The team investigating an explosion at a lithium-ion grid-scale battery storage facility in Arizona say it could be weeks before the cause of the accident is known.
A probe was launched by the Arizona Public Service (APS) utility after its 2MW/2MWh McMicken energy storage system in the city of Surprise suffered what was described as a “catastrophic failure” last April.
Investigators have now begun safely discharging battery modules. The McMicken system comprises 27 racks of 14 modules each— a total of 378 modules that will be removed.
APS said in an update on the investigation: “The team has developed precautions and contingencies should any modules behave erratically during the discharge process or cannot be discharged. The modules will be stored on site until the next phase of the work, which will include further inspection of any components that may help determine the root cause of the incident.”
A “safe and secure area” has already been established around the system in which to conduct inspections, disassembly and the investigative activities, APS said. “This included installing a climate-controlled tent around the immediate area of the battery and a temporary perimeter fence for safety and security reasons.”
APS and the investigation team said they “intend to share what they can of the ultimate findings, especially to the extent they are helpful to the industry and response agencies”.
BESS manufacturers and users have backed an industry-led initiative in the US to “prioritise safety” in the production and operation of equipment.