Storing heat in sand?

[Mart Hale]

I made a video of my progress.... I have been tied up with gardening I may have more time this winter to move forward.

This video is quality about sand battery storage ->

This is my progress I have made with my sand battery.

Testing different types of sand batteries.. Results of testing I have done.

My progress and videos I have gained info from: Overview of the sand battery: 1752 A DIY Sand Battery - The Theory, Practice And Use https://www.youtube.com/watch?v=Icai6OOIh2M Using the waste heat of

rumble.com

On my thread on Permies on this subject I ran into a guy who uses this to cook food for a school in Kenya.

 

[orangezero]

Watched your video, thank you for sharing. I like the idea of using your sand to get water out of wood or to make quick lime.

Cleaning out the garage today, and found two bags of sand. At the very least I should do an "experiment" where I heat the sand enough to dry it out...

I know this is the "sand thread" but a serious disadvantage of sand compared to water; sand doesn't magically get pumped into my house when I turn a faucet handle.

 

[Mart Hale]

Watched your video, thank you for sharing. I like the idea of using your sand to get water out of wood or to make quick lime.

Cleaning out the garage today, and found two bags of sand. At the very least I should do an "experiment" where I heat the sand enough to dry it out...

I know this is the "sand thread" but a serious disadvantage of sand compared to water; sand doesn't magically get pumped into my house when I turn a faucet handle.

Yeah, that is why I do both... After my batteries are charged from my solar panels, my system auto magically flips a relay to my hot water heater and it heats my hot water. I have had to only use propane for back up for a few days.... Storing heat in water is indeed the way to go.

 

[Michelle Konzack]

I'm quite sure it's physically impossible to achieve a heater greater than the source..without more work input, say, from a compressor or something. This is a fundamental limit if you're using hot water as the heat source. If it was a steel bucket of sand, you could of course just place it over a fire and it will get hotter than that.


Hmmm.. if you can seal an engine, there will be sealing materials out there that can withstand very high temperatures. But you are right that heat is a concern and does deserve some engineering attention. You would have to make your vessel out of uniform material, so that it all expands evenly.


Is there any need for a pressurised vessel? It could be vented, unless I'm missing the glaringly obvious? I had in mind something like a steel drum? You can get some that secure the top on with a band clamp, allowing you to remove the lid to add fittings to it easily and place items on the inside.

Regarding mold, you would have the option of treating the water of course - though many cooler towers do just dump the water periodically as far as I know. The addition of chlorine, or keeping a low pH, to prevent stuff growing are options is potentially damaging to process equipment - certainly the mild steel drum as above would not fare well in either of those situations.

Simply add Glycole to it (minimal 20%) to prevent mold and reduce rusting of the barrel

 

[Michelle Konzack]

Sounds like you are off by about factor of five.
Specific heat of Water is 1 btu/lbs/F but sand is only 1/5 of that. https://www.engineeringtoolbox.com/specific-heat-capacity-d_391.html

Water is hard to beat as heat storage medium. Easily available, easy to heat and extract the heat from and excellent heat capacity per weight and volume.

This was my first idea too,

But it would require under my Greenhouse 5 bunker cells 4,0x6,8m, insulated with 50mm EPS and then a bag of HDPE or EDPM, which can be even ordered from Chinaman for a resonable price. Heated up to 70degC, you can store per Meter hight roughly 1.250kWh of energy. The make it 2m high and you have already 2.500kWh. My Greenhouse is 21,5m long and I can have 5 cells...

1.250kWh at a temperatur difference of 40degC (70-30 because of the underfloor heating system)

12,5MWh of Energy.

On top of it put 10cm of EPS and 50cm of sand as insulator.

This should be enough to keep the Greenhouse over the winter nicely warm and additional you can heat your house.

Hahaha, I need roughly 50kWh a day to heat my house at -20degC and the Water Storrage would keep my house 250days warm MINUS losses for the Greenhouse.

And there is another option, by using washed Gravel together with the water.

Mixing Sand with Oil give a nice problem with the authorities.