The main challenge was evaluating a large- scale BESS at an operating Lower Tier COMAH site. Although BESS is not directly regulated under COMAH, the Health and Safety Authority requires operators to demonstrate that new developments do not increase the risk or consequences of major accidents.
Battery energy storage poses specific hazards including fire from thermal runaway, explosion, toxic gas release and contaminated firewater. Cell chemistry materially influences these hazards. Lithium iron phosphate (LFP) is often presented as inherently safer than nickel-based chemistries, but it is not a closed book: LFP cells still vent flammable and toxic off-gas under thermal runaway, can propagate cell-to-cell, and present credible deflagration and toxic dispersion scenarios that must be assessed on their own terms.
These risks face growing regulatory scrutiny as larger BESS units are built near infrastructure and sensitive areas. The regulatory landscape is still evolving, and while standards such as NFPA 855 and UL 9540A offer valuable guidance, they are not tailored to a COMAH context and there is currently limited precedent in Ireland or the UK for integrating BESS risks into an existing COMAH safety case.
For the Power Station, the challenge was compounded by existing generation assets, previous BESS developments, and proximity to sensitive environmental designations. The client needed a robust, defensible consequence assessment to support regulatory engagement and planning progression.
