September 20, 2023
By Tina Casey

Exxon Knew All About Zinc Bromine Flow Batteries

New zinc bromine flow batteries take center stage in the long duration energy storage field, while adding to the list of things that Exxon knew about.

Attention has been turning to new long duration energy storage systems that can deliver more wind and solar power on demand, taking the place of gas peaker plants, diesel emergency generators, and other fossil-fueled facilities. Zinc bromine flow batteries have emerged as a key part of the picture, which is interesting because Exxon was among those exploring the technology back in the 1970s, only to drop the ball in favor of its core business.

Exxon Knew…

By the 1970s, Exxon was doing a stellar job of gathering knowledge about the link between fossil energy emissions and human-caused climate change. Sharing that knowledge with the general public, not so much.

A Harvard research team put some numbers behind Exxon’s non-sharing of climate information last January. They took note of skillful, accurate global warming forecasts made by Exxon scientists from 1977 to 2003, which had never been previously reported.

“The Harvard team discovered that Exxon researchers created a series of remarkably reliable models and analyses projecting global warming from carbon dioxide emissions over the coming decades,” the Harvard Gazette recounted.

“Specifically, Exxon projected that fossil fuel emissions would lead to 0.20 degrees Celsius of global warming per decade, with a margin of error of 0.04 degrees — a trend that has been proven largely accurate,” they added.

…About Flow Batteries, Among Other Things

For the record, Exxon’s corporate roots also include a high profile foray into solar technology back in the 1970s. The effort included funding for a startup called Solar Power Corp., but that didn’t last long. Exxon retreated to its core business in the 1980s.

A similar fate befell the company’s efforts to commercialize algae biofuel as a carbon-reducing solution, which began in 2009. Fourteen years and $350 million later, the company untangled itself from algae biofuel research last year.

Along the same lines, Exxon collaborated with Sandia National Laboratories on zinc bromine flow batteries back in the 1980s. The shared-cost, multi-phase project deployed flow battery technology previously developed at Exxon going back to the 1970s.

Exxon’s interest in zinc bromine flow batteries didn’t last much longer. Johnson Controls acquired the technology from Exxon in the 1980s, with an eye on adapting it for electric vehicles.

Zinc Bromine Flow Batteries For Long Duration Energy Storage

Interest in applying flow batteries to electric vehicles has been growing in recent years, but that has been far overshadowed by opportunities in the long duration energy storage field.

The US Department of Energy defines long duration as anything over 10 hours A full day, week, month, or season is also in their sights.

Currently, lithium-ion batteries are the go-to technology for storing energy from wind and solar power, but limitations are emerging as more renewables enter the grid. Among other issues, lithium-ion batteries only last about six hours. That’s long enough to handle some grid balancing tasks, but not all.

Flow batteries have emerged as a longer-duration alternative that also provides for enhanced safety, improved performance, and reduced lifecycle impacts. They operate by circulating two specialized liquids in a controlled environment. Scaling up is mainly a matter of building larger tanks to hold the liquids.

A number of different flow battery formulas have emerged in recent years (see more CleanTechnica coverage here), and zinc bromine is the latest focus of interest for the Energy Department.

In 2021, a Columbia University research team received a $3.4 million award from the Energy Department’s ARPA-E office for a three-year dive into zinc bromine flow battery technology.

The grant program is due to wrap up at the end of this year. In the meantime, the Energy Department’s famous Loan Programs Office has granted conditional approval for an assist of almost $400 million to commercialize next-generation zinc bromine technology developed by the Pennsylvania company Eos Energy Enterprises.

“If finalized, the project is expected to manufacture 8 GWh of storage capacity annually by 2026,” the Energy Department noted on August 31. “That is enough to provide electricity to over 300,000 average U.S. homes instantaneously or meet the annual electricity needs of approximately 130,000 homes if fully charged and discharged daily.”

More Zinc Bromine Flow Batteries For The US Military

While that is happening, an Australian zinc bromine flow battery company called Redflow has been zeroing in on the market for US military decarbonization systems.

CleanTechnica has been spilling lots of ink on the US military as an early adopter and driver of clean technology, and flow batteries have the potential to accelerate the Pentagon’s net zero aspirations.

Among other flow battery projects under its belt, Redflow has hooked up with the firm Ameresco, which has been providing US military facilities with soup-to-nuts energy overhauls. The two companies are collaborating on a $2.83 million Defense Department contract for the delivery of a prototype solar-powered microgrid and long duration energy system to the Stewart Air National Guard Base in New York.

At a planned range of 1.2 to 1.4 megawatt-hours for the Redflow battery, the microgrid system may seem relatively small. However, it could have an outsized impact on military decarbonization, considering that Stewart is just one among the 450+ facilities owned by the Defense Department around the world.

The Redflow-Ameresco project is specifically aimed at demonstrating how existing facilities can be retrofitted with microgrids. If all goes according to plan, the flow battery-enabled microgrid will also enhance grid resiliency in the communities around Defense Department facilities.

“The microgrid will also provide a dispatchable solar + storage resource that is capable of peak shaving and supports the State of New York’s clean energy goals,” Redflow explains. “If successful, the solution could be rolled out across numerous US Department of Defense facilities and critical infrastructure around the world.

What Is This Defense Innovation Unit Of Which You Speak?

The project comes under the wing of the Defense Department’s Defense Innovation Unit, which bills itself as “the only DoD organization focused exclusively on fielding and scaling commercial technology across the U.S. military at commercial speeds.”

DIU was established during the Obama administration. Until now it has been functioning a separate office “somewhat apart” from the rest of the Defense Department, as described by the news organization Breaking Defense.

That’s about to change. DIU got a new chief last April, Doug Beck, who is a former vice president at Apple and captain in the Navy Reserve.

In an interview with Beck last week, Breaking Defense reporter Jaspreet Gill noted that DIU is pivoting into an embedded model that focuses more attention on scaling existing technology to fill strategic gaps.

“It’s about taking the capability that we have built during DIU 2.0 of solving real military problems with commercial technology and getting them deployable and scalable for the warfighter, taking that capability now and applying it for strategic effect,” Beck told Gill.

Whether or not zinc bromine flow batteries fit that bill remains to be seen, though the Redflow-Ameresco wheels are already in motion. Military applications for long duration energy storage create a huge market all on their own, in addition to utility-scale civilian uses.

The home energy storage market is also beckoning, as the cost and size of flow battery technology comes down.

It’s too bad that Exxon didn’t stick around to see the fruits of its early stage research in action, but that’s on them.

Follow me tinamcasey on Bluesky, Threads, Post, LinkedIn, and Spoutible.

Photo: Zinc bromine flow batteries with solar array for long duration energy storage, courtesy of Redflow.