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Vistra restarts Phase I and Phase II of Moss Landing Energy Storage Facility

Batteries at Moss Landing Energy Storage Facility, California. Image source: LG Energy Solution. 

After facing two shut-downs in September 2021 and February 2022, Vistra Corp's (Vistra) Moss Landing Energy Storage facility in California is back online. 

Vistra on Monday announced, that its Moss Landing Energy Storage Facility has successfully restarted with more than 98% of its 400-megawatt capacity now storing and releasing power to the California grid for the all-important summer season.

Vistra's Moss Landing's energy storage facility consists of two separate buildings, the first housing a 300MW - Phase I system and the second, housing a 100MW - Phase II system. The company began its efforts to incrementally bring the facility online throughout May and June after implementing corrective actions identified in its investigation including those related to connectors in the water-based heat suppression system.

While Vistra continues to work with regulators, state and local officials as it completes the restoration of the facility, Vistra noted, that the remaining 7MW is expected to be restored later this summer once replacement batteries and electrical components are received.

Currently, construction is underway for the 350MW - Phase III expansion which is expected to be commercially operationally by the summer of 2023. Vistra is contemplating further expansion of the fourth phase to the site which would take the capacity to 1,500 MW – enough to power approximately 1.125 million homes in California.

Phase I outage in Fall 2021

On Sept. 4, 2021, Moss Landing Energy Storage Facility's Phase I (300MW/1,200 MWh)  sprinkler system was triggered, at first, believed to be because of battery modules overheating. While there was no injury or community impact from the incident, Vistra shut down the facility and investigated the root cause of the incident in partnership with its engineering contractor, Fluence, and battery manufacturer, LG Energy Solution. 

In January 2022, Vistra announced the findings of its investigation and the corrective actions needed. 

The investigation found that batteries were not the initial source of smoke or the cause of the incident, since at the time water was first released by the heat suppression system, all battery module temperatures were recorded as within established temperature limits.

According to Vistra: "In response to detection of very low levels of smoke in one area of the facility, the water-based heat suppression system armed and, because of failures of a small number of couplings on flexible hoses and pipes, improperly sprayed water on battery racks. The smoke is believed to have originated from a failed bearing in an air handling unit, which is separate from the battery system. The water damaged the batteries and caused some to overheat, thus creating more smoke which, in turn, resulted in the release of more water and caused damage to additional batteries. In total, roughly 7% of the facility's battery modules were damaged."

Phase II outage in February 2022

According to Vistra, on Feb. 13, 2022, the early detection safety system was activated in the 100MW/400 MWh Phase II building at the Moss Landing Energy Storage Facility.

The preliminary findings suggested that the water-based suppression system released water that contacted some batteries. Early evidence suggested that water hoses leaked and that some batteries shorted, similar to the incident that was reported in September 2021. While the suppression system contained the incident and no injury to personnel was reported, Vistra decided to pause Phase II activities. 

Activities at the Phase I facility, which was in the process of being brought online were also paused till Phase II incident assessment was complete so as to incorporate any learnings from the incident.  

Author : Shraddha Kakade
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