by Julian Spector
September 16, 2020

It's been over a year since the McMicken battery facility in Surprise, Arizona began to smoke and eventually exploded. 

We've learned a lot since then. I spent the last several weeks digging through a series of investigations, tracing what happened, why safety systems failed, how designs should change and what approaches can better protect firefighters. (You can read those analyses here, here and here.) 

But now it's time to take a step back from the details and the theories and think broadly about what all this means for the energy storage industry. 

Despite the high-profile failure, energy storage is heading toward a record year of U.S. deployments, and it has never enjoyed more widespread support from utilities, regulators and even presidential candidates. Power industry consensus is shifting to an understanding that highly renewable grids need batteries now, not in some future theoretical state.

At the same time, the specter of fiery explosions lingers, and the threat of future incidents demands constant vigilance so that a repeat of McMicken doesn't bring the build-out to a halt.

This week in Storage Plus, I break down the biggest takeaways from all this reporting. Here's what this means for the competitive landscape, and here are the missions the industry still needs to complete.

1. Spread the word

The storage industry will never be caught as unprepared as it was at McMicken, for the simple reason that now everybody knows that scenario can happen. The easiest way to prevent a dangerous buildup of explosive gases is to vent the battery enclosure. That has now become standard design practice for top-tier suppliers.

That doesn’t mean that the risk is gone entirely. Conventional thinking holds that lithium-ion will always have some risk of thermal runaway, meaning dangerous events cannot be ruled out entirely.

The other key risk comes from the human element. The U.S. has nearly 30,000 fire departments, many of which are staffed by volunteers. It’s entirely possible that the lessons from the McMicken investigations fail to spread to all of those firefighters. If that happens, the risk of human injury remains. It’s incumbent upon storage developers to make sure that doesn’t happen.

2. No rest for the lithium challengers

We can't know for sure what deployments would have looked like without the McMicken fire. We do know that site owner Arizona Public Service put its massive battery build-out on pause during the investigations and that at least a few communities have blocked battery projects based on concerns stemming from the McMicken fire.

That said, the U.S. will install twice as much battery capacity in 2020 as it did in 2019, according to Wood Mackenzie’s latest projections. Deployments will grow sevenfold from 2019 to 2021. Concerns over battery safety clearly did not stop this meteoric rise.

In fact, this year saw the completion of the largest battery plant in the world: LS Power’s Gateway project in San Diego County. The deep-pocketed developer chose lithium-ion batteries, supplied by none other than LG Chem, the manufacturer whose cells entered thermal runaway at McMicken.

I’m not sure how you can look at these data points and conclude that safety concerns around lithium-ion cells pose a serious threat to the industry’s growth. Those concerns need to be dealt with, and mitigating them increases costs, but profit-seeking investors are still choosing lithium-ion in almost every instance.

That’s a problem for all those technology startups that base their pitch on lithium-ion being too dangerous. We’ve heard it again and again:

Lithium-ion may look like the preferred option now, but did you know it’s flammable? Just wait until developers get their hands on my (insert preferred exotic technology here). They’ll jump at the chance to risk their project returns on my small-batch production, limited field operations and the undeniable chance of bankruptcy in the next 20 years!

If a startup built its business plan on scaring customers away from lithium-ion, it’s time to pivot. If the nonflammable storage technology confers a cost advantage over lithium, that’s something. And if the goal is to tackle niche applications where fire risk is intolerable, maybe that’s fine.

Just don’t try to compete with lithium-ion head-on if the only advantage is fire safety. The developer community has spoken, and it’s satisfied with the risk/reward ratio of today’s batteries.

3. "Nimbyism" is a real issue

The fear of the McMicken fire has spread faster and more widely than the technical learnings. This has already spiked a few major battery projects after local residents objected to hosting the kind of technology that went wrong in Arizona.

This is just a fact of doing business in the energy storage industry now. Detailed investigations into root causes and module designs to limit thermal propagation will not capture the imagination of ordinary folks the same way that fires and explosions do.

The most important thing the industry can do is prevent another emergency, thereby eliminating further causes for concern. The next step is playing the ground game to get a community on board, addressing legitimate safety concerns before the permitting vote goes down.

Reading the fearful comments in local news coverage, it’s clear that the safety upgrades made since 2017 have not yet permeated the public dialogue on the subject. I also noticed a theme: People don’t want to take on risk in their community for a facility they perceive as primarily helping other people. It’s one thing to say, “You’re part of the broader grid, and this battery will help the system as a whole.” But if developers can show specific benefits to the host community — jobs and tax base, sure, but what about local reliability? — that could change the narrative, or at least counterbalance the fears.

4. Professionalize emergency planning

Companies that are good at integrating batteries aren’t necessarily as skilled in the arts of emergency preparedness. McMicken showed that an inadequate emergency response plan can lead to real human casualties.

“It’s not as complicated as electrochemistry or something like that, but it’s just not something that they’re used to,” said battery fire expert Nick Warner, referring to storage experts trying to do emergency planning.

Warner combined years of volunteer firefighting with electrical engineering to work on battery fire safety at DNV GL, the firm that studied the risks of lithium-ion for New York City and identified the risks of explosive gas buildup. APS tapped DNV GL to write its report on the McMicken incident. Last year, Warner co-founded the Energy Storage Response Group with the goal of translating between the fire service and energy storage industry to close any safety gaps.

ESRG helps storage developers and owners create robust emergency response plans, and even run drills and casualty exercises. The firm can also train local fire departments on specific battery installations, provide cloud-based situational awareness if responders need live guidance on how to deal with an issue, and assist in investigations after an incident.

The good news, Warner said, is that the storage industry is paying more attention to safety now, taking a more holistic, systems-level approach to it. But there's value in having an outside opinion to engage in the "doom and gloom" analysis that could stop future problems before they happen.

"If we have another APS-like incident, the industry’s going to get the brakes thrown on real quick," Warner said.

Another approach is to bring that kind of perspective in-house to help identify and resolve safety gaps.

For instance, Will Mitchell, Strata Solar's Western region VP of business development, also serves as a volunteer firefighter and elected fire commissioner in California's Marin County. Going into permitting for Strata's 100-megawatt/400-megawatt-hour battery in Ventura County, Mitchell could speak the same language as the local fire agency. 

5. Still room to improve on thermal runaway

Battery developers have grown more comfortable with a paradigm of minimizing the risk of thermal runaway, isolating the batteries in discrete modules or cabinets in case it happens anyway. But the industry can aim higher.

Battery cell failure should prompt a service event, not a catastrophe, said storage entrepreneur Christina Lampe-Önnerud. She previously founded battery manufacturer Boston-Power, but since 2012 has been working on redesigning battery cells as CEO of startup Cadenza Innovation.

Batteries need to compete on cost. Designing systems to minimize the damage from thermal runaway leads to higher embodied costs, Lampe-Önnerud explained. It also reduces energy density because installations need physical distancing to prevent potential fires from jumping between racks or containers.

"It is not enough to say, 'We're going to put insulation between the units,' because you don’t stop the root cause," she said. "In order to get to cost efficiency, you have to get to the root cause, which is thermal runaway."

That's easier said than done, of course. For one thing, the battery needs to identify and isolate a failing cell faster than is possible with electronic controls, Lampe-Önnerud said. Cadenza's technology uses chemical and mechanical triggers inside the cell to shut things down immediately if something goes wrong.

After eight years working on it, Cadenza is taking its technology live with a demonstration at the New York Power Authority headquarters by the end of this year (the coronavirus pandemic pushed back the timeline of its plans). It's too early to say when it will get to widespread commercial use, but it serves as a reminder that lithium-ion innovation is not over, and expectations around an acceptable level of thermal runaway risk could shift if better, cheaper options become available.