| Work Detail |
American Clean Power has published a guide for first responders on emergencies in lithium-ion battery energy storage systems.
Following a spate of thermal runaway incidents this summer, American Clean Power (ACP) has published its “ Guide for First Responders to Incidents with Lithium-Ion (Li-ion) Battery Energy Storage Systems ”.
The publication coincides with the convening by the state of New York of a group of experts to re-evaluate the installation guidelines for energy storage systems. The decision came after several lithium battery projects faced thermal issues in New York state this summer, including the Three Mile Bay incident pictured above. And while it hasnt been explicitly stated, presumably the call has also been influenced by the incidents at the Moss Landing energy storage facility.
The ACP guide focuses specifically on energy storage systems (ESS) that use lithium-ion batteries, highlighting hazards such as fire, explosion, electric arc, electric shock, and exposure to toxic chemicals. The guidance is based on the 2023 revision of NFPA 855, the requirements of which apply to ESSs housed in multiple outdoor enclosures with a total energy capacity greater than 600 kWh. For systems of this size, requirements highlighted by ACP include a hazard mitigation analysis, fire and explosion testing in accordance with UL 9540A, emergency planning, and annual training sessions.
The conclusions drawn from the thermal runaway and explosion at the McMicken plant in Arizona are reflected in the current code.
Pre-Incident Planning
Facilities with a capacity greater than 600 kWh must submit a comprehensive set of pre-incident documentation to both local authorities and fire brigades. Key documents include fire and explosion test results, a risk mitigation assessment, and a detailed emergency response plan.
While the fire and explosion test results focus primarily on the smaller components such as battery cells, packs, and racks, the risk mitigation report focuses on the larger-scale scenarios that could result in leading to a total fire in the premises. The guide cites examples such as the loss of insulation that causes the formation of electric arcs or mechanical damage due to impacts from vehicles or projectiles.
Following the McMicken incident, first responders now have mandatory access to battery management system data. During the Arizona accident, adequate sensors and data would have alerted first responders to the buildup of gases in the battery enclosure. Knowing the temperatures of adjacent energy storage units can guide fire brigades on any added protective measures.
Incident Response
Emergencies involving fires, explosions, arc flashes, and toxic chemicals require rapid assessment and the proper protective equipment from the start.
If there is an active fire, allowing it to burn out completely ensures that all fuel sources are consumed, reducing the risk of reignition. It is essential to monitor the neighboring enclosures to stop the spread of fire.
When there is no obvious fire, data from battery management systems provide valuable information about the internal situation of the case and whether thermal runaway has occurred. During these types of events, the accumulated gases and increasing pressure within the battery unit create a volatile mixture, with a risk of explosion if left unchecked.
The McMicken event was triggered by the accumulation of gas. The interveners, uninformed due to lack of data, opened a breach in the enclosure, introducing large amounts of oxygen and causing an explosion that injured eight of them. One of them was thrown 73 feet from the container while trying to access it.
In any incident, the hazards of arc shock and toxic chemical exposure must be considered. Power units, regardless of the extent of damage or their visual status, should always be treated as fully charged. Burning materials may release toxic gases such as hydrogen fluoride and carbon monoxide, requiring caution.
Hazard Discussions
To conclude the guide, ACP sheds light on new industry views on incident management. Debates on lithium-ion batteries oscillate between robust systems that reduce thermal events - with the risk of explosions - and the “make it burn” approach:
Some ESS designs employ a “make it burn” strategy, in which a spark gap ignites the flammable gas when the lower flammability limit is exceeded but before the lower explosive limit is reached. These designs do not include fire suppression, since loss of an enclosure by controlled combustion is preferable to increasing the risk of explosion.
In potentially explosive scenarios, the convenience of using rooms with active ventilation is reiterated. If a rescuer is unsure of the ventilation status of an enclosure, simply opening it can be helpful, but dangerous. Simple ventilation measures may not be sufficient in all cases, so active gas extraction is considered a more effective risk mitigation strategy. |
