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Been pondering something for a few days, so prompted by a vid on it by the Electric Viking, and Ken's recent thread on huge RE generation and curtailment, thought I'd post and ponder wider.

So, as the title says, iron-air batteries. They've been in the news for years, but recently gotten more attention with the planned deployment of an 85MW/8,500MWh battery in the US.

Form Energy iron-air battery in Maine granted $147 million

The U.S. Department of Energy has granted $147 million to construct an energy storage facility at a shuttered paper mill. The battery energy storage system (BESS) from Form Energy, a Somerville, Massachusetts-based grid-scale energy storage developer, will be able to store enough wind and solar power to serve up to 85,000 homes.

The 85 MW iron-air battery system is both safer and more affordable than its lithium-ion counterparts since it uses abundant iron and oxygen. The battery storage project will be one of the largest of its kind in the world and is meant to support one of the most congested parts of the New England grid.

Form Energy will deploy the 85 MW battery system at Lincoln Technology Park, which can discharge energy for up to 100 hours or just over four days. The Power Up New England program includes strengthening the transmission system to deliver higher power loads from renewable sources, including nearby onshore wind turbines.

In June 2023, Form Energy announced a definitive agreement with Georgia Power, a Southern Company utility, to deploy a 15 MW / 1.5 GWh iron-air battery into the utility’s Georgia grid, providing a 100-hour dispatch long-duration energy storage (LDES) system. In July 2023, Minnesota’s public utilities commission approved Form Energy’s 10 MW/1 GWh iron-air long-duration energy storage facility construction project for Xcel Energy.

This article has the news that really surprised me, and got the Viking's attention:

Low-cost iron-air technology to feature in world’s biggest battery project in US

Form Energy says its iron-air battery systems can be deployed anywhere to meet utility-scale energy needs, and while they are able to complement the function of traditional lithium-ion batteries, they also store energy at less than 1/10th the cost of lithium-ion battery technology.

And this is where my brain went with it. So, first off, let's assume it's cheaper than Li-ion, but not necessarily 10x. Also we need to consider round trip efficiencies which it seems can be upto 70%, but are more likely to be ~50%. And another concern is profitability, since it sounds great to have a 100hr battery, but that's only because the technology has a very low charge and discharge power level. So in the very best case it takes 8days to fully cycle. But a low level of cycling may be OK if operational costs are low, and you are buying up the very cheapest*, least wanted leccy, and selling it when all other smaller/shorter term storage can't, at best prices.

So this 85MW/8,500MWh battery has a very, very different role to say Dinorwig with i's 1,800MW/9,100MWh, despite a relatively similar energy figure.


Next, putting all that aside. If** the technology is cheap enough, then doesn't that possibly suggest that it can be deployed on vast scale? So perhaps 100 of these deployed around the UK, that's 8.5GW of power when RE is very low. Or maybe 400 of them (or variations in numbers and size) providing 38GW of power.

Please don't get too hung up on the specifics, I'm just pondering if an affordable long duration technology exists that could in theory be deployed and dispursed to help time shift excess RE around the UK for later use. Hopefully CAES (compressed air energy storage) will also be viable and similar in nature. My ponderings revolve around the problem of meeting low generation / high demand periods, which is, I think, the last hurdle that RE faces.

Maybe we are getting closer?


*I was going to suggest buying at negative prices, but I suppose RE can simply curtail generation when prices get too low/negative. At least perhaps in the medium/longer term.

**I appreciate the 'if' is a very big IF, but I'm just playing with the possibilities given that the technology does exist today and is easily scaleable.

The next big cab off the rank for cutting the cost of BESS is Sodium-Ion and that doesn't seem to come with as many of the downsides of Iron-air. Surely a better target for deployment?

Perhaps, but tbh I didn't think Sodium Ion batteries were really suitable for LDES. They seem to have similar roles as Li-ion in the 2-4hr short duration role, possibly medium duration 4-10hrs if cheap enough, but as they are 'only' about 20%-40% cheaper than Li-ion, I didn't think vast scale LDES was a suitable role for them.

The point I was trying to stress, was that 'if' the cost claims are true*, then iron-air batts, like a few other technologies being tested, may be cost viable for the LDES role. If that happens, then the final criucial problem may already be being addressed, with the construction of storage like the proposed 85MW/8,500MWh battery.

*But I struggle to believe that they are 1/10th the cost.

The material costs appear to be cheap but the scale means that land value is a factor and the big killer would be how many of these batteries globally would be built ? it would need to be significant otherwise the commercial incentives to develop the technology and build a company / companies to service the demand wouldn't stack up. Nuclear power traditionally struggles with this last commercial issue with the resource base only ever typically being around for one generation of new build followed by a contraction of the workforce and knowledge base before the next round of new builds starts to come to the market.

Moxi

Thanks Moxi, the land/space issue is important and I missed that. I suppose the same applies to flow batts too. Csertainly gives CAES an edge if it can use underground storage, with a relatively small surface footprint.

One more to watch, and more fingers/toes to cross.

Mart wrote: ↑Thu Aug 22, 2024 3:35 pm Thanks Moxi, the land/space issue is important and I missed that. I suppose the same applies to flow batts too. Csertainly gives CAES an edge if it can use underground storage, with a relatively small surface footprint.

One more to watch, and more fingers/toes to cross.

With Flow batteries surely underground storage would be feasible, some undrground storage tanks are measured in millions of tonnes iirc.

That Rough gas storage facility is pretty big!

I think at this end of the storage scale there are lots of plausible technologies that could be used and its just going to come down to demand and supply to determine the commercial value of the technology and the ability to deliver revenue or more simply the market will determine the appropriate technology.

Not the most efficient route but it is what we seem to be locked in to at present.

Moxi

Countrypaul wrote: ↑Thu Aug 22, 2024 4:26 pm

Mart wrote: ↑Thu Aug 22, 2024 3:35 pm Thanks Moxi, the land/space issue is important and I missed that. I suppose the same applies to flow batts too. Csertainly gives CAES an edge if it can use underground storage, with a relatively small surface footprint.

One more to watch, and more fingers/toes to cross.

With Flow batteries surely underground storage would be feasible, some undrground storage tanks are measured in millions of tonnes iirc.

Funnily enough, I was wondering the same as I typed it.

I'm not sure how all of this would work, but I was picturing the CAES 'simply' pumping air via a pipe into a hole in the ground. So I suppose for flow batts you'd need actual access to the 'hole' say an old salt mine(?) in order to construct the tanks.

Of course, if the chamber is airtight, then maybe it would be ok for fluids too, so long as they aren't 'nasty' and don't soak into their surroundings. So if two suitable chambers existed next to each other?

Or maybe you could excavate huge holes, build the flow batt chambers, then cover over and use the land above - sports fields, solar farm, park and ride with PV canopies and charge points ...... etc etc.

Clearly, I don't know enough on the subject.


As Moxi suggests, looks like demand, supply and economics will help choose. And I'm just hoping that the list of possible/economic solutions has grown slightly larger.

dan_b wrote: ↑Thu Aug 22, 2024 6:37 pm That Rough gas storage facility is pretty big!

I wonder if it's suitable for CAES, would make a lovely big battery.