Clean Energy Foes Will Try to Weaponize This “Three Mile Island Event”

A battery storage facility burns at Moss Landing Power Plant in Monterey County, California, on January 17, 2025. Tayfun Coskun/Anadolu/Getty

This story was originally published by Inside Climate News and is reproduced here as part of the Climate Desk collaboration.

Days before President Donald Trump returned to the Oval Office and took actions to stall the transition to clean energy, a disaster unfolded on the other side of the country that may have an outsize effect on the pace of the transition.

A fire broke out January 16 at the Moss Landing Energy Storage Facility in California, one of the largest battery energy storage systems in the world. The fire raged through the weekend, forcing local officials to evacuate nearby homes and close roads.

Battery storage is an essential part of the transition away from fossil fuels. It works in tandem with solar and wind power to provide electricity during periods when the renewable resources aren’t available. But lithium-ion batteries, the most common technology used in storage systems, are flammable. And if they catch fire, it can be difficult to extinguish.

This month’s fire is the latest and largest of several at the Moss Landing site in recent years, and I expect that it will become the main example opponents of carbon-free electricity use to try to stop battery development in other places. “This is really a Three Mile Island event for this industry,” said Monterey County Supervisor Glenn Church at a January 17 news conference.

He was referring to the 1979 incident at the Three Mile Island nuclear power plant in Pennsylvania. The partial meltdown led to panic across the region and helped to cement the idea that nuclear power was unsafe.

I’ve been to enough local public hearings on energy projects to know that I’m going to spend years hearing Church’s quote used to oppose any battery project, even ones that have little in common with Moss Landing in terms of design and technology.

My initial reaction is that Church is justified in being upset that the operator of the plant, Vistra Corp., has been unable to prevent this string of safety incidents. I don’t want to minimize the disruption, damage, and constituent fears to which he is responding. (Vistra, based in Texas, didn’t respond to a request for comment.)

The battery storage facility is on the site of a closed power plant, and it’s right next to a natural gas power plant that is still operating. The storage facility was built in three phases, the first two going online in 2021 with a combined capacity of 400 megawatts, and the third phase going online in 2023 with capacity of 350 megawatts. The batteries are built to run for up to four hours before needing to be recharged.

The problems at Moss Landing could be used to boost safety fears about battery storage in general, with grave consequences for the energy transition. Or officials could look specifically at what aspects of Moss Landing’s design contributed to its fire risk, and use those lessons to make existing and future projects safer.

To get a better sense of what can be done, I spoke with Matthew Paiss, a technical advisor for battery materials and systems at Pacific Northwest National Laboratory. He advises on safety issues, but it’s a second career for him: He spent most of his adult life as a firefighter. “I have a really strange background,” he said.

He knows the Moss Landing plant well, having seen it inside and out as part of his work at the lab. He lives in Santa Cruz, close enough to Moss Landing that he could see flickering light in the sky last week as the fire burned.

He began his description of the fire risk by explaining “thermal runaway,” a self-heating process in which a lithium-ion battery is damaged or misused and triggers a chemical reaction that releases highly flammable gases and lots of heat.

If there is a spark or other flame, the gases can serve as fuel for a fire that can spread from one module to entire racks of batteries. Sprinkler systems may be able to help in an early stage, but many of these fires are too powerful and burn too hot to be suppressed.

So how do system designers reduce the chances of thermal runaway?

A big factor is the system design. Many, if not most, battery storage systems being built today look like rows of shipping containers that sit outdoors. These “cabinets,” as they’re called, can help to reduce the chances of large fires because flames would need to burn through the container’s shell and then leap across an outdoor space and burn through the shell of a nearby container. That’s not easy and it rarely happens.

In contrast, the systems that have now caught fire multiple times at Moss Landing are indoor installations, set up inside the shell of a building left over from the natural gas plant that used to be on the site. The project is an unusually large example of repurposing an old building for energy storage.

“There are some real challenges in protecting batteries in indoor installations,” Paiss said.

He said that writers of safety codes have been reluctant to prohibit indoor installations, but he thinks there is a growing body of evidence that designers of these systems need to take steps to offset the potential for higher fire risk. One strategy would be to have greater separation within the buildings, so there are hard barriers to reduce the spread of fire. This would also allow a portion of the facility to continue to operate even while another part is damaged and offline.

Another significant fire risk factor is battery chemistry. The part of Moss Landing that caught fire housed lithium-ion batteries that used a nickel-manganese-cobalt (NMC) technology. This kind of battery has high energy density, which is good in terms of the amount of energy that can be stored, but has downsides in terms of heat tolerance. “The higher the energy density, the spicier” it can be when damaged, Paiss said.

NMC batteries have lost market share in favor of lithium iron phosphate, or LFP, a chemistry that has lower energy density. Among the other tradeoffs is that LFP can produce more flammable gas than NMC, although the severity of the fires is often less.

“One consistent thing you can say is when you go down in energy density, you increase in safety,” Paiss said. “It’s safer because it can tolerate higher temperatures, and that’s a good thing. And when it does fail, it doesn’t necessarily produce a lot of arcing and sparking in flames right away.”

I asked what he wanted to still learn about this most recent fire.

“I like making decisions based on data, and I encourage others to do the same,” he said. “I think one of the most important datasets that we need to see is whether or not there was any toxic emissions that were actually measurable, either airborne as far down the smoke column as could be measured or where people were, as well as any surface contamination.” (The US Environmental Protection Agency said on Wednesday that its air monitoring of the site during and after the fire showed “no risk to public health” from the incident, based on testing for hydrogen fluoride and particulate matter.)

Just like I expect this fire to be a topic at public hearings about proposed systems across the country, Paiss expects it to be a topic at gatherings of officials and experts who set safety codes. “I think that the question that will be on a lot of discussions in upcoming code meetings is, should they be allowed indoors? Should we look closer at that and would limiting the installation indoors be an undue burden on electrifying our grid?” he asked.