Battery storage in the converted gas turbine halls of the Moss Landing Energy Storage Facility. The recently completed 100 MW Phase II has stayed online. Image: Vistra Energy.
The preliminary assessment of a battery module overheating incident that occurred over the weekend in the world's largest project for battery energy storage systems (BESS), Moss Landing Energy Storage Facility, has begun.
Some of the lithium-ion battery modules overheated on Saturday, September 4, in the 300MW / 1,200MWh Phase I of the facility in Monterey County, California. Safety functions kicked in and realized that temperatures in a limited number of modules had exceeded operating standards. Targeted sprinkler systems aimed at the affected modules were triggered.
Project owner and operator, power generation and retail company Vistra Energy, said that nonetheless, local Monterey County firefighters were visiting the site “in accordance with Vistra's emergency response planning and with the greatest of caution,” according to the request. No casualties were reported and the company said no harm was done to the community as a result of the contained situation.
Just a few weeks ago, the completion of phase 2 of the Moss Landing energy storage facility was celebrated. Phase 2 added another 100MW / 400MWh BESS power and capacity to the site. The battery storage was installed in a former gas power plant with lithium-ion battery racks in former turbine halls. Vistra said the site has the space and site infrastructure to reach Moss Landing's final size and capacity to a total of 1,500 MW / 6,000 MWh.
Phase I was taken out of service immediately after the incident on Saturday and remains so, while Phase II, which is housed in a separate building, is still in operation.
The project partners Vistra, the battery rack supplier LG Energy Solution and the energy storage technology supplier Fluence, who performed engineering and construction tasks, carried out an inspection of the phase I building on September 7th. External experts were also brought in for this.
They gathered information to investigate the problem and its cause. Vistra said they are assisted by the Monterey County's North County Fire Protection District, the crew who were in attendance Saturday night.
After the damage assessment – which according to Vistra could take “some time” – a plan for repairing and restarting the system is developed. The company said it is taking all necessary safety precautions to ensure that the risks are minimized in the process.
With California pledging to decarbonize its electricity system by 2045 while still having energy deficits to meet peak demand in the summer months, state utilities, including PG&E, the main consumer of the Moss Landing facility, are closing large amounts of four hours of permanent battery storage and solar plus Storage.
Incidents remain rare but require special attention
Battery storage fires are relatively rare given the rapid global adoption of the technology, but industry is certainly keen to limit the risks associated with working with energy dense devices of this type. In an article for this website last year, a team of experts from energy storage and power device safety firm Energy Safety Response Group (ESRG) wrote about the importance of developing emergency response plans related to fire safety for lithium BESS projects.
This included the crucial importance of communicating with first responders, including the fire brigade, what is included in the systems, what the risks are and how to deal with them. Nick Warner, founder of ESRG, said in an interview that given the rapid growth of the battery storage industry and the anticipated provision of hundreds of gigawatts over the next five to ten years, it is imperative that incidents are prevented with best practices as well as technological developments.
LG Energy Solution recently recalled some of its residential battery storage systems due to overheating issues, while the company also supplied modules for the Arizona BESS, which caught fire in 2019 and caused an explosion that injured several firefighters. A DNV GL report on the incident stated that an internal cell failure in a 0.24 kWh NMC battery cell triggered thermal runaway that spilled over to surrounding equipment.
There was a high profile incident when a Tesla Megapack BESS unit caught fire in another of the world's largest battery storage systems, the Victorian Big Battery in Australia, in late July. The incident occurred while initial tests were being carried out on the 300MW / 450MWh project, which were scheduled to go into operation and commercial operation a few days later.