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The bomb next door You may have seen the recent news about the fire at the PG&E Elkhorn Battery Storage facility near Monterrey, California. The facility has a total capacity of 730 MWh of storage spread across 256 individual containers of lithium-ion batteries. One of those containers caught fire early in the morning on September 20, and the smoke and gasses produced were deemed harmful enough to warrant closing down a nearby highway, issue a shelter-in-place advisory, and recommend that nearby residents turn off their AC systems.

Most people don’t put much thought into the electrical grid, or how power makes its way from far-flung power plants to their homes. Substations and storage facilities are generally full of wires, towers, and large anonymous metal boxes. And that’s fine for the most part. But what people do need to start learning about is what goes into some of those metal boxes.

Lithium-ion batteries, used in most storage facilities, are generally safe under most operating conditions, but have the potential to turn into veritable bombs if damaged. The container of batteries that caught fire in California contained as much energy as four metric tons of TNT. Now multiply that by 256.

While lithium batteries (thankfully) can’t explode quite as forcefully as TNT, they’re also not slow burners. Lithium and the liquid electrolytes inside the battery cells can quickly catch fire when exposed to air or water, and lithium battery fires burn hot and fast. Once a lithium battery fire starts it’s notoriously hard to extinguish, and fires can quickly move from one battery to another.

The residents of Monterrey got lucky this time. The PG&E fire was confined to a single container and fire teams managed to keep it cool enough to prevent it from being worse, but not before an unknown amount of substances including hydrofluoric and hydrocholoric acids, carbon and nitrogen monoxide, and sulfur dioxide were released into the environment. If the fire had spread to the rest of the facility, we could have been looking at a large-scale health and environmental disaster.

How do we prevent future disasters? The answer is not to stop adding battery storage to the grid—that’s an absolutely vital part of transitioning to a clean energy future. Instead, the answer is to move away from lithium-ion batteries to other technologies that are much less flammable and much less toxic. Some of these technologies already exist, including flow and molten metal batteries. Others will be available soon, such as the kind we’re developing at Alsym Energy. But nothing is likely to change until the public starts to better understand the dangers that may be coming soon to their neighborhoods and push their local utilities and government officials to demand that more attention is paid to the safety of the batteries being used.