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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

#101

Post by ajb »

robviren wrote: post #43
datameta wrote: post #38

Earlier quoted context omitted.

The sand is gravity-fed into a heat exchanger which transfers the heat to a fluid that drives a combined cycle turbine, in this case. I'm curious what the conversion loss is here. To add to that, what is the energy expenditure of building the battery compared to sand containment plus heat exchanger and turbine - i.e. mining, refining, transport, manufacture, delivery?

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.

IIUC there is a physical limit from thermodynamics in converting back, based on the temperature. So when efficiencies are quoted, it could be either the proportion of input energy retrieved, or the proportion of the theoretical max efficiency achieved. I'm guessing you're quoting the former?

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

#102

Post by dagurp »

jarito wrote: post #10

Undecided 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

I like this one too https://youtu.be/KVqHYNE2QwE?si=GM80NBsE_Ms8oT-n

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

#103

Post by jaggederest »

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.

Half of all primary energy usage is for heating purposes. Heat is the best format to displace, as well, since a significant chunk of all that primary energy use is direct fossil fuel combustion right now.

Especially since you can use heat to drive a heat pump, which ends up actually achieving above unity efficiency effectively since the heat input is used to move additional heat from the environment. Even if it's inefficient, if the heat would otherwise have been wasted, it's a net benefit.

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

#104

Post by specialist »

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.

Thermovoltiacs, converting heat dirctly to electricity. IIRC, At least one of the "box of rocks" thermal battery startups (interviewed on the Volts podcast) intends to have both a two way heat exchanger and electricity play.

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

#105

Post by Tagbert »

jaggederest wrote: post #103
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.

Half of all primary energy usage is for heating purposes. Heat is the best format to displace, as well, since a significant chunk of all that primary energy use is direct fossil fuel combustion right now. Especially since you can use heat to drive a heat pump, which ends up actually achieving above unity efficiency effectively since the heat input is used to move additional heat from the environment. Even if it's ine…

The Pernell with heat compared to electricity is portability. It is easy and efficient to transmit electricity but heat is not

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

#106

Post by pimlottc »

Tagbert wrote: post #105
jaggederest wrote: post #103

Earlier quoted context omitted.

Half of all primary energy usage is for heating purposes. Heat is the best format to displace, as well, since a significant chunk of all that primary energy use is direct fossil fuel combustion right now. Especially since you can use heat to drive a heat pump, which ends up actually achieving above unity efficiency effectively since the heat input is used to move additional heat from the environment. Even if it's ine…

The Pernell with heat compared to electricity is portability. It is easy and efficient to transmit electricity but heat is not

> The Pernell with heat

Did you mean to type "problem"?

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

#107

Post by kaliszad »

Using heat for energy storage and then converting back to electricity are ok if you don't care about cost of electricity, the facility or the maintenance. In basically all other cases they are some of the worst ideas. We have much better technologies that are known for the last ~50 years. They are simple, they do work and have volumetric energy density within striking distance of fossil fuels however don't include carbon. Just reading the expired US patents would reveal that.

I guess there are worse things to invest into but come on, we teach the physics needed to comprehend why this is a bad idea in high school.

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

#108

Post by SECProto »

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.

> This is to be a 8 GWh, 1 GW facility

That is big for time-shifting daily energy usage, but way too small for seasonal energy storage

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

#109

Post by kaliszad »

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…

When you can store electricity more directly instead of the (inefficient) conversion to and from heat it is just crazy to not do so. With electricity, thanks to heat pumps you can "move" heat instead of producing it, which makes heating a lot less expensive since the "efficiency" can often reach 300-400%. For that reason you want to keep using electricity for as long as possible in most cases. Of course, if you have a huge source of cheap heat the equation might change. In such cases you might still want to use some of the heat to get higher temperature heat. (https://en.wikipedia.org/wiki/Absorption_heat_pump)

And no, it will not help too much if you use a heat pump before storing the energy in this facility. You still have huge conversion losses, the volume for low-temperature heat storage will be huge. If you want high temperature storage your heat pumps will need more stages and run less efficient.

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

#110

Post by pfdietz »

SECProto wrote: post #108
pfdietz wrote: post #76

Earlier quoted context omitted.

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.

> This is to be a 8 GWh, 1 GW facility That is big for time-shifting daily energy usage, but way too small for seasonal energy storage

Right. PHES is not a good fit for seasonal storage.
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