I'm not talking about district heating. I'm talking about high temperature storage for conversion back to electricity. Round trip efficiency could be around 40%, better than green hydrogen burned in combined cycle plants.

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bryanlarsen 13 hours ago | parent [-]

Standard Thermal's website's front page only covers heat delivery; did you mean to link to somewhere else?

Those are 2 very different use cases.

Thermal is low rate extraction. It's 1 cycle per year, but the extraction is performed over months so is low rate.

Electricity long term storage is high rate extraction. It's only used a few times a year, but when it is used it needs to cover roughly 100% of the entire grid's needs. I doubt thermal storage is suitable for high rate extraction, but I'd love to be wrong.

Edit: rereading your parent comment you seem to think thermal is suitable for a different use case? Could you elaborate further? When is "prolonged discharge" useful?

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pfdietz 11 hours ago | parent [-]

That's what they're focusing on to start with, but the temperature is high enough to drive heat engines to make power. There's more on the concept at the seed company's (Orca Sciences) web site and at Austin Vernon's blog.

https://www.orcasciences.com/articles/standard-thermal

https://austinvernon.substack.com/p/building-ultra-cheap-ene...

They talk about temperature up to ~600 C, which I believe is limited by the desire to use cheap steal (much hotter and creep becomes a problem). This is also perhaps not coincidentally about the temperature of steam from a coal fired boiler, so one of the eventual goals is to repower retired coal fired power plants with this storage providing the heat instead of coal combustion.

You're right this is not good for something needed "a few times a year" for relatively short periods, for example to cover Dunkelflauten. Combustion of an e-fuel is better for that. But it's well suited to seasonal storage of solar energy, as that would be extracted over months, more or less continuously. The resistive heaters should also be much cheaper per W than electrolyzers.

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bryanlarsen 10 hours ago | parent | next [-]

> But it's well suited to seasonal storage of solar energy, as that would be extracted over months, more or less continuously.

But what is that useful for? During almost all of those months it would be a lot cheaper to use renewables & short term storage. And it's not fast enough for the few days it's not beaten by something cheaper.

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pfdietz 10 hours ago | parent [-]

It's useful for storing cheap solar energy for use in winter. Sizing the solar collectors for winter would require them to be much larger. Basically, this lets 2.5 W of solar in summer deliver 1 W of solar in winter. For a high latitude where the change in insolation is higher than that, this is superior. In Hamburg, for example, insolation varies by more than a factor of 10 from July to December.

Put another way: if you oversize the solar to be adequate in winter, you have enormous amounts of surplus solar in summer. So why not store it?

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bryanlarsen 10 hours ago | parent [-]

> So why not store it?

Because 0.10 $/kWh(th) / 0.4 kWh(e)/kWh(th) is expensive.

	▲	pfdietz 8 hours ago \| parent [-]
		That's the capex for storage capacity. It's amortized over the number of charge/discharge cycles. Divide by 20 or more. It's amazingly cheap, actually.

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skybrian 5 hours ago | parent | prev [-]

I thought that post was interesting when I read it over a year ago, but the startup seems to have gone dark since then.

	▲	pfdietz 5 hours ago \| parent [-]
		They appear to be focusing on Europe, and have raised $11M (or maybe 11M euros, I'm not sure which). There is some favorable buzz in Germany, which makes sense because natural gas has become quite expensive there. https://www.cleanthinking.de/thermischer-erdspeicher-erdhueg...