Quick Take
Residents who live in the area outside Watsonville where a battery storage plant is proposed are arguing against the facility on safety grounds. The company proposing it, however, insists that new technology is safer and more reliable.
On a sunny day in February at Pinto Lake City Park, more than 100 Watsonville residents came out to oppose a battery storage plant proposed nearby. A top concern was that a toxic fire at the plant could destroy homes and pollute the area.
There’s a reason for their worry.
About a year ago, 10 miles away, the world’s biggest battery fire broke out at Moss Landing and burned for several days, releasing toxic fumes and causing the evacuation of more than 1,000 people.
Researchers are still calculating the toll on the environment and public health. Speakers at the Feb. 28 event in Watsonville, the latest in a series of meetings about the proposed facility, talked about the dangers of having another battery plant nearby.
Phoenix Artemisia, lead organizer of the event, and who owns a home within a half mile of the proposed battery farm, vividly remembers the Moss Landing fire.
“I saw it burning. I had to shut down my business,” she said. “I saw the black smoke.”
The company behind the new project, however, says advancements in battery technology and stricter safety standards significantly lessen the chance of an event similar to the Moss Landing fire.
The county had wanted to decide the fate of the project this year, but that is now less likely. In January, the Santa Cruz County Board of Supervisors approved an environmental impact report and the framework of an ordinance on battery-energy storage systems.
The environmental impact report isn’t yet underway, and there could be revisions to the ordinance based on the report’s findings and public comments. In addition, New Leaf Energy, the project’s developer, could bypass the county and seek approval from the state to meet the 2030 operation date it set with California’s main grid operator, Lookout previously reported.
“We wanted to wrap up this process by the end of the year, but given that we have not been able to start the environmental review yet, I cannot guarantee that we will be able to meet the original timeline,” said Jason Hoppin, the county’s public information officer.
BATTERY STORAGE IN SANTA CRUZ COUNTY: Read more Lookout news and Community Voices opinion coverage here
The battery-energy storage systems project, known as BESS, would occupy about 14 acres of land, or nearly 11 football fields, at 90 Minto Rd., which is across from the Pacific Gas & Electric Green Valley substation, near a residential area. Proponents say the location is ideal because of nearby transmission lines and the substation’s recent upgrade in 2019. The $200 million plant, first proposed in January 2025, is slated to go online in 2030 per an agreement with California’s main grid operator.
The site will have around 8,000 batteries in 200 containers that store electricity when it is plentiful and cheaper during the day thanks to California’s abundance of solar and wind power. When there is higher demand, typically at night, it will sell the energy at a profit. The batteries can store up to 200 megawatts of electricity, or enough to power around 200,000 homes for four hours.
Energy storage via batteries is key to California’s goal of meeting 90% of its electricity needs with renewable and zero-carbon sources by 2035. At certain times of the day, the state generates too much solar and wind power, some of which could be stored at the site and used later.
California often has to curtail, or temporarily cut, wind and solar power output because generation exceeds demand. The state curtailed nearly 3.8 million megawatt hours of wind and solar in 2025, an increase of about 10% from 2024, according to the California Independent System Operator, or CAISO, the state’s main grid operator. That’s enough electricity to power about 350,000 homes for one year.
MOSS LANDING FIRE: Read more Lookout news and Community Voices opinion coverage here
Despite the environmental and energy case, communities across California are hesitant to have large-scale battery storage near them after the high-profile fire at Moss Landing.
New Leaf Energy, the developer of the project, called Seahawk Energy Storage, has designed the site with state-of-the-art systems to prevent and respond to fires, said Max Christian, New Leaf Energy’s senior project developer for energy storage.
“Our design already met many of the additional safety requirements that California put on in response to Moss Landing,” he said. “We were already designing and building to the state of the art.”
How do battery fires start?
Fires at utility-scale BESS plants are rare and haven’t meaningfully increased after a dramatic buildout of the facilities, according to the Electric Power Research Institute, a nonprofit group tracking BESS failures. Even so, there have been at least 31 fires or explosions at BESS plants in the U.S. since 2012.
Failures that lead to a thermal hazard can happen for many reasons. Between 2018 and 2023, issues with integration, assembly and construction were the top cause in 36% of cases, followed by operation problems at 29%, according to EPRI.
New Leaf Energy, which already has an agreement with the landowner, plans to sell the development to, or partner with, a power company that will build and run the site, Christian said. Construction would take about a year and a half.
Typically, the operator would be selected after the developer receives approvals from the county or state. But Christian said that may happen earlier because it’s taking a long time for Santa Cruz County to finalize its BESS ordinance, which is expected to be among the strictest of its kind.
In compliance with the county’s draft ordinance, the company’s double-walled-steel battery containers would be more than 1,000 feet from any schools and hospitals and more than 300 feet from any buildings including homes, Christian said.
Whatever company ends up running the plant will need to be vigilant of thermal runaway. For lithium-ion batteries, thermal runaway is when too much heat is generated and isn’t dissipated adequately, resulting in an uncontrolled chain reaction.
Various problems can lead to thermal runaway, including a battery overcharging or rapidly discharging, manufacturing defects, extreme heat from weather and physical damage, such as impacts or punctures. If the separator, a key component in lithium-ion batteries, degrades or is damaged, the battery short-circuits and can trigger thermal runaway.
Neighboring batteries can then overheat and enter thermal runaway. And once batteries generate too much heat, the lithium turns into flammable gas.
“It will look like a blowtorch,” said Brian O’Connor, senior fire protection engineer at the National Fire Protection Association, a nonprofit group that studies fire prevention.
“When it does this in a really big pack, surrounded by other batteries which are other fuel, it can cascade,” he said. “It is really difficult for first responders to get to the seat of a fire, basically put water on the actual fire itself, because it’s protected,” referring to enclosures around the batteries.
In 2019, the NFPA released its first standard for installing battery-energy storage systems, known as NFPA 855, which is updated every three years.
All California BESS projects have to follow NFPA 855, which requires prevention methods including sprinklers, a minimum of 3 feet between battery units, vents for expelling flammable gas and a battery management system to monitor temperatures, current and voltage to shut off batteries if there are unusual readings.
“I’d love to say, do X, Y and Z for every energy storage system installation and you’ll be 100% perfectly fine,” O’Connor said. “But that’s not always the case, there’s so many variables.”
O’Connor said the failure rate for lithium-ion batteries is low, but acknowledged that fires inevitably happen.
“We don’t ever want to say that nothing can ever catch on fire when we know there’s fuel, oxygen and heat,” O’Connor said.
Fire prevention standards for batteries are also “constantly evolving,” said LaTanya Schwalb, a member of the NFPA’s 855 technical committee and principal engineer, energy and industrial automation at UL Solutions, which provides safety certifications and lab testing for battery energy storage systems.
For instance, she said NFPA 855’s 2026 edition calls for a large-scale fire test, which is when the vented gases from failing cells inside a battery container are intentionally lit to see how a fire would spread inside and beyond.
“There’s a lot of movement, and codes and standards are working really hard to keep up,” she said.
What fire prevention systems would be at Seahawk Energy Storage?
If high temperatures are detected during 24/7 monitoring, the system would be shut off remotely, Christian said, and each battery would also have a tray below circulating coolant to prevent overheating if a remote shut-off failed. If the shut-off and coolant fail, a fire suppression system will release an aerosol to cut off oxygen supply. Then, it will put out a fine powder mist to stop ignitions.
The Watsonville plant is also designed to use lithium-iron phosphate batteries, a version of lithium-ion technology, instead of the lithium-ion with nickel manganese cobalt chemistry used in Moss Landing and commonly found in electronics and electric cars. Lithium-iron phosphate batteries are less prone to fire, Christian said.
A rack of 16 lithium-ion phosphate battery modules have a lower overall fire hazard than lithium-ion nickel manganese cobalt batteries, according to fire tests by property insurer FM Global and the NFPA. For instance, a single sprinkler was enough to contain the fire to the ignited rack and the fire didn’t significantly affect modules in the adjacent rack.
“There’s a lithium battery here, but the chemistry is far more stable,” he said.
Still, there have been at least 18 thermal hazard incidents globally, including two explosions, involving lithium-iron phosphate batteries at utility-scale BESS sites between 2018 and 2025, according to EPRI.
And in nearly half of 127 thermal incidents EPRI documented with lithium batteries, the group was unable to determine the sub-chemistry that would show if they were lithium-iron phosphate, said Lakshmi Srinivasan, senior principal team lead, energy storage at EPRI.
Given the limited data on chemistry, significant evolution in BESS design and deployment trends in sub-chemistries, Srinivasan said “it is not possible to draw a conclusion on chemistry as a factor influencing likelihood of failure.”
“Cell-level chemistry is only one factor in the safety design,” she said.
A 2024 study from England’s University of Sheffield also found that lithium-ion phosphate batteries are much less likely to enter thermal runaway, but they are “significantly more toxic” when they burn compared to lithium-ion nickel, manganese and cobalt batteries, Lookout previously reported.
Could the batteries use safer technology?
Purchases of the batteries would likely happen in 2028, meaning the plant could use newer technologies then, Christian said. When batteries are replaced in typically five to seven years, safer batteries could be available.
Diane Dutton-Jones, who is opposed to the project and lives nearby, said New Leaf Energy should use nonflammable sodium batteries, pointing to Massachusetts-based startup Alsym that aims to start commercial-scale manufacturing in 2027.
“Santa Cruz County should lead California in choosing to protect our community with nonflammable batteries while achieving our energy goals,” Dutton-Jones said.
Christian said he is aware of activists calling for sodium batteries, but he said reliable supply chains haven’t yet been developed.
“The front-runner was somebody who literally went bankrupt [during permitting],” he said, referring to Natron Energy shuttering in late 2025. “If in two years from now, there is something better, even safer, then that’s what we would do.”
What is the political response to the Seahawk Energy Storage project?
Safety concerns about the battery energy project could sway some voters in the fast-approaching June 2 primary for the county’s District 4 supervisor, who represents the area where the project would be built. A Change.org petition to halt battery storage projects in the county has more than 5,000 signatures.
Activists are hosting their next public meeting in mid-April, which politicians and candidates are invited to attend. Updates are regularly shared on the STOP LITHIUM BESS IN SANTA CRUZ COUNTY Facebook page.
District 4 Supervisor Felipe Hernandez is “not in a position to express support for or opposition to the project” because it hasn’t yet come before the county board of supervisors for “formal consideration,” Hernandez’s chief of staff, Ramon Gomez, said in an emailed statement.
“Doing so could necessitate recusal from the decision-making process, which would result in District 4 residents lacking representation on this issue,” he said.
Still, Gomez said concerns about lithium-ion battery safety, fire risk and the potential for toxic exposure would be considered in any future review.
The other two candidates in the race, Elias Gonzales and Tony Nuñez, are both against the project.
“I have spoken with residents across District 4, and I have not encountered support for this project,” Gonzales said in an emailed statement. “What I hear consistently is anger, frustration, and a clear message that our community deserves to be part of decisions that impact our health and safety.”
“There are well-documented safety concerns associated with lithium-ion battery storage, particularly when projects are located near neighborhoods and sensitive natural resources,” Nuñez said in an emailed statement. “I’ve met with residents in the area and environmental experts, and their concerns about this project are valid.”
Have something to say? Lookout welcomes letters to the editor, within our policies, from readers. Guidelines here.
