The Moss Landing lithium-ion battery fire, the world’s largest lithium battery fire, now represents an important case study of the significant heavy metal contamination spread by such fires. The fire burned in mid-January 2025 and was exacerbated by poor storage of the batteries in a 1950s-era power plant. Standard safety now calls for battery banks to be stored in isolated metal containers, such as shipping containers that are far enough apart that a fire wouldn’t spread. Thus, while the fire was horrible, fires of that scale are not likely to be repeated.
The Moss Landing Site, owned
and operated by Vistra, deposited about 55,000 pounds of toxic heavy metals in the study area,
including nickel, manganese, and cobalt. The fire
began on January 16, 2025, and resulted in 1200 local residents being
evacuated. 300 megawatts of NMC batteries were stored in a converted 1950s
power plant. The fire burned for two days. People complained about burning eyes
and sore throats, as well as a metallic taste. The EPA reported, however, that
air quality was safe.
A paper published in Nature
Scientific Reports concluded that surface metal concentrations in nearby soils
and marshlands had increased between tenfold and more than 1,000-fold compared
with pre-fire levels. An article in Hit Points summarized the findings:
“The 300-acre study area captured only 2% of the total
heavy metals lofted into the atmosphere by the fire. Scientists estimate
roughly 1,000 to 1,400 metric tons of cathode material entered the smoke plume,
meaning approximately 2.7 million pounds of toxic dust fell somewhere beyond
the study zone.”
Elkhorn Slough, California's
second-largest estuary, bears the brunt of the contamination that dropped out
of the sky. The heavy metals will bioaccumulate in the abundant local wildlife
in the estuary. The fire was also very near to important California
agricultural areas, with irrigation water and crop soil being contaminated as
well, although the state has not issued any safety alerts. Residents have sued
the company for improper storage and fire protection. Elevated heavy metal
concentrations have been found as far as 46 miles from the site of the fire.
Experts agree that this fire
was an anomaly and something like it is not likely to happen again. Lithium-ion
Nickel-Manganese-Cobalt (NMC) batteries for power grids continue to be replaced
by less flammable lithium-iron-phosphate (LFP) batteries. New fire code
standards based on NFPA 855 are poised to take effect in January 2026, but they
only apply to new projects. The Hit Point article notes:
“Months after the fire, the U.S. EPA ordered Vistra to pay
for the safe removal, treatment, and disposal of the batteries. Crews have
disposed of over half a million gallons of contaminated water and hauled away
thousands of battery modules.”
“However, the cleanup authority remains fragmented
across multiple agencies, resulting in a patchwork of overlapping jurisdictions
and testing methods.”
Scientists from San Jose
State University's Moss Landing Marine Laboratories (MLML) collected and
analyzed soil and water samples and found dramatic increases in battery metals.
The study, published in Scientific Reports, is the first real-world evidence of
metal fallout from a grid-scale battery fire. Two years prior to the fire, MLML
scientists had collected soil samples, which provided a baseline for heavy
metal concentrations before the fire.
"Because we already had baseline data and could
respond immediately, we were able to spot a very thin layer of battery-related
metals that traditional sampling would have completely missed," said Ivano
Aiello, lead author and chair of MLML. "Our field readings were later
confirmed in the lab, and we are now tracking how these metals move through
different habitats and how they may interact with organisms in the estuary."
The paper concluded that a
thin but widespread layer of toxic metals was deposited across the wetlands of
Elkhorn Slough.
Portable X-Ray Fluorescence
(XRF) sampling was key to getting accurate testing results, especially to get
low-cost, rapid, and high-density data that is complementary to more accurate
lab analysis. They also noted some known limitations of XRF, such as giving
higher readings for metals in water samples, which was also confirmed in this
study.
According to the paper:
“The fire destroyed approximately 75% of the facility
and produced a smoke plume visible from tens of kilometers away, depositing ash
and soot across the surrounding area.”
As the authors note, this
study will be a key study for determining the local and regional effects of NMC
battery fires. Of note is that plume dispersion modeling will be key to finding
where the metals are likely to be deposited. In this case, the deposition of
the heavy metals was found to be at the highest concentrations several
kilometers downwind of the site. Deposition was also found to be “patchy”
rather than a blanket deposit. Another important factor is to sample as quickly
as possible after the fire, before rain, wind, and, in this case, tides as
well, disperse the material.
Some of the conclusions of
the paper are given below, along with key figures from the paper:
“To our knowledge, this study represents the first
field-based documentation of battery-associated metal fallout following a
large-scale lithium-ion battery fire and offers a framework for assessing
future events of this kind. Use of field instrumentation enabled immediate
collection of hundreds of measurements, critical given the spatial patchiness
of battery metal aggregates in an extensive fallout layer in the vicinity of
the fire and given the rapidity with which the metals were transported
downstream by tides and rain. As battery energy storage systems continue to
expand in scale and density, the risk of both localized and widespread
contamination will increase even as safety protocols improve.”
“This incident also calls attention to the limitations
of standard environmental sampling protocols. Conventional soil sampling
depths, such as the commonly used top ~ 6 cm of soil28, may fail to detect
thin, spatially heterogeneous deposition layers. The patchy nature of ash
deposition observed in this study suggests that sampling strategies must be
adaptive and designed to capture contamination at multiple spatial scales and
depths. This is especially critical in the first few days following an event, since,
over time, rainfall, tides, and wind can rapidly redistribute surface-bound
contaminants.”
“Environmental response frameworks must also consider
the potential offset between fire origin and deposition zones. In this case,
the most significant contamination occurred not adjacent to the site of the
fire, but several kilometers downwind. This spatial offset highlights the need
for evacuation protocols and monitoring networks that integrate plume
dispersion models, meteorological data, air quality monitoring and ground-based
measurements of deposition.”
References:
Massive
California battery inferno rains heavy metals over 5-mile zone—1,200 evacuated.
Ava J. Hit Points. December 6, 2025. Massive
California battery inferno rains heavy metals over 5-mile zone—1,200 evacuated
Monterey
Co.: Newly Released Study Verifies Dispersion Of Metals After Moss Landing
Battery Fire. Bay City News Service. SF Gate. December 2, 2025. Monterey
Co.: Newly Released Study Verifies Dispersion Of Metals After Moss Landing
Battery Fire
Coastal
wetland deposition of cathode metals from the world’s largest lithium-ion
battery fire. Ivano W. Aiello, Charlie Endris, Steven Cunningham, Monique
Fountain, Maxime M. Grand, Wesley Heim, Amanda S. Kahn & Kerstin Wasson. Scientific
Reports volume 15, Article number: 42113 (2025). November 26, 2025. Coastal wetland
deposition of cathode metals from the world’s largest lithium-ion battery fire
| Scientific Reports
Moss
Landing Marine Laboratories Scientists Confirm Metal Fallout in Elkhorn Slough
From World’s Largest Battery Storage Fire. Sean Woodland. San Jose State
University, News Center. December 1, 2025. Moss
Landing Marine Laboratories Scientists Confirm Metal Fallout in Elkhorn Slough
From World’s Largest Battery Storage Fire | SJSU NewsCenter
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