The Mystery Of The Massachusetts Battery Tender

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It has been a couple weeks since CleanTechnica published an article titled “Massachusetts’s First Big Energy Storage Tender.” The tender is a result of a law on battery storage, signed by Governor Maura Healey on November 20.

Addressing the 1,500-megawatt (MW) tender, author Zachary Shahan wrote, “If you’re upset because you’d like to know the actual energy storage capacity (not power storage capacity) of these projects, join the party — the GWh figure was not revealed. However, the tender required at least 4 hours of energy storage duration, so that would imply at least 5,072 MWh of energy storage capacity.”

I am sometimes a bit rankled at a mystery, and this did just that to me. I finally gave in to my irritation and took another look at the issue, including a bit of further research. What I found really astonished me.

The 1,500 MW of storage is part of a bigger amount, 5,000 MW, that is to be installed by 2030. There is no specific duration for the storage given, not even in the law that is creating it. No wonder no one quoted it! But there has to be something in the law relating to duration, so I looked into that. And what I found got me thoroughly excited.

The law is a bit complicated. The battery systems are to fall into three groups, organized by ranges of duration. Of the total 5,000 MW, 3,500 MW is required to be in the range of 4 to 10 hours, 750 MW is to be 10 to 24 hours, and 750 MW is to be at least 24 hours. Thus, the minimum for the 5,000 MW of batteries, in terms of the energy, is 39,500 MWh. I think that the 5,072 MWh Zach suggested was correct for the tender that just appeared, however.

We seem to expect that large battery storage is based on lithium-ion batteries with up to four hours duration. But in the Massachusetts tender, that is the minimum requirement for any battery system. Of the battery storage required under the Massachusetts law, 15% is of 10 to 24 hours or more, and 15% is 24 hours or more. That is a lot!

Lithium-ion batteries may be improving very rapidly, and they could be used to much of the total amount required could use them to meet the law. But it seems a bit unlikely that lithium-ion batteries could deliver a system with 10 hours duration by 2030. And I don’t think there is much hope they will do at all for the requirement of 24 hours or more.

Silly laws do get passed. (After all, there was a law in Kansas that if two trains were stopped at a crossing, neither was allowed to move until the other did.) But I think this is very unlikely to be one of them. What is much more likely is that someone gave some really interesting testimony to the legislature before the bill was passed. And it might have been about other types of batteries that will be able to hold the energy required.

One company comes to mind. CleanTechnica’s Steve Hanley covered Form Energy in an article about a year ago. This company is based in Somerville, Massachusetts, and it has been working on batteries for grid energy storage that are very inexpensive, and provide 100 hours of energy at the full rate of discharge.

On October 29, 2025, just a few weeks before Governor Healey signed the law on grid storage, word came from Form Energy, saying it was in engaged in installing its first battery system. According to news from the Latitude Media article “Form’s first 100-hour batteries are hitting the grid,” the battery was being installed in Minnesota.

The Form Energy battery work on iron-air chemistry. It is really simple, though it is also a bit incredible. Electricity is generated as iron rusts, and the rust can be turned back into iron by applying electricity. The problem was to turn this simple but incredible idea into reality. And that is what a small group of scientists at Form Energy did.

The cost of battery storage using an iron-air battery is so low that 100-hour batteries may have an important place in our future. There is a down-side to this for now, which is that iron-air batteries are very big, compared to lithium-ion or LFP batteries. So we might guess that EVs will continue to be powered by the physically smaller batteries they use now, or possibly even the somewhat larger sodium-ion batteries. But I expect that iron-air batteries could become really important very soon for certain applications, such as grid storage.