Fire Safety in Battery Energy Storage Systems: Going Beyond Standards

Fire safety should always be a top priority in the Battery Energy Storage Systems (BESS) industry, and there are effective measures that can be implemented to achieve this goal, according to Angus Moodie, engineering manager at Enertis Applus+.

Though incidents involving fires in battery energy storage systems are rare, they attract significant attention from the public and authorities due to the dramatic nature of such failures and their potential long-lasting effects on surrounding communities, first responders, and the environment.

While the frequency of these incidents is declining, as illustrated in Figure 1, each occurrence presents an opportunity for investigation and learning to enhance safety. However, relying primarily on lessons learned post-incident is a reactive approach; industry standards often lag behind the rapid pace of technological advancements. Although standards and regulations provide a baseline for the design, construction, operation, and decommissioning of BESS, it is crucial not to stop there. A comprehensive risk management strategy that considers all relevant variables is essential for ensuring the safety of BESS installations.

Elimination Strategy

The elimination strategy focuses on removing potential fire hazards from the design and operation of BESS installations. Developers and owners should critically assess whether the introduction of a storage technology that poses a fire risk is absolutely necessary. In some cases, the viability of a BESS project may hinge on lithium-ion storage systems, acknowledging that this choice introduces fire hazards. If an alternative technology is feasible, the subsequent safety measures may need to be adjusted or minimized.

Substitution Strategy

The substitution strategy advocates for the use of safer materials and technologies in battery cell composition to reduce fire risks. For example, lithium iron phosphate (LFP) cells have a lower risk of thermal runaway compared to nickel manganese cobalt (NMC) cells. Compliance with established testing standards does not completely eliminate the risk of fire incidents.

Engineering Controls

Engineering controls involve the implementation of systems to manage fire hazards, such as physical barriers and fire suppression mechanisms. Most efforts to mitigate the likelihood and severity of fire incidents are concentrated in this area after identifying potential hazards. Battery manufacturers must implement a battery management system (BMS) to monitor cell health, protect against abnormalities, and maintain safe operating conditions through effective cooling systems. In the event of a thermal runaway, the design of cells and modules, along with fire detection and suppression systems, will help minimize the fire’s impact. Additionally, gas detection and ventilation systems can prevent explosions.

Currently, BESS cabinets and containers are designed to restrict fire spread for at least one hour. These containers must also facilitate the build-up of gases or smoke particles, allowing fire detection and suppression systems to function optimally. International standards mandate these features, and the level of fire and gas detection, suppression, and ventilation, along with operational protocols during emergencies, are critical design considerations.

Another key aspect of engineering controls is safeguarding the BESS from external influences that could trigger thermal runaway. Proper electrical protection is vital to prevent faults within the system. Careful selection of protection schemes and devices is crucial for minimizing risks.

The layout of the site also plays a significant role in managing fire severity. Although standards provide guidelines for site layout, the associated risks are not always explicitly detailed in the documentation. Key risk areas include:

• Limited access to BESS equipment blocked by fire or other objects.
• Access routes through smoke paths.
• Fire spread between units or into the wider environment.

To address these risks, standards recommend several solutions, such as:

• Multiple access points to the site.
• Roads suitable for fire service vehicles, with adequate turning space.
• Sufficient access width for multiple fire service vehicles.
• Break points between battery rows to facilitate movement and limit fire spread.
• Minimum distances between BESS units/buildings/vegetation and other flammable materials, with fire-rated barriers where distances cannot be maintained.

Manufacturers are now conducting large-scale fire testing (LSFT) as outlined in standards like CSA TS-800. These tests assess the likelihood and severity of fire events and provide valuable evidence for fire risk assessments and management strategies.

Administrative Controls

Administrative controls encompass the policies and procedures established to manage fire risks effectively. This level of risk management addresses residual risks after implementing the aforementioned measures. It is advisable to develop these administrative controls in consultation with local fire authorities and the operations and maintenance service provider early in the project. Their feedback can enhance the design and further mitigate risks to personnel and improve emergency response actions.

By diligently addressing fire safety risks beyond the standards and regulations, the frequency of potential fire incidents can be reduced even further. Although it may seem like an additional cost or effort, these measures can prevent small incidents from escalating into severe emergencies.

About the Author

Angus Moodie serves as the engineering manager for the UK & Northern Europe at Enertis Applus+, a provider of technical consulting, engineering, and quality control services in the renewable energy and energy storage sectors. He has expertise in product and system design, including energy storage and power systems, and is a chartered member of the Institution of Engineering and Technology (IET).