https://robfreeman.com/what-thermal-runaway-how-be-avoided/ - Energy storage is being deployed across the U.S. in a wide range of applications from electric vehicles to use in commercial buildings such as peak shaving and demand response. 

Lithium-ion batteries are the most common type of batteries used in energy storage systems today…. However it can be difficult to get proper insurance for energy storage systems because of a hazard known as thermal runaway.

Thermal runaway occurs in lithium-ion batteries when heat builds up more quickly inside the battery than it can be dissipated. The result is ignition of the battery or even explosion. 

Thermal runaway often starts in a single cell of an energy storage rack and can lead to a domino effect of all the cells catching fire, hence the term “thermal runaway”. Thermal runaway may be caused by thermal, electrical, mechanical or physical abuse of lithium-ion batteries. 

FM Global is involved in a series of small, medium and large scale energy storage fire hazard tests to evaluate the best practices for energy storage risk management. 

Here's a video of a thermal runaway test:
https://www.youtube.com/watch?v=yIH9ED0j5dQ 

2019 Thermal Runaway test report: 
https://sprinkler.nl/wp-content/uploads/2019/07/Development_of_Sprinkler_Protection_Guidance_for_Lithium_Ion_BasedEnergy_Storage_Systems.pdf

FM Global tests confirmed that ignition of a single module was sufficient to ignite other modules in the same rack. FM Global tests evaluated the impact of installation in regard to proximity of combustible and non-combustible materials and the performance of sprinkler protection systems in commercial facilities. They observed that the risk of thermal runaway could be reduced by taking the following precautions:

- Ensure proper installation
- Separation of racks a minimum distance from combustible and non-combustible objects 
- Use of sprinkler protection according to expert guidelines and according to battery chemistry
- Maintain adequate ceiling height to avoid off-gassing build up 
- Maintain an environment at an ambient temperature at or below 75 degrees 
- Maintain a fire watch in the event of an ESS fire because ESS systems are known to reignite

If you’re deploying an energy storage system work with your insurance broker, risk management and fire prevention team to ensure your system is deployed as safely as possible. New technologies are being developed to prevent thermal runaway from occurring in the first place.