US Government funds pilot project for heated sand energy storage

Post by politician » Thu, Apr 04, 2024, 4:37 PM UTC

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.

Post by regularfry » Thu, Apr 04, 2024, 4:40 PM UTC

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%

Post by sandworm101 » Thu, Apr 04, 2024, 5:03 PM UTC

mecsred wrote: post #41

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.

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…

Post by westmeal » Thu, Apr 04, 2024, 5:17 PM UTC

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.

Post by sgc » Thu, Apr 04, 2024, 5:27 PM UTC

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.