Battery Maker Disputes APS Report on 2019 Explosion in Arizona

An Arizona utility and the South Korean battery maker LG Chem Ltd. are at odds over what caused an explosion at an energy-storage facility last year that left multiple fire fighters injured.

A defective battery cell overheated, melting other nearby cells and leading to the buildup of flammable gases, Pinnacle West Capital Corp.’s Arizona Public Service utility said in a report released Monday.

But LG Chem, the supplier, counters that protective measures at energy storage facilities go beyond batteries, and that newer sites now include fire suppression equipment and improved safety systems. The company is conducting its own investigation into the fire, a spokesman said by text message.

“LG Chem has a different view on the cause of fire and the company will soon make an announcement on the matter,” the spokesman said.

Firefighters unintentionally ignited the gases when they opened a door to the facility located near Phoenix in April 2019, according to the report, which was prepared by DNV GL for Arizona Public Service and submitted to state utility regulators.

Jacob Tetlow, senior vice president of operations for Arizona Public Service, said the utility stands by the findings of its report. The utility included LG Chem and other parties in the investigation and also brought in outside experts.

Seoul-based LG Chem said it’s investigating the incident with Exponent, a company that specializes in battery analysis, and plans to release its own report on the cause of fire.

The storage facility was assembled by Fluence Energy, a joint venture between AES Corp. and Siemens AG. Fluence worked with APS during the investigation and will incorporate the findings of the report to prevent future incidents, according to an emailed statement.

The explosion forced Arizona Public Service to halt plans to install 850 megawatts of battery storage on its grid, one of the most ambitious efforts by a U.S. utility at the time. It came after a series of fires at energy storage facilities in South Korea, a global leader in battery manufacturing and deployment. The energy storage industry has been working to address safety concerns about its equipment, which is seen as critical to helping make solar and wind power more reliable and ubiquitous.

The Arizona Public Service probe found that a fire suppression system failed to stop a faulty cell from melting other nearby cells, leading to a “cascading thermal runaway.” Limited space between cells, inadequate ventilation for flammable gases and a lack of proper training for emergency workers also contributed to the blast, according to the report.

Arizona Public Service will use the report’s findings to establish new requirements and standards, Tetlow said.

“Our intent is to be very transparent and share this widely,” he said. “We believe there is a lot of lessons to be learned here.”

–With assistance from Rob Verdonck.