Stationary battery storage has become a load-bearing piece of the energy transition. It trims peak loads, makes better use of renewable generation and takes some of the strain off grid expansion, all of which matter for the fast-charging infrastructure that electric mobility now depends on.
The technology is not without temperament, however. Lithium-ion cells offer high energy density, but also bring a recognised set of fire and explosion risks, whether triggered by external impact, technical fault or thermal stress on the cell itself. Fire-protected enclosures, in particular technical containers built for the purpose, shield the system from external hazards and protect its surroundings should something go wrong inside. They also smooth the regulatory route and help speed permitting.
The risk that should not be underestimated
Even with extensive safety mechanisms at cell and system level, lithium-ion storage remains susceptible to thermal runaway: an uncontrolled, self-reinforcing process triggered by thermal, electrical or mechanical stress. Within seconds, temperatures can climb to several hundred degrees Celsius, releasing flammable gas mixtures.
The result can be a fire or explosion that is unusually hard to control, because the reaction takes place inside the cells and keeps releasing fresh energy. Water will not extinguish such a fire. Only cooling can prevent the reaction spreading to neighbouring cells, the phenomenon known as propagation.
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High-quality systems built to recognised standards and properly installed have a low intrinsic fire risk when operated within design parameters. The picture changes if an external fire reaches the storage system, because stored energy can intensify a fire event considerably. Hence the importance of ensuring that fire cannot spread to or from the installation and endanger adjacent buildings.
Building approval: a moving target
No EU-wide building regulation yet covers stationary battery storage. National regimes vary, and projects are typically handled as special structures by local building authorities, often on a case-by-case basis. A site-specific fire protection concept is generally required as part of the building permit, with the operator responsible for compliance. Bringing the insurer into the conversation early in planning is sensible, since additional requirements can arise on the property protection side, beyond building law.
Structural fire protection
Structural fire protection sits at the centre of any serious safety concept, with measures tailored to local conditions and protection goals. The fire protection certificate calls for information on the fire performance of materials (material class) and components (fire resistance class), ensuring that all elements can withstand fire for a defined period without losing structural integrity. Materials are tested rigorously and certified to standards such as DIN 4102 or EN 13501.
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A second key element is the creation of fire compartments. Dividing a building or site into compartments is the most effective way to contain the spread of fire and smoke, preventing it from running unchecked through a building or jumping to nearby fire loads. Each compartment is designed to hold fire for a specified time, buying emergency services valuable minutes. Compartments are formed either through structural measures, such as dedicated fire protection rooms, or by maintaining safety distances.
Certified containers
A steel-built technical container with fire-resistant wall panels protects the storage system from external fire hazards. Some models go further, with bi-directional fire protection that also contains fire originating inside the unit. The footprint is reduced to the dimensions of the protective shell, which makes installation close to buildings or in densely built-up areas feasible.
Where the container manufacturer can present a European or national certificate of suitability, such as a European Technical Assessment (ETA), structural fire protection is generally considered fulfilled. The benchmark in several markets is 90 minutes of fire resistance, enough time to set effective countermeasures in motion.
Tomorrow – Part 2: detection, suppression, response turns to sensors, extinguishing systems and pressure relief inside the container, and what that means for planning and emergency response. (Alina Möbius/TF)
Alina Möbius is Sales and Product Manager BESS at Denios SE in Bad Oeynhausen. She specialises in lithium battery safety and stationary battery storage.
