UPDATE 9 May 2022: Salt River Project has described the incident as thermal runaway in its official statement. However, Energy-Storage.news has heard from a source close to the project that the exact cause of the fire is not yet known and so could have originated from outside the battery system itself. It is therefore too early to describe the incident as thermal runaway before the investigation has taken place, the source said.
Power company AES Corporation is investigating the cause of what has been described as a thermal runaway incident at a 10MW battery energy storage system (BESS) site it owns and operates in Chandler, Arizona.
The fire at the Dorman battery storage facility, which provides energy to local utility Salt River Project (SRP), began on 18 April. The sprinkler system was deployed automatically and continued to spray water for several days to keep the temperature down, and was turned off on April 29.
SRP said that on 1 May the fire department turned control of the site back over to AES so that it could begin its investigation, with the battery building stable with no visible indication of smoke or fire for more than two days.
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“Since the turnover to AES, CFD (Chandler Fire Department) returned to the site to respond as needed. The situation is considered under control and remains under AES control,” the statement said. “The investigation of the incident will be led by AES.”
There have been no injuries associated with the event and no damage to SRP electrical electrical facilities, SRP told Energy-storage.news in a statement. The nearest freeway was closed, the City of Chandler notified nearby businesses to evacuate and SRP disconnected its adjacent Knox Substation from the BESS.
Dorman is a 10MW, four hour, standalone BESS project owned and operated by AES Corporation. It was completed in 2019 and provides energy storage to SRP under a 20-year agreement. The utility has enlisted several large system integrators to deliver projects in its region of responsibility in Arizona, including Fluence and Tesla.
AES Corporation provided Energy-Storage.news with a statement from Mark Miller, AES Market Business Leader and General Manager for California who has been on site overseeing the response:
“On Monday, April 18, smoke was detected inside the Gilbert (the name of the holding company of the project) battery energy storage facility in Chandler, Arizona. Safety systems responded properly, and the local fire department was dispatched. The fire department effectively managed the situation until Sunday, May 1, when the facility was deemed combustion free, and management of the building was returned to AES.”
“AES experts and consultants remain at the site as the situation shifts to the investigation phase. When safe conditions permit, we are committed to conducting a full analysis.”
