Question and Submission History

In the rare event of a thermal runaway fire, standard safety protocol is to allow the affected container to burn out under controlled conditions to prevent contaminated water runoff. The smoke contains compounds like hydrogen fluoride and carbon monoxide. The site layout keeps the equipment approximately 500 feet from the nearest residential building, and the battery systems are designed to prevent fire from spreading between units, a design validated through UL 9540A large-scale fire testing.

A battery fire can release hydrogen fluoride and other irritant gases. Wind and atmospheric stability determine how far these gases travel. Breezy days disperse the plume quickly, whereas calm or humid air holds it together longer. Real-world monitoring data supports this conclusion. During the 2025 Moss Landing fire, which is the largest documented battery storage fire to date, the EPA reported that its air monitoring for hydrogen fluoride and particulate matter found no exceedances of health standards and no risk to public health at any distance sampled. An industry assessment by American Clean Power, reviewing 35 documented U.S. battery fire incidents from 2012 through 2024, found no case where gas concerns extended meaningfully beyond the immediate fire area. Our state application includes a site-specific plume analysis that models stagnant, breezy, and humid conditions to confirm this outcome here. We will publish the finalized analysis in the public docket.

Smoke from a battery fire can contain carbon monoxide and hydrogen fluoride, and even small amounts of hydrogen fluoride can be harmful. It is a real hazard close to the fire, mainly for firefighters and anyone nearby. What has been measured at other fires is reassuring but limited. A September 2026 report by Fire & Risk Alliance, an independent fire engineering firm, reviewed air monitoring at seven U.S. battery fires, plus the January 2025 fire at Moss Landing, California. At the fires where air was sampled, including in nearby communities, nothing was found above public health limits. At Moss Landing, six days of community air monitoring detected no hydrogen fluoride. The report also explains why: hydrogen fluoride dissolves in water, sticks to surfaces and smoke particles, and is diluted by air as smoke travels. The incident review it draws on was commissioned by the American Clean Power Association, the industry trade group. These were other sites with other equipment, and the sampling covered air only, so this does not tell us what would happen here. We have committed to publish a gas plume analysis, which looks at where smoke and gas could travel. We have not published it yet, so we cannot tell you that any road or home would be unaffected.

Smoke from a battery fire can contain carbon monoxide and hydrogen fluoride, and even small amounts of hydrogen fluoride can be harmful. It is a real hazard close to the fire, mainly for firefighters and anyone nearby.

What has been measured at other fires is reassuring but limited. A September 2026 report by Fire & Risk Alliance, an independent fire engineering firm, reviewed air monitoring at seven U.S. battery fires, plus the January 2025 fire at Moss Landing, California. At the fires where air was sampled, including in nearby communities, nothing was found above public health limits. At Moss Landing, six days of community air monitoring detected no hydrogen fluoride. The report also explains why: hydrogen fluoride dissolves in water, sticks to surfaces and smoke particles, and is diluted by air as smoke travels. The incident review it draws on was commissioned by the American Clean Power Association, the industry trade group. These were other sites with other equipment, and the sampling covered air only, so this does not tell us what would happen here.

We have committed to publish a gas plume analysis, which looks at where smoke and gas could travel. We have not published it yet, so we cannot tell you that any road or home would be unaffected.