The Anonymous Widower

Form Energy’s New Low-Cost, Iron-Air Battery Runs For 100 Hours

The title of this post, is the same as that of this article on the Singularity Hub.

This paragraph sums up the genesis of the battery.

A secretive startup backed by Bill Gates’ Breakthrough Energy Ventures thinks it may have the answer, though. Form Energy, which was co-founded by the creator of Tesla’s Powerwall battery, Mateo Jaramillo, and MIT battery guru Yet-Ming Chiang, has unveiled a new battery design that essentially relies on a process of “reversible rusting” to provide multi-day energy storage at ultra-low costs.

And this paragraph describes the operation of the battery.

The company’s batteries are each about the size of a washing machine, and are filled with iron pellets and a water-based electrolyte similar to that used in AA batteries. To discharge, the battery breathes in oxygen from the air, converting the pellets to iron oxide, or rust, and producing electricity in the process. To charge, the application of a current converts the rust back into iron and expels the oxygen.

It’s all very fascinating and leads to a battery made from very affordable materials.

The article quotes between $50 to $80 per kilowatt-hour for lithium-ion batteries and around $20 per kilowatt-hour for Form Energy’s battery.


The article is definitely a must-read.

I feel that Form Energy should be added to my list of viable batteries.

August 3, 2021 - Posted by | Energy, Energy Storage | , , ,


  1. Not quite so secret, as well as Gates interests, Arcelor Mittal, Macquarie Capital, Eni and a venture capital firm are backing it, to the tune of $500 million. ArcelorMittal has two iron ore operations in the Mesabi Iron Range of Minnesota and will be supplying the iron for the Form Energy trial facility in a former coal powered generating site close by.
    From what I can deduce you need a 10 acre site to house an assembly capable of storing 20-30MW, how much capacity they really have I’m not sure. They claim it’s capable of providing backup to a shortfall of intermittent renewables for up to 4 days although I have no idea the rate of decay.
    Is it any good, we’ll have to wait and see in the meantime have a look at this Washington Post article

    Comment by fammorris | August 3, 2021 | Reply

    • The one I like is Highview Power. In the 1970s, I did a lot of work sizing chemical plants for ICI and this leads me to believe that Highview Power will work.

      Effectively, Highview’s systems are built by bolting together proven components. They use turbomachinery from MAN and cryogenic storage commonly in use to story gases at low temperature.

      They’ve also sold almost a dozen systems.

      Comment by AnonW | August 3, 2021 | Reply

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