Battery fire at Bolster Substation in Peoria, Arizona contained by controlled burn

A fire broke out in the evening at the Bolster Substation Battery, a battery storage facility located at a Salt River Project substation in Peoria, Arizona. Flames were visible coming from one of several battery storage containers. Multiple fire departments responded and worked to contain the blaze. Crews used water to cool adjacent battery units while allowing the fire in the affected unit to burn out under controlled conditions, a standard approach for lithium ion battery fires where direct extinguishment is difficult. The battery system, supplied by Tesla, was taken offline, though no customers lost power as a result of the incident. No injuries were reported. The cause of the fire had not been determined at the time of reporting. The system had been in service for approximately four years at the time of the incident.

Not reported at the time of publication; cause of the fire was undetermined.

1. Emergency response plans for battery storage sites should include coordination with multiple local fire agencies given the scale of resources needed.
2. Controlled burn-out with perimeter cooling of adjacent units remains a standard and often necessary approach for lithium ion battery fires rather than attempting direct suppression.
3. Isolating the affected system from the grid without causing customer outages demonstrates the value of segmenting battery storage installations and having islanding or isolation capability built into site design.

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