Thermal Sand batteries: cheap but I question the efficiency

[EbS-P]

Insulated piles of sand heated with resistive heaters to 500dF. Air heat exchanger. Seems simple enough to DIY and scale down.

Need to do some math. To figure out system size. Drying the sand would be important.

(broken link removed to https://www.euronews.com/green/amp/2022/07/06/sand-batteries-could-be-key-breakthrough-in-storing-solar-and-wind-energy-year-round)

 

[ABMax24]

Insulated piles of sand heated with resistive heaters to 500dF. Air heat exchanger. Seems simple enough to DIY and scale down.

Need to do some math. To figure out system size. Drying the sand would be important.

(broken link removed to https://www.euronews.com/green/amp/2022/07/06/sand-batteries-could-be-key-breakthrough-in-storing-solar-and-wind-energy-year-round)

It wouldn't even have to be sand, almost any material can work. The issue is where do you get the 500c temps to heat that sand?

I've posted this before, but it has been done up here using wells to store energy in the earth:

Drake Landing Solar Community

 

[ABMax24]

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[Corey]

Well, the article says 500°C which is more like ~930°F... so think more 'molten lead' vs 'oven on broil'. Interesting concept. While 'most any material can work', it seems like there would be some 'ideal' point of many factors... cost, availability, thermal conductivity, specific heat capacity, material density, temperature tolerance, etc.

Many of these factors are at odds... eg - high specific heat capacity would actually point to things like hydrogen, helium, lithium, etc. But good luck getting enough density there to do any good. Water might be cheap, dense and have moderate heat capacity, but good luck with anything over 212°F. A steel block might seem good from a density point, but less than half the heat capacity of water. So overall, sand might not be a bad compromise of all factors. Plus, at 930°F, it would most certainly be self drying! Just be sure to provide some way for the vapor to escape!

 

[woodgeek]

Storage in a geological repository works well (low loss rate) as the system gets large... but obv you need to avoid any aquifers.

I have often thought we should get cheap fusion power by blowing up H-bombs deep in certain geological formations, and then tapping out the heat for 50 years thereafter. Cost per watt-hour pencils out close to existing geothermal (large H-bombs being pretty cheap). This would be a non-renewable use of Lithium. LOL.

But I estimated that a decent size plant (1 GW output for a few decades) would require an explosion big enough to rival the largest recorded earthquakes. So still need to design the 'shock absorber' for that.

And I suppose the NIMBY's will give me a hard time too.

Might be a good idea for Mars.... I'll shoot a message to Elon.

 

[begreen]

What could possibly go wrong?

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