Battery Energy Storage Systems (BESS) are a rechargeable electrical storage medium used to absorb and later release energy.
Constructed near an electric provider’s substation, BESS units store energy purchased from the grid during low demand periods and store it for resale to the utility provider during times of higher demand. Supplementing power grids with BESS units can trim spikes of peak energy use periods, helping stabilize not just power use but the cost of such usage.
BESS units function something like large scale models of the lithium-ion batteries used in common power tools. Much larger than the battery of a drill or circular saw, BESS batteries come in preconstructed portable housings similar to shipping containers. Modular units with their own HVAC and monitoring systems, they are self-contained. No water is employed to operate or cool a BESS battery and the compounds inside them are not water soluble.
The specific type of lithium-ion battery that would be used by the proposed Pierce County BESS installation are lithium iron phosphate batteries, more commonly referred to as LFP batteries.
Instead of more scarce rare earth materials such as nickel and cobalt, LFP batteries utilize their namesake lithium iron phosphate, an inorganic compound which is easier and cheaper to source. Iron and phosphates are readily available in the earth’s crust and less at risk of being monopolized by a single government or corporation.
More stable than similar batteries made with nickel manganese cobalt (NMC), LFP batteries are less prone to “thermal runaway” and the resulting fires. NMC releases oxygen as it heats up, which can add fuel to flames. LFP batteries take longer to decompose, meaning they are not only more stable but also last longer.
Overheating and fires, while less common, can still occur with LFP batteries, but the internal 24/7 monitoring systems built into BESS units are designed to shut batteries down before ignition if a spike in electricity or temperature is detected.
Local fire departments near BESS facilities receive special training on how to contain a fire in the event one occurs.
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