Home thermal energy storage
Discussion
On the one hand, cool. On the other hand, slightly disappointed when the title reads "thermal energy storage" and the content reads "water". Look into sand batteries.
"Sand batteries heat up to very high temperatures, typically reaching around 500°C to 600°C (932°F to 1112°F), storing energy from renewables like wind and solar in the sand or crushed soapstone, and then releasing it as hot air, water, or steam for district heating or industrial processes. The exact heat depends on demand, but these systems are designed to store thermal energy efficiently for long periods, with output temperatures ranging from 60°C to 400°C."
"Sand batteries heat up to very high temperatures, typically reaching around 500°C to 600°C (932°F to 1112°F), storing energy from renewables like wind and solar in the sand or crushed soapstone, and then releasing it as hot air, water, or steam for district heating or industrial processes. The exact heat depends on demand, but these systems are designed to store thermal energy efficiently for long periods, with output temperatures ranging from 60°C to 400°C."
Hoofy said:
On the one hand, cool. On the other hand, slightly disappointed when the title reads "thermal energy storage" and the content reads "water". Look into sand batteries.
"Sand batteries heat up to very high temperatures, typically reaching around 500°C to 600°C (932°F to 1112°F), storing energy from renewables like wind and solar in the sand or crushed soapstone, and then releasing it as hot air, water, or steam for district heating or industrial processes. The exact heat depends on demand, but these systems are designed to store thermal energy efficiently for long periods, with output temperatures ranging from 60°C to 400°C."
You're not going to get the multiplier effect of a heat pump with that sort of set up. A water tank is exactly the right solution for a house being heated by cheap electricity. It's cheap and scales up. The bigger the better for thermal efficiency. It's also far better than using a battery to try to store the electricity. One colossal winning feature of a thermal store is that you can shove heat into it from as many sources as you can be bothered to plumb in ... heat pump, biomass burner, direct solar, your old gas or oil boiler for backup. And the other is that they can dump a huge amount of power into your house when you want it."Sand batteries heat up to very high temperatures, typically reaching around 500°C to 600°C (932°F to 1112°F), storing energy from renewables like wind and solar in the sand or crushed soapstone, and then releasing it as hot air, water, or steam for district heating or industrial processes. The exact heat depends on demand, but these systems are designed to store thermal energy efficiently for long periods, with output temperatures ranging from 60°C to 400°C."
Water is nice and cheap, easy to store, easy to heat evenly, easy to extract heat from or just use directly, and has great heat capacity.
What you're limited on is how hot you can make it, but that also helps with the storage as no exotic containers and simple to insulate.
If your demand is all going to be thermal and to drive output at normalish 55/60 type degrees for heating etc then it's a fine simple solution.
If you've got the space and the free power why not?
What you're limited on is how hot you can make it, but that also helps with the storage as no exotic containers and simple to insulate.
If your demand is all going to be thermal and to drive output at normalish 55/60 type degrees for heating etc then it's a fine simple solution.
If you've got the space and the free power why not?
cptsideways said:
A big tub of candle/paraffin wax I think is even more storage capacity.
Only half the specific heat capacity vs water, vastly more expensive, and who wants thousands of litres of hot paraffin nearby?Water is great stuff for storing energy if you can accept the temperature range.
Fantastic DIYing. Seriously cool.
What's the plan for the thermal store? Are you planning to DIY that as well? 10 tonnes is "quite a lot". I can see there are polymer vertical tanks of that capacity for a little over a thousand quid, only rated to 40C, put maybe you could push that up to your target temp with a bit of bracing. I'm guessing an uninsulated polymer tank lagged in several foot of fibre glass inside a kingspan box with a watertight roof, weatherboarding and a trellis up the front to make it look pretty in the garden might work.
What's the plan for the thermal store? Are you planning to DIY that as well? 10 tonnes is "quite a lot". I can see there are polymer vertical tanks of that capacity for a little over a thousand quid, only rated to 40C, put maybe you could push that up to your target temp with a bit of bracing. I'm guessing an uninsulated polymer tank lagged in several foot of fibre glass inside a kingspan box with a watertight roof, weatherboarding and a trellis up the front to make it look pretty in the garden might work.
I believe phase change heat storage is available now, which stores the same amount of energy in a much smaller space, using a wax.
For heating I’d be inclined to run UF heating in a thick concrete slab, heat the slab on cheap overnight electricity, and let it emit all day, sort of giant economy 7 heater.
The only slight downside is it tends to be colder overnight so HP efficiency would be a lower, but if your leccy is 25% of day rate that doesn’t matter too much.
For heating I’d be inclined to run UF heating in a thick concrete slab, heat the slab on cheap overnight electricity, and let it emit all day, sort of giant economy 7 heater.
The only slight downside is it tends to be colder overnight so HP efficiency would be a lower, but if your leccy is 25% of day rate that doesn’t matter too much.
AnotherUsername said:
Inbox said:
I think it would a good idea to know where the water would go if the tank failed catastrophically, not sure if you have any neighbours close by but 10,000L of hot water on the loose won't make you any friends.
OMG I hadn't considered that. Having it above the children's nursery was a terrible idea after all!
For starters its a plastic tank, the water will be hot with an element of thermal cycling up near the max rated temperature of the tank, plastic softens with heat and lastly it is holding 10 tonnes of water (about a third of a swimming pool).
Definitely worth a phone call to the tank manufacturer to check your intended use is okay.
Definitely worth a phone call to the tank manufacturer to check your intended use is okay.
Edited by Inbox on Saturday 6th December 20:16
ATG said:
Hoofy said:
On the one hand, cool. On the other hand, slightly disappointed when the title reads "thermal energy storage" and the content reads "water". Look into sand batteries.
"Sand batteries heat up to very high temperatures, typically reaching around 500°C to 600°C (932°F to 1112°F), storing energy from renewables like wind and solar in the sand or crushed soapstone, and then releasing it as hot air, water, or steam for district heating or industrial processes. The exact heat depends on demand, but these systems are designed to store thermal energy efficiently for long periods, with output temperatures ranging from 60°C to 400°C."
You're not going to get the multiplier effect of a heat pump with that sort of set up. A water tank is exactly the right solution for a house being heated by cheap electricity. It's cheap and scales up. The bigger the better for thermal efficiency. It's also far better than using a battery to try to store the electricity. One colossal winning feature of a thermal store is that you can shove heat into it from as many sources as you can be bothered to plumb in ... heat pump, biomass burner, direct solar, your old gas or oil boiler for backup. And the other is that they can dump a huge amount of power into your house when you want it."Sand batteries heat up to very high temperatures, typically reaching around 500°C to 600°C (932°F to 1112°F), storing energy from renewables like wind and solar in the sand or crushed soapstone, and then releasing it as hot air, water, or steam for district heating or industrial processes. The exact heat depends on demand, but these systems are designed to store thermal energy efficiently for long periods, with output temperatures ranging from 60°C to 400°C."
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