Singapore – A technical study published on July 31, 2026, analyzes a battery fire in a 485.52 kWh NMC storage unit at the Equinix SG4-4A data center. To do this, researchers modeled 10,000 cases of full thermal runaway, taking into account ventilation, fire suppression, and the configuration of the storage system. In all simulations, hydrogen fluoride exposure levels exceeded the NIOSH threshold for concentrations immediately dangerous to life or health. However, there were no actual casualties or damage, as the study computationally models a hypothetical incident scenario; consequently, it focuses on the effectiveness of technical safety systems.
Battery fire releases toxic hydrogen fluoride
Thermal runaway occurs when a battery cell heats up in a self-reinforcing manner, triggering further chemical reactions. This can cause adjacent cells to fail as well, while generating toxic and flammable gases. In the case of the NMC cells studied, these gases include hydrogen fluoride (HF). NIOSH sets the IDLH threshold for HF at 25 milligrams per cubic meter, or 30 ppm. Therefore, the rapid evacuation of enclosed battery rooms is crucial.
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For a ten-minute exposure period, the simulation calculated an average of 1,161 milligrams of HF per cubic meter in the single-room model. In the two-room model, the value dropped to 580 milligrams but remained well above the IDLH threshold. Consequently, a battery fire of this magnitude could render the affected room inaccessible to emergency personnel lacking appropriate respiratory protection. Splitting the space reduced the average time required to fall below the limit value from 599 to 301 minutes. Even with this more favorable scenario, the calculated time required was around five hours.
Water alone has limited effectiveness in the model
In the model, water alone achieved an average extinguishing effectiveness of only 37.9 percent. This is primarily due to the assumed delay before water application begins. By contrast, the model projected 78 percent effectiveness if activation occurred within three minutes. However, the simulated delay had a median value of 7.9 minutes. Therefore, the authors view a combination of extinguishing gas followed by water application more favorably.
The extinguishing gas is intended to contain open flames at an early stage, while the water subsequently cools the battery. With this combination, the modeled annual “Expected Risk to Life” metric dropped by 80.3 percent. While the battery fire remains hazardous, the model shows a significant reduction in the likelihood of uncontrolled flames. However, the extinguishing gas does not prevent the release of primary hydrogen fluoride resulting from thermal runaway. For this reason, the current NFPA 855 standard also relies on multiple layers of protection for stationary energy storage systems.
Results cannot be generalized to all battery storage systems
However, the results do not apply across the board to every battery storage system. The study examined a specific NMC-based installation within an enclosed data center, based on set assumptions regarding ventilation, failure probabilities, and fire suppression times. Some parameters were derived from literature rather than tests performed on the installed system. Furthermore, the exposure scenario assumes the presence of a person in the battery room during the incident, whereas existing emergency protocols are specifically designed to prevent personnel from remaining there.
The cell chemistry involved is also a crucial factor for context. In the US, approximately 90 percent of newly installed large-scale storage systems now utilize LFP chemistry, which offers greater thermal stability. According to MIT, severe BESS fires remain rare, despite the growing number of installations worldwide. Consequently, Singapore mandates measures such as fire compartments, sprinkler systems, gas detection, and mechanical ventilation for larger systems. Thus, the study primarily provides concrete figures for a potential major incident scenario involving an enclosed NMC system.
Author: Blackout News
Sources: Climate Portal (05.08.26) – MDPI (01.08.26) – NFPA (29.07.26)