Big Batteries Are Booming. So Are Fears They'll Catch Fire

The world needs thousands of new grid battery installations to fight climate change. They rarely catch fire—but many people are skeptical of having one next door.
Moss Land Power Plant grid outside on a sunny day
A retired natural gas plant in Moss Landing, California, now houses banks of batteries and associated infrastructure to back up the electric grid.Photograph: Carlos Avila Gonzalez/The San Francisco Chronicle/Getty Images

People don’t take electricity for granted in Raquette Lake, New York, in the remote high peaks of the Adirondacks. In winter, when ice and wind often down the power line into the hamlet, the 100 or so year-round residents stay warm by cranking up diesel generators. Prep for the busy summer tourist season begins in February, when they gather on the lake to saw out 250-pound blocks of ice. The meltwater will cool beers at the taproom all season long. Steve Viscelli, a part-time resident of 16 years, chalks it up to a mix of century-old tradition and precaution. “Let’s talk about green energy,” he says. “That’s green energy.”

Earlier this year, National Grid, the local utility, presented the village with a new solution: a microgrid anchored by 12 trailer-sized containers filled with lithium-ion batteries. Raquette Lake experiences 12 times more outages than less remote customers, the utility says. The 20-megawatt battery bank would put an end to that. It would also contribute to New York’s goal of installing 6 gigawatts of energy storage by 2030, a crucial part of keeping the grid stable as the state rapidly retires fossil fuels.

Locals were skeptical. Viscelli worried about the battery's location, a few hundred feet from the lake and surrounded by state-protected forests. Aris Bird, one of the village’s only year-round emergency medical technicians, wondered what would happen if someone got hurt. She had read about lithium-ion battery fires in the news. Her husband Mark, born and raised in Raquette Lake, is chief of a tiny, all-volunteer fire department. The nearest hospital is 75 miles away.

Bird could see the need to contribute to the climate fight, but “we’re feeling that this is being thrown at us,” she says. The local benefit—about four hours of power during an outage—wasn’t enough to feel secure in a severe winter storm, she believed. Worried whispers gathered into a movement. A handful of residents gathered in the bar to make signs and rallied on TikTok. In late May, about 100 people, many in neon yellow T-shirts reading “No! No! No! Lithium Battery farm,” crowded into a town meeting that included utility officials, the project developers, and a fire safety expert from New York City. Shocked officials were repeatedly drowned out by chants and boos. “Why are you trying to ravage our community?” one resident demanded.

Scenes like that are growing more common around the US, where grid battery storage is poised to double this year to more than 18 gigawatts, according to the US Energy Information Agency. As the industry has grown, so have local concerns about where exactly the truck-sized, 40-ton battery containers are being placed. In California, proposals that once sailed through have been mired in opposition campaigns and lawsuits. In New York, public meetings meant to hear proposals have instead given rise to battery storage moratoriums or bans.

The immense need for grid batteries are clear: In addition to backstopping on-and-off wind and solar energy and preventing blackouts, they can directly replace dirty parts of the grid, such as natural-gas-fired “peaker plants” that fire up when demand exceeds supply. For neighbors, installing a battery can allow the removal of toxic fossil fuel infrastructure.

As with any development proposal, community opposition is complex and localized. Though easier to hide than wind turbines or solar panels, battery installations can mar a view, and construction can create noise or dust. But concerns about safety have become potent fuel for opposition efforts. Developers can point to data indicating that grid battery fires are rare, but neighbors will fixate on the unknowns. Just how rare is rare? “If there have been fires and explosions, then people will connect that to the infrastructure proposed in their community,” says Sanya Carley, codirector of the University of Pennsylvania’s Kleinman Center for Energy Policy, who has studied opposition to clean energy projects.

Most news headlines about deadly battery fires refer to scooter or ebike batteries, which can be made dangerous by low-quality components or improper storage. Larger grid batteries have a better track record. They are typically known to local officials, and composed of parts that are reputably sourced. An analysis by the California Public Utilities Commission estimated that 2 percent of grid storage facilities will experience “major safety-related” incidents, with the risk greatest during the first two years of operation. Most other incidents are addressed quickly.

But grid batteries do have their own risks, which some experts say should be better explained to would-be neighbors. Guillermo Rein, a professor of fire science at Imperial College London, says that the industry has done an excellent job making fires rare despite the inherent volatility of lithium-ion technology. But safety measures are still evolving, he adds, and there are significant gaps in our understanding of how to prevent and lessen the impact of the most catastrophic blazes. “We’re playing catch-up,” he says. “The risk is unknown, and it has to be measured.”

Sparks, arcs, and flames are a risk in any electrical system. When they occur in or around a battery, the outcome can be disastrous. When flames warm a battery cell, one of the repeating components of a larger battery, beyond a certain temperature, a chemical reaction begins that produces more heat, triggering the same process in neighboring cells. Thermal runaway can take off in just milliseconds, before smoke or heat can be detected by an alarm system. The fire spreads first within a cluster of surrounding cells that share electronics, known as a module, and then onto others, until a whole rack of batteries is ablaze.

The first layer of fire safety is preventing that initial spark from happening. Most fire testing involves ferreting out faults in individual battery cells—something the industry, which makes millions of those cells each year for all kinds of energy applications, does well, explains Rein. But as they are packed into larger groups for grid-scale systems, testing becomes more complex, and the pathways to ignition multiply: coolant leaks, shorting electronics, faulty installation. Not every pathway is reproducible in the lab, says Rein, who authored a 2020 review of battery safety standards, which he describes as “chaotic.”

In the absence of extensive tests on large grid batteries, the “foundation” of safety design in the grid battery industry is making tweaks in response to real-world incidents, Rein says. They include a system in Surprise, Arizona, that in 2019 caught fire and later exploded, after fire suppressants mixed with the burning batteries, turning the warehouse in which they were installed into a pressure cooker. Nine first responders were injured. Two years later, near Geelong, Australia, a fire broke out during testing at what was then the world’s largest battery installation, a collection of Tesla Megapacks, the EV maker’s grid storage product. High winds spread the flames from one Megapack to a neighboring device, and the blaze took four days to put out.

In both cases, the industry came away with lessons: Battery containers are increasingly designed to better avoid explosions by venting out flammable gases, and made more insulated to prevent flames spreading from one container to another. Controls are more accessible from the outside of the container. Firefighters are advised to limit use of suppressants, monitoring the situation while spraying down the surrounding area to contain the fire. Design principles favor fire containment. A single container may catch fire and be allowed to essentially burn itself out; the goal is to prevent catastrophic spread and protect first responders.

But strategies for how to halt growing fires—including systems to quench or corral blazes within the containers, vary between manufacturers. “I think there’s still a lot of engineering that is believed to be best-practice but is not completely proven,” says Steve Kerber, executive director of the Fire Safety Research Institute, an affiliate of the Underwriters Institute, or UL, a nonprofit that creates the most widely used fire safety standards. Battery systems installed by Vistra Energy in a former natural gas plant in Moss Landing, California, were shut down for months after incidents in 2021 and 2022 in which heat-suppression systems, intended to curb thermal runaway, were accidentally triggered, dousing batteries in water that caused arcing and short circuiting.

To some in the industry, the incidents were evidence that advanced suppression techniques are more trouble than they’re worth, introducing yet more potential faults. When Vistra began constructing a third installation in Moss Landing, which it switched on last month, it pursued the outdoor container model instead of putting the racks under a single roof. (Vistra says it has improved the suppression systems and that it chose the outdoor design to expedite construction.)

The containerized design doesn’t fix every problem. Last September, firefighters responded to a 2:30 am call triggered by infrared cameras at a separate battery facility at the Moss Landing site, a 183-megawatt array of Tesla Megapacks owned by the utility PG&E. By daybreak, surrounding communities were under a shelter-in-place warning that would last through the day as a container burned. Waiting out a fire can be unsettling for firefighters like Joel Mendoza, fire chief of the North County Fire Department, which serves Moss Landing. He preferred Vistra’s initial strategy, using advanced fire suppression and providing training to his department to go in and douse the flames. But by the containment standard, and according to Tesla’s safety guidance, the response to the September fire was considered a “safe failure.” No one was hurt, and the fire didn’t spread.

The watch-it-burn method can be unsettling to a grid battery’s neighbors. In Moss Landing, residents describe being unsure why they were being told by local officials to close windows and turn off ventilation systems as the Megapack burned. In a farming community where young people often work in the fields surrounding the plant, parents worried about whether word had reached their kids. What was in the air, exactly?

At the time, it wasn’t entirely clear. PG&E had not conducted “plume modeling” that would predict how gases from burning battery chemicals might travel. The gases produced vary between batteries, but of particular concern to Environmental Protection Agency officials dispatching responders to the fire, according to an incident report, was the possible presence of hydrogen fluoride, or HF, which can be deadly within minutes at even low concentrations.

The EPA team arrived after the smoke had largely dissipated and found no evidence of harmful gases but did not have the capacity to test for HF. (The agency has since added it.) Under one scenario presented in a plume analysis by Vistra for its own facilities at the site, concentrations of HF above California exposure limits could spread across an area roughly 1,300 feet in diameter, including a portion of the iconic coast road Highway 1, in wind conditions that occur 7 percent of the time. Paul Doherty, a PG&E spokesperson, says its analysis is in draft form and will be presented publicly soon.

Researchers who study battery safety acknowledge they must strike a difficult balance: critiquing a young industry’s blind spots while also keeping the past in perspective. Fredrik Larsson, a Swedish researcher who has studied HF emissions from batteries, points out that incidents involving batteries are dwarfed by those in the fossil fuel industry. Pipes transporting natural gas cause thousands of explosions in the US each year. “It’s ridiculous that we combust gasoline inside cars,” he says. “But we’ve figured out how to make it safe.”

Batteries could reach a similar level of social acceptance, with the right data. His group’s research is among the only public data on HF emissions, and other potential contaminants, including heavy metals and other fluoride compounds, are even less well-studied. He wants to see the battery industry share more about its chemistry and its internal safety data. That would lead to better strategies for managing fires, potentially avoiding shutting down a highway or a town. He believes it would also give localities considering batteries more assurances about safety.

Others, like Rein, the fire scientist, continue to be frustrated by the mantra that battery fires should be watched, not fought. The industry has done an excellent job of making fires infrequent, he says, principally by minimizing the faults within cells. But work on system-level suppression is far behind, Rein argues, raising the specter of infrequent but potentially catastrophic incidents. “It’s unacceptable that we know how to create a fire that we don’t know how to put out,” he says. He thinks the industry finds it difficult to talk about safety because it fears giving the impression that grid storage might be unsafe. “The amount of denial I’ve been exposed to over 15 years is astounding,” Rein says.

That may be changing, especially as the rapidly growing industry faces more questions about past incidents. “I think there’s been continuous improvement,” says Andy Tang, vice president of energy storage at Wärtsilä, a global power infrastructure provider. He points to changes in the container design and better training for first responders as well as a shift to iron-based cells that reach thermal runaway at higher temperatures than their nickel-rich predecessors. His company is keen to point out the ways in which its systems go beyond basic safety requirements, including extra rounds of system testing and sensors that track local weather conditions to avoid overheating. Other improvements, including lithium-free designs with lower fire risks, will be arriving on the grid in a few years.

In the meantime, hundreds more battery installations need to be built to meet renewable goals in the next few years alone. Work needs to happen quickly in places like New York, which has a goal of producing 70 percent of its electricity from renewables by 2030. It’s an ambitious target: Shortages of power lines and transformers constrain where batteries can be installed. Industrial sites like in Moss Landing, outside bustling areas yet already served by power lines and well-trained fire brigades, are ideal but hard to come by.

In Raquette Lake, National Grid and Rev Renewables, the developer, say the chosen site, purchased in 2019, meets state and local requirements, away from wetlands and properly distanced from other buildings. They claim that safety is paramount and promise to extensively detail emergency-response plans with local officials. Still, the project could face delays. After the unexpectedly combative meeting in May, town leaders proposed a one-year moratorium on battery permits, which passed last week.

Opponents were galvanized over the summer by fires at three new battery installations in New York state, including a small town called Lyme, near the Canadian border. That fire burned and produced smoke for four days, leaving first responders exhausted and residents wondering what was in the air and concerned about the potential for contaminated runoff.

Bird, the Raquette Lake resident, says she welcomes the moratorium as an opportunity for the area to assess its emergency plan and for the technology to continue to evolve. She’s skeptical that her opinion will change. “We’re going to keep being as noisy about this as we can be,” she says.