Sand battery heater

[BBSA]

I've been thinking about using a geyser element powered by spare solar energy to heat sand in a bucket, which could then be used to warm a small room later. It sounds like a promising idea, but I'm unsure about how long the element would last under such conditions. Has anyone tried this or have any thoughts on the longevity of the heating element?

 

[BBSA]

Here is a video on it

 

[Gordon_R]

Sounds like a really bad idea IMO. You need a whole degree in heat transfer and thermodynamics to make it work. Sand is cheap but not ideal, and you need fans and other equipment to get the heat out when you need it.

 

[BBSA]

Sounds like a really bad idea IMO. You need a whole degree in heat transfer and thermodynamics to make it work. Sand is cheap but not ideal, and you need fans and other equipment to get the heat out when you need it.

Will a Thermal Fan like this help:

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[BBSA]

I have an off-grid solar system, but my batteries is fully charged by 11 AM, meaning any electricity produced after that is essentially wasted. While I could buy additional batteries, they're quite expensive, which is why I thought the sand heater might be a good alternative.

 

[HobieDave]

Will a Thermal Fan like this help:

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Looking through some of the comments, it does not look good.

 

[HobieDave]

Hot sand for hot winters – tomorrow

Wouldn’t it be great if the summer heat could be recovered for heating in winter? Scientists worldwide are researching this. tomorrow presents two novel means of storage: sand and acid.

schaeffler-tomorrow.com

 

[Gordon_R]

Will a Thermal Fan like this help:

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Doing it properly requires a lot of infrastructure:

Batsand - Household sand battery for Heat Storage (TES)

Heating battery works with solar panels to charge during summer and heat the house during winter. Decrease your heating costs with a sand battery.

www.batsand.com

 

[BBSA]

 

[TheChamp]

Why not heat water instead of sand? Same concept that's used in a car? I am sure it will also needs a lot of fine tuning but it's a tried and tested method.

 

[BBSA]

Why not heat water instead of sand? Same concept that's used in a car? I am sure it will also needs a lot of fine tuning but it's a tried and tested method.

Sand can retain heat for a longer period compared to water.

 

[TheChamp]

Sand can retain heat for a longer period compared to water.

Good point, water needs continous power input to maintain the heat and no retention to speak of.

 

[Gordon_R]

Sand can retain heat for a longer period compared to water.

Sand is a better insulator than water, but has less heat capacity than the same volume of water. A geyser has both an insulating layer, and a water outlet. A pile of sand needs some mechanism to get the heat out, otherwise it is a rather non-linear source of warmth.

Once again there are industrial solutions, but the infrastructure requirements are prohibitive:

Product - Caldera

A Comprehensive Solution for Anytime Green Heat Caldera’s Storage Boilers provide cost-effective, on-demand heat for industrial applications. While they can tap into grid electricity, our primary focus is on utilizing affordable, nearby solar power. This approach helps companies decarbonise...

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[HobieDave]

Sand is a better insulator than water, but has less heat capacity than the same volume of water. A geyser has both an insulating layer, and a water outlet. A pile of sand needs some mechanism to get the heat out, otherwise it is a rather non-linear source of warmth.

Once again there are industrial solutions, but the infrastructure requirements are prohibitive:

Product - Caldera

A Comprehensive Solution for Anytime Green Heat Caldera’s Storage Boilers provide cost-effective, on-demand heat for industrial applications. While they can tap into grid electricity, our primary focus is on utilizing affordable, nearby solar power. This approach helps companies decarbonise...

www.caldera.co.uk

They say the sand goes up to 500+ degrees Celsius - water you are limited to just under 100 degrees - you don't want to play with steam.

But have seen videos where they do thermal heat storage burying pipes underground and recirculating water through underfloor pipes.

 

[netstrider]

Reminds me of my dad's geyser setup.

 

[leon.davibe]

I've been thinking about using a geyser element powered by spare solar energy to heat sand in a bucket, which could then be used to warm a small room later. It sounds like a promising idea, but I'm unsure about how long the element would last under such conditions. Has anyone tried this or have any thoughts on the longevity of the heating element?

another type of element maybe like the stove spiral elements someone posted about
the geyser element is designed to be in contact with water to extract the heat quick , without quick transfer the element outer material tears if it heats up to much

 

[BBSA]

another type of element maybe like the stove spiral elements someone posted about
the geyser element is designed to be in contact with water to extract the heat quick , without quick transfer the element outer material tears if it heats up to much

A Ceramic heating elements would probably be better than a standard element.

 

[leon.davibe]

I have an off-grid solar system, but my batteries is fully charged by 11 AM, meaning any electricity produced after that is essentially wasted. While I could buy additional batteries, they're quite expensive, which is why I thought the sand heater might be a good alternative.

yea lots are going wasted especially if you have low baseload
i have a small array (3.65kwp) so could easily keep it busy all day to get an idea what percentage is lost
naturally you gotta calculate your baseload for the rest of the day from time battery is full to see actual

ie if battery is full 11 i produced 32% of possible
+ lets say base load is example 300w x 7hrs means another 2kwh which is 7.6%of day total +whatever you can time shift naturally
hence total for the day is 39.6% of total possible

don't charge the battery in the morning and then use the excess when battery is full
try and use as much of your time shifted load in the morning preventing battery charging
as the battery can accept the peak mid day load not so easy

naturally this is based on my area and azzimuth doing the same test for your area is recommended
ie get some heaters contribute to global warming for a day keep battery away from full at all costs to get a profile for your system

time​	kwh produced​	cumulative % to x time​
07:00:00​	0.12​	0.46%​
07:30:00​	0.41​	1.56%​
08:00:00​	0.95​	3.63%​
08:30:00​	1.75​	6.68%​
09:00:00​	2.79​	10.65%​
09:30:00​	3.97​	15.15%​
10:00:00​	5.33​	20.34%​
10:30:00​	6.81​	25.99%​
11:00:00​	8.38​	31.98%​
11:30:00​	10​	38.17%​
12:00:00​	11.8​	45.04%​
12:30:00​	13.5​	51.53%​
13:00:00​	15.2​	58.02%​
13:30:00​	17​	64.89%​
14:00:00​	18.6​	70.99%​
14:30:00​	20.2​	77.10%​
15:00:00​	21.6​	82.44%​
15:30:00​	22.9​	87.40%​
16:00:00​	24​	91.60%​
16:30:00​	24.9​	95.04%​
17:00:00​	25.6​	97.71%​
17:30:00​	26​	99.24%​
18:00:00​	26.2​	100.00%​

 

[TheChamp]

It should also help to take the element with its control mechanism, in my mind heating gradually and in a controlled manner would be beneficial compared to just the element going from zero to full blast.

I am not sure but I think those hotplates had a heat switch of sorts that turned in off to protect the element.

 

[Lupus]

Sand can retain heat for a longer period compared to water.

The opposite actually, remember the desert gets extremely cold at night, sand is terrible at retaining heat. Great at absorbing it

Why does the sand on a beach cool down at night more quickly than the ocean water? | Socratic

The thermal conductivity and heat capacity of sand are less than those of water, so it does not absorb as much heat, and releases it more quickly. Four factors are involved: The mass of the substance, the interface to another medium (air), the heat capacity of the substance, and the heat...

socratic.org

A Sand Battery: Not obviously a great idea.

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