A fire at a battery storage facility in Otay Mesa is out — but the stubborn nature of the blaze has sparked opposition from some residents about the relative safety of at least three other battery projects that developers want to build in other parts of San Diego County.
Renewable energy supporters say battery facilities are essential to meet California’s goals to develop a carbon-free electric grid. State policymakers and battery companies say the risk of future fires will decrease over time, counting on technological improvements in battery chemistries and better designs at the facilities housing the batteries.
“My hope is that these projects continue to move forward, concerns are addressed and people really understand that we need these types of projects here in our region,” said Jason Anderson, CEO of CleanTech San Diego, a business association that promotes renewable energy growth.
What happened in Otay Mesa
According to Cal Fire, the fire at the Gateway Energy Storage facility in an industrial park in Otay Mesa broke out at 3:45 p.m. on May 15. The blaze was centered in one of the seven buildings at the 250-megawatt site that stores lithium-ion batteries to help bolster the state’s electric grid.
Evacuation orders and warnings were put into effect in the immediate vicinity, which includes several businesses.
By early the next evening, officials thought the fire had been extinguished but a few batteries reignited on successive nights, keeping about 40 firefighters and a San Diego County hazardous materials crew on the scene.
Though relatively rare, lithium-ion batteries have experienced instances of what’s called “thermal runaway,” in which excessive heat leads to a chemical reaction that spreads to other batteries.
It took until May 31 at 10 a.m. for the last unit to clear the scene — nearly 17 days after the fire broke out.
Cal Fire officials estimated that crews sprayed 8 million gallons of water onto the site. The county’s hazmat team tested water runoff and no toxic levels were reported. The crew also monitored smoke around the area and no dangerous levels were reported.
Opened in 2020, the Gateway facility is owned and operated by LS Power and its subsidiary, Rev Renewables.
In an email to the Union-Tribune, the company said it’s still trying to figure out the precise cause of the fire and assessing the damage to the 95,000 square-foot facility that stores about 6,700 racks of batteries.
Cleanup inside the building at the fire’s epicenter is expected to take several months, company officials said, and preliminary work has begun to get the facility’s other six buildings up and running again.
“While this event is unfortunate, we aim to do right by all our stakeholders,” the company said. “Safety is and always will be our No. 1 priority.”
The fire is the second such incident in recent months in San Diego County.
In September, a battery fire broke out at the Valley Center Energy Storage Facility, operated by renewable energy company Terra-Gen.
While fire officials said the fire was put out in about 45 minutes and extinguished by the site’s internal fire prevention system, businesses and the small number of homes within a quarter-mile of the industrial park where the facility is located were evacuated and shelter-in-place orders were in effect within a half-mile of the site out of an abundance of caution.
The 139-megawatt, 560 megawatt-hour Valley Center facility was back in operations the next day.
Why battery fires are hard to put out
Lithium-ion batteries that power electronic devices such as smartphones and laptops can pose a fire risk if they overheat, get damaged or are defective.
Battery flaws in electric vehicles have prompted car makers to issue recalls. In 2023, a massive fire broke out at a warehouse in France that stored thousands of automotive lithium-ion batteries. It took roughly 100 firefighters to douse the blaze. Many of the same materials in electric vehicles are also used at battery energy storage sites.
What makes battery fires so difficult to put out?
A lot of it has to do with the batteries themselves, said Robert Rezende, battalion chief and the Alternative Energy Emergency Response coordinator for the San Diego Fire-Rescue Department, shortly after the Otay Mesa fire broke out.
Rezende listed different classes of fires, which include commonly combustible materials (like plastic), flammable liquids, electrical fires and metal fires.
“A lithium-ion battery fire involves all four of (those classes) — all four of them together,” he said.
When batteries go into thermal runaway, the situation gets even more complicated because while pouring water on the batteries may cool the temperature in the immediate area, it often doesn’t resolve matters.
“Historically speaking, we usually tend to see a much longer period of time where this cascading damage just keeps going, almost like the domino effect,” Rezende said. “The batteries are just going to do what they’re gonna do until they decide to stop doing it. That’s the simplest way to describe it.”
An explosion in 2019 at an energy storage facility in Surprise, Ariz., injured nine first responders.
In September 2022, a Tesla Megapack caught fire at a battery storage facility operated by Pacific Gas & Electric in the Northern California town of Moss Landing. No injuries were reported, but California Highway Patrol closed a section of Highway 1 and redirected traffic away from the site for hours.
Proposed battery projects
No fewer than three battery storage projects are currently being debated in San Diego County.
The largest is the Seguro Energy Storage Project that global Fortune 500 company AES wants to build on a 22.5-acre plot in Eden Valley, between San Marcos and Escondido. If approved, the site would generate 320 megawatts and 1,280 megawatt-hours of electricity that would flow to California’s electric grid — enough to power about 240,000 homes for four hours.
But the project has run into opposition from neighbors who say the location southwest of the junction of Route 78 and Interstate 15 off County Club Drive is too close to homes, the Palomar Medical Center and businesses in the area, should a fire break out.
The Gateway fire has hardened some opinions.
“After what happened at Otay Mesa, I don’t think there’s going to be any politician in the county that’s going to be pushing a large-scale energy storage project that’s close to our largest public health care district that services 1.7 million patients,” said Jeff Griffith, chair of the board of directors at Palomar Health and a former captain at Cal Fire.
AES officials have made safety enhancements to Seguro’s original design, including extending buffer zones, improving access and exit routes and training local fire and EMS crews on all the equipment and emergency response protocols. The company also plans to place the project’s transmission line underground to further reduce the risk of fire.
AES has not decided what type of battery chemistry will be used at Seguro, but company officials said the batteries will be housed in steel containers — rather than in buildings, as they were at Gateway — and will be equipped with fire insulation and several redundant layers of hazard controls.
“We completely understand there’s always going to be some discomfort with converting a previously disturbed yet relatively open lot into any kind of industrial use,” said Corrine Lytle Bonine, director of permitting for AES. “But we are very confident this is going to be the safest battery storage project in the world, at the time we build it.”
A draft version of an environmental impact report is expected soon. Eventually, the decision to accept or reject the Seguro project will go before a majority vote by the seven members of the San Diego County Planning Commission.
Another battery storage project of similar size is being debated in Poway.
Arizona-based renewable energy company Arevon (pronounced “ah-REE-von”) wants to spend about $500 million on a 300-megawatt, 1,200 megawatt-hour facility called Nighthawk that is expected to generate enough electricity to power about 300,000 homes for four hours.
The project would be located on a nine-acre parcel at the corner of Paine Street and Kirkham Way and connect to SDG&E’s nearby Sycamore Substation. Company officials say Nighthawk is more than a half-mile from the nearest residences and the project would generate at least $10 million in sales and property tax revenue.
Arevon has six battery storage facilities up and running and the company touts none of their projects have reported any fires.
“Our record has been stellar with our operations and we’re certainly proud of that record,” said Arevon CEO Kevin Smith, “and we expect to continue that with the facilities we’re building.”
The company uses Tesla Megapack batteries. But unlike the Tesla batteries that caught fire at Moss Landing, Arevon officials say the megapacks in Poway would use lithium-iron phosphate chemistry that “are significantly more stable” than the batteries used at the Gateway facility in Otay Mesa.
To enhance security, the company has pledged to construct a 12-foot concrete wall and added buffer zones up to 200 feet around the facility’s perimeter. Arevon would also install a city-owned fire loop with hydrants inside Nighthawk, as well as infrared detection cameras that would trigger automatic notifications to the Poway Fire Department and emergency responders, should anything go wrong.
But some Poway residents don’t want it.
An online petition has gathered more than 700 signatures. “We’re not against clean energy and change is good but installing this new-technology battery storage facility in our backyard is not,” the petition said.
The fate of the project is up to Poway’s city government.
Currently, an addendum to an environmental impart report is being prepared in conjunction with the city of San Diego (because Nighthawk’s power lines would extend into San Diego). Arevon will submit a project application that will ultimately go before the Poway City Council for a vote — perhaps within a few months.
Out in La Mesa, a much smaller battery project is up for discussion.
EnerSmart, a local renewable energy company based in Solana Beach, wants to construct what’s called the Murray Project on a 22,000-square-foot property at 8135 El Paso St. The facility would generate 18 megawatts, or 36 megawatt-hours of electricity.
In an email to the Union-Tribune, EnerSmart CEO James Beach said the batteries will be housed in 21 containers that keep fires from spreading and the cells can extinguish themselves “in a matter of hours.”
EnerSmart uses lithium-iron phosphate battery chemistries in its projects “that are much safer to operate and at lower temperatures” than conventional lithium-ion, Beach said.
But La Mesa Vice Mayor Laura Lothian took her opposition to battery storage projects to social media during the Otay Mesa fire.
“This battery storage facility here, this is going to be proposed in La Mesa in a high-density neighborhood that has stores, coffee shops and people’s homes,” Lothian said on Instagram while standing in front of the Gateway facility on May 22. “This has no business being in La Mesa.”
Like other California utilities, SDG&E has been a big player in the battery storage sector. The company has 19 battery energy storage sites in operation in San Diego and Imperial counties, with seven more under construction or in development.
Why battery storage is critical for California
Energy storage has taken on a higher profile as more renewable sources of power have come onto California’s electric grid.
Solar production is abundant during the day but practically vanishes after sunset or when smoke and clouds obscure the skies. And when the wind doesn’t blow, production from wind farms peters out. Energy storage — particularly from batteries — is seen as a key way to fill in the gaps.
Storage systems take solar power generated during the day and discharge the electricity later, especially from 4 to 9 p.m. when California’s grid is under the most stress. Batteries can help reduce the risk of rotating power outages and replace natural gas “peaker plants” used during those critical hours when customers crank up their air conditioners.
Boosting energy storage is crucial for California to reach its target of deriving 100 percent of electricity from carbon-free sources by 2045, if not sooner.
Five years ago, the state counted a mere 770 megawatts of battery storage available to the California Independent System Operator, which manages the grid for 80 percent of the state and a small part of Nevada. By the end of this year, 10,379 megawatts are expected to be online and the state aims to grow that number to 52,000 megawatts by 2045.
Siva Gunda, vice chair of the California Energy Commission, said policymakers have faith that advancements in battery chemistries will reduce the risk of thermal runaway and battery fires. “As we move forward, technology is really getting better,” he said. But at the same time, “we take (safety concerns) very, very seriously.”
