Battery energy storage systems (BESS) are experiencing explosive growth, with the global market expected to increase exponentially over the next decade. However, along with this huge potential comes complex safety challenges facing the industry. Fire incidents at BESS facilities worldwide have raised safety concerns and accelerated the development of comprehensive BESS safety solutions.
For engineers, project developers and facility managers, understanding safety requirements and how to implement them effectively is not only a matter of regulatory compliance but also a determining factor in project success and sustainability.
Why is BESS safety a top priority?
Thermal Runaway – Thermal Runaway Phenomenon
Thermal runaway is the most serious threat to lithium-ion battery systems. When a battery cell overheats, it can trigger a chain reaction, raising the temperature of neighboring cells and leading to a fire or explosion. Research from industry experts shows that thermal runaway not only causes fires but also releases toxic gases, creating a hazardous environment for people and equipment.
Emission of toxic gases
During thermal runaway, lithium-ion batteries can emit toxic gases such as hydrogen fluoride (HF), carbon monoxide (CO), and volatile organic compounds. These gases are not only dangerous to humans, but can also corrode surrounding equipment and structures.
Risk of explosion
The accumulation of hydrogen gas in a confined space can create a dangerous explosive mixture. This is especially important in large-scale BESS systems where a large number of batteries are concentrated in a confined space.
Current Regulatory Framework and Safety Standards
NFPA 855: The Gold Standard for BESS Safety
NFPA 855 – Standard for the Installation of Stationary Energy Storage Systems – is the most comprehensive standard available for the installation of stationary energy storage systems. To comply with NFPA 855, developers need to:
1/ Systemic risk analysis
Comprehensive assessment of potential hazards
Determine the minimum safe distance
Environmental impact analysis
2/ Fire protection system design
Early detection system with smoke and heat sensors
Automatic fire extinguishing system suitable for battery type
Emergency ventilation system to discharge toxic gases
3/ Distance and separation
Minimum distance between BESS units
Separation of hazardous areas
Design safe escape routes
UL 9540A: Latest Testing Requirements
UL 9540A is the standard test method for evaluating the safety of energy storage systems, including a series of tests at different levels (cell, module, unit, and installation) to evaluate potential fire hazards, fire propagation rates, heat release rates, and other factors relevant to fire safety. The latest requirements include:
Test level 1: Single Cell Testing
Evaluation of individual cell thermal runaway behavior
Temperature, pressure and exhaust gas measurement
Determine the conditions for thermal runaway activation
Test level 2: Module testing
Check thermal runaway propagation between cells
Assessing the effectiveness of containment measures
Measure propagation time
Test level 3: Unit testing
Testing the entire BESS unit
Fire protection system assessment
Check the fault tolerance
Test level 4: Installation testing
Tested under real installation conditions
Assess the impact on the surrounding area
Confirm the effectiveness of protective measures
Technical solutions to prevent heat transfer
Prevent heat transfer in the battery module
1/ Advanced insulation design
Preventing heat spread in the battery module requires a multi-layered approach:
- Insulation material: Use ceramic or aerogel material between cells
- Optimal Spacing: Design suitable spacing between cells to prevent heat transfer
- Active cooling system: Integrated air or liquid cooling system
2/ Smart thermal management system
- Real-time temperature monitoring: Temperature sensor at each cell
- Predictive Algorithms: AI/ML to Predict and Prevent Thermal Runaway
- Auto Disconnect: The system automatically isolates the faulty cell.
3/ Fire retardant materials
- Intumescent coatings: Coatings that expand when exposed to high heat
- Fire-resistant barriers: Fire-resistant partitions between modules
- Vent systems: Fixed directional ventilation systems for exhaust control
Building a safe future for BESS
Implementing an effective BESS safety solution requires a combination of standards compliance, advanced technology, and best operating practices. With the continued evolution of standards such as NFPA85 and UL 9540A, the industry is moving toward a safer and more sustainable future.
Organizations that want to be more successful in the BESS space need to invest in a deep understanding of safety, from initial design through to long-term operation. Only by putting safety first can we fully exploit the potential of energy storage technology to build a clean and sustainable energy future.
