Battery Energy Storage System (BESS) deployment is accelerating globally, quickly outpacing existing fire suppression technologies and the standards that govern their use.
As systems grow larger, more energy dense, and more widely deployed near critical infrastructure and populated areas, the limitations of traditional fire protection approaches have become increasingly clear.
In many BESS fire scenarios today, particularly once thermal runaway is fully established, incident commanders are faced with a lack of effective and safe suppression options.
Carver Anderson
As a result, controlling exposures while allowing the fire to burn has often become the safest available course of action.
This approach is not a strategy of choice, but rather a risk management decision driven by responder safety, gas toxicity, deflagration risk and the limited leverage that conventional suppression methods may offer late in an event.
Mandated Large Scale Failure Testing (LSFT) has played an important role in clarifying these risks.
LSFT data has significantly improved industry understanding of heat release, gas generation and escalation behavior in BESS failures, reinforcing why direct intervention can be dangerous or ineffective once thermal runaway is fully underway.
At the same time, these tests have highlighted a critical gap: while LSFT has helped define the problem, it has not yet adequately defined suppression or intervention options capable of safely changing the outcome earlier in the event.
One reason this gap exists is that the core problem in BESS fires is not flame, as in most traditional fire scenarios.
Instead, it is thermal runaway — a series of exothermic reactions occurring inside battery cells that generate extreme heat along with large volumes of flammable and toxic gases.
Once initiated, this process can sustain itself independently, shifting suppression strategies toward rapid cooling as the most effective means of intervention.
Many existing fire suppression standards were developed around flame-based fire models and were appropriate for the hazards they were designed to address.
However, they do not fully account for sustained internal heat generation, gas production, deflagration risk and the potential for re-ignition that define BESS fire events.
As battery systems have continued to scale, this mismatch between hazard and response has become increasingly difficult to ignore.
Carver Anderson
In response, standards organizations and risk engineering bodies such as UL, CSA Group and FM Global are actively working to develop updated frameworks that better reflect the realities of BESS fire behavior.
While prevention and early detection remain central to these efforts, there is growing recognition that suppression and intervention must also address the underlying failure mechanisms involved, rather than treating battery fires as conventional flame events.
The objective is to provide guidance and tools that will enable earlier, safer and more effective intervention, reducing reliance on “let it burn” outcomes.
If thermal runaway is the core challenge, the critical question becomes how quickly and effectively heat can be removed once a failure begins.
This has driven increased interest in suppression and intervention approaches that prioritize rapid cooling while also managing the flammable gas mixtures produced during battery failure.
Within this broader category, cryogenic systems, including those being developed by Carver Fire, are being explored for their potential to deliver cooling rates that are difficult to achieve with conventional methods.
These approaches leverage agents such as liquid nitrogen and solid carbon dioxide (dry ice), which provide subzero cooling and expand rapidly into very cold, inert gases.
Early testing suggests this combination may help reduce battery temperatures more rapidly while simultaneously cooling and diluting flammable gas mixtures generated during thermal runaway.
Current BESS standards often rely on ventilation systems to manage explosive gas accumulation.
Carver Anderson
While ventilation remains an important control, cooling- and inerting-based approaches may offer additional tools to both limit thermal escalation and reduce deflagration risk, particularly when applied early in an event.
Ongoing research and testing will be critical to understanding where and how these systems can be safely and effectively integrated into future BESS fire protection strategies.
Looking ahead, prevention will continue to be the most effective form of BESS fire protection. Improvements in cell design, system architecture and early fault detection are expected to steadily reduce the likelihood of catastrophic failures over time.
Early detection remains especially critical, as BESS fire events can escalate rapidly once thermal runaway begins.
However, prevention alone is unlikely to eliminate all risk.
When intervention is required, the work being done today across standards development, testing and emerging technologies is likely to provide clearer guidance and more capable tools for earlier, safer and more effective responses that reduces escalation, limits damage and protects personnel.
Solving BESS fire risk is one of the most complex challenges facing the fire protection industry today and it will require solutions and standards grounded in the physics of battery failure rather than legacy assumptions.
Carver Anderson
At Carver Fire, we are actively collaborating with manufacturers, standards organizations, insurers and the fire service to help determine how technologies like ELSA may fit within future battery fire protection standards and response strategies.
