 2016, Moss Landing was California’s largest power station, boasting a total capacity of 2,560 MW.
History
Construction of the Moss Landing Power Plant began in 1949 under Pacific Gas & Electric (PG&E), initially featuring five steam units powered by natural gas and oil built throughout the 1950s with a combined output of 613 MW.
In 1964, PG&E added two more units (numbers 6 and 7), each equipped with supercritical steam technology and capable of producing 750 MW at , resulting in an additional 1,500 MW capacity.
The original five units were decommissioned in 1995, with PG&E allowing their operating permits to expire in 1997. Following the deregulation of California’s utilities market, PG&E sold Moss Landing to Duke Energy (DENA) in 1998. That same year, to comply with heightened environmental regulations, units 6 and 7 were retrofitted with selective catalytic reduction systems and upgraded digital controls.
Starting in 2000, the plant underwent significant modernization: eight exhaust stacks and nineteen fuel oil tanks were dismantled and replaced by two new combined cycle units (1 and 2) that became operational in 2002. Each unit consists of two paired gas turbines producing 170 MW each, which supply steam to a 190 MW turbine. Together, each unit delivers approximately 530 MW and operates at roughly 50% greater efficiency than the older units. Upon completion of these upgrades, Moss Landing reclaimed its status as California’s largest power plant with a total capacity of 2,560 MW.
After investing more than $500 million into these improvements, Duke Energy sold the facility to LS Power Equity Partners in 2006. The following year, in April 2007, Dynegy acquired Moss Landing from LS Power.
In 2015, a transmission tower failure triggered a significant blackout across Monterey County. On December 31, 2016, Dynegy retired the supercritical steam units (6 and 7) due to their declining economic viability but retained their operating permits.
By February 2017, Dynegy was contemplating shutting down Moss Landing amid a surplus of wholesale electricity supply in California. This oversupply made it difficult for independent producers without guaranteed returns—unlike regulated utilities such as PG&E—to maintain profitability. The surplus was partly driven by policies promoting new plant construction despite existing excess capacity. This downturn also negatively impacted Monterey County’s tax revenues.
On April 9, 2018, Vistra Corp completed a merger with Dynegy and took ownership of Moss Landing. Instead of closing the site, Vistra opted to expand its operations. By 2021, the facility was rebranded as the "Vistra Moss Landing Energy Storage Facility," highlighting its transition toward energy storage technologies.
Links to the California electrical grid
The facility is integrated with Path 15 and interconnected with routes such as Path 26 and Path 66, facilitating electricity transmission to remote areas. It also supplies power to nearby consumers, including those in the San Jose region, through dedicated transmission infrastructure.
Generation of power from natural gas
Both the supercritical steam and combined cycle units employ once-through cooling methods, with the supercritical units requiring per minute and the combined cycle units .
Supercritical Steam Units 6 and 7
Units 6 and 7 utilized supercritical steam technology before their decommissioning at the close of 2016. These units mainly functioned as peaking plants, operating approximately 3% of the time during their last year. Natural gas was combusted in boilers to produce steam, which then powered both high-pressure and low-pressure turbines connected to generators. Cooling water was drawn from Monterey Bay or the adjacent Elkhorn Slough, treated for purity, used for turbine cooling purposes, and subsequently discharged back into ocean waters.
Combined Cycle Units 1 and 2
These units operate on a typical Brayton cycle, where combustion gases directly drive gas turbines. The waste heat from these gases is captured through a heat exchanger to generate steam for an additional turbine, thereby improving overall efficiency. Compared with supercritical units, these combined cycle plants provide enhanced operational agility, featuring start-up durations near one hour instead of the 24 hours required by supercritical units.
Battery energy storage systems
Following California’s 2013 directive mandating significant battery storage capacity by 2024, Moss Landing Power Plant was selected as the key location for large-scale battery energy storage deployment in the state. This initiative supports commercial grid integration of renewable energy sources such as solar and wind. On June 29, 2018, Vistra Corp revealed plans to construct what would become the largest commercial-scale electric battery storage installation worldwide at Moss Landing.
Vistra Corp project
On June 29, 2018, Vistra Energy announced intentions to establish a 300 MW / 1,200 MWh battery energy storage system at Moss Landing, California, repurposing the existing turbine building and utilizing the interconnection infrastructure formerly used by units 6 and 7 to access the 500 kV grid. The project targeted becoming the world’s largest lithium-ion battery storage system with commercial operation slated for late 2020, subject to approval by the California Public Utilities Commission (CPUC). Construction commenced in December 2019, with Phase 1 entering service by year-end 2020. The facility incorporates LG JH4 battery cells arranged in TR1300 racks stacked over two levels inside the former turbine hall.
Phase 2 expanded capacity by an additional 100 MW / 400 MWh, completed in August 2021, elevating total output to 400 MW / 1,600 MWh. In 2023, Phase 3 added another 350 MW / 1,400 MWh through installation of approximately 113,000 modules housed within 122 outdoor containers, increasing aggregate capacity to 750 MW / 3,000 MWh; this phase became operational in August 2023.
An approved plan to extend capacity further to 1,500 MW / 6,000 MWh connected to the 500 kV grid received authorization in August 2020; however, Vistra has stated that advancement depends on favorable market conditions before committing additional investment.
Elkhorn development
Under a 2013 California mandate, utilities are required to deploy significant battery storage capacity by 2024. Pacific Gas & Electric (PG&E) requested approval from the California Public Utilities Commission (CPUC) for four energy storage installations near the Moss Landing facility. Among these is the "Elkhorn" lithium-ion battery system, rated at 182.5 MW / 730 MWh, owned by PG&E and supplied by Tesla, which connects to the 115 kV regional grid.
The Elkhorn Battery Facility was created to bolster energy reliability and facilitate greater integration of renewable sources at Moss Landing by increasing the state's electricity storage capabilities. Its purpose includes reducing PG&E’s dependence on expensive peaker plants during periods of high demand. To fulfill these objectives, the project utilizes 256 Tesla Megapacks.
In July 2019, Monterey County issued a Mitigated Negative Declaration under the California Environmental Quality Act (CEQA), determining that with appropriate mitigation measures, environmental impacts—especially those affecting biological and cultural resources at the Megapack site—would be "Less than Significant."
Environmental opposition came from California Unions for Reliable Energy, which challenged the county’s CEQA review, claiming it fell short of legal requirements. This approach echoed previous strategies used to negotiate labor terms in other renewable energy developments.
The Monterey County Planning Commission granted unanimous approval for Elkhorn in February 2020. Construction was initially slated to start in late March with completion targeted for 2021; however, the COVID-19 pandemic delayed the start until after shelter-in-place directives were lifted. Construction commenced in July 2020 using Tesla Megapack units.
PG&E officially commissioned the Elkhorn Battery Facility on June 7, 2022, marking a major milestone in advancing large-scale battery storage technology to support California’s shift toward cleaner energy.
Vistra Corp's high temperature safety incidents
In September 2021, Phase 1 of the facility was taken offline following a high temperature safety event caused by a leak in a liquid cooling hose; Phase 2 remained operational.
A subsequent high temperature safety incident occurred in February 2022, resulting in both Phases 1 and 2 being shut down. By July 2022, most of the plant had resumed functioning.
January 2025 fire
On January 16, 2025, a fire erupted within the Phase 1 building (300 MW / 1,200 MWh) operated by Vistra Corp. The battery units involved utilized lithium nickel manganese cobalt oxide chemistry—an older generation technology—and ignited inside an enclosed concrete structure. The installed fire suppression system failed to extinguish the blaze, which remained confined within the building. Unlike more modern designs that house batteries in separate outdoor containers to limit fire propagation, this enclosed layout may have contributed to the fire’s severity. Emergency responders evacuated approximately 1,200 nearby residents.
Fire crews adhered to lithium battery fire protocols by allowing the fire to burn itself out due to the release of toxic gases and extreme heat risks. Despite initial concerns over hazardous substances such as hydrogen fluoride, no such emissions were detected. Calm wind conditions allowed smoke to rise vertically before dispersing. By Friday morning, the fire had largely diminished but experienced a brief resurgence before subsiding again. Nearly 80% of this battery section was destroyed.
Evacuation orders were lifted by the evening of January 17, and local roadways reopened by January 22. The incident led some regulatory bodies to impose restrictions on battery storage projects and enforce new emergency rules.
In February, the fire reignited briefly but was swiftly contained. As of March 2025, most affected batteries have been disconnected; cleanup operations are projected to extend beyond one year. The cause of the fire remains unknown; however, California has since revised fire safety regulations governing battery energy storage systems.
Fire Incident at Elkhorn Battery Facility
On September 20, 2022, a blaze ignited at PG&E's Elkhorn Battery Facility due to a Tesla Megapack catching fire. Safety mechanisms quickly isolated the site from California’s electrical grid, ensuring no disruption to PG&E customers and resulting in zero injuries. The facility resumed operations on December 30, 2022. However, after the Vistra fire in January 2025, Elkhorn Battery was taken offline once more. A restart attempt on June 1, 2025, was halted because of a leak in the cooling system, postponing the facility’s reactivation.