this post was submitted on 30 Sep 2023
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A solar concentrator.
The collected thermal energy can then be conducted into a working fluid whose thermal expansion can be leveraged to push pistons which crank a driveshaft (like a steam engine) or blast in high pressure jets through rotor blades (such as a turbine). This rotary kinetic motion can then turn a generator.
It's also possible to set up a thermocouple to generate voltage. It doesn't pack a lot of 'oomph' but it's allegedly low maintenance, and only as unreliable as the weather is (instead of creating additional unreliability on top of weather fluctuations.)
Means exist to store the thermal energy in a well insulated 'reservoir' containing of a large volume of some working fluid with a high thermal capacity and bleeding that thermal energy out as needed, but ... well... heat is already waste. my gut can be very wrong but nevertheless my gut still tells me that if i want to store energy that is collected as heat, it is not ideal to leave it as heat, because heat is waste and heat dissipates. The impulse I have is to try to convert it to another form of potential energy that has some kind of metastable storage state. I mean shit, even if it's hoisting a heavy object to the top of a slope so i can extract the kinetic energy as it rolls back down, the heavy object at the top of that slope isn't going to rapidly cease to exist before my eyes just because i left it alone; as long as it's chocked and secured, it will be ready to roll (literally) when I need it to and not before (brooking some direct physical disruption).
so... big fuckin batteries, or that prodigious concentrated heat can be used to thermally depolymerize some organic waste like plastic to turn it into a slurry of monomers that can be refined into a synthetic internal combustion fuel. Or a shit ton of compressed air in a tank, i dunno. Because batteries aren't very easy for someone to just cobble together out of consumer grade materials but most hardware stores have compressed air tanks available and shit.
Keeping the energy thermal avoids a conversion step, and hence one area of inefficiency, especially as we use a lot of our energy for heating. There's been some interesting progress on heat batteries which would pair well with a solar concentrator.
The funny thing is, converting to electricity and running a heat pump can be more efficient than simply using the heat, as long as the outside temperature is not too low
Air transfer heat pumps just seem like poor planning to me. Ground or groundwater heat sink is so much better. Some initial expense when building a house but works forever.
Air medium heat pumps: Let's heat the house to 70F using 20F air Let's cool the house to 70F using 110F air
Groundwater medium heat pumps: Let's heat the house to 70F using 60F groundwater when it's 20F out Let's cool the house to 70F using 60F groundwater when it's 110F out
Forever lol. Those ground installs need to be replaced at least every 20 years with new drilling. Air to water heat pump is way nicer when you have the space.
It's because the sand is at 600c which would wreak havoc if you had water pumping through the tubing. Air is cheaper to do handle at those temperatures.
Yet it's still more efficient than using the heat directly to heat
Wow that's some cool tech, cheap simple and you can store heat for months.
Extremely interesting!
You make some good points but heat can be stored as thermal mass. The losses in converting the solar heat into another type of energy storage like batteries negates simply storing it in a large vat of sand for example.
the kinds of lovely insights i can usually find on lemmy 💜
Heat isn't waste. It's considered waste in a lot of situations because it's a byproduct that is sometimes difficult to get rid of, but that doesn't make it inherently useless.
Otherwise I agree that it's maybe not the most intuitive type of energy storage but if those large solar-thermal power plants use it to generate power throughout the night there's gotta be something to it. I imagine it's also something that scales well because the area grows slower than the volume.
in a Missouri USA they pump water up a hill then drain it back when demand increases, it's a rather large system. In Al'Abama an individual is using underground salt water tanks to store hot an cold salt water for HVAC and electric on his farm.
personally.... I use solar electric to drive a 10k/btu AC and scavenge the unit's waste heat as a food dehydrator, storing food is also storing solar energy and the AC keeps is pleasant indoors.
Note: Haven't actually read the article, but in general the idea of heat storage is a tried and true energy storage method.