Sand battery - thermal mass proto type.

https://www.amazon.com/Barocook-Fuel-Pack-Set-10-Piece/dp/B00N1CI1FU?crid=Z81DAL9H70RH&keywords=barocook&sprefix=barocook%2Caps%2C121&sr=8-3&language=en_US&ref_=as_li_ss_tl&th=1


They sell quicklime packets on amazon....


https://youtu.be/CXwJ0N6wUYY

 Meals sold with these packets......

Now, how do i make my own?

Long term energy storage......

https://www.snappyheat.com/how-it-works.html

This is close to what I am looking to do,    store heat chemically as this hand warmer does, and after use have it go back to my solar heated oven to re-charge....

I want to cook with this method.         I have ordered quicklime to start testing.

I have found how to make my own food cooking with quicklime and aluminum powder...

https://survival-kompass.de/en/make-your-own-heating-pad-at-home/

I am impressed with this stove setup.     Excellent way of using sand battery...

Yesterday  my sand battery with the dutch oven, insulated with fiberglass hit over 600 F!          This morning the next day the lowest temp it was at was 234 F!    

The temp is going up again,   looks like I will have this well over 200 F  for over 24 hours!      

This is with 3 solar panels  220 watts each...    I have about 1 5 gal bucket of sand in the mix.              

I am now thinking about what if I used an aluminum puck in the dutch oven so that I could pull it out and cook on it......

These temps are with partially cloudy days,   next week they are calling for clear sunny days....

Now I am thinking of moving forward with building a sand battery the size of a IBC container 250 gal.......  

I would then use the power I am not using after my batteries are charged to dump into that to store heat.....  

The present setup should give me a good idea of how to scale up....    

Today hit the highest temp ever,  over 803 deg F....

It was a bright sunny day,  I had replaced the wire with silicon covered wire..

Also I removed some of the sand and I put a 12 inch long rail road rail in the dutch oven with some sand inside.

I believe if I opened this up and put a pot on the top with water it would instantly boil......

I am most curious how long this will take to cool off......    

The real questions I have now is how much mass can I add to this equation, as bricks or steel, and how does that affect the cool off time?      

Hitting this temp blew me away.     Tomorrow is another sunny day,   I imagine I will have some residual heat and the temp will get higher.

I put a 2.5 gal pot of water on my sand battery, and I watched the temp shoot up. Made it to about 180 deg.... as it is looks like I could put on 1.5 gal and it would make it to boiling...


One graph is the 2.5 gal pot, the other is the thermo coupler in the sand.

I was surprised that the pot did not get hotter....

Think I will try again with 1/2 the amount in the water pot.

I found this interesting, I did not remove the 2 1/2 gal pot from last night but covered it over still sitting on the sand / steel base. I removed the water when it started to boil, but I found that the temp of the thermocoupler was surprisingly high... I have also noticed that i was loosing a good deal of heat from the top so I added a bit more fiberglass insulation on top, after removing the boiling water. Plan to recharge this and try again with 1/2 of the amount of water...

The last 5 days temps have been over 250 deg 24 hours a day.


I want to add more metal bolts to the thermal mass to see what effect it would have....      I really don't want to go higher on the temp as I will be entering the range that I will be damaging the fiberglass.

As I think about this perhaps I use a layer of sand  on the inside, then outside of that metal, then fiberglass... so that I can obtain higher temps, and that I can add more coils

Found another sand battery experiment.    Thought I would post here...

Painful not being able to contact those on youtube.......   because you deleted your google account, but glad I see what they are doing.

I had a request to make a video of my present sand battery setup.    I thought I would take the time to review where I have been, and ideas of where I am going with this project.

https://rumble.com/v4d95if-testing-different-types-of-sand-batteries..-results-of-testing-i-have-done..html

The Rumble video did not resovle the thumb nail trying again with bitchute.

https://www.bitchute.com/video/7o2FwRdm6Kii/

Odysee

https://odysee.com/@Marthale7:f/sandbattery1-2024-02-13_18.22.49:7?r=EA8qJECQFAWVJwDNfim4NmBXt5rt7WCZ

From Gab

https://gab.com/HaleMart7/posts/111926973098948083

Since I added 5 lbs of bolts to thermal battery temps have not been as high as before. Min temp is right around 300 deg. amazes me days at a time above 300 degrees 24 /7…

Hi.  I am very happy to find this chat

We are building the same thing but for schools so they can cook and not use any biomass. Schools will have zero cost zero pollution cooking

Economics on this are pretty awesome.  Schools in central Africa spend $1500usd a year. Varies greatly to feed 300 students buy wood


A sand battery cooker costs $5000 to build and will run for 20 years.


We will begin installing April 2024


The system is a cubic yard of sand mixed with shredded aluminum cans  24” of mineral wool around that.  Stucco then shreded plastic trash 24” thick and more stucco

10kw of panels.   The cooks use 25 gallons of water a day to boil beans corn rice etc.

Our system is charged to 400c in 5 days


We have 100 gallons of water I. The insulation too but in a region so it does not boil

Cook comes in uncovers the hot cooking pots adds food and adds hot water from the tanks. The pots are surrounded by the 400c sand and aluminum.  The food cooks for as long as needed. 1/2 the 25 gallons goes up as steam

The system consumes / losses about 50 kWh per day. The power from pv ranges from 16 to 80.   The sand and water storage buffers us through the cloudy days

30% of the world uses wood to cook. Expensive polluting and causes deforestation. We are working to switch the schools and institutions over to solar to save them money. Stop the air pollution and deforestation

Any suggestions please let us know!  Thanks. Dan wastefree23.org

Dan Wastefree wrote:Hi.  I am very happy to find this chat

We are building the same thing but for schools so they can cook and not use any biomass. Schools will have zero cost zero pollution cooking

Economics on this are pretty awesome.  Schools in central Africa spend $1500usd a year. Varies greatly to feed 300 students buy wood


A sand battery cooker costs $5000 to build and will run for 20 years.


We will begin installing April 2024


The system is a cubic yard of sand mixed with shredded aluminum cans  24” of mineral wool around that.  Stucco then shreded plastic trash 24” thick and more stucco

10kw of panels.   The cooks use 25 gallons of water a day to boil beans corn rice etc.

Our system is charged to 400c in 5 days


We have 100 gallons of water I. The insulation too but in a region so it does not boil

Cook comes in uncovers the hot cooking pots adds food and adds hot water from the tanks. The pots are surrounded by the 400c sand and aluminum.  The food cooks for as long as needed. 1/2 the 25 gallons goes up as steam

The system consumes / losses about 50 kWh per day. The power from pv ranges from 16 to 80.   The sand and water storage buffers us through the cloudy days

30% of the world uses wood to cook. Expensive polluting and causes deforestation. We are working to switch the schools and institutions over to solar to save them money. Stop the air pollution and deforestation

Any suggestions please let us know!  Thanks. Dan wastefree23.org

Hi Dan,

Thank you for your reply  to this thread.      

The major reason I started this thread on multiple platforms was to connect to others who are exploring this concept and see what they have learned via trial and error of how to improve the storage of heat in thermal mass like sand, or other materials  for long term storage of heat.

Sounds like you have a very interesting project there.     I would like to know how many solar panels you are using, and what you are using for the heat source,  my self I am using a stove top burner.   If you have any pictures of your setup or could post a video that would be most helpful to understand your setup.


400c  would be 752 deg F  (  Fahrenheit )    So we are hitting the same temp high temp range.     My system lacks proper insulation and I have plans on how I can correct that.       The last insulation I added greatly improved the temps I had for longer duration.


I have been adding more metal to my sand battery as it does seem to help things along very interesting that you are mixing Alum with sand...

Please let us know with your progress with your project next month.


Cheers,

Mart

Most of the reason I have been doing my experiments was laying the ground work for a thermal mass  and resistive loads that would match the configuration of my present dump loads of my 4000 watt solar.

I have the bottom axel of an old trailer  on my property that is doing nothing...   I was thinking of cutting it up and making that my thermal mass as it is dense, heavy, and I could put  stove top coils all around it,   and the amount of insulation would not be as great.    

I was thinking this axel could be on the bottom of an open air space that would be an oven  perhaps a cob oven  with dry sand all around for insulation.     The walls of which I was thinking could be skids taken apart to hold a huge mass of dry sand in, and covered with a tarp to keep dry.

This has been my brain storm..

Still testing out ideas.

A friend sent this to me..

https://www.youtube.com/watch?v=KVqHYNE2QwE

Interesting, I did giggle at the sand worm comment!

Mart Hale wrote:A friend sent this to me..

https://www.youtube.com/watch?v=KVqHYNE2QwE

great video

David Baillie wrote:

Mart Hale wrote:A friend sent this to me..

https://www.youtube.com/watch?v=KVqHYNE2QwE

great video

I normally don't like his videos as he talks about things you can't purchase or get.        But this video was far better in that these were real companies and the advantages / problems with sand batteries were shown.

The use of a vacuum thermos to contain the sand caught my attention,   I have been searching to find the largest thermos one can buy, so far the one that I have found is 30 littler that is for liquid nitrogen, but my search continues.

I have been thinking of heating sand up to 500 deg inside a vacuum thermos, but I don't know if the thermos can take those temps,   so I will need to do more research before I try anything like that.

I was thinking a heat pipe put into a thermos then packed with sand,  with a coil in the thermos for warter heat transfer,  heat pipe goes into a rocket stove,  harvest the heat,   then take  a shower, or store the heat for the next morning....

We are boiling 100 liters a day to cook for 300 so we are using 12kw of panels because rven though the system is near the equator they city does not have many sunny days.

Since we are feeding a school full of children there can be no days with a lack of heat

We are use the coiled cooktop electric elements. When they are new they are easy to unbend and straighten out

The sand is working great for a slow cook.  The cooks who will be using this system are use to a fast heat and boil with the wood fire they have been using    To keep the cooks happy:) we are going to pump 200c oil to the area next to the pot sides and bottom to get more heat faster.  

Will post all the details next month

Well I’m glad I stumbled across your post! 👍
I’m actually in the process of an experiment for making a larger 6x8x2 sand battery that will be connected to 790 watts of solar to 50ft 24v heating cable. The object is to store heat under a a small greenhouse to release it at night with a pipe manifold in the sand to transfer heat out when needed.
 So far I have dug my hole and constructed my greenhouse but haven’t started filling yet until I finish several small bench tests with different sand and materials.
I have done several small test with different sand and sand with granite gravel in a small soup cans heated in the oven but soon will conduct a bit larger one to resemble the same shape, insulation and 1/8th size scale that I can convert my findings.
 So far I have found that 1.5 part fine dry sand like masonry sand or beach sand mixed with 1 parts silica sand (pool filter sand) mixed into 1/2”-3/4” granite gravel has held heat the longest. I found that silica sand (6.5-12.5 W/mK) has a higher thermal conductivity than sand by itself (.15-.25 W/mK) and the granite gravel retains the heat longer.
I’m only trying heat ranges around 200°F because I don’t want to damage my heating cable.

Mart Hale wrote:I had a request to make a video of my present sand battery setup.    I thought I would take the time to review where I have been, and ideas of where I am going with this project.

https://rumble.com/v4d95if-testing-different-types-of-sand-batteries..-results-of-testing-i-have-done..html

Very impressive temperatures! 👍
I have read that brick does hold heat for a very long time if you’re interested to try instead of steel. It was a bit too pricey for my budget to try with my greenhouse heating application. You may want to look into rock wool insulation for your higher temperatures, I was debating on using this but knowing that it will compress with the weight of sand I opted to stay with foam board thus another reason why I’m aiming for lower temperatures.
I must admit that I was impressed with how my little test to add silica sand (pool filter sand) made a difference which is another option you could try since silica can handle higher heat better.
Keep up the great work! 👍
If you have any suggestions for my application would be greatly appreciated. 🙏

Solid carbon thermal battery....

https://www.youtube.com/watch?v=cwDly9pjSJg

I never heard of a thermal solar panel before.....  40%   efficient!..

Dan Wastefree wrote:We are boiling 100 liters a day to cook for 300 so we are using 12kw of panels because rven though the system is near the equator they city does not have many sunny days.

Since we are feeding a school full of children there can be no days with a lack of heat

We are use the coiled cooktop electric elements. When they are new they are easy to unbend and straighten out

The sand is working great for a slow cook.  The cooks who will be using this system are use to a fast heat and boil with the wood fire they have been using    To keep the cooks happy:) we are going to pump 200c oil to the area next to the pot sides and bottom to get more heat faster.  

Will post all the details next month

Thank you Dan for the update...

Please do keep us updated.      Any pictures you can send  of your solar panels, your setup would be great as well.

The oil should indeed make for fast heat transfer.        

You might want to look into  "retention heat cooking"...         If you were to use the heat of the system to heat the food to boiling for 20 min, then insulate the pot  for 4 hours,    you could cook even more,  may take longer to cook but you would save much energy in the  heat battery.

Just an idea.

Cheers.

Jim Griff wrote: Well I’m glad I stumbled across your post! 👍
I’m actually in the process of an experiment for making a larger 6x8x2 sand battery that will be connected to 790 watts of solar to 50ft 24v heating cable. The object is to store heat under a a small greenhouse to release it at night with a pipe manifold in the sand to transfer heat out when needed.
 So far I have dug my hole and constructed my greenhouse but haven’t started filling yet until I finish several small bench tests with different sand and materials.
I have done several small test with different sand and sand with granite gravel in a small soup cans heated in the oven but soon will conduct a bit larger one to resemble the same shape, insulation and 1/8th size scale that I can convert my findings.
 So far I have found that 1.5 part fine dry sand like masonry sand or beach sand mixed with 1 parts silica sand (pool filter sand) mixed into 1/2”-3/4” granite gravel has held heat the longest. I found that silica sand (6.5-12.5 W/mK) has a higher thermal conductivity than sand by itself (.15-.25 W/mK) and the granite gravel retains the heat longer.
I’m only trying heat ranges around 200°F because I don’t want to damage my heating cable.

Hi Jim,

Glad to hear that you are become one of the "sand people'   lol visions of walking in single file from Star Wars comes to mind....      

Yeah I have been gathering all sorts of data from multiple sources on the storage of heat in thermal mass.    I have dumped many of those links in this thread.       All kinds of of options on this have sort of stymied my progress as each new video I watch on thermal storage unlocks even more ways we can use thermal storage.  

But to be reasonable, I have limited myself to items that I have here for the most part  extra solar panels, and I did need to by some wire from the solar panels to the battery, and destroyed several heating elements  to find ways to use them that don't destroy them.

Something you might want to consider is to recycle the heat you are releasing into the greenhouse and capturing from the sun.      some people take  a pipe to the top of the green house, and pull that air down and snake it around in the grow beds below to do two things.     1) lowers the temp of the green house.     2) banks the heat for later....    Just a suggestion to think about.      Other considerations is to create hot compost and use black soldier flies to constantly turn the compost giving even faster creation of heat from the compost...

Love to hear about your testing of different sand,    I used sand from my yard after I put it thru  my rocket oven to dry it.       My neighbor told me that is not sand, that I should be using construction sand....       It did get me to wonder what different types of sand would test as.       This is why I bought a thermo coupler  to record temp changes and see how each change I made how it affected the overall result.

Please do share pics of your testing and everything of your setup if you are open to that,    I have been wanting to open source the ideas so others can take the ideas that work best for them and run with them.

I understand you heating limits,    right now I can't go higher because once I get past 1000  deg I will start burning the fiberglass insulation.         I have several ideas in mind, but I really don't know what is possible with the setup I have, I have over 4,000 watts of solar that I can dump into this but I am in no way ready  in terms of building a structure that can capture that much heat, and then to  convert that to a form that is useful....

My best thoughts are to make charcoal that I can run my small engines from a wood gas generator I have made...   I have to make a list of things I want to try then prioritize .....

Thanks for sharing your scope of your project and feel free to share your progress or questions.

Jim Griff wrote:

Mart Hale wrote:I had a request to make a video of my present sand battery setup.    I thought I would take the time to review where I have been, and ideas of where I am going with this project.

https://rumble.com/v4d95if-testing-different-types-of-sand-batteries..-results-of-testing-i-have-done..html

Very impressive temperatures! 👍
I have read that brick does hold heat for a very long time if you’re interested to try instead of steel. It was a bit too pricey for my budget to try with my greenhouse heating application. You may want to look into rock wool insulation for your higher temperatures, I was debating on using this but knowing that it will compress with the weight of sand I opted to stay with foam board thus another reason why I’m aiming for lower temperatures.
I must admit that I was impressed with how my little test to add silica sand (pool filter sand) made a difference which is another option you could try since silica can handle higher heat better.
Keep up the great work! 👍
If you have any suggestions for my application would be greatly appreciated. 🙏

The battle I have seen is this....      Sand does not transfer heat very well  so if you are trying to extract heat slowly over a long period of time it is awesome.        I have found it works awesome to diffuse heat  under my cast iron pans so that I get an even heating of the cast iron,   the pizzas have come out great...

The more dense the thermal mass is the more heat it can store....     The trick seems to be is to look at all of the choices you have for thermal mass and mix them to a ratio that  stores the amount of heat your heating apparatus  makes,  and gives it off at the rate you want it to give off.        So  this is why I am doing a mixture of sand  to metal in my testing metal being very dense.

I am amazed at  what I have created so far.       This unit  with the solar panels can keep temps above 300 deg for multiple days at a time.       And....  this was done at WINTER time   ;-)      

I have garden projects that simply must be done now and I have had to put this project on the back burner...           I  do hope to come back and  begin testing on new designs once I set priorities of what I want to achieve.

Mart Hale wrote:

Jim Griff wrote: Well I’m glad I stumbled across your post! 👍
I’m actually in the process of an experiment for making a larger 6x8x2 sand battery that will be connected to 790 watts of solar to 50ft 24v heating cable. The object is to store heat under a a small greenhouse to release it at night with a pipe manifold in the sand to transfer heat out when needed.
 So far I have dug my hole and constructed my greenhouse but haven’t started filling yet until I finish several small bench tests with different sand and materials.
I have done several small test with different sand and sand with granite gravel in a small soup cans heated in the oven but soon will conduct a bit larger one to resemble the same shape, insulation and 1/8th size scale that I can convert my findings.
 So far I have found that 1.5 part fine dry sand like masonry sand or beach sand mixed with 1 parts silica sand (pool filter sand) mixed into 1/2”-3/4” granite gravel has held heat the longest. I found that silica sand (6.5-12.5 W/mK) has a higher thermal conductivity than sand by itself (.15-.25 W/mK) and the granite gravel retains the heat longer.
I’m only trying heat ranges around 200°F because I don’t want to damage my heating cable.

Hi Jim,

Glad to hear that you are become one of the "sand people'   lol visions of walking in single file from Star Wars comes to mind....      

Yeah I have been gathering all sorts of data from multiple sources on the storage of heat in thermal mass.    I have dumped many of those links in this thread.       All kinds of of options on this have sort of stymied my progress as each new video I watch on thermal storage unlocks even more ways we can use thermal storage.  

But to be reasonable, I have limited myself to items that I have here for the most part  extra solar panels, and I did need to by some wire from the solar panels to the battery, and destroyed several heating elements  to find ways to use them that don't destroy them.

Something you might want to consider is to recycle the heat you are releasing into the greenhouse and capturing from the sun.      some people take  a pipe to the top of the green house, and pull that air down and snake it around in the grow beds below to do two things.     1) lowers the temp of the green house.     2) banks the heat for later....    Just a suggestion to think about.      Other considerations is to create hot compost and use black soldier flies to constantly turn the compost giving even faster creation of heat from the compost...

Love to hear about your testing of different sand,    I used sand from my yard after I put it thru  my rocket oven to dry it.       My neighbor told me that is not sand, that I should be using construction sand....       It did get me to wonder what different types of sand would test as.       This is why I bought a thermo coupler  to record temp changes and see how each change I made how it affected the overall result.

Please do share pics of your testing and everything of your setup if you are open to that,    I have been wanting to open source the ideas so others can take the ideas that work best for them and run with them.

I understand you heating limits,    right now I can't go higher because once I get past 1000  deg I will start burning the fiberglass insulation.         I have several ideas in mind, but I really don't know what is possible with the setup I have, I have over 4,000 watts of solar that I can dump into this but I am in no way ready  in terms of building a structure that can capture that much heat, and then to  convert that to a form that is useful....

My best thoughts are to make charcoal that I can run my small engines from a wood gas generator I have made...   I have to make a list of things I want to try then prioritize .....

Thanks for sharing your scope of your project and feel free to share your progress or questions.

Sand man!😆 Good one!👍
I have heard about taking hot air from the greenhouse and sending it to the ground which I probably will do after finding out how much the solar heating cable does. I believe the manufacturer told me the cable I got can handle up to 400° before it starts getting damaged so I might have to get a thermocoupler to keep an eye on the sand/gravel temperatures. The compost one will take up to much room in the greenhouse plus creates a lot of mold which I’ll want to stay away from that one.
For density I have lots of granite boulders that I pulled out while digging the hole under the greenhouse and many more in my wife’s flower gardens. I’m thinking of putting them on the bottom of the hole after insulating and snaked the heat cord between them before starting to filling a layer with the sand/gravel mix, then the pipe manifold with more sand on top.
I was thinking of using pavers to top it off so some heat could radiate up but perhaps not a good idea since the heat would make the greenhouse to hot during the day so I’ll probably just use foam board and plywood.
I hear you on the garden chores because I’m falling behind on that as well, of course it doesn’t help with all the rain we have been getting where I live. I’ll eventually get my battery completed and make a video so I can share with you.
Any way best of luck with the garden chores!

Mart Hale wrote:Today was a sunny day I was able to test my setup with the addition of fiberglass insulation.

temps ranged  better.     I went from the old standard of  200 - 340 deg  for 6.5 hours   to now     200 - 400 degrees for 8 - 9 hours.......    


So.........     having this as a base, I now move to my next level with this....

Storing this heat for long term......    

I plan to take quicklime   add it to water and release the heat to make slate lime......

Then taking the slate lime  I will put it into this cooker  and attempt to remove the water and create quicklime again....

The idea is to take the quicklme  and put it into a bowel  inside another bowel  to heat that water as needed,  as quicklime releases large amount of heat in a short amount of time.....     Thus one could in theory cook a meal in a few minutes with the heat exchanged heat,  then use the solar panels to recharge the lime....        I also believe I could do this with the rocket stove,   also considering using a vacuum water removing process.

I do like this progress,  slowly getting results I can now turn into usable results.

Hey Mart, BiggKidd here you know that stuff can be a bit dangerous if you mishandle it in the least little way so use a hefty dose of caution!

Jim Griff wrote:

Mart Hale wrote:

Jim Griff wrote: Well I’m glad I stumbled across your post! 👍
I’m actually in the process of an experiment for making a larger 6x8x2 sand battery that will be connected to 790 watts of solar to 50ft 24v heating cable. The object is to store heat under a a small greenhouse to release it at night with a pipe manifold in the sand to transfer heat out when needed.
 So far I have dug my hole and constructed my greenhouse but haven’t started filling yet until I finish several small bench tests with different sand and materials.
I have done several small test with different sand and sand with granite gravel in a small soup cans heated in the oven but soon will conduct a bit larger one to resemble the same shape, insulation and 1/8th size scale that I can convert my findings.
 So far I have found that 1.5 part fine dry sand like masonry sand or beach sand mixed with 1 parts silica sand (pool filter sand) mixed into 1/2”-3/4” granite gravel has held heat the longest. I found that silica sand (6.5-12.5 W/mK) has a higher thermal conductivity than sand by itself (.15-.25 W/mK) and the granite gravel retains the heat longer.
I’m only trying heat ranges around 200°F because I don’t want to damage my heating cable.

Hi Jim,

Glad to hear that you are become one of the "sand people'   lol visions of walking in single file from Star Wars comes to mind....      

Yeah I have been gathering all sorts of data from multiple sources on the storage of heat in thermal mass.    I have dumped many of those links in this thread.       All kinds of of options on this have sort of stymied my progress as each new video I watch on thermal storage unlocks even more ways we can use thermal storage.  

But to be reasonable, I have limited myself to items that I have here for the most part  extra solar panels, and I did need to by some wire from the solar panels to the battery, and destroyed several heating elements  to find ways to use them that don't destroy them.

Something you might want to consider is to recycle the heat you are releasing into the greenhouse and capturing from the sun.      some people take  a pipe to the top of the green house, and pull that air down and snake it around in the grow beds below to do two things.     1) lowers the temp of the green house.     2) banks the heat for later....    Just a suggestion to think about.      Other considerations is to create hot compost and use black soldier flies to constantly turn the compost giving even faster creation of heat from the compost...

Love to hear about your testing of different sand,    I used sand from my yard after I put it thru  my rocket oven to dry it.       My neighbor told me that is not sand, that I should be using construction sand....       It did get me to wonder what different types of sand would test as.       This is why I bought a thermo coupler  to record temp changes and see how each change I made how it affected the overall result.

Please do share pics of your testing and everything of your setup if you are open to that,    I have been wanting to open source the ideas so others can take the ideas that work best for them and run with them.

I understand you heating limits,    right now I can't go higher because once I get past 1000  deg I will start burning the fiberglass insulation.         I have several ideas in mind, but I really don't know what is possible with the setup I have, I have over 4,000 watts of solar that I can dump into this but I am in no way ready  in terms of building a structure that can capture that much heat, and then to  convert that to a form that is useful....

My best thoughts are to make charcoal that I can run my small engines from a wood gas generator I have made...   I have to make a list of things I want to try then prioritize .....

Thanks for sharing your scope of your project and feel free to share your progress or questions.

Sand man!😆 Good one!👍
I have heard about taking hot air from the greenhouse and sending it to the ground which I probably will do after finding out how much the solar heating cable does. I believe the manufacturer told me the cable I got can handle up to 400° before it starts getting damaged so I might have to get a thermocoupler to keep an eye on the sand/gravel temperatures. The compost one will take up to much room in the greenhouse plus creates a lot of mold which I’ll want to stay away from that one.
For density I have lots of granite boulders that I pulled out while digging the hole under the greenhouse and many more in my wife’s flower gardens. I’m thinking of putting them on the bottom of the hole after insulating and snaked the heat cord between them before starting to filling a layer with the sand/gravel mix, then the pipe manifold with more sand on top.
I was thinking of using pavers to top it off so some heat could radiate up but perhaps not a good idea since the heat would make the greenhouse to hot during the day so I’ll probably just use foam board and plywood.
I hear you on the garden chores because I’m falling behind on that as well, of course it doesn’t help with all the rain we have been getting where I live. I’ll eventually get my battery completed and make a video so I can share with you.
Any way best of luck with the garden chores!

Oh yes another way of going about the job....

I forgot to mention earth tubes.      Look up "citrus in the snow"   on youtube and see how that guy grows citrus in Nebraska.        If one can use the earth temp stored heat, one can keep a green house above freezing,    if one can do that, then one can grow a citrus crop with only using the heat of the ground.        the only thing you have to do is keep the fan turning to move the air in the earth tubes to exchange with the air in the greenhouse...       Just another way of keeping the green house warm enough so it does not freeze.....

larry kidd wrote:

Mart Hale wrote:Today was a sunny day I was able to test my setup with the addition of fiberglass insulation.

temps ranged  better.     I went from the old standard of  200 - 340 deg  for 6.5 hours   to now     200 - 400 degrees for 8 - 9 hours.......    


So.........     having this as a base, I now move to my next level with this....

Storing this heat for long term......    

I plan to take quicklime   add it to water and release the heat to make slate lime......

Then taking the slate lime  I will put it into this cooker  and attempt to remove the water and create quicklime again....

The idea is to take the quicklme  and put it into a bowel  inside another bowel  to heat that water as needed,  as quicklime releases large amount of heat in a short amount of time.....     Thus one could in theory cook a meal in a few minutes with the heat exchanged heat,  then use the solar panels to recharge the lime....        I also believe I could do this with the rocket stove,   also considering using a vacuum water removing process.

I do like this progress,  slowly getting results I can now turn into usable results.

Hey Mart, BiggKidd here you know that stuff can be a bit dangerous if you mishandle it in the least little way so use a hefty dose of caution!

Ha hey BigKidd,

Yeah, I work only with small amounts of the qucklime at a time.        I have not had much success with that project, but at least failing is a direction ???        But yes there is a way to work with quicklime and water that one needs to be aware of when playing with it.        Sheilds up, steady as we go.

Mart that is a very good video with citrus in the snow. 👍
I wish I had the land to do something like that but I live in a small city with very little land but I still manage to grow lots of vegetables during the summer and raise quail for meat and eggs because they don’t take up much space.
I would like to grow during the winter in my small 6x8 greenhouse and wanted to dig as deep as possible in the ground but rocks and ledge stoped me at 2 feet which is the reason why I’m attempting a sand/gravel battery under the greenhouse. 🤞
 I do intend to insulate my north and west walls in the greenhouse and try to double layer the south and east clear walls which should make some improvements.
I very ambitions get more done with the greenhouse but we’re in for another 4 days straight of rain 🌧️ 😒 and I really want to put dry sand in the greenhouse than wet.

Hello.  We here at wastefree23.org have finalized the design. I will post video of it work next week

The larger the system the better it works because of heat retention in the sand heat bank

Our application is using pv to heat sand. Then the sand to heat a pot with food. Beans rice etc.

30% of the world uses wood to cook. So everyone is better of if they can use solar

Our final solution is to braze a 1/4” diameter stainless steel tube to the outside of a pot. Low temp brazing with aluminum/zinc for heat transfer.    A little water is dropped in the tube in the sand. It turns to steam and then coils around pot. As it condenses it looses a lot of heat that goes into pot.  For a 25 gallon pot we will be able to brig that to a boil in 30 minutes.   Everything has a a lot of insulation.  The hot water from the steam stays beer the heat bank so heat loss is minimal


This system will cost about $6000 to build labor and material in the 30% of the work with low income.  Many of these 2 billion people spend $1000 or $2000 a year for wood to feed the kids at school. This system will replace that expense. And after the third year no more fuel cost:).

Plus these schools are burning 50 or 100 pounds of wood a day.  If we can install this in a few thousand schools. That is a lot of trees not cut down. And a lot of smoke not put in the air. And a lot of cooks who won’t be breathing the smoke:).  

Interesting take on sand battery,   PDF attached....

Very useful to compare the heat ability, and how fast the meterial can release that heat...


For those of you who build rocket stoves you already know how well cob holds heat in the PDF it spells that out.

Mart Hale wrote:

Interesting take on sand battery,   PDF attached....

Very useful to compare the heat ability, and how fast the meterial can release that heat...


For those of you who build rocket stoves you already know how well cob holds heat in the PDF it spells that out.

Pure silica sand (pool filter sand) I have tested and does some amazing stuff. Definitely more pricey but well worth it. Good for the smaller projects.

>>  Pure silica sand (pool filter sand) I have tested and does some amazing stuff. Definitely more pricey but well worth it. Good for the smaller projects.


My neighbor told me that there is a difference between the sand you buy verses the sand in my ground.       I have been testing the sand from my ground, as it is free, and I want to know what free sand can do....

Well seems we are wrapping up summer and today i decided to go out and check the status of the sand battery I made...

Top of the lid was over 500 degrees!    This impressed me as I have not cleaned off the solar panels or done anything to this for all of these months.

Now that I know this thing will last,  and as the weather gets cooler,   I hope to try out some new designs I have in mind with cement cloth.    

Slowly I hope to get back to this project...

Heat stored in graphite blocks,    advantages is the heat is released quickly...