Preventing the Next Battery Incident: Rethinking Battery Energy Storage Safety
As battery energy storage systems expand, recent fires and explosions prove compliance isn’t enough. James Close and Edric Bulan say only a layered, system-wide safety approach can meet the risks of thermal runaway and real-world failure
Quick read
- Layered Safety Is Essential: Relying on battery management systems and suppression alone is insufficient – robust, multi-level protection strategies must be integrated from cell chemistry to system design to effectively mitigate thermal runaway risks
- Chemical Engineers Are Critical: The expertise of chemical and process safety engineers is vital to designing safer battery energy storage systems, applying proven tools such as hazard analysis, gas dispersion modelling, and inherently safer design
- Compliance Is Not Equal to Safety: Many failures occurred in systems that met current standards, highlighting the urgent need for regulations to incorporate consequence-based design and holistic risk management, particularly as systems scale and move closer to populated areas
BATTERY energy storage systems have become essential for balancing electricity supply, especially alongside intermittent renewables like wind and solar. However, as these installations grow, so do the risks, particularly from lithium-ion battery thermal runaway, which can trigger fires and explosions.
Understanding these risks begins with visualising the scale of a grid battery energy storage system. All lithium-ion battery systems share the same basic structure, cells grouped into modules and then packs. In electric vehicles (EVs), these packs sit within the vehicle. In grid-scale systems, they are housed in metal containers the size of shipping units.
A Tesla Model 3 contains around 4,000 cells and stores about 75 kWh.1 In contrast, a small grid-scale system like the APS Surprise facility in Arizona, US, stores 10 to 20 MWh across two containers (each 15 m long x 4 m wide x 3.6 m high), each with around 14,000 cells, contained within 36 racks, with 14 modules each.2
Inside each container, battery racks are stacked like servers in a data centre, with integrated systems for cooling, monitoring, fire suppression, and gas detection. Most containers include automated suppression systems that release fire suppressants such as aerosols or inert gases when smoke, heat or gas buildup is detected.3 Each container functions as a largely self-contained unit, managed by a battery management system composed of sensors, control electronics, elements and software. The battery management system monitors voltage, temperature, current and state of charge, and can trigger cooling or isolate faulty modules. While essential, these systems alone have repeatedly proven insufficient to prevent cascading failures.
Past incidents: what went wrong and why?
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