On their website, EnergyStorage.org, American Clean Power addresses this claim.
The truth is that battery cell failure rates are extremely low, and safety features in today’s designs further reduce the probability of fires.
One estimate from 2012 quotes a failure rate ranging from 1 in 10 million to 1 in 40 million cells (Vehicle Battery Safety Roadmap Guidance, National Renewable Energy Laboratory, October 2012, https://doi.org/10.2172/1055366), and there are undoubtedly improvements from these levels.
Lithium-ion batteries experience extremely low failure rates, as shown by electric vehicle data. Tesla alone sold nearly 900,000 vehicles in the first half of 2023. (https://www.cnbc.com/2023/07/07/ev-sales-hyundai-overtakes-gm-but-teslas-us-dominance-continues.html#:~:text=Tesla’s%20global%20deliveries%20were%20more,million%20electric%20vehicles%20in%202023.) These sales of new vehicles represent around three-quarters of a billion cells, but safety events involving all EVs on the road globally, from all manufacturers, amounted to just a few dozen fires.
Today’s energy storage systems (ESSs) predominantly use safer lithium-iron phosphate (LFP) chemistry, compared with the nickel-manganese-cobalt (NMC) technology found in EVs. LFP cell failure results in less energy release and a lower probability of fire. ESS designs incorporate features to avoid propagation of cell failure within the battery, contributing to improved safety.