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Len Rosen's picture
Principal Author and Editor 21st Century Tech Blog

Futurist, Writer and Researcher, now retired, former freelance writer for new technology ventures. Former President & CEO of Len Rosen Marketing Inc., a marketing consulting firm focused on...

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  • Oct 19, 2021

ESS Inc., a ten-year-old, Oregon-based company has developed a low-cost, iron-flow battery for long-duration energy backup requirements of up to 12 hours per battery pack. Iron-flow batteries combine iron, salt, and a water-based electrolyte to produce reliable electricity storage suitable for utilities and industrial sites where flexible energy capacity is needed.

The battery's four components include two electrodes, the electrolyte and a separator. A pump keeps the electrolyte flowing as charged particles shuffle between the electrodes while the separator prevents a short circuit. Each battery comes packed into a shipping container. These can be daisy-chained to other containers to rapidly expand energy storage for any site. That's why you can see the efficacy of use for utility and large industrial and commercial operations.

Matt Chester's picture
Matt Chester on Oct 19, 2021

Would these batteries be able to be readily used in all the same applications, or might we be moving towards a suite of potential battery techs where some are pre-disposed to certain applications and other techs fill in gaps elsewhere? 

Len Rosen's picture
Len Rosen on Oct 20, 2021

Hi Matt, The iron flow battery is meant for large-facility implementations. You will never see one in a car.

Stuart McCafferty's picture
Stuart McCafferty on Oct 19, 2021

The big issue with iron batteries has been "redox" or the reduction of battery effectiveness over time due to electron loss.  Obviously, iron batteries would be wonderful replacements to poisonous lithium and their negative environmental concerns.  Iron is not only safe, it is abundant and inexpensive when compared to lithium.  How is the redox issue being addressed at ESS?

Len Rosen's picture
Len Rosen on Oct 20, 2021

I thought the link that follows might address the redox issue. Take a look at  And this 2016 article may also be helpful in addressing how ESS technology is addressing the potential of electron loss over time. See



Jim Stack's picture
Jim Stack on Oct 21, 2021

This type of batteries based on Iron should be good for data centers and telcom central offices. They are big and heavy but in a stationary locate would be perfect.

     As to a remark in an other post about lithium batteries the EPA  classes them as non toxic. Only lead and cadmium are toxic. 

Randy Dutton's picture
Randy Dutton on Oct 29, 2021

But the generation after that will belong to graphene. It's better than LiOn in almost every conceivable category (safer, 60X faster charging, can go to near zero depletion without damage, 3X longer lasting, and more) and has much higher power density (7000 W/kg) than flow batteries. Admittedly Al-G batteries are starting small with coin batteries in 2021 and then pouch batteries in 2022, but Al-G scales up very well, and the resources are virtually unlimited. I also contend that Al-G batteries are the future of galactic expansion because methane (the base for graphene production) and aluminum are in great supply (its Mar's 3rd most common element).

Len Rosen's picture
Thank Len for the Post!
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