Arizona battery fire sparks blazing row

Arizona is known for getting excessively hot - and the heated debate about a 2019 battery fire in the US state is no exception.

What happened?

In April 2019, a fire at a battery facility owned by utility Arizona Public Service caused an explosion that put eight firefighters and a police officer in hospital.

The 2MW / 2MWh McMicken battery facility was commissioned in 2017 near an APS substation. APS used it to manage fluctuating production from its fleet of solar farms, and help to match supply to demand.

However, it closed down McMicken after the fire, along with two other similar facilities in Arizona, in order to refit them with ventilation systems.

The system used lithium-ion batteries from LG Chem and was run by Fluence, the AES and Siemens joint venture. Since the fire, all parties have been looking into what caused the accident – and a report from APS came out last month.

On 27th July, APS published a report by DNV GL about the cause, and how the risk could be reduced in future. It reported that a fault in a battery cell in one of the 27 racks of cells caused a fire that led to thermal runaway in that rack. The fire didn’t spread to the other 26 racks, but the melting of the cells in that one rack lead to a build-up of flammable gases that exploded when fire fighters entered.

The report also recommended measures to prevent thermal runaway between neighbouring cells, including updating standards, and more ventilation.

You can read that full report here.

However, LG Chem has refuted the claim in the APS / DNV GL report.

It said the root cause of the fire and subsequent explosion was not a fault in the cell itself. It reported an analysis from its own third-party investigator Exponent that said a possible cause was an external electrical arcing, and it ruled out the cause suggested by DNV GL.

In a letter to Arizona Corporation Commission on 30th July, it wrote that “independent experts retained by LG Chem rules out DNV GL’s theory regarding the cause of the initial thermal runaway event”; and said that “DNV GL ignored other experts’ views and key evidence without any explanation”.

You can read LG Chem’s full letter here.

And finally, Fluence has taken part in investigations too. So while there is a dispute about what caused this accident, all parties are committed to learning from McMicken to support the expansion of the battery market.

Why does it matter?

It would be easy to dismiss McMicken as a one-off. But when an industry has growth plans as ambitious as energy storage does, these stories matter.

The most obvious reason is safety. Companies have a moral duty to protect people’s safety, and the fact there’s such debate about the cause of a fire at a relatively small storage facility shows us that companies in the storage sector to take this seriously.

And safe storage of flammable materials will be high in the minds of safety professionals in all sectors after the devastating Beirut explosion last week.

But the storage sector is unique in that stories about battery fires in utility-scale facilities will prompt homeowners to ask whether they should install these systems in their homes. That is a potential threat to the market. Like fires, negative stories spread and this one has gone far and wide.

Similar incidents can only do further damage to companies’ ‘social license to operate’. In other words, fire safety is crucial if communities are to accept battery facilities and factories near them, and if governments are to keep providing the support needed for them to happen.

Repeated incidents would also curtail future investment.

We wrote last week about some of the technical challenges for manufacturers to overcome if they are to unlock more institutional capital for storage.

Fire is clearly one of these. Investors want to ensure any storage schemes in their portfolios run as expected, and that they don’t need to worry about, for example, the impact of excessive load-shifting on fire risks – as a report from South Korea warned about earlier this year. They need confidence that these risks are being designed out and managed as effectively as possible.

The reaction to McMicken is a test that the industry must pass.

The bottom line

This is one case. But the industry, investors and the wider world are watching.