California’s Battery Storage Fire: Precursor Or Outlier?

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A fire broke out at the Moss Landing Power Plant, not too far from San Francisco, on January 16, 2025, prompting the evacuation of approximately 1,500 residents and the temporary closure of Highway 1. No one was harmed in the incident. Given the massive growth in grid storage battery systems, is this something everyone should be worried about, and is it likely to recur? No and no.

Firefighters allowed the blaze to burn out, citing the challenges of extinguishing lithium-ion battery fires. Authorities lifted evacuation orders the following day after air quality tests confirmed safe conditions. The first phase facility has 300 MW of capacity and about 40% of it was destroyed, roughly 120 MW. Phase 2 and 3 added another 450 MW. Given the value that batteries have been providing in flattening the duck curve in the state, this is going to have some grid impacts. However, the state has over 10,000 MW of battery capacity, so missing 1.2% of it isn’t going to be a big deal.

In the United States California is the storage leader, unsurprisingly, but there’s another 5,500 MW or so scattered around other states. Globally, there are about 400,000 MW of battery capacity on grids, so this represents 0.03% of the world’s current capacity. In other words, this isn’t a significant portion of California’s, the United States or the world’s battery capacity that’s out of service. To put US battery storage systems in context, the roughly 15,500 MW it has deployed is less than a single December auction in China, in which 76 bidders averaged US$66 per kWh for 16,000 MW of requested capacity.

Let’s do some rough statistical comparisons to some recent hydrogen for energy data out of South Korea. Testing on 147 hydrogen buses after one exploded at a refueling station in December found that 11%, one in nine, were leaking. Testing on hydrogen cars in the country found that 1,463 out of 9,482, 15.4%, were leaking. There have been three explosions and fires at the 203 hydrogen refueling stations in the country that I’m aware of, so 1.5% of them, killing two people and hospitalizing nine to date. Statistically, hydrogen vehicles and their refueling systems appear at least equally likely to see fires as gasoline vehicles, although the numbers of vehicles and stations are so small that the law of small numbers cognitive bias needs to be taken into account so we don’t over rely on the data. We have vastly more surety about the much lower rate of fires in electric vehicles than any rate of concerns about hydrogen vehicles because there are 40 million battery electric vehicles on roads globally.

You wouldn’t know it from many media commenters, fossil fuel propagandists and hydrogen fans of course. On LinkedIn, many people are battling the flames of disinformation. I’ll share the insights from various people here.

Phase 1 of the facility, commissioned in December 2020, is housed within a repurposed turbine building at the former Moss Landing Power Plant in California. The facility contains 4,500 battery racks arranged in sections, each equipped with dedicated cooling and fire suppression systems. At the time of construction it was one of the biggest battery storage facilities in the world. There were a couple of previous thermal incidents in 2021 and 2022 which were contained and attributed to a faulty sprinkler system.

As one of the earliest storage systems, the facility predates leading practices for battery systems. Authorities having jurisdiction are now mandating Large-Scale Fire Testing (LSFT) to ensure safety and compliance. Traditional evaluations, such as UL 9540A, assess thermal runaway and fire propagation at the cell, module, and system levels. However, these tests may not always result in actual fire conditions, leaving uncertainties about real-world hazards. To address this gap, LSFT procedures, like the CSA TS-800:24, have been developed to simulate and evaluate the effects of a fully involved fire in one BESS unit on adjacent units and external exposures.

Further, modern grid storage systems tend to be outdoors on concrete pads with containerized and air gapped battery units. Tesla was a western leader in containerized batteries with its Megapack, as Wärtsilä’s Vice President of Energy Storage & Optimization Andy Tang told me a few years ago when we recorded a CleanTech Talk, but it’s now the dominant model by far because they can be built in factories and delivered like any other container. The air gaps means that if thermal runaway happens in one container, it’s much less likely to spread to other containers. The 182.5 MW of Tesla Megapacks at the Moss Landing facility are deployed like that and were unaffected by the fire.

Next up is that as an older facility, the batteries were nickel manganese cobalt (NMC) lithium ion batteries. The dominant chemistry for modern grid storage batteries, and increasingly for electric vehicles, is lithium iron phosphate (LFP), which has a much lower likelihood of thermal runaway.

EPRI and TWAICE used their global data set of battery incidents, used by the industry for root cause analysis, to assess the change in statistical likelihood of battery energy storage systems over time, making it publicly available in May of 2024. The likelihood of failures has plummeted due to changing chemistries, air gapped open air containerized deployments and the new standards for battery and thermal management systems to global industry is using.

Note that these aren’t fires which destroyed battery systems, but all failures of all kinds in battery systems. The blue bars, by the way, aren’t GW, but incidents. Given the massive scale of the industry, a global database having one failure of any kind per GW of deployed capacity makes it clear that grid storage batteries are incredibly safe.

Rank	Fuel Type	Fires (per 100k Sales)	Total Fires
1	Hybrid	3,474.5	16,051
2	Gas	1,529.9	199,533
3	Electric	25.1	52

This is the data from the AutoinsuranceEZ study of vehicle fires for cars. They took data from the US National Transportation Safety Board (NTSB) and the US Bureau of Transportation Statistics (BTS) to determine the number of fires for different drive trains. Statistically, it’s clear that battery electric cars are vastly less likely to catch fire, although the characteristics of the fires are different. Specialized fire extinguishers designed for lithium-ion batteries, fire blankets to contain and isolate burning EVs, and advanced cooling agents are being deployed to improve firefighting effectiveness. Additionally, fire departments are undergoing specialized training to handle thermal runaway risks and the complexities of extinguishing EV fires, which often require prolonged cooling periods and different tactics compared to conventional vehicle fires.

Similar to the comparison between EVs and internal combustion cars, it’s worth asking what the comparison is between natural gas electrical generation turbines and battery grid storage. Interestingly, there is no global data set on turbine fires and failures, so researchers have to assemble their own. That said, a paper presented at the 6th European Conference on Industrial Engineering and Operations Management in Portugal in July of 2023 on reducing fires at turbine facilities is pertinent.

“There are several explosion incidents that have happened in gas power plants and resulted in several injuries and economic losses in the past. In 2010 a catastrophic explosion has taken place in North Carolina that killed 6 employees and more than 50 people were injured, when a cleaning process was initiated in the gas pipe using natural gas at high pressure it starts to ignite and it caused an explosion according to NBC Connecticut, 2020. Recently the number of gas turbine explosion incidentshas significantly decreased after the health and safety regulations. However multiple accidents have occurred. In 2019 a massive explosion happened in New Orleans in the US that destroyed a major electric power plant. It was caused by an operator error, and it resulted in injuring two employees with severe burns (David, 2021). Moreover, according to New Indian Xpress 2020, an explosion of a gas power plant in Karnataka was initiated by an undetected oil leakage that caused a fire and 15 workers have painful burn injuries. The last accident caused the fatality loss of one employee and two others were severely injured due to a leakage issue of one of the pumps that caused an enormous explosion in Mumbai 2022 (Mendonca 2022).”

These are just the big ones at these facilities. As there is no statistical data on prevalence of fires at gas turbines, it’s impossible to draw a clear conclusion, but when the entire focus of the site is moving a flammable and explosive gas into the site and burning it, my assumption is that it’s quite probably much more likely from an incident per GW perspective.

As a contrast, there are no recorded fatalities due to fires at operating grid battery storage system facilities that I have been able to find. This makes sense because battery systems are solid state. There are some moving parts in the HVAC components, but that’s it. They are lights out facilities with no staff on site except possible security guards, unlike gas generation facilities. A 565-MW gas-fired combined-cycle power plant might need around 27 full-time staff, and they are obviously more exposed to danger should an incident occur.

Once again, battery fires have unique characteristics and there are potential health concerns, hence the precautionary evacuation. Air quality monitoring at Moss Landing has so far detected no significant levels of toxic gases such as hydrogen fluoride or particulate matter.

Meanwhile, when used as directed, combustion of natural gas releases carbon dioxide, a greenhouse gas contributing to climate change, along with nitrogen oxides, which can form smog and acid rain. Incomplete combustion may also produce carbon monoxide and trace amounts of volatile organic compounds. Additionally, methane leaks during production and transport can significantly amplify greenhouse gas emissions.

Nitrogen oxides contribute to respiratory issues such as asthma and bronchitis by forming ground-level ozone and fine particulate matter. Exposure to these pollutants has been linked to cardiovascular diseases and increased hospital admissions, particularly among vulnerable populations. Natural gas plants can emit trace amounts of hazardous air pollutants, including benzene and formaldehyde, which have been associated with long-term health risks such as cancer.

Concerns about occasional battery fires, in other words, are vastly out of proportion to the harm caused by what they displace. The health concerns of officials and the temporarily displaced residents — they were back home after one day — are due to this being an unknown quantity, but the constant health impacts of the 1,060 MW, twin turbine, natural gas generation facility that’s also located at the Moss Landing facility. This aspect of the story is completely missing as everyone focuses on the unusual and short-lived battery fire. The natural gas portion of the plant is making local residents and their kids sick.

The 2022 capacity factor of the Moss Landing facility was about 58%, fairly typical for plants in the USA. However, the facility has decommissioned seven of its oil and gas burning generation units. That’s right, it was burning oil, which is a lot worse than even the still bad burning of natural gas for human health. A big part of the story of the battery systems in California is that they are displacing burning fossil fuels for electricity, so everyone’s air quality has gone up considerably, including that of the 1,500 residents evacuated around the time of the fire. The two remaining gas turbines at the facility are high-efficiency, low-emission combined cycle units. Additionally, the plant employs dry low nitrous oxide combustors to minimize emissions that cause smog.

All of this is to say that the Moss Landing fire is a man bites dog story. It’s unusual, so it gets lots of press. It’s also being amplified by delayers and deniers, both institutional and individual. It feeds the confirmation biases of those who think batteries are dangerous fire hazards and it suits the narratives of the fossil fuel industry and a quite remarkable percentage of right-wing media. Overall, the Moss Landing battery system is part of what’s making everyone in California breath easier and battery storage systems are safe grid components.