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Comment by dmix | Hacker News Reader

Vandium Redox Batteries [1] sound like they have a bright future, I recently came across a startup building home kits which have a significantly longer lifespan than Tesla Powerpacks (allegedly):

https://www.startengine.com/storen-technologies

There's a huge plant being built in Dalian, China with 200MW/800MWh with Vanadium (for comparison Tesla Australia plant is 129MW/100MWh with Lithium-ion with plans to double scale this year, but currently only powers 30k homes which isn't much)

https://electrek.co/2017/12/21/worlds-largest-battery-200mw-...

Wikipedia has a nice list of largest battery deployments in the world:

https://en.wikipedia.org/wiki/List_of_energy_storage_project...

https://en.wikipedia.org/wiki/Vanadium_redox_battery

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Sorting by capacity on the energy storage wiki, I had no idea that there's a 2.8 GWH compressed air plant in the US!

Same here. Looks like it's a combination gas + compressed air generator.

It's a bit of funny accounting. If someone says they have an energy storage facility with a capacity of 2.8GWh, you would expect to be able to store there 2.8 GWh worth of electricity and then be able to get back a large part of it, let's say 90%. This is how you think of a battery-based storage system. The facility described here is anything but that: you inject in a cavern a large quantity of air, and then, when needed, you get this air back under pressure and feed it to an old-fashioned gas-powered generator, who will burn old-fashioned gas for 26 hours and generate 110 MW electricity (26h * 110MW = 2.860 GWh). The generator will have higher efficiency, but pumping air at 1100 psi into a cavern doesn't happen for free, so all in all, it's not very clear how to compare this with a Tesla's Powerpack in Australia [1], which is listed at 129 MWh.

[1] https://www.tesla.com/blog/tesla-powerpack-enable-large-scal...

Interestingly the heat output of the gas turbine is also used to pre-heat the released air; it looks like this combo is what drives a lot of the gas+CAES efficiency.

So you can't easily subtract gas from the equation.

What's the liquidity expected out of these power plants, e.g. how fast is the expected turnaround between pumping in and liquidating pumped energy?

15 minutes.

Redflow of australia actually makes zinc bromide flow batteries now. It has not been a financial success to put it mildly... Much as I like the idea of flow batteries I think their window of opportunity may be closing.

How much are the batteries? Why do you think the window is closing?

Because if lithium becomes established as cheap and good enough then there will less incentive to develope other technologies.

Redflow I believe costs as much as a lithium battery but claims to degrade less and be able to be 100% discharged. In practice they have proven hard to manufacture reliably or competively. They seemed better when they stayed theoretical. Share price is down about 95%...

The big advantage of flow batteries for large scale long term storage is to expand capacity you just need larger tanks and more chemicals. With lithium-ion you need to build more batteries.

They have two big problems:

1. lack of efficiency - only 80% roundtrip, much less than Lithium.

2. they go completely offline for periodic maintenance. This is done automatically by Redflow, but the loss of availability is problematic in some circumstances.

Lithium seems to have won the high efficiency niche, but there's probably room for lower efficiency flow type batteries as long as they're super cheap.

Agreed, but unfortunately, they are not cheaper and I'm not sure if its economies of scale or something else

Are you saying they tried out Vanadium before Zinc Bromide or are you just lumping them both together?

I'm lumping them together as flow batteries... Mix two liquids get electricity. Add electricity and they separate again. No memory effect, last as long as the pumps. Always liked the idea of replacing my heating oil tank with one. Not sure its ever going to happen though.

You mean flow batteries in general or just vanadium redox? Because if it's in general, why would you think its opportunity window is closing?

Closed batteries have no inherent advantage on large scale stationary projects, only problems. The only gain they bring is that you can ride on the scale of mobile applications.

I'm waiting for the old car batteries to start coming online, I think that will kill anything else for stationary systems, and will just get bigger.

You can't discharge and recharge a lead acid car battery very many times before it loses capacity.

I didn't believe it was necessary to specify this, but I meant Lithium car batteries, not lead.

Ah, sure, that makes more sense. I have to retrain myself to think of "car batteries" as something other than a heavy, plastic box of acid.

If we're talking about battery technologies that haven't (yet) achieved liftoff, then Ambri[1] high-temp liquid metal cells is another.

[1] https://ambri.com

I've watched some of Sadoway's talks and they're definitely interesting. I'm curious to see if they play out favorably in the market. They're stationary-only from what I can tell, but if they're more robust that Li-ion the power-grid folks will love them.

> Vandium Redox Batteries sound like they have a bright future

... and have had, since at least the 1990s.

My understanding is vanadium costs too much, so there is a lot of research into cheaper chemistries.

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