SLO County's first battery plant is up and running. How does fire safety work?

San Luis Obispo County's first battery energy storage facility now buzzes with electricity - capturing extra power that flowed across California's electrical grid.

The Caballero Energy Storage project can store up to 99.7 megawatts of electricity at a time, which is enough to power 100,000 homes for up to four hours per day, Alpha Omega Power chief technology officer Guillaume Dufay said.

The purpose of the facility is to store excess power and deliver it to PG&E customers during the day's peak energy demand - which is often around 5 p.m., he said.

"Batteries are doing an incredible job to stabilize the grid," Dufay said.

Owned by Alpha Omega Power, the controversial facility opened on April 1 - despite strong objections from the community. People were especially worried about a repeat of the Moss Landing fire in Monterey County, which forced the temporary evacuation of more than 1,000 residents due to air quality concerns.

But Dufay assured residents that Caballero's design incorporates more effective fire prevention measures than Moss Landing.

"Energy storage is done safely around the world every day," Energy Safety Response Group founder Nick Warner said. "Batteries are keeping the lights on inside and outside of California."

San Luis Obispo County Supervisor Jimmy Paulding toured the Caballero battery energy storage facility in Nipomo on June 5, 2025.

What does the facility look like?

Alpha Omega Power offered a tour of the facility to the media, County Supervisor Jimmy Paulding and Cal Fire on June 5, to display the 33 blocks of battery energy storage systems housed at Caballero.

The 6-acre battery plant sits on a 20-acre property at 650 Joshua St., nestled among agricultural land west of Highway 101.

Each block includes 3-foot-long lithium ion battery cells stacked in racks and stored in outdoor cabinets; a transformer; gas, smoke and heat detectors; a fire alarm panel; and a power distribution panel.

The facility was built next to a PG&E substation, which delivers the electricity to the grid.

The nearest containers are 800 feet away from Highway 101, while other containers are just more than 300 feet away from the nearest houses.

People standing on the property can see into the backyards of two homes and a nearby farm.

Fire safety at Caballero v.s. Moss Landing

Chief among objections to the plant have been concerns about safety in light of the recent Moss Landing fire.

The Moss Landing fire sparked and spread in the oldest of Vistra's three facilities on site, which started operating in December 2020. That facility holds 300 megawatts of lithium ion batteries stacked in racks in one large building.

Caballero, however, stores batteries in individual containers spaced apart rather than in one big building - so if a fire starts in one container, it would be nearly impossible to spread to another container, Warner said.

"You want a system where if a single cell fails, it's not going to spread rapidly to other cells," he said.

Vistra's Moss Landing facility stores batteries composed of nickel, magnesium and cobalt. Meanwhile, Caballero stores lithium iron phosphate batteries, which are more stable and less likely to catch fire, Warner said.

Fire safety and suppression standards set by the industry are updated every three years. Moss Landing was built according to earlier fire safety standards. Caballero, however, was built in compliance with the 2021 fire code, he said.

The Energy Safety Response Group will perform a site inspection each year at Caballero and upgrade the facility to meet evolving fire codes, too, he said.

The battery plant is equipped with two levels of monitoring. First, each container of batteries has fire alarms, smoke and gas detectors. Meanwhile, the batteries are remotely monitored 24 hours a day, seven days a week by Pearce Renewables, whose staff can shut down a battery immediately if they sense a problem with it.

Two people also work on site to perform daily, routine maintenance and monitor the batteries.

Finally, Caballero is about a third of the size of Moss Landing, so if a fire did ignite at the Nipomo facility, there would be far less material to burn, Warner said.

Due to its size, Moss Landing's fire risk is comparable to an oil refinery, while Caballero's is comparable to a parking lot, where each container of batteries is similar to a vehicle holding a tank of gas, he said.

The more gasoline a facility holds, the higher its fire risk - and the same goes for batteries, Warner said.

A bystander watches the smoke and flames from Castroville as a fire at the Vistra battery storage plant burns in Moss Landing on Friday, Jan. 17, 2025.

How to fight fires at a battery plant

Right now, fire departments are encouraged to allow battery fires to burn out, Warner said.

"If you have a fire deep inside a hay bale, you can spread all the water you want on that thing - that hay bale's going to burn until you get up there and pierce it and flow water through it," he said. "It's not necessarily practical or safe to go and pierce it, so you let it burn."

The same goes for a fire at a battery energy storage facility. If the blaze is located inside of a container, firefighters couldn't just spray water on the container to put the fire out. They'd have to open the container to located the fire - but it's safer to let it burn out, he said.

"There's not enough water in the Pacific Ocean to put that out," he said. "If you don't have direct access to the batteries, there's no benefit to it."

Alpha Omega Power hired the CSA Group to perform a fire test on the Caballero technology. The laboratory ignited a block of batteries to study the fire behavior and assess what gasses would be released by the blaze.

Alpha Omega Power declined to share what gasses would be released by the fire - but Dufay said a plume analysis showed that if one container of batteries burned, the smoke toxicity would reduce to safe levels 100 feet from the fire. Nearby homes are more than 300 feet away, while Highway 101 is 800 feet away, so nearby residents and commuters would not be harmed by such a fire, he said.

In October, Alpha Omega Power offered a full-site emergency response training to Cal Fire and other local fire departments.

Cal Fire and the San Luis Obispo County Office of Emergency Services have an emergency response plan that outlines how to respond to incidents at the battery plant, Cal Fire spokesperson Ryan Grebe said.

"These fires don't respond well to water," he said, so if a fire ignites in a battery storage container, firefighters won't apply water to it. Instead, they would allow the fire to burn out while preventing it from spreading to other containers or structures.

"We're confident that we can keep these fires contained," he said.

Cal Fire, the San Luis Obispo County Sheriff's Office and the San Luis Obispo County Office of Emergency Services have an evacuation plan in place for the community, and would evacuate nearby residents if needed during an emergency, Grebe said.

He assured neighbors that the facility was built according to the state Fire Marshal's code.

"This facility is running because they met the requirements," Grebe said.

A battery storage facility at the southern end of San Luis Obispo County is nearing completion. Following Moss Landing fire, some Nipomo residents are asking the county to put it on pause.

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