To advance the energy transition and stabilize fluctuating electricity generation from wind and solar power, a large number of grid-scale battery storage facilities using lithium-ion and lithium iron phosphate batteries are currently being built in Germany and worldwide.
In January 2025, a fire broke out at one of the world’s largest battery storage facilities in Moss Landing, California. Due to the release of toxic gases, authorities ordered the temporary evacuation of up to 1,500 residents. In this case, the batteries were housed inside the hall of a former gas-fired power plant—an arrangement no longer considered state-of-the-art for such facilities.
A similar incident occurred in September 2022 and again in June 2024 in Isseroda in the Weimarer Land district. There, an overseas container filled with batteries caught fire, and the subsequent firefighting operation lasted around twelve hours.
Such events highlight the importance of taking the risks of this technology seriously. Fires in grid-scale battery storage facilities are rare, but when they do occur, they can quickly escalate beyond control if appropriate fire protection measures are not in place.
Authorities in California later described the incident as a wake-up call for the entire industry and announced stricter safety requirements. In Europe as well, questions arise as to how fire protection, monitoring, and emergency management should be conceived and implemented for new storage projects.
As part of the permitting process for grid-scale storage facilities, a fire protection report must usually be prepared. This report is based on the building code of the respective federal state as well as the applicable technical building regulations, such as the ordinance on electrical operating rooms or the directive on fire service access areas. However, these regulations are not specifically tailored to battery storage facilities.
Therefore, assessments are additionally made on a performance-based approach, relying on individual hazard analyses and targeted measures to achieve protection goals. Recommendations from professional associations such as the German Association of Chief Fire Officers (AGBF) or the German Energy Storage Systems Association (BVES), which provide practical guidance on preventive and defensive fire protection in lithium-ion storage facilities, may also be considered.
In preparing the fire protection report as part of the approval process, Müller-BBM BSO compiles all relevant legal and technical assessment bases and develops an overall fire protection concept tailored to the specific battery storage facility.
The greatest risk in battery storage facilities originates from the battery cells themselves. If a cell enters a critical state due to manufacturing defects, improper use, or technical faults, thermal runaway may occur. In this process, the liquid organic electrolyte inside the cell ignites, and the oxygen present in the cell further supports combustion.
Battery management systems (BMS) provide continuous monitoring and ensure operation within optimal parameters. In emergencies, they also initiate shutdowns of affected sections or the entire facility.
Battery cells are densely packed and store large amounts of energy, which in the event of fire results in high heat release. When one cell burns, the fire can spread to adjacent cells or components, causing them to ignite as well. Gas extinguishing systems are often used to suppress incipient fires.
Further fire spread is prevented primarily through spacing, as well as by using non-combustible construction materials such as concrete, steel, or mineral wool. If spacing cannot be achieved structurally, fire-rated walls are employed to prevent fire propagation.
If a fire breaks out that cannot be controlled by a gas extinguishing system, direct extinguishing of the affected cell is only possible to a limited extent. Storage systems are compact and encased in metal, making it difficult for extinguishing water to penetrate. In addition, batteries generate oxygen internally and can continue burning autonomously. In many cases, the only option is to allow the affected cells to burn out under controlled conditions.
Active cooling of the surroundings and sufficient spacing between battery containers can prevent the fire from spreading to other parts of the facility.
Depending on the fire protection measures in place, it may even be possible—after consultation with the operator—to forgo a dedicated extinguishing water supply if sufficient spacing between containers is ensured. Subdivision into “blocks,” similar to fire compartments, is also advisable, since active cooling requires significant amounts of extinguishing water.
In the event of a fire, appropriate infrastructure for fire departments must be provided and coordinated in advance. This typically includes adequately dimensioned access and maneuvering areas, extinguishing water supply via public hydrants or private sources, and accessibility through a fire service key depot.
On-site training and drills ensure that firefighters can quickly orient themselves in case of an emergency.
Safety in battery storage facilities does not begin on the first day of operation but already in the planning stage. It is advisable to involve all stakeholders early on—planners, operators, authorities, fire departments, and insurers. A holistic consideration of structural, technical, and organizational measures ensures safety for facilities, users, and emergency responders, while enabling an approvable and ultimately economically viable overall concept.
Contribution by Susanne Oesterheld, Consulting Engineer in Fire Protection, Müller-BBM Building Solutions GmbH
