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Comment by ambicapter | Hacker News Reader

Glad I finally have a name (flow battery) for a concept that I've been wanting to be made for a long time (liquid batteries).

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The idea has been kicking around for a while because it's superficially appealing.

Benefits:

- you can store huge amounts of energy in relatively cheap tanks

- because the + and - storage are physically separate, self discharge can be very low

- those two make it appealing for long term storage

Downsides:

- reagents end up being some combination of expensive (vanadium), poisonous, corrosive, etc. resulting in safety overhead

- requires specialized plumbing. This is very expensive. Ultimately this is the issue with nuclear as well, every joint requires careful inspection

- does not scale down nicely to house sizes

- ultimately likely to get economically lapped by incremental improvements to lithium or sodium battery chemistry

- the charge/discharge cell requires a liquid/liquid membrane separator which can exchange charge; these tend to have lifetime issues.

I’ve been sending these guys $10 a month for a while now. Thir test cell is chemistry agnostic, and I think they have tried several ferrous solutions. The membrane issue is not that big of a deal it seems if you aren’t trying to miniaturize the device- separator material used in car batteries can be used to good effect and it’s easy to replace if needed.

https://fbrc.dev/

I love this kind of work. They had an ambitious timeline and the last entry was at the beginning of this year -- do you have a sense if they are still going strong?

I’m really not sure. Things like this often run out of steam, get picked up later, etc as the interest and the lives of the people change, new people come, old ones move on. We will see.

It's not a new idea, they already exist.

A huge redox-flow battery is currently under construction in Switzerland https://www.swissinfo.ch/eng/climate-solutions/switzerland-b...

A vanadium one, which (as mentioned in the piece) is symmetric.

The 'Just Have a Think' channel did a video on the Swiss battery here - https://www.youtube.com/watch?v=CPAFeTvjVzY

The advantage of vanadium batteries, as I understand it, is that leakage does not corrupt the system. The vanadium gets converted to the right chemical species on either side.

"We will be able to inject or absorb up to 1.2 gigawatt-hours (GWh) of electricity in a few milliseconds"

1.2GWh in a few milliseconds? I'm pressing (X) to doubt.

An energy comparison: a semi tanker of gasoline hauls about 300 MWh of chemical energy potential.

That must be the total capacity and response time.

Nope. Total capacity is going to be 2.1GWh. The peak power will be 1.2GW, and milliseconds is the response time of the system. [1]

[1] https://flexbase.ch/en

I would assume it's a typo on GWh. It seems probable to me that the battery can supply/absorb 1.2GW on a millisecond response time, so it would be able to fully charge/discharge in a little less than 2hours, supplying/absorbing 1.2GW with 2.1GWh total capacity.

They in theory combine well with pump-station powerplants where the medium is also the medium?

Flow batteries specifically are liquid, or more accurately fluid, there can be gas flow batteries, where the chemical sub-products are pumped in and out of the cells.

They tend to be large utility scale things that look like a chemical plant, correction, are a chemical plant with electrical storage as the product.

Liquid electrolyte batteries have been a thing from when batteries have been invented. But not much work has been done to really scale it up.

You might find the home made batteries of this guy interesting as well https://www.youtube.com/watch?v=eq7fR9ISuCw

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