Sandra D. Kennedy, commissioner on the Arizona Corporation Commission (ACC), has submitted a letter to the ACC (pdf) suggesting that in light of the two energy storage fires that have occurred in Arizona (2012 and 2019), lithium ion batteries – specifically those that will release hydrogen fluoride – “are not prudent and create unacceptable risks”.

The letter, dated August 2, noted that in the 2012 fire at Arizona Public Service’s (APS) Elden Substation a battery cell was overcharged due to a failure of the energy storage management system. Additionally, inadequate electric circuit protection, and temperature sensor issues were found. The report states that the facility was initially doused with water to put out the flames, which – per the document – can make lithium ion batteries extremely volatile.

Yesterday, August 7, APS released an update (pdf) on the 2019 McMicken Energy Storage Facility fire of April 9, around 5 PM. The utility has completed of phase one of the investigation, and has begun the second phase. 377 of 378 battery modules were “safely” removed from the the installation, with one module unable to be discharged. Phase two has seen hardware believed to have failed sent to a lab in Scottsdale, Ariz to be x-rayed and further taken apart for analysis. Afterwards, they’ll be sent to experts in Michigan.

South Korea, which due to strong incentives supporting local manufacturers is one of the world’s leading lithium ion battery markets, has had 23 individual energy storage facility fires out of almost 1,500 systems installed since August of 2017.

On June 11, 2019, a report was released on these fires suggesting four factors: a lack of proper ground from electrical shocks; insufficient management of the operation environment (ocean side installations caused humidity damage); bad contractor installation; and a lack of integrated control and protection systems.

And while battery cell defects were found, testing of the units didn’t result in fires, and the cells – the issue highlighted by the Commissioner – weren’t considered the root cause. Instead all issues were related to the energy storage management systems and contractor installation.

Other Technologies

The letter from the Commissioner went on to highlight other energy storage technologies.

Liquid flow batteries “that are easy to scale up linearly in terms of capacity”

Liquid metal batteries with electrodes made of sodium and nickel chloride

Zinc air batteries with no expensive components

Nickel-Iron battery that are “almost immortal”, environmentally benign, and able to take aggressive use

Magnesium batteries that are non toxic and very abundant