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
#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 Wikipedia) at 1,713 C. Hotter would obviously be more efficient (basic thermodynamics) - but from the linked govt. report, it sounds like getting usefully hotter would lead to excessive technical problems.
Beyond sourcing the sand (a real issue in many places), this tech sounds incredibly benign, environmentally. Zero-ish rare elements / nasty chemicals / emissions. And the worst-case "melt-down" leaves just a pile of burning-hot sand.
Edit: IANAME (not a Mech. Engineer), but that govt. technical report looks like great stuff if you're seriously into energy storage tech, or just an amateur gearhead. Direct link: https://www.nrel.gov/docs/fy23osti/84728.pdf
Re: US Government funds pilot project for heated sand energy storage
#3Thermal storage works nicely with solar thermal plants. Not so good for direct electricity storage though.
Re: US Government funds pilot project for heated sand energy storage
#4> 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…
Huh, it intuitively seems like piping working fluid to the sand ought to be easier than moving the sand to the working fluid. Is the moving-sand approach fundamentally desirable thing (I can't imagine why) or is it just a simplification for the proof of concept?
Re: US Government funds pilot project for heated sand energy storage
#5> 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…
Huh, it intuitively seems like piping working fluid to the sand ought to be easier than moving the sand to the working fluid. Is the moving-sand approach fundamentally desirable thing (I can't imagine why) or is it just a simplification for the proof of concept?
I suspect it's because the thermal conductivity of sand isn't that great. If you've got your working fluid running through pipes embedded in hot sand, the system is likely bottlenecked on getting the heat energy from the main body of the mass through the cooler sand closest to the pipes.
Do it the other way and the enormous surface area is working for you, so you can presumably get the energy out arbitrarily fast (or, at least, that's no longer the bottleneck).
Re: US Government funds pilot project for heated sand energy storage
#6> 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…
Huh, it intuitively seems like piping working fluid to the sand ought to be easier than moving the sand to the working fluid. Is the moving-sand approach fundamentally desirable thing (I can't imagine why) or is it just a simplification for the proof of concept?
Storing & moving fine-grained bulk dry stuff is really old, cheap, & reliable technology - think of grain silos.
Re: US Government funds pilot project for heated sand energy storage
#7I 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 need and how big a sand battery would it take.
I am not planning on doing this, but explaining it on a scale that I can relate to would be helpful, because I know, for example, that said house can store a winter's worth of heat in a 1000 gallon oil tank, or small woodshed big enough for 6 cords of wood.
Re: US Government funds pilot project for heated sand energy storage
#8Earlier quoted context omitted.
Huh, it intuitively seems like piping working fluid to the sand ought to be easier than moving the sand to the working fluid. Is the moving-sand approach fundamentally desirable thing (I can't imagine why) or is it just a simplification for the proof of concept?
I suspect it's because the thermal conductivity of sand isn't that great. If you've got your working fluid running through pipes embedded in hot sand, the system is likely bottlenecked on getting the heat energy from the main body of the mass through the cooler sand closest to the pipes. Do it the other way and the enormous surface area is working for you, so you can presumably get the energy out arbitrarily fast (or…
The thought occurs that if that is indeed the problem, you could attack it by mixing a metal in with the sand. You'd still get the thermal mass, but conductivity would no longer be a problem as long as it had been in a liquid phase at least once.
Re: US Government funds pilot project for heated sand energy storage
#9Does this differ in design from the Finish sand battery from 2 years ago: https://news.ycombinator.com/item?id=32006791
Re: US Government funds pilot project for heated sand energy storage
#10Undecided did a couple of videos on this technology. It seems quite useful for heat storage - as other commenters have noted, it isn't that efficient for pure electric electric storage.
* How a Sand Battery Could Change the Energy Game - https://www.youtube.com/watch?v=G6ZrM-IZlTE
* Sand Batteries for Home Usage - https://www.youtube.com/watch?v=KVqHYNE2QwE