Fire Protection Guidelines for Energy Storage Systems

Energy storage systems are devices with the ability to store a significant amount of energy, up to hundreds of megawatt-hours, and thus play a crucial role in the future of energy. However, their capacity to store energy may also present certain fire hazards that cannot be overlooked. These hazards stem from the design of lithium-ion batteries, which are highly reactive substances.

Types of Electrical Batteries and Fire Hazards

We can divide battery cells or batteries into two groups:

The first group consists of cells with higher energy density, such as lithium-polymer (Li-Po) or nickel-manganese-cobalt (NMC) cells.
The second group, lithium-iron-phosphate (LFP) cells, is characterized by higher safety. These two groups of cells differ in how they behave in a situation of overheating. LFP cells reach lower temperatures in case of ignition and are more stable, meaning they do not explode.

Fire Hazards Associated with the Use of Lithium-Ion Batteries

The fire hazards resulting from the use of lithium-ion batteries in energy storage systems are not a new phenomenon. It is important to remember that batteries are capable of storing a significant amount of electrical energy, enough to power an entire town. However, fire hazards often arise from negligence and can be avoided. To prevent fire incidents, special attention should be paid to the materials used, the quality of workmanship, the method of installation, the applied preventive safeguards, as well as the aging of the devices and their use.

Fire Protection (PPOŻ) Guidelines for Energy Storage Systems below 600 kWh

Guidelines for LFP and LTO cells

Ventilated room with smoke detector (EN14604), not intended for permanent human occupancy.
Walls and ceilings of the room made of non-combustible material or protected with gypsum board. BESS enclosures and support structures should be made of non-combustible materials.
Temperature range in the room between -20°C and +50°C and relative humidity not exceeding 95%.
Doors constantly closed or equipped with self-closers or other means to allow automatic closing of the doors. The door to the protected room should open outwards.
Proper labeling of the room and the equipment.
Energy storage system marked on the room plan.
Additional protection against mechanical damage in the vehicle traffic area.
The interior of the energy storage system should be divided into a battery section, a charging equipment section, and a section containing the circuit breaker. A 1m clearance maintained between battery cabinets.
In rooms below ground level, the battery system should be mounted on a raised platform of at least 30 cm in height.
The room equipped with 4 kg ABC fire extinguishers.
Prohibited installation near/in evacuation routes.
Maintain a minimum 1m distance from easily ignitable materials, except for cable connections to the rest of the installation.
For energy storage systems with a combustible top surface, it should be:

protected from above with an additional non-combustible canopy against dripping burning plastic or
located outside the area of dripping burning plastic / falling other burning elements

Guidelines for NMC and Li-Po cells

In addition to the guidelines above, the following guidelines must be met:

Installation in a room with direct outdoor access only
Prohibited installation in rooms below ground level
It is recommended that the power electronics have a function to prevent the formation of electrical arcs on the DC side (AFCI)
Warning sticker on the energy storage system informing of the risk of explosion

Additional Recommendations for Energy Storage Systems in Buildings

It is recommended that the opening of the doors for a period longer than necessary for entering the room be signaled and recorded in the building management system
It is recommended that the location of the energy storage system be equipped with a Fire Alarm System (SSP) and an Automatic Fire Extinguishing System (SUG)
It is recommended that if the storage is located on a floor, it should be accessible for rescue teams (using lifts and ladders).
The storage should be equipped with devices for fire control and extinguishing. The sprinkler system wetting intensity for 50 kWh of energy is assumed at 12.2 mm/min.
Locations of energy storage systems must be equipped with a smoke or radiation detection system (e.g., according to NFPA 72). Fire detection systems protecting the storage should have additional power supply capable of 24h standby operation and 2h alarm operation.
Fire resistance of walls, doors, and penetrations at the level of 2h. (NFPA 855 standard allows separation by partitions with 1h fire resistance if the batteries meet the requirements of the UL 9540 standard.)
Provision of water for external firefighting. This requirement may be omitted for buildings dedicated to energy storage and outdoor units located more than 30.5 m from other objects.

Additional Recommendations for Outdoor Energy Storage Systems

The distance from public roads, property boundaries, buildings, flammable materials, power lines, and hazardous materials must be at least 3m, unless otherwise specified in other regulations. In certain cases, it is permissible to reduce the distance to 0.9 m, provided the fire resistance of the enclosure is at the level of 2h. When arranging the storage, the safe distance for the evacuation route should be the guiding principle.
The maximum size of the room/container is 16.2 m x 2.6 m x 2.9 m, not including HVAC equipment and other devices. Storage systems exceeding these dimensions should be subject to individual assessment.
Classification of the storage in a “remote location” while maintaining a distance of more than 30.5 m from other objects.
Access to the storage only for qualified personnel.
No vegetation within 3m of the storage.
Enclosures made of non-combustible and water-resistant materials.
It is recommended to use emergency ventilation, at least 0.3 m3/min/m2, triggered by gas sensors.
Fire Protection Guidelines for Energy Storage Systems above 600 kWh

General Requirements, including for solutions with FK-5-1-12 (NOVEC 1230) and LITHFOR (water dispersion of vermiculite) type extinguishing agents

The storage should be equipped with fire control and extinguishing devices, with a smoke or radiation energy detection system.
Fire detection systems protecting the storage should have additional power supply capable of 24h standby operation and 2h alarm operation.
It is recommended that the room protected by the SUG and the room containing the extinguishing agent tanks be fire-separated according to the building class in which they are located.
When assessing the tightness of the protected room, particular attention is paid to the areas below the outlet nozzles where leaks occur or may occur.
Each room extinguished by a gas system should be sufficiently tight to maintain the extinguishing concentration for the required time, called the retention time. To check the tightness according to ISO 14520 (NFPA 2001 and PN-EN 15004), a door fan test should be performed. Performing the room tightness test allows determining the retention time of the agent in the extinguished room.
The manufacturer’s declarations of the SUG system should be checked, and whether the use of a relief damper in the protected room is required.
It is required that the master control center, upon receiving a signal transmitted from the CSUG, control the fire dampers (if present) to the closed position and shut off the ventilation in the protected room before initiating the gas release. This procedure is necessary to ensure the appropriate tightness and thus maintain the extinguishing concentration and effective extinguishing.
If there is air conditioning with internal circulation in the protected room, there is no need to turn it off during a potential firefighting action.
An external disconnector that switches off receivers or prevents the system from operating in order to limit the risk of electric shock to the emergency services during extinguishing.
Energy storage systems should be accessible without passing through other electrical traffic rooms.
An action plan in case of a failure should be prepared.
Marking showing the electrical risk, the extinguishing system used, contact information for technical support, and the places where the system can be disconnected in the event of a hazard.
No storage of flammable materials in the vicinity of the energy storage.

Additional Requirements for the INERGEN (inert gas mixture: argon and nitrogen) Type Extinguishing Agent:

It is recommended to install a relief damper
Preparation of the building’s SSP system for the needs of the extinguishing installation
Providing power supply to the extinguishing control panel and grounding to the cylinders and pipework.

2.1. Exceptional Situations

Waiving the main fire protection requirements is allowed if we are dealing with a building dedicated solely to an energy storage system located more than 30.5m from the main hazards.
Provision of water for external firefighting. This requirement may be omitted for buildings dedicated to energy storage and outdoor units located more than 30.5 m from other objects.
Normative Standards and Other Documents It is also worth familiarizing yourself with the normative requirements, which allow for a more detailed understanding of the fire protection requirements and the applied standards.

Applicable Standards in Poland

PN-EN IEC 62485-5:2021-08
PN-EN IEC 62619:2023-02
PN-EN IEC 63056:2020-12
PN-EN IEC 62933-5-2:2020-07