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US Government funds pilot project for heated sand energy storage

pv-magazine.com

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Re: US Government funds pilot project for heated sand energy storage

#61

Post by inetknght »

chii wrote: post #33
retrac wrote: post #28

Heat storage has an aspect that was counterintuitive to me, but follows from basic geometry. It benefits greatly from large scale, since the ratio of the volume to surface area [1] decreases the larger you make a container. Accordingly, if a heat tank is large enough, the surface area becomes negligible relative to its volume, and it, in effect, becomes well-insulated by its own mass. For really big tanks, like might…

> better than most rechargeable battery technologies you can't compare heat storage to electricity, because you can't directly use heat for anything else other than for heating, where as electricity can be used to perform motion. If you used heat storage as a battery, there's an additional loss when converting to electricity. However, if the heat is cheap/free during summer, storing it for winter is a no brainer.

> you can't directly use heat for anything else other than for heating, where as electricity can be used to perform motion.

Maybe today. But NASA has some interesting metal tires [0][1] which might change your mind for the future.

[0]: NASA info https://technology.nasa.gov/patent/LEW-TOPS-99

[1]: Neat youtube vid: https://www.youtube.com/watch?v=vSNtifE0Z2Q

Re: US Government funds pilot project for heated sand energy storage

#62

Post by leecarraher »

it seems the primary benefit for sand over water, is a 1:10 operating temp vs. 5:1 specific heat. So it depends on whether the added complexity of working with a hotter, solid is worth not having to build a facility that is 2x bigger. Are there other benefits I'm missing, or is this concrete block gravity storage vs pumped water storage, all over again?

Re: US Government funds pilot project for heated sand energy storage

#63

Post by zardo »

ejb999 wrote: post #7

I am really intrigued by using sand for energy storage - what I don't get (not my field) is given a typical 2000sf house, located in the colder part of the country as an example, how much heat could be stored for how long? i.e. is it even feasible to use solar panels to power resistance heaters all spring/summer/fall, to save up enough heat to keep a house warm for the entire winter? if so, how many panels would you…

https://www.renewableenergymagazine.com/storage/first-commer...

This is 8MWh (of heat), the 1000 gallon oil tank is about 40MWh.

Something like a two story basement filled with sand at the maximum temperature of a home oven is probably in the ballpark.

Re: US Government funds pilot project for heated sand energy storage

#64

Post by quickthrowman »

chii wrote: post #33
retrac wrote: post #28

Heat storage has an aspect that was counterintuitive to me, but follows from basic geometry. It benefits greatly from large scale, since the ratio of the volume to surface area [1] decreases the larger you make a container. Accordingly, if a heat tank is large enough, the surface area becomes negligible relative to its volume, and it, in effect, becomes well-insulated by its own mass. For really big tanks, like might…

> better than most rechargeable battery technologies you can't compare heat storage to electricity, because you can't directly use heat for anything else other than for heating, where as electricity can be used to perform motion. If you used heat storage as a battery, there's an additional loss when converting to electricity. However, if the heat is cheap/free during summer, storing it for winter is a no brainer.

> you can't compare heat storage to electricity, because you can't directly use heat for anything else other than for heating

You can use heat to generate steam that can spin turbines to perform work. But, I am not sure if it’s practical to generate steam from a sand battery, my background is in electrical construction. I’m guessing the sand battery isn’t nearly as hot as a natural gas steam boiler’s combustion chamber.

https://www.johnsoncontrols.com/en_sg/hvac-equipment/chiller...

Re: US Government funds pilot project for heated sand energy storage

#65

Post by adverbly »

retrac wrote: post #28

Heat storage has an aspect that was counterintuitive to me, but follows from basic geometry. It benefits greatly from large scale, since the ratio of the volume to surface area [1] decreases the larger you make a container. Accordingly, if a heat tank is large enough, the surface area becomes negligible relative to its volume, and it, in effect, becomes well-insulated by its own mass. For really big tanks, like might…

I also think this is a very interesting approach to take. This might be a pipe dream but it would be really cool if we could just turn a big chunk of desert into a battery by plumbing some heat exchangers through it.

Or maybe just putting a gigantic Fresnel lens in the desert and pointing it at the ground. I almost wish someone would try this just to see what would happen.

Re: US Government funds pilot project for heated sand energy storage

#69

Post by cogman10 »

politician wrote: post #51
chii wrote: post #33

Earlier quoted context omitted.

> better than most rechargeable battery technologies you can't compare heat storage to electricity, because you can't directly use heat for anything else other than for heating, where as electricity can be used to perform motion. If you used heat storage as a battery, there's an additional loss when converting to electricity. However, if the heat is cheap/free during summer, storing it for winter is a no brainer.

Nit: Rechargeable batteries have a loss when converting the chemical energy stored inside to electricity. There’s no free lunch.

Yes, but for Lithium and sodium batteries you are looking at 90+ efficiency.

Re: US Government funds pilot project for heated sand energy storage

#70

Post by smallmancontrov »

chii wrote: post #33
retrac wrote: post #28

Heat storage has an aspect that was counterintuitive to me, but follows from basic geometry. It benefits greatly from large scale, since the ratio of the volume to surface area [1] decreases the larger you make a container. Accordingly, if a heat tank is large enough, the surface area becomes negligible relative to its volume, and it, in effect, becomes well-insulated by its own mass. For really big tanks, like might…

> better than most rechargeable battery technologies you can't compare heat storage to electricity, because you can't directly use heat for anything else other than for heating, where as electricity can be used to perform motion. If you used heat storage as a battery, there's an additional loss when converting to electricity. However, if the heat is cheap/free during summer, storing it for winter is a no brainer.

Is absorption refrigeration bad enough to be permanently non-viable here? Or is it "just" a matter of scaling a niche technology?
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