Bridging the fire protection gaps: Fire and explosion risks in grid-scale battery storage
Iain Hoey
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Bishoy N. Awad, Karli Steranka and Ulises Rojas-Alva assess fire and explosion risks in grid-scale BESS and the challenges of standardising hazard mitigation techniques
Introduction
The challenges of providing effective fire and explosion hazard mitigation strategies for Battery Energy Storage Systems (BESS) are receiving appreciable attention, given that renewable energy production has evolved significantly in recent years and is projected to account for 80% of new power generation capacity in 2030 (WEO, 2023).
This acceleration towards renewable energy adoption has contributed to the growing imbalance between electricity demand and renewable energy generation solutions (e.g., solar power plants) due to the misalignment between supply and demand (Bowers et al., 2023).
One of the robust and reliable solutions for this imbalance is BESS, which can be used to store energy generated during low demand for use during high demand periods.
In the US, the cumulative BESS capacity has increased since 2015, with 11.9 GW installed in 2024 (Martin et al., 2025).
A significant growth in BESS installation is anticipated worldwide, with over 1 TWh of new installations between 2023 and 2025 (Martin et al., 2025).
Figure 1 shows this increasing trend in global battery deployment and directly plots the battery failure rate per deployed GW of battery energy.
This graph shows an overall decrease in battery failures per GW installed with increasing installations.
Despite the global decrease in battery failure rates per GW installed, the deployment of BESS technology is hindered due to inherent fire and explosion hazards, public fear due to misinformation, and knowledge gaps in the fire safety industry, including a lack of clear guidelines or standards for the safety design of BESS across various applications.
Figure 1 Global Grid-Scale BESS Deployment and Failure Statistics (ERPI Failure Incident Database, Wood Mackenzie)
BESS Hazards
Lithium-ion (Li-ion) battery technology is commonly used for stationary grid scale BESS and poses inherent fire safety hazards due to li-ion battery failure.
Li-ion batteries can fail due to physical abuse (e.g., puncture, deformation and/or exposure to elevated temperatures), electrical abuse (e.g., short circuity and/or overcharge), or manufacturing defects.
As a result, the battery generates heat and releases flammable battery vent gas.
This phenomenon can lead to thermal runaway.
Thermal runaway is a condition in which a self-heating chemical reaction occurs within the battery cell and releases flammable vent gas from the battery cell.
The battery gases released during thermal runaway vary in composition based on the battery chemistry (e.g., lithium-cobalt oxide (LCO) and lithium-iron-phosphate (LFP)), form factor, state of charge and manufacturer (Baird et al., 2020).
Depending on the installation conditions, thermal runaway may be limited to the initiating cell(s), or thermal runaway may propagate to adjacent cells due to conductive and convective heating or physical damage to adjacent cells due to swelling of the initiating cell.
Thermal runaway propagation can occur without oxygen and a flame (Gagnon, 2024).
The primary hazards posed by BESS are the flammable vent gases and heat generation associated with thermal runaway.
Figure 2 provides a high-level diagram of a battery failure scenarios and event pathways which lead to varying consequences.
As shown in the figure, the consequences associated with thermal runaway vary depending on multiple factors, including the point at which the battery gas reaches a competent ignition source.
Additionally, the severity of consequences depends on multiple factors, including but not limited to the initiating event, vent gas composition, state of charge, ambient conditions, installation conditions, and mitigation techniques (Jin et al., 2021).
Figure 2. Battery failure scenarios
Mitigating Technologies & Approaches
The consequences associated with a BESS failure can be reduced with appropriate mitigation techniques and emergency response.
Mitigation techniques can be subdivided into passive and active protection methods.
Passive techniques typically reduce the likelihood of a consequence and provide passive protection to reduce the severity of consequences.
Active techniques focus on preventing an explosive atmosphere and providing active cooling to reduce the severity of thermal effects.
Figure 3 provides an overview of passive and active mitigation techniques.
Figure 3. Passive and active mitigation techniques
Explosion hazard mitigation for BESS typically involves deflagration venting in accordance with NFPA 68, Standard on Explosion Protection by Deflagration, emergency ventilation system in accordance with NFPA 69, Standard on Explosion Prevention Systems, or a novel explosion protection system based on full-scale testing.
Because explosion control mitigation design requires the design engineer to make critical assumptions regarding the quantity of vent gas and vent gas composition, better characterization is needed on the quantity and composition of flammable gases to support the design of these systems (Long, 2021).
Typical explosion mitigation techniques are shown in Figure 4.
Figure 4. Explosion hazard mitigation techniques
Fire hazard mitigation is typically provided via active suppression systems or passive exposure protection techniques.
There are no proven fire suppression methods to extinguish li-ion battery fires.
It is recommended that BESS fires burn in a controlled environment and that exposure control is provided to mitigate property and life safety hazards from the fire by reducing the radiant heat flux and pre-wetting adjacent combustibles to prevent fire spread.
Separation distances provided between BESS cabinets can also be used as a passive mitigation technique to reduce the thermal exposure from a fire event and limit container-to-container propagation, as proven by FM Global large-scale fire test (Ditch & Zeng, 2020).
Typical fire hazard mitigation techniques are shown in Figure 5.
Figure 5. Fire hazard mitigation techniques
Figure 6 shows computational fluid dynamic modelling results demonstrating the effectiveness of exposure control cooling water on the incident heat flux exposure at the exterior of a target BESS.
Figure 7 shows an iso-contour of an incident heat flux of 12 kW/m² and the impact of the separation distance on target units.
Figure 6. Target BESS exterior heat flux and TR propagation analysis with & without exposure cooling.
Figure 7. 12 kW/m2 heat flux contour vs BESS separation distance.
Although there are commonly accepted mitigation techniques, there is no widespread industry standard or code requirement for the design of these systems, which leads to significant variations in the level of safety provided between BESS products.
There is a need for widespread guidance to support BESS safety system designers for uniformity among BESS products.
EPRI, Fire and Risk Alliance, and RISE have all published explosion control guidance, which can be referenced in lieu of current formal guidance (Grönlund et al., 2023; Lauren Gagnon, 2024; Long, 2021).
Summary and outlook
BESS safety involves mitigating explosion and fire hazards through various techniques such as deflagration venting, emergency ventilation, and exposure protection.
Techniques for explosion mitigation include vent gas characterization and full-scale testing, while fire mitigation involves active suppression systems or passive exposure protection.
There are no proven methods to extinguish lithium-ion battery fires, so controlled burning and separation distances are recommended to prevent fire spread.
The future of BESS technology is promising, with expected growth in installations worldwide.
Ensuring safety is crucial for widespread adoption, and comprehensive guidance and standards are needed for uniform safety measures.
Effective mitigation techniques and improved safety design guidelines can help the industry overcome challenges and realize the potential of BESS in supporting renewable energy solutions.
Authors
Bishoy Awad, Karli Steranka, & Ulises Rojas-Alva
Affiliations
Fire & Risk Alliance, Department for Fire-Safe Sustainable Built Environment (FRISSBE), Slovenian National Building and Civil Engineering Institute (ZAG)
References
Baird, A. R., Archibald, E. J., Marr, K. C., & Ezekoye, O. A. (2020). Explosion hazards from lithium-ion battery vent gas. Journal of Power Sources, 446. https://doi.org/10.1016/j.jpowsour.2019.227257
Bowers, R., Fasching, E., & Antonio, K. (2023). As solar capacity grows, duck curves are getting deeper in California. US Energy Information Administration, Today in Energy.
Ditch, B., & Zeng, D. (2020). Development of Sprinkler Protection Guidance for Lithium Ion Based Energy Storage Systems.
Grönlund, O., Quant, M., Rasmussen, M., Willstrand, O., & Hynynen, J. (2023). Guidelines for the fire protection of battery energy storage systems (Rise Division Safety and Transport Fire Safe Transport, Ed.). RISE Research Institutes of Sweden AB.
Jin, Y., Zhao, Z., Miao, S., Wang, Q., Sun, L., & Lu, H. (2021). Explosion hazards study of grid-scale lithium-ion battery energy storage station. Journal of Energy Storage, 42. https://doi.org/10.1016/j.est.2021.102987
Gagnon, L.. (2024). Explosion Control Guidance for Battery Energy Storage Systems Overview of Current Standards and Additional Recommendations. www.fireriskalliance.com
Long, D. (2021). Battery Energy Storage Systems Explosion Hazards.
Martin, H., Wang, C., & Buckley, T. (2025). International Solar PV and BESS Manufacturing Trends.
