A nasty, long-burning fire near San Diego, Calif., last month provides graphic evidence of a risk inherent in large lithium-ion battery energy storage systems. As battery storage becomes more common with the rise of intermittent energy generation from solar and wind power, fire protection likely will become a prominent public concern.
On May 15, a fire broke out at a 250-MW battery energy storage facility in East Otay Mesa, a San Diego suburb near the Mexican border. The fire burned through the roof of the building housing the lithium-ion batteries at LS Power’s Gateway project, prompting local fire officials to issue evacuation orders and road closures in the area surrounding the storage plant.
Authorities also issued a “shelter-in-place” order for a nearby state prison because of the possibility of toxic fumes from the fire.
It took some six days the contain the fire and it was still smoldering 11 days later, according to the California local news service Hoodline. The evacuation order was lifted but road closures remained in place. Hoodline reported, “During the height of the firefight, an estimated 50 firefighters and county and city hazardous materials teams were involved in the effort.”
New York-based LS Power began operating the Gateway project in August 2020. At the time, the company bragged that it was “the largest battery energy storage project in the world.” The company added, “Gateway Energy Storage, currently at 230 MW and on track to reach 250 MW by the end of the month, follows another LS Power battery project, Vista Energy Storage in Vista, California, which has been operating since 2018 and was previously the largest battery storage project in the United States at 40 MW.”
LS Power is a non-utility generation and transmission company founded in 1990, with over 13,000 MW of generating capacity and 780 miles of high-voltage transmission.
The tendency of lithium-ion batteries to catch fire, from cell phones to electric vehicles to stationary energy storage, is well-known. The National Fire Protecting Association lists five failure modes for battery storage:
- Thermal abuse. “Energy storage systems have a set range of temperatures in which they are designed to operate, which is usually provided by the manufacturer.”
- Electrical abuse. “Electrical abuse takes place when a battery is overcharged, charged too rapidly, or externally short-circuited.”
- Mechanical abuse. “Mechanical abuse occurs if the battery is physically compromised when the battery is crushed, dropped, penetrated, or otherwise distorted to failure by mechanical force.”
- Internal faults. “Internal faults can result from inadequate design, the use of low-quality materials, or deficiencies in the manufacturing process. It might be worth noting that the failure rate for lithium-ion cells is said to be on the order of one in a million.”
- Environmental impacts. “This can be the result of ambient temperature extremes, seismic activity, floods, ingress of debris or corrosive mists such as dust (deserts) or salt fog (marine locations), or rodent damage to wiring.”
The NFPA also lists three hazards from Li-ion fires:
- Thermal Runaway. “Thermal runaway is the uncontrollable self-heating of a battery cell. It begins when the heat generated within a battery exceeds the amount of heat that can be dissipated to its surroundings.”
- Off Gassing. “The gasses that are released from battery energy storage systems are highly flammable and toxic. The type of gas released depends on the battery chemistry involved but typically includes gases such as: carbon monoxide, carbon dioxide, hydrogen, methane, ethane, and other hydrocarbons. If the gas is able to reach it’s lower explosive limit before finding an ignition source then there is the potential for an explosion. An example of this occurred in Surprise, Arizona back in 2019.”
- Stranded Energy. “Stranded energy is the term used for when a battery has no safe way of discharging its stored energy. This commonly occurs after an ESS fire has been extinguished and the battery terminals have been damaged.”
The Electric Power Research Institute has long investigated battery storage safety issues, including publishing a 16-page “Battery Storage Fire Safety Roadmap” and a “BESS Failure Incident Database,” initiated in 2021. EPRI notes, “The global installed capacity of utility-scale BESS has dramatically increased over the last five years. While failure incidents continue to occur, the overall rate of incidents has sharply decreased, as lessons learned from early failures have been incorporated into the latest designs and best practices.”
–Kennedy Maize
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