SAN DIEGO COUNTY, Calif. — Battery Energy Storage Systems (BESS) help support the power grid, but operating such facilities carries inherent risks of fire and toxic fumes.
As San Diego County decides how to regulate them, CBS 8 is learning more about the evolving technology and potential hazards of building them close to residential neighborhoods.
Three fires have broken out at battery plants over the past year, including one at the Terra-Gen facility in Valley Center, another at the Gateway Energy plant in Otay Mesa and the most recent in Escondido at the SDG&E BESS facility, where one of 24 battery containers caught fire.
Thermal runaway is a chemical reaction that happens when lithium-ion batteries overheat.
“Once it starts, there’s no way to stop it,” said San Diego Fire-Rescue Battalion Chief Robert Rezende. “Really, the fire that’s happening inside the battery has to run its course, so that chemical reaction really can’t be stopped.”
BESS fires can take days or even weeks to burn out. The one in Escondido lasted 13 hours, and the one in Otay Mesa lasted 17 days.
“The big concern for us is what’s toxic and how far is it going?” said Chief Rezende, who serves as Alternative Energy Emergency Response Coordinator throughout San Diego County.
He told CBS 8 that their hazardous response crews use atmospheric monitoring to check for toxic gases like hydrogen fluoride and hydrogen cyanide, which can be deadly.
“You’re going to smell that carbon, that soot material that’s being burned off with the fire. The question is, ‘Is the toxicity traveling with it?’" said Chief Rezende. "And that’s what we do. We go into the smoke. We take readings from the smoke.”
The instrument readings determine how far away people should evacuate from a BESS fire. Weather factors, such as temperature, wind, and humidity, are also considered when determining how or where a plume will spread.
“From our experience, the soot in the air floats way further than any of the toxic gases that are coming from the battery,” said Chief Rezende. “So realistically, you’re going to smell smoke much further than the toxic particles from the gases can travel.”
Chief Rezende further clarified to CBS 8 that the smoke from a battery fire is also toxic and harmful to humans and animals in close proximity.
BESS facilities in residential neighborhoods
People living in Eden Valley near Escondido are on edge as the developer AES plans to build a 320-megawatt energy storage plant in their neighborhood. It would be the third largest BESS facility in California, potentially powering 240,000 homes for four hours.
“It’s ridiculous to put this toxic bomb in this valley," said resident Drew McSparron. "If you look around the valley, it’s a small valley. It’s surrounded by homes.”
The 22-acre site at 925 Country Club Drive would be 1,600 feet upwind from Palomar Hospital.
“The risks of battery projects are very real,” said Joe Rowley, a former Sempra Gas & Power executive who lives in Escondido and works with the Stop Seguro group pushing back against the project.
“The Seguro project is the poster child for where not to put a large-scale battery project,” said Rowley. “It’s too close to residences. It’s too close to a hospital. It’s too big."
Battery energy storage systems are typically located in industrial zones. AES chose the site in Eden Valley partly because of its proximity to SDG&E’s Escondido substation, where it would tie into the power grid.
“I think it’s something that instills fear in all of the residents here," said Ashley Robertson Bedard, who helped gather more than 4,700 signatures on a petition opposing the project. "Our biggest concern is the fact that these lithium-ion batteries light on fire, and once they light on fire, they’re emitting toxic gases.”
Local governments seek to regulate BESS facilities
On Oct. 9, 2024, the City of Escondido passed a temporary moratorium on permits for new Battery Energy Storage Systems to allow more time for city staff to study safety measures and potential restrictions. The moratorium was initially set for 45 days, but it can be extended up to 10 months and 15 days if needed.
The proposed Seguro project is outside Escondido city limits in an unincorporated area of San Diego County, so the Board of Supervisors will decide.
In September, San Diego County decided against a moratorium on new BESS facilities and instead hired a consultant, Jensen Hughes, to make recommendations on guidelines.
On Nov. 13, the engineering firm released a 95-page report on safety standards, but it did not include any recommendations for a residential buffer distance.
"The report is disappointing," said Rowley. "It does not define the distances that these projects need to be separated from residences."
Part of Rowley's disappointment stems from a generalized plume modeling study not being conducted to safeguard residential neighborhoods.
According to meeting notes from the County Board of Supervisors meeting on September 11, 2024, the board's action was to "have the County Fire Chief analyze appropriate residential buffer distances based on plume modeling and develop a plan for Battery Energy Storage Systems (BESS) facilities."
Without a proper plume modeling study that accounts for worst-case scenarios, many residents fear future regulations by county officials will not go far enough to protect neighborhoods.
BESS facilities support the power grid
To see the technology firsthand, CBS 8 toured one of SDG&E’s battery energy storage facilities in Kearny Mesa. The facility was built in 2021.
“The glycol system really feeds each of these units to make sure they stay at a nice, ambient 72 degrees, which is what batteries really like,” said Fernando Valero, director of the Advanced Clean Technology Group at SDG&E.
Valero told CBS 8 that BESS plants are crucial for storing energy from renewables, like solar and wind, and making it available to customers during peak hours. Battery energy systems are also a key element in helping the state reach its goal of a 100-percent clean energy grid by 2045.
“Even though this is a 40 megawatt-hour facility, effectively, this is somewhere around 600 or 700 Teslas that are sucking up those excess renewables and then putting them back on the grid,” said Valero.
Valero said the extra storage capacity from the BESS systems has dramatically improved the electric grid's reliability, helping to avoid rolling brownouts. CBS 8 asked him about safety measures at the Kearny Mesa site.
“You’ll see up here you have smoke detectors, which detect any smoke, and temperature detectors, which detect any elevated temperatures within the cube. You also see a leak detector that would detect any leaks that would come from the glycol system,” said Valero as he showed CBS 8 inside one of the battery storage cubes.
"The battery management systems in here measure voltage, amperage, and temperature within these cells so that if anything is out of whack, that'll get sent to our controller in our operator room," said Valero. "If we were to have an event, these also have aerosol that would try to put out any smaller electrical fires."
As local cities and San Diego County attempt to catch up on zoning regulations, people near proposed sites like Seguro remain on edge.
“The technology is still evolving; the fire suppression and fire detection systems are still evolving," said Rowley. "Everything about this industry is new and changing rapidly.”
What's next?
The County Board of Supervisors will discuss the issue of BESS facilities again on Dec. 11, 2024. CBS 8 will monitor this story to bring you the latest developments.