In any situation where flammable gases and vapors or combustible dusts are present, it is vital to control or mitigate the risk of fire and explosions which may be caused by excessive heat and various other ignition sources. Incidents have already occurred in several BESS facilities across the globe, prompting investigations into the causes and effects, and the development of safety standards and guidelines is ongoing in relation to this comparatively new field. BESS installations can incorporate several different battery types, and the most common risks associated with these include:
• Thermal runaway - battery failure giving rise to extreme heat which eventually leads to fire or explosion.
• Hydrogen development - in some batteries the risk of explosion exists due to the presence of excess hydrogen and other combustible vapors during off-gassing.
• Control system failure – dangerous overheating can occur if the battery management system malfunctions or one or more components fail.
• Toxic gases generated from battery fires and explosions also require special attention in the design of BESS safety systems.
NFPA 855-2020: Standard for the Installation of Stationary Energy Storage Systems, and other global industry standards provide specific guidance in the safe design, testing, operation, and maintenance of BESS installations. In terms of explosion protection options these fall into two categories – Passive and Active Protection. NFPA 855 does provide a third alternative of using Gas Detection with Emergency Ventilation under certain circumstances where this is approved by the Authority Having Jurisdiction (AHJ) based on large scale testing.