Mesa staff propose zoning and fire-code standards for battery energy storage systems

City of Mesa staff on Oct. 6 presented draft zoning and fire-code amendments intended to regulate battery energy storage systems (BESS), a land use staff described as "emerging and increasingly prominent" and carrying unique public-safety and compatibility concerns.

"BES is an electrochemical device that charges and collects energy from the grid or a generation facility," Planning Director Mary Kopaski Brown said. She told council the draft ordinance would create a land-use definition for BESS and distinguish principal from accessory uses based on nameplate capacity: principal if greater than 1,000 kilowatts (1 megawatt); accessory if below that threshold and serving only the host site.

Staff proposed allowing principal BESS facilities in General Industrial (GI) and Heavy Industrial (HI) districts subject to approval of a planned area development (PAD) overlay, giving council discretion similar to the approach used for data centers. Accessory BESS would be allowed in agricultural, residential, commercial, employment and downtown districts, staff said.

The draft includes several site- and safety-related standards. Appiah, development services director, summarized technical provisions the fire and building…