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US Government funds pilot project for heated sand energy storage

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

#81

Post by usrusr »

scotty79 wrote: post #40
stingraycharles wrote: post #34

Earlier quoted context omitted.

Gravity seems much more natural to me than heat; eg pumping water up a dam and releasing it again when you need the energy. It strikes me that heat has the problem that it always loses energy in its “stable state” because the surrounding environment absorbs the heat, and gravity doesn’t have this problem.

With water you lose some due to evaporation.

With a mineshaft gravity storage you could actually try to spin up a convective loop powered by geothermal that dries the sand over time, allowing you to lift dry sand when charging and abseil heavier wet sand when discharging.

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

#82

Post by bumby »

smallmancontrov wrote: post #70
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.

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

Define "bad enough" in more specific terms.

I believe it largely depends on the application. If you have a lot of waste heat, it's potentially a way to get "free" refrigeration. (e.g., a paper plant that uses a lot of steam can use absorption chillers to make use of waste heat.) If fuel is much cheaper than electricity, it can be economically viable. Peak shaving can save lots of money. etc. But it's probably not competitive purely in terms of energy efficiency or GHG emissions.

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

#83

Post by usrusr »

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…

A very low key variation of heat storage is using a ground-source heat pump in winter and then in the summer using the same heat pump for cooling the house and replenishing the ground source while doing so.

Small ground sources, or ground sources with neighbors too close who do the same, will actually accumulate noticeable ground cooldown from season to season if they are not replenished. Free air conditioning comfort from the replenishing effort, or free replenishing from the air conditioning, you can spin it however you like. It's very low gradient and certainly won't get you through winter without a another power source, but it absolutely is seasonal heat storage.

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

#84

Post by spxneo »

I go to the beach fill up 50 gallon drums with it and then pipe hot water through it so that you can enjoy heat without electricity or gas.

im obsessed with it. i love the way it feels on my body. i take warm sand baths with it. i have cold feet so i use nylon socks, fill it with sand providing endless massage and keeping it warm.

ive yet to try different types of sand from other regions but Canadian beach sand does the job.

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

#85

Post by mecsred »

pfdietz wrote: post #76
mecsred wrote: post #41

Earlier quoted context omitted.

The issue of finding a location that has dramatic elevation change, a basin capable of storing vast amounts of water, and a suitable source/sink for pumping make pumped hydro difficult to deploy. Then there are additional logistics challenges such as environmental damage and proximity to human settlements for maintenance and engineering teams (prior challenges mean you don't really get to select the locations). Heat…

The "vast basin" part of that is an exaggeration. Look at https://www.whitepinepumpedstorage.com/ and the sizes of the upper and lower reservoirs there. This is to be a 8 GWh, 1 GW facility.

"vast" is a pretty non specific word so I can maybe see why you would think that? I feel like it's pretty obvious from context I'm not talking about an inland sea here. The quoted 5000 "acre-feet" in that project is a considerable amount of water for a man-made structure!

Either way, the details page[1] supports all of my above points. It even comments on the page how rare it is to find a suitable site like the one they've chosen.

[1]https://www.whitepinepumpedstorage.com/project-details

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

#86

Post by smallmancontrov »

bumby wrote: post #82
smallmancontrov wrote: post #70

Earlier quoted context omitted.

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

Define "bad enough" in more specific terms. I believe it largely depends on the application. If you have a lot of waste heat, it's potentially a way to get "free" refrigeration. (e.g., a paper plant that uses a lot of steam can use absorption chillers to make use of waste heat.) If fuel is much cheaper than electricity, it can be economically viable. Peak shaving can save lots of money. etc. But it's probably not com…

If I had exact figures, I wouldn't need to ask for anyone's intuition. Thankfully, ChatGPT was willing to work with me, and I will summarize the results here.

Typical refrigeration COP (Coefficients of Performance):

Absorption refrigerator: 0.6-1.2

Compressor refrigerator: 1.5-4.0

Estimated TES economic advantage: 1.1-2.5x

Conclusion: yes, absorption refrigeration is probably inefficient enough to make it a long shot in this application. The only way I can see it becoming viable is if extremely hot TES can completely change the efficiency game, and then only just.

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

#87

Post by spxneo »

AlexAndScripts wrote: post #39
bell-cot wrote: post #2

> The sand used in the thermal energy storage (TES) system could be heated to the range of 1,100 C using low-cost renewable power. [...] when electricity is needed, the system will feed hot sand by gravity into a heat exchanger, which heats a working fluid, which drives a combined-cycle generator. So this is definitely not a "bury your heating coils in a sand dune, then connect..." technology. Quartz melts (per Wikip…

This seems like a really cool technology that also doesn't need much engineering to make it viable. Why isn't it already widespread?

there is a DIY community around it and because it is so simple to make I just dont see any need to rely on commercial solutions. Literally store sand somewhere and heat it, use it for days or months depending on the setup.

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

#88

Post by [deleted] »

smallmancontrov wrote: post #86
bumby wrote: post #82

Earlier quoted context omitted.

Define "bad enough" in more specific terms. I believe it largely depends on the application. If you have a lot of waste heat, it's potentially a way to get "free" refrigeration. (e.g., a paper plant that uses a lot of steam can use absorption chillers to make use of waste heat.) If fuel is much cheaper than electricity, it can be economically viable. Peak shaving can save lots of money. etc. But it's probably not com…

If I had exact figures, I wouldn't need to ask for anyone's intuition. Thankfully, ChatGPT was willing to work with me, and I will summarize the results here. Typical refrigeration COP (Coefficients of Performance): Absorption refrigerator: 0.6-1.2 Compressor refrigerator: 1.5-4.0 Estimated TES economic advantage: 1.1-2.5x Conclusion: yes, absorption refrigeration is probably inefficient enough to make it a long shot…

[deleted]

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

#89

Post by adrian_b »

NavinF wrote: post #48
robviren wrote: post #43

Earlier quoted context omitted.

Gas turbine efficiency targets for combined cycle are targeting 65%, so loss is at least 35%. To me I the loss sucks, but if it can be cheap to build and maintain it matters less. If solar is the energy source and that gets driven cheap enough then that loss could be acceptable.

No way you'll get 65%. This sand won't be stored at the same temperature as a natgas generator's combustion chamber. Efficiency depends on delta T. I'd guess 20%

Nope.

The report says that the sand will be heated up to 1200 Celsius degrees.

This is much higher than the maximum temperature for steam turbines and equal to the temperature of the gas in the best gas turbines.

Therefore they will use a combined cycle, first a gas turbine will use hot air passed through the sand and the exhaust from the gas turbine will produce steam for a chain of steam turbines with decreasing working temperatures.

There should have been no problem in reaching a 65% efficiency for the conversion from heat to electricity, except that between hot sand and a gas burner there is the same difference as between an electric capacitor and a battery, while heat is extracted from the sand, it cools down.

Presumably, when the sand becomes too cold, the gas turbine is bypassed and the hot air just produces steam. When it becomes even colder, I suppose that the first steam turbine is also bypassed and only the low-temperature steam turbines are used.

This will lower the average efficiency, probably to around 50%. If the residual heat (after the steam turbines) had been used for heating or for cooling (i.e. heat-powered air conditioning), the efficiency could have been higher, e.g. over 80% in the beginning, while the sand is still very hot.

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

#90

Post by bumby »

smallmancontrov wrote: post #86
bumby wrote: post #82

Earlier quoted context omitted.

Define "bad enough" in more specific terms. I believe it largely depends on the application. If you have a lot of waste heat, it's potentially a way to get "free" refrigeration. (e.g., a paper plant that uses a lot of steam can use absorption chillers to make use of waste heat.) If fuel is much cheaper than electricity, it can be economically viable. Peak shaving can save lots of money. etc. But it's probably not com…

If I had exact figures, I wouldn't need to ask for anyone's intuition. Thankfully, ChatGPT was willing to work with me, and I will summarize the results here. Typical refrigeration COP (Coefficients of Performance): Absorption refrigerator: 0.6-1.2 Compressor refrigerator: 1.5-4.0 Estimated TES economic advantage: 1.1-2.5x Conclusion: yes, absorption refrigeration is probably inefficient enough to make it a long shot…

The temperature in TFA are outside the range of most commercial absorption chillers, so this is more about making cheap electricity. I would imagine absorption would be more applicable if the same tech was used to generate lower-quality heat that's not suitable for a combined-cycle generator.
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