1604 The Sand Battery - A DIY Option Or Not?
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- เผยแพร่เมื่อ 9 ก.ค. 2022
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I daily cook my food in a heat battery filled with quartz sand. The temp gets around 350 C at sun down ( even in cloudy wetter ). In the morning it's fallen to 250 C
It's powered with two 120 Watt solar panels connected to a 16 Ohm resistor in the sand. Works great!
@marthale7 I'm lucky to live in a area where there are natural quartz sand Deposits.
After building a few promising prototypes i want to move to magnetite sand instead.
My current setup:
Two 120 Watt / 26 volt solar panels in series connected.
A metal paint bucked around 20 liters.
I use aerogel glass-fiber insulation on the inside of the bucket. ( 12 mm Double layer )
Homemade heater coil with NiCh wire.( 16 Ohms ) on the bottom.
Filled the space with sand.
On top of the sand i placed a thick round aluminium disk ( to cook on ) with thick aluminium bars connected to it going into the sand to transfer the heat.
The outside of the bucked is then wrapt with extra rock-wool insulation.
Not sure about induction cookers, not tested this. Don't you need a relative big battery bank an a pure sine wave inverter for this?
One day i make a "you"tube vid about this project.
@@RogerJonker I bought some variable speed controllers, one which operated my immersion heater from electric via my solar inverter and the other controller was for my small electric over to reduce its voltage and therefore consumption. Think RMS did a video on improving such a small oven, cannot remember what he did though other than insulating it. Best wishes.
Yes please make a video im very interested to about your setup and in Winter it's a great heater too?
@marthale7 Sorry, i can not place a direct link. My first two replays where removed by YT. There are a few web shops that sell this blanked where i live in Holland.
Shame this stuff is sooo expensive and a real pain to work with.
With the current energy prices its paying back very soon tho🙂
Yes, magnetite has a high heat capacity and i hope to bridge a few dark solar days with it.
@@CUBETechie
Have a look at my channel. I just uploaded a video i made earlier where i cook my dinner directly on solar ( no heat storage )
Soon i show my heat battery setup and how it's constructed.
Some of the builders in my area (Alberta Canada) have been making greenhouses that have pipes layed a couple feet beneath the ground. The blow air through these pipes and exchange heat year round as a thermal battery. They are able to extend the growing season by several months -which is amazing given the conditions.
Back in the 70's my father built a house with a solar wall that heated air, and warm air was blown into a large volume of rocks in an insulated space. It wasn't sand, they were sizable stones that had air space between them. It wasn't the miracle the clients expected, but they asked him to do it. They sued him and lost, but it was expensive in more ways than one. I still think it's a good idea, the insulation of the thermal mass is very important, so is the circulation of the air. Heating with the sun when it shines is easy, but the real trick is to cool with the sun where there is too much of it and the days get hot. Convection and cupolas can help. Insulation is a very important factor.
As 'C H' pointed out in an earlier comment, Dick Strawbridge did a similar greenhouse heat-store, but using broken glass as the thermal mass, in a series of programs around 'Eco-friendly' living.
Broken/crushed bricks can be used for similar effect (and people will pay you to take it away!).
I've used a couple of cubic metre water tubs, boxed in and well insulated with discarded 3-4 wall poly-carbonate sheets; old radiators and curved shower enclosures gather/concentrate enough heat to raise the water to unbearably hot some days. I haven't had to use any fuel-heat in the greenhouse for a couple of decades, and I grow salads etc 365. Everything runs by passive circulation as there is a 2.8m height difference (I do live on a fairly steep hill). Everything is from 'rescued' materials.
please make a video this sounds really intresting
Storing heat in sand can be considered to date back thousands of years.
The bricks in ovens that store heat are made up of sand.
The ovens are heated up and the bricks store that heat.
There are also coolers that can be made with terracotta containers and sand to preserve perishables. Once built, you pour water into the sand and as the water evaporates, it cools the inner chamber. I think that's how it works.
Sometimes, going ancient school is the solution to modern day conundrums.
It’s all trying to mimick building into the side of a mountain with diy stoves where the surrounding stone holds the heat.
The old greenhouse heater,,,was a Rocket Stove,,, with a sand/, water battery!!
It was an old Victorian system, and was absolutely brilliant!!
Unfortunately,my mother was a Vandal,,, unless she was able to make money out of someone/thing...
And the whole set -up was certainly a homemade one...
But also incredibly efficient!!
Mother spent Thousands having a logburning stove put in,,,,By the morning it'd be bleeping freezing throughout the house again...
However,,,my Greenhouse would still be nice and cozy!!
(The Hens used to lay me a couple of eggs,I like to think that they enjoyed the extra warmth and fussing they got whilst in with me!)
I designed and built greenhouses with two ft bedded sand heated w electrically heated water back in the mid eighties as starting houses...they worked awesomely 👌....
I bet you did. Did you know that zeolite holds heat longer than sand?
@@earthmike532Cost comparison of Zeolite vs sand?
@@ronson-natsarim good question. Zeolite is volcanic rock. It's an amendment that farmers put down, so it's not astronomical but I'm sure it's more finite than desert sand (the best sand for this project price wise because construction sand is more costly and more finite and works the same). When something lasts forever and functions a large percentile better, then the cost effectiveness is year after year so I'm sure it's a good idea. I was thinking 50/50 sand/zeolite would be the best.
As a youngling, my great uncle used to have crates full of what looked like beach sand in his basement. I would ask him what it was for. He would say, wait until fall and I will show you. Fall came around, and we harvested all the potatoes and turnip. We brought them into his basement and would take out all the sand just to bury the potatoes in one crate and turnip in another. I immediately discovered that while taking the sand out that it was so much cooler than the ambient air temperature. My uncle explained to me that this was how to keep them fresh for the entire winter with very little spoilage. He was right. The concept appears to be the same, or the opposite of storing heat, but I totally get it. Great video Robert! ☺️
we used to call those clamps - cheers mate
I worked in labs for years, you must be one of the clevers people I have ever listened too.
Love the idea that miners and quarrymen have been living inside their own stone built thermal batteries for hundreds of years. Only for people to recently disable them with concrete, gypsum, central heating and the latest insulated flues... all in the name of progress.
Progress in 2022: toxic building materials prone to mold.
Love it! Stuff like this was the vision of those that created the internet! I agree that digging a big hole and filling with sand would be a great way to store the heat - the next thing we need to know before getting in the details is how mich heat energy you could theoretically be stored per cubic meter of sand at 100deg C, 200 deg. C etc
Absolutely sparked some ideas!!! Thank you so much!
I really like the idea of thermal storage that is so dead easy anyone can make it. Right now i am on pause with a little project of mine where i plan on storing heat in a large water tank with sodium acetate stillrods because Im working on the bicycle machine for the competition, but when i finish that I could definitely share the heating project with you! :D
I had a Tarm wood gasification boiler about 20 years ago now in a house I don't live in anymore. But I built a 700 gallon thermal mass water tank outside with R60 insulation to keep the water out of a finished basement. It worked very well in New Hampshire where we get temperatures as low as -30f. I could shut down the boiler in the spring and fire it once in the summer to get all my domestic hot water. I have plans to do something similar at my current home as an opportunity load for solar panels I just haven't gotten to it yet. Too many projects. I would recommend looking into the plastic float valve used in energy free cattle waterers to keep the tank full. The hot water destroyed the shutoff valve in my old tank with minimal buildup and crossion. But the plastic floats don't have any trouble in a very similar environment in my cattle waterer.
please do mate I would be fascinated and I am looking forward tot he bike competition entry
What are you using to stop phase separation of the Sodium Acetate Trihydrate when it's supercooled? What about the method of kick-starting the nucleation of crystallisation?
We have had thermal storage for centuries minutes in the southwestern deserts. 3 foot thick walls on adobe houses. : ). And it uses the desert "sand" which technically clay.
My house has 2ft thick stone walls over three floor plus attic. It takes quite a few weeks after summer to loose its store until the wood burner is needed. I will complete my long awaited external insulation this year along with a Trombe Wall, im determined. Hopefully this will drastically diminish my 12-14m3 of fire wood, perhaps to less than half or more. Solar heats my water and provides electricity, the wood provides hot water and central heating and cooking in the winter. Wrapping in part your uk brick homes in glass is perhaps an easy and relatively cheap option considering total life cycle costs and much better than vast amounts of cellular plastics...but you'd have to send the local planning dept packing first. Best wishes.
Chinese have been using sand batteries for sometime in poly tunnels to grow all year round, something I've been looking at for a while 😉👍
interesting - thanks for sharing mate
You normally need a pretty massive well insulated store if you want to make it interseasonable. Earlier today I worked out that if you wanted to draw 1kW for four months over winter you need something like 32 tons of water heated to 90C. And many houses need much more than 1kW to stay warm
@@ColinWatters If you are interested in using water as an interseasonal thermal storage, you might check out Thorsten Chlupp's talks on the REINA, LLC TH-cam channel (they are long, but worth the time, I think). Thorsten built at least 2 houses and one public building (a library) in the Fairbanks, Alaska area, all of which used large volume water tanks (~5000 US gallons) and trickle down solar water heating panels in conjunction with a small variable speed solar cell powered pump (and very good insulation, of course). Even at that high latitude and in such a cold climate, in his own house he only burned about 1 cord (128 cubic feet, or about 3.6 cubic meters) of split and stacked fire wood (probably mostly spruce, being somewhat familiar with boreal forests, as I am), burned in a thermal mass heater during the coldest part of the year, as an auxiliary heat source. He also obtained direct solar gain via south facing windows shining on a floor slab. Unless you are at a similarly high latitude, or in an area which is extremely cloudy during the prime heating season months, you might find the same - that is, you may not need as much water as you think, _IF_ you are able to add thermal energy to your store over the course of the heating season.
In particular, Thorsten developed a simple and cheap automatic mechanism which releases the heated water at the appropriate level within the stratified storage tank, based only on buoyant forces. His domestic water heating coil was immersed in the storage tank, but his heating loop pulled directly from the heated water in the tank.
The last I heard, Thorsten was no longer actively involved with Reina, but had moved to Bhutan (?) to work on affordable housing with an NGO.
The "Chinese greenhouses" which use a large volume of earth as the thermal store rely on phase change to transfer thermal energy to the ground, at least in some embodiments: a low speed blower circulates warm moist air from the upper reaches of the glazed volume through perforated drain tile laid several feet or a couple of meters underground (often more than one layer of drain tile); as the air cools, the humidity condenses, with the condensate draining through the perforated tile into the soil; the cooled, dried air is returned to the glazed volume to "lather-rinse-repeat". Many of the Chinese greenhouses actually located in China also use phase change through sorption mechanics of the clay constituents of the soil block north walls and end walls, though the process is entirely passive.
@@ColinWatters yup, the bigger the better for sure. I've been looking into using a bank of evacuated tubes with solar heated pipes with parabolic mirrors to keep an insulated sand battery wall topped up on sunny winter days.
On you tube you can find it : Chinese solar passive greenhouse
The great advantage of using Saudi sand is that harvested during some times of the year it will come preheated. ;-)
I had the exact same thought about necessity when I first heard about it… Thanks for sharing your thoughts on this Rob
yes! loved the video. I've been wondering about this myself!
Living in an Earthship. We heat and cool our home with temperature stored in dirt. We heat our water direct from sun with a solar collector and always have hot water. Electricity comes from a 2.6 KW solar system and is stored in a small 14kw LiFePO4 battery bank. Water is from rain water off the roof and we have managed to have enough but if we get low we have it hauled in.
Hi Rob. Long time no message. Dick Strawbridge did a tv programme back in the day where he used glass. He sent his kids to the local pub to collect all the used bottles. Crushed them, basically back to sand, then dug a hole in the ground. Put uPVc pipe in it and filled said hole with the crushed glass. He then built a greenhouse on top of the hole. A solar panel and a 12v fan later the very hot air from the greenhouse in daytime was fanned down the pipe, heating the glass, that was then released over night, keeping the greenhouse warm at night. I feel confident that between yourself and Dick you could take over the world
In the early 2000 a friend of mine and myself came across heat storage in the form of sand, molten salts and some other ideas.
We were trying to find different ways of running big sterling engines after dark for power generation.
We found all sorts of stuff about heat storage going back decades, so it's surprising that it's just now someone is making a commercial unit.
Hi there, what sort of materials did you fine ?
Here in Michigan there are thousands of old silos on farms no longer in use, imagine filling one with sand and putting solar panels every few feet surrounding them from top to bottom. Have some heat generating resisters in the sand and you have a massive sand battery! I only wish I had one 🤔🤔 Spray foam the inside for insulation, sure seems like this would work. And top it off with a wind turbine!
solar panels ?nah.
Simply insulate the upper part.
Reflect radiant sunlight onto the exposed lower sections using concave mirrors and use thck fresnel glass panes(lighthouse glass)to line this exposed area.
Glasiers produce window panes of the fresnel type for pub windows.
These capture ambient light and redirect it into a horizontal beam just as lighthouses do.
I switched from a petrol car and an oil fired boiler to an EV and a heat pump. My electricity usage tripled. However my energy usage dripped by around 70%.
Converting my annual petrol and home heating oil usage to MWh and adding it to my annual electricity usage (6 MWh), I used around 70 MWh a year. Now that I've shifted to just using electricity, I'm only using 20 MWh annually. I've offset 1/3rd of that with PV panels. Hopefully in the coming years I can offset more with wind turbines and more storage.
Thanks mate. That's a good topic. I've been thinking about building one. Maybe do the math for my house. The fun thing is, if this battery is in the house somewhere all loses contribute to heating the house. That was the idea to begin with so all together it is a losless system
Water has over four times the specific heat capacity and plays nice with heat exchangers. You can get the heat in and out quickly. To be viable sand would need to be heated to 350C to contain the same specific heat as the same mass of water at 80C.
Im so glad to be in south Africa. Heating of houses isn't really a thing. Add an extra blanket and your good. So want to save energy move to south Africa. Hehe. Thanks Rob. So a thaught. Strap a stirling to the top and generate power and heat your home.
Thanks for your videos. Very interesting and informative. My father was a mechanical engineer who taught himself electrical and electronic engineering as well. When he was approaching retirement in the 1980's, he researched how to build his retirement home in the country. he took all the Environment Canada weather data for decades for the area (north shore of lake Ontario) and designed a south facing, ranch style (one story) 4800 sq. ft house, that had a large solar porch. Fans would take the hot air and blow it into an insulated gravel box, which only took up a small portion of the 4800 sq. ft. basement. His calculations showed that in the worst possible sunlight conditions, he could heat the entire house for about $150 per month. The local power utility sent out reps to look at his house as it was being constructed. Unfortunately that house is no longer in the family so don't know the current use of the system, as he also had other "backup" systems installed.
I remember seeing the larger storage heater banks in domestic housing that had air ducts below the floor to blow out the heat into the rooms. Same sort of thing I guess.
A very useful conversation.
Good points, thanks for sharing 👏
I didn't know there were patent applications for that. Kinda funny...
Sand Battery is essentially a varfiant on Geo-thermal where you not only run water through to moderate your living space temperature, you purposefully heat the dirt.
You are selecting a type of dirt (sand) and separating it from the mass of the planet.
There have been other "thermal mass" modes of moderating the living space temperature.
Thick Adobe walls are a thermal mass energy storage and temperature moderation system.
A hot water tank is a thermal mass system...
We change because... economics. Cost to benefit.
When the only way to moderate a home's temperature in the middle of Texas and down into Mexico, they did use the Adobe. Sometimes 4 ft thick clay + grass walls. the walls were hard to heat and hard to cool so the temperature stayed pretty steady in the home.
Expensive in labor to build this way...
So when cheap air conditioning was invented, that and the common 2X4 stick built house replaced most of the adobe houses.
Now, the AC is getting expensive and unreliable... so variant thermal mass is coming back.
Compressed air is another way to store energy. I have modified a wind turbine with a York compressor and a 500 gal. Propane Tank. I run all my power tools on air for free. Working on an air generator now.
I think that's a fantastic idea. I'm surprised I haven't heard of a practical application before now. Thank you for sharing this with us.
yes - I am a fan of compressed air
The Amish have been using compressed air for years to run their workshops, air-conditioning and refrigeration. If you are looking for alternative ways of doing things looking at how the Amish do thing's is a very good start.
@@kevinleebailey Thanks, I'll check them out.
Hi rob. Night hawk has done a fantastic video yesterday of heat reflecting paint well worth a gander if you haven’t seen it yet
Using thermostorage also allows use of solar concentrators, not only using PV panels and resistive heating elements. Using concentrators should allow us to get more energy per sq.ft. from the sun than a PV panel could ever dream of. If you tried to concentrate solar light on a PV panel you will melt it. But a solar concentrator will take huge amounts of concentrated sunlight and it makes it more efficient not less efficient like a PV panel. Just having a PV panel in the sun lowers its efficiency, solar concentrators quite the opposite. Even if you did only some concentration on PV panels, it still won't work very good because the excess heat ruins efficiency and life expectancy of the panels,
A concentrator lasts probably 10 times longer than PV panels too. A concentrator is just polished SS parabolas and pipes, lasts for hundreds of years. And it don't care how much light you shine on it it just reflects it to the absorber pipe. Pipes are even more mass produced than PV panels, easy, simple, and cheap but long lasting. Then you need some heat exchanger anyway to store the heat in the sand, so the oil in the pipes being heated will just run thru the sand in a matrix to maximize storage, and then recapture efficiency.
You can argue all day long resistive heating is 100% efficient but i agree, they are doing their research and i agree with their approach because we already have PV panels everywhere, and we already have wind turbines, hydro, etc...I was just throwing in the solar concentrator ideal too because if you are doing a project directly from zero(no existing wind turbines, hydro, PV with enough energy to have it work), then instead of buying PV panels to heat sand, i suggest using solar concentration technology, simple, safe, more efficient than using PV to heat sand, built like a horse.
I really like how you narrate the whole idea...
thank you mate
I also did some math and drew some plans up for storing up heat in the summer for use in the winter. EPDM sheet rubber (generally used for industrial roofing) is rated to withstand temperatures up to 130C for long periods of time, and 150C for short periods of time. 100C is plenty for me. Since I have room in my basement, the container would made of 3/4" plywood and rectangular. Simple wooden frames constructed of 2x6's every 12" are sufficient to resist the weight/force of the water. Polyisocyanurate foam insulation is rated for temperatures exceeding 300F. I only need 212F or less. Water has about 2-4 times the specific heat capacity of stone, cement or brick. So your heat battery can be half the size (or less) of the equivalent capacity sand or stone heat battery.
The big advantage to sand or stone is that there is no problem with phase change at 212F. Sand doesn't care if you heat it to 500 or 600F. But the insulation can be problematic and it's more complicated to get the heat in and out again compared to water.
Outdoor or underground water tanks are pretty straightforward as well. But the advantage of locating the water/heat battery in the basement is that once heating season starts there is no loss of efficiency because of heat loss. "Heat loss" heats the house. As you are collecting the heat in the summer, heat loss is legitimately a problem since you don't need or want to heat the house in the summer, so cooling costs escalate. But sufficient insulation reduces that to a manageable problem.
Tubes of parrafin or carnuba wax inside the water vessel will allow you to take advantage of phase change for a 2-4 + times greater heat storage capacity than water alone.
1460 is a company in Australia which has a large scale silica battery plant on trial at the moment. Dumping solar and wind energy as heat into large scale silica (sand) batteries then using the heat to drive turbines to generate power. They are also working on using 'waste' heat from large scale industrial processes to generate power.
Thanks for all your hard work Robert, here's an idea. I see you have over 300k subscribers on your channel and it gives me great hope that there are so many people genuinely interested in solving some of our energy problems. I was thinking, if a couple of thousand of us threw in ten or twenty pounds each, it could fund research into a sand battery by providing the funds to dig the hole (preferably beside a solar array), insulate the hole, fill with sand, piping and temperature sensors. Connect an air to water heat pump or whatever heat source is most appropriate to the piping to heat the sand. We probably need another pipe for extracting the heat. The next step is measuring how many kW it takes to heat the sand, see what temperature can be reached, then measure weekly for a number of months to see how long it lasts. A pump can also be set up for extracting the heat, I presume this is also an air to water heat pump. If it was an open source project, the learnings could be shared and if the results were favourable, it would help others to replicate the system in the quickest possible way around there World. What do you think Robert, is it worth a try?? 🙂
I don't know the current status but I read a few years ago that a solar farm in the US (AZ or NV?) was gong to use salt to store heat during the day and extract it for power at night.
@@briankeithwood thanks, I'll check it out
Firstly, thanks Rob for a well thought out overview of thermal storage. I was thinking about using water as the mass to heat, but thinking over the last couple of weeks I see that sand is the way to go.
I have ordered some high wattage resistors and some nichrome wire to play with in my sand box :-)
Now having watched your take on this subject I thought about using a conductive ink mixed with the sand, so that the sand mass as a whole could be the resistive load. 🤔
That is a neat idea with having a resistive mass. I believe it will not be needed as long as your element can be controlled not to overheat the resistance wire locally. The heat will spread through the mass by conduction, convection and radiation at reasonable speeds even if the element was placed exclusively inside the centre of the mass (to benefit from lower heat losses from the cooler outside).
Having the heat at close to melting point for the sand just in the middle would be ideal.
Your method would be good to dump a LOT of energy into the sand all at once but that might be a rather unusual requirement unless you has free energy from over speed wind turbines you wanted to store instead of just dump into the atmosphere.
I had a book called soft tech from the 70s in it was an article on dwelling development in a desert area
The article highlighted 3 new technologies one clear heat reflecting film on glass almost standard now
One a film for glass that turned opaque when it reached a set temp and finally
What they called thermo Crete it was an aerated concrete with calcium chloride impregnated zeolite that would absorb heat from the sun until it reached the set temp which could be adjusted by varying amounts of Ca Cl if I remember correctly
The dwelling constructed of this concrete was inside a large greenhouse when it reached set temp inside the greenhouse would get warmer and when that reached set temp the film would go opaque and not allow more heat into the building
I always liked the idea of this thermocrete but couldn’t wrap my head around how it works
Hmm, interesting.
A similar effect could be achieved using bi-metal strips or wax-capsule activators to adjust blinds/shutters.
Thanks Robert! :D Nice video! We wanted to say that at least what we know our system is first commercial storage that is connected to district heating network. =)
In future we will try to make this for single house use too. At the moment price would be something like 50 000 €.
And we can use desert sand and not to use building sand. =)
Don't get me wrong mate - I think your system is awesome and any system is incredibly hard to get to commercialisation - most folks don't realise how hard that step actually is - it is a fantastic thing you have done and all credit to you - I don't really know enough about your system but I am also sure there are things you have done and problems you have solved that have defeated others - my sincerest congratulations on your achievement
@@ThinkingandTinkering Thanks! Yes it has been hard and also on field that district heating companies in Finland are very slow to take new technologies to use, of course others than Vatajankoski. :D
@@tommieronen7424 Rock on, Tommi. That'll do for me. ;-)
In the UK many large/commercial properties are now built upon the ground up remains of the old brick/concrete buildings (they vibrate/compact it then drive piles through this aggregate). If the finer material was screened out the remainder should be porous enough. Could your system make use of this surplus/debris as a thermal mass?
@@tommieronen7424 love it, can you make it store electricity rather than heat? Or convert the heat to electricity? Would clay work better as they have a higher negative charge content than sand
@@tommieronen7424 or make the sand boil water to turn a steam turbine :)
possibly one could use a waste product like coal fly ash. I have seen a couple people in Alaska use large water tanks to shift heat from summer to winter. very interesting stuff.
Back in the 70-80s there used to be a home heating system called a Night Store Heater, it was designed to use cheap late-night/early-morning electricity to heat sand or bricks and during the day that heat would be slowly radiated into the house. This is clearly a modern take on that old commercial product.
It was installed in the first new house my parents bought, it was an expensive nightmare, barely heated two downstairs rooms and cost a fortune to run, and was very noisy, electricair heating as memory serves, made by creda, they were binned in short order by everyone on the estate in favour of what was then cheap to run gas centralheating, was just a huge grey tower about seven feet tall in the kitchen.
It was called economy 7 as I remember
They were cr@p....
@@dudeatx Economy 7 (and Economy 10) are electricity tariffs. Essentially they allow you to draw electricity from the grid during periods of low demand and pay less for it. It’s main use is for household devices with timers, such as washer-dryers. And night storage heaters.
@@hel1copter yeah, I remember in the 80s my mate's dad fitted storage heaters into his new build. The first electricity bill he got he went round the house and turned them all off!
It's thermal mass, you can use just about anything that can stand the temperature you want to use.
This is exactly the way a passive solar greenhouse works with a climate battery. The savings are huge. You pump excess heat into it in the summer months charging the system and extract heat from it in the cooler months.
If it were a pressurized closed loop system, then you could add water to the sand and increase the thermal inertia of the storage device thereby increasing its thermal storage capacity. Great idea Robert!
Water can only be heated so far before it becomes steam and requires vastely more space while sand and rock can be heated to near molten temperatures with little thermal expansion.
Rob is there an electrical component that can be used to cool it’s surroundings and create a second cold sand pile near to the hot one (insulated of course), or via evaporative cooling perhaps. Then we can also use these sand piles to drive a heat engine.
Or just go direct and create some Solar sand ovens 😄 (multiple sand piles to cap the max heat at 180 C)
Great video, very well explained to someone who struggles understanding electronics! Do you ever do live q&A's? I reckon you'd be kept pretty busy!
I had an idea i am going to try and sure its not new. Just wondering what you thought. How about using a cylinder like a 100 lb propane tank, cutting it open, put your rocket stove inside it, weld it back up and fill it with sand and use that as a sand battery.
I saw a system back in the 80's where a guy heated his house with a 15' x 15' x 8' saw dust composting system. It took a few months to get up to temp, but then it provided heat in Michigan for a complete winter.
Jean Pain heater
I think many inventions from the past should be revisited with modern insulating materials and composites... at what point do we realize patents hinder progress?
About 30 years ago for me at least.
I thought sand was a terrible heat storage medium because the deserts get so cold at night but then it occurred to me that if the sand absorbs heat during the day and holds onto it the surrounding air Would be colder at night.
yeah I thought pretty much the same - a bit of an eye opener for me tbh
@@ThinkingandTinkering
You`d be better off using soil which is usually available on site :) Transporting tons of sand from UAE would be a lot more expensive
@@ThinkingandTinkering order out of chaos Mr MUrmith?
Aka
Problem action solution.
Mantra of the darling of media. The people’s champion, Mr. K-louse Schwab
While there is some truth to this, there are many more variables to how cold/hot an area gets than just the soil. Some of them are cloud cover (holds in heat radiated towards space), reflectivity of the surface, humidity, and plant life among others.
Also, whether in the desert or arctic tundra if you go down 10 to 20 feet or so below ground the temperature will actually stay constant relative to the average monthly temperature of a given area. This is the reason geothermal air conditioning systems can work in just about any climate. So the ground is not actually changing temperature by a ton except on the surface layer.
This brings the molten salt battery to mind.
RMS, I like the one with a datacenter in a concrete building that looks like and upside down funnel. Inside are hundreds of computers, producing waste heat. The waste heat rises and a turbine inside the outlet pipe turns and creates electricity. Simple!
Years ago I as a safety guy had meeting with a incinerator company. They described giant sand ponds of waste stuff burned to carbon. Than stored there. I often wonder what it could be used for. This could be one.
I thought about using a mini split to charge the battery in the summer as I cool my home. Instead of exhausting the hot air in the atmosphere it would exhaust to the sand battery. All comments welcome.
Bricks In Storage Heaters Are Made From Sand !
Bless Up Fella
for sure mate - clay is also a good material by the way
Molten salt or molten wax energy storage are interesting technologies, because phase change is an effective way to store energy without excessive temperatures and insulation.
Yep, the temperature excursions are less and you can sometimes select/tune the phase change temperature to suit your project.
The beauty of the sand battery is that it is cheap and if you still have energy available you dump it in and ramp up the temperature a bit more at the expense of increases insulation losses while a phase change system does not like more energy close to boiling point.
I recall my brother did a science fair project in high school in South Africa in 1983 or 84 with a solar heated molten salt heat storage system. These were discussed in (university) text books at the time so the technology was mature, just not very profitable yet.
also salts, waxes, etc can be fouled or lose their characteristics a bit over time.
me personally,I’m still on the hunt for info related to heating element spacing and material, heat recovery piping spacing and recovery regime.
I remember a Mother Earth News article about a HAHSA (Heat And Heat Storage Apparatus) Basically they built a small building, put in a wood stove and ran pipe through the building, then filled it with sand. The pipes were fed from a well so low water cost. This unit provided their heating and hot water for the house while the well could be used for cooling with a switch. Water was recycled through the system so the well only kept it topped off. They did have to light a fire every few days during the Summer for hot water needs. Combining that idea with solar panels on the roof might be something to look into.
There is this another prototype(probably panented too...) Where they put rocks in 2 sealed insulated bunkers, and use heat pump(refrigerator of some sort) to move heat from one bunker to another creating temperature difference between 2 bunkers, rocks hold temperature, to extract energy back they use stirling engine(heat pump in reverse can work as stirling engine so most likely it is the same unit). Roundtrip efficiency about 30% for AC electricity in -> AC electricity out.
I cook my food during the summer in my car but only when I'm at work bc it will get upwards past 100 to 120 degrees in there helps save time but excellent use of thermal energy
I just did a back of an envelope energy density calculation. At 300C above ambient, 1m3 of silica sand would store about 175kWh, not inc insulation. 1m3 of iron at similar temperature would store about 295kWh.
At the lower end of volumetric energy density, 1m3 of lithium ion would be as much as 250kWh, although I suspect this is rather too much as electrical connections and cooling for the individual cells would be needed.
So thermal store, if high temperatures can be used, compares surprisingly favourably with the best commercial chemical batteries, particularly in the longer term as there should be no loss of capacity.
Just found an article about magnetite being used for heat storage. It has about double the volumetric thermal energy storage capacity of silica!
Perhaps it might be appropriate to use recycled cement-based pavement/building materials for the storage mass as sand is a constituent. A repurpose of a waste material, diversion from landfills, and double the benefit of the original embodied energy/mining. But perhaps the temperatures involved preclude suitability.
I saw a couple of „night storage stoves“ working with Exit that system. Heating sand with electricity at night when the price was low and the stove then will heat the house for the next day. Now we don’t have those cheaper night tariffs anymore so those stoves are gone.
Of course for hundreds of years wealthy houses had an ice house to keep food fresh and to show off in the summer! Perhaps with climate heating you could combine the two for summer cooling and winter heating. It might even make sense to have a small solar powered heat pump to add or remove energy from the heat battery. Then the thermal batteries energy level could provide the immediate temperature control requirements with a high efficiency but low rate feed from the heat pump.
Use 2 thermal batteries, one hot, one cold. The heat pump could draw the heat out of the cold one and transfer it to the hot one. Then in the summer you can still have a hot one to use for other purposes like say a hot water heater.
Resistive heating gives us a COP of 1, while ammonia has a COP of 8. My thinking is that using renewables to power a compressor to draw thermal energy from air and thermal solar collectors to pack away 8x the energy than is used to power the compressor. In reverse a gas turbine to draw energy from the hot sand heated air.
The US has used molten sodium to store heat and then use that to heat water to run steam turbines. They also have plans to use molten sodium with fusion reactors.
For DIY builders water is probably as good as anything for storing heat. It has a better specific heat capacity than most materials. Can easily be pumped through heat exchangers etc Down side is its limited to max temperature of
Awesome an other film with a good finish! And You have lift the Idea then you build the Rocket stove!!
Or storing the heat endothermically . Long time ago in popular mechanics magazine was an article about using sodium sulphide for heat storage . Add water to dry sodium sulphide , and it gets very hot , so too caustic soda but of course the caustic soda would slowly become sodium carbonate from co2 absorbed from atmosphere. Use the summer heat to dry out the solution of sodium sulphide again ready for the cold winter. A house was built and tested using this compound 45years ago now .It grabbed my interest at the time cos the sodium sulphur battery was something of great promise but along came the lithium battery and we've forgotten now the NaS battery .
Added sand to prolong heating of coil in solar water heater years back. Didn't know this is called the sand battery, until now...
I think a sand battery and a combination of a Stirling Engine would be a good duo.
Definitely be a great off grid solution.
Hi, I’m seriously considering moving to central Portugal with very hot summers, it would most likely be a property with limited or no connection to utilities. I’ve been thinking about alternative methods of generating and storing energy as I think this will be my major expense. I saw the news about the sand battery and was wondering about the possibility of scaling it down to a domestic property. You’re the first person I’ve found discussing this possibility. I’d be interested in any further experiments and discussions you might put together in the future. Cheers.
Perhaps could be combined with a peltier module(s) to make use of any escaping heat to make electricty.
Awesome info as always.
As I've stated on your previous videos ,We will go backwards before we go forward , as in old proven technology, well done I say nature non toxic opinions are best.
I saw Lesley Stahl interview a guy on 60 minutes at least 10 years ago who had already marketed this technology to companies like Amozon and Microsoft. It was called a Bloom Box and it had one production facility up and running in Delaware at that time. The companies only had a handful of the boxes. It appeared the guy was trying to scale it up.
In dry desert areas could sand store cold at night and then be used for cooling during the day?
Ah heck, I told some farmers awhile back who had greenhouses and who lived in cold environments that they should put a tower of cinder blocks filled with sand and painted black in the middle of their greenhouses, and that this would act as thermal regulator for colder nighttime temps. And in the summer, if painted white or something white was put over it, it would do similar with the regulating heat till at least noonish or so. Specified that it should be the finest sand that they can get and packed in.
I thought it was pretty clever, but no apparent interest.
i dunno. I thought about putting down 6" of sand on top of both electric and liquid underfloor heating. But, if you imagine the sand at a hot beach, as soon as the sun goes down that sand gets pretty cool and that is a very deep layer being heated all day long.
There's a gentleman that just built a sand battery for his home. He fires it outside removing it from the fire brings it inside using a CPU fan to release the stored heat (TH-cam video)
Maybe a sand space heater, similar to the clay pot candle heaters? A 3 gallon pale should hold about 42 pounds of sand, which is a fair amount of mass for heat storage in a space heater.
Heat a 3 gallon metal pale, or several metal 3 gallon pales of sand in a solar oven or use a parabolic dish or on a rocket stove, or on an oil or gas burner. Bring the pale inside and let it radiate the heat into the room.
Maybe put a pipe through the middle of the pale so a small fan can blow air through it into the room. And maybe put a few candles or other heat source beneath the pale after it is inside to make the heat radiate longer.
Maybe put metal rods inside the pale sticking up from the bottom to help conduct heat into the sand from the bottom, where the rocket stove or candles might heat it.
Sand can hold a lot of heat, so blasting it on a rocket stove might really get it going. Don't know about the candles (maybe a Crisco candle with several wicks?) adding enough heat to help it radiate heat longer, though. I figure someone here smarter than I am can contribute if the idea is feasible.
If 42 pounds is too heavy to comfortably carry, maybe scoop into a smaller container and fill a bigger container inside the home in 2 or 3 trips.
Just seems like a way to use the heat generated outside to warm a small space inside the home. A solar oven would be the most passive way to heat the sand, though a rocket stove would heat it much hotter much quicker. Heck, I'd bet the rocket stove could heat the sand hot enough to cook on. Wonder if the sand can be insulated well enough to retain most of the heat for a day or two. If it can, this might work for both space heating and cooking a few meals, all from just one long burn at the rocket stove.
(I make concrete garden figurines at home, so I have bags of sand on hand.)
Sand battery, thought blast furnace checker blocks in the stoves as a thermal battery, decades , magnesite block is as dense as iron ( almost) can store heat for months
Keep the following technologies to the front of your mind, #1 Gravity Battery (gravity not included) #2 Faraday Disk #3 Flywheel energy storage, in which the Faraday Disk is basically also a Flywheel.
Having all them on your mind, develop something from the basement/ground up, try to make the perfect merging of all 3 technologies, that will be an awesome solution, especially if you can make the weight take 24 hours to completely fall from top to bottom.
So basically a gigantic and freakishly hot electro-magnetic object dropped from a stupendous height while it's rotating fit to bursting. Sounds like a plan.
Could you also work into it reversible electro-chemistry and super-capacitance and spring-deformation, maybe a few bits of fission/fusion/super-conductivity and atomic spin stability for good measure? Perhaps with manipulation of torque/precession you could incorporate a trade off between kinetic energy and momentum to periodically replenish/reverse the overall enthalpy and mean free energy equation.
Not asking too much.?
Good luck with that.
In outback Australia most people have to catch rainwater for their own household to my way of thinking it forms a great thermal store with little modification just insulate it and have a small cold water header tank ..
Ground source heatpump, in reverse it dumps summer heat into the ground, in the winter you pull it out.
Ford wanted model t to run alcohol, which every decent house knew how to make, big oil said no.
Two thermals, one cool and one hot. Great idea.
If you use heat storage say from wind in an ad plant the third of gass that is used to heat the plant can be put into storage. If that gass is they burnt say at my a council swimming pool in a combined heat and power plant you get heat for the pool and power for the grid. supposedly super efficient when you use heat from an engine
There is an ancient building method called rammed earth that basically uses this method to stablise the temperature in a house.
I’ve thought about digging up a pool sized hole in my backyard, insulating it, using pex to deposit and withdrawal solar thermal heat.
How about cooling the same sand pit in summer? Cool air circulating on hot sticky nights.
Thinking about cement-charcoal blocks can be a good option as well 🤔
Scrap bricks from redundant electric storage heaters are free/very cheap resource for heat storage projects, forges etc. Often find them 'fly-tipped'! (Love these vids from R M-S)
Problem with sand batteries for low grade domestic heat is that you can't use heat pumps easily, some companies such as Malta inc are using brayton cycle turbines to do this, but they are limited to the creep cliff of steel so about 600degs. Ohmic heating will be necessary to decarbonise industrial process and temperatures above 600degrees.
The only option for domestic heat is to reduce demand by infilling/urban densification, renovating/sub-divding and retrofitting buildings with high performance envelopes and good geometry (
There was a company back in the 1970s in Vermont in the USA which did a passive solar home system that used cement blocks set on their side to cycle air through a thermal mass under the foundation. There is a book about it the passive solar house IIRC by Chelsea Green Publishing. That book is good because it has spreadsheets with the calculations needed to duplicate the system. But a better design is more modern it uses insulation under the foundation with 2 feet of sand IIRC with pex pipes running through it and a cement slap to build on over the sand mass. Same basic system but without the mold problems that you can get pumping humid air under the foundation in an air passage.
that is great info - thanks for sharing mate
In Colorado a man made video of building a green house living room. He dug down like 18 feet lined it. To be water proof. Than put pvc with holes facing down. 6 inch pipe with two inch holes every so inches. He had two inch rocks brought in to go on top. Brought all way to top. Then had large stones that was like walking stones set on top. Polished on room side. Gaps on edges alowed heat to slowly rise. During day fan would take hot solar air from ceiling where it goes. This area from my take. Was 75 ft by 20. Top green house that housed his lap pool and tv area but was adjacent to real house. That had ducts to pull heat into main house. During summer he cool in reverse. Open big flaps in ceiling open doors in bottom caused a major breeze.
Like you said there are many videos on youtube, But I thought you were going to make a coffee mug sand battery LOL
The idea I am basically working on a pizza oven type thing in the house with storage to cook and heat the house.
When I was camping in my van mid winter on the coast I would heat up a big pot of dry sand on the gas burner and wrap it in a spun glass insulation and sleep with it near my head under my bed . It would still be warm in the morning . Probably got it upto 400 degrees or more. Sometimes even hotter if it was a cold snap. I got a few other people doing it but for some people they felt it was dangerous and were scared . Not everybody has common sense ! 👍🏻
lol - no indeed they don't!
Can you use a solar water heater coil on roof to heat the sand under floor?
I have access to free sand from our garden, play pit soft, like kiln dried. Also in our basement I have an old plunge pool that used to be used after using the sauna. It's aprox 3'5 long x 2 wide and 1.5 meters deep, as its underground the surrounding earth keeps it at a constant temp of about 10/12 degrees. I have been toying with the idea of insulating it and using it as a water storage battery, kind of like a big buffer tank. I think sand could be a better option but I have no idea to be honest, total novice to this, What do ya think?
Early sixties popular mechanics magazines had several articles on building rock bins that were solar heated and you blew air threw the bins at night to heat your home. A very simple design was an outdoor bin that was triangular upright with one face facing the sun. The bottom and sides were all insulated and the inside was baffles with rock filling the enclosure. The sun facing side was a solar collector with an insulated cover that also reflected more sun toward the collector when opened. Air from the collector heated the rock all day. Late in the day you closed the collector cover to insulate against heat loss and circulated indoor air through the rock heating your home with just the cost of the fan. Even simpler was a rock bin in your basement heated by solar that could provide several days worth of heat. These collectors were even reversable to provide cooling if your summer nights were cool. You chilled them down over night to provide cooling during the hot daytime. I don't see any reason the sand banks couldn't be used in the same way.
I'm wondering if you couldn't use your conductive ink radiator idea to heat sand in a closed container made from Aircrete, filled with sand and powered with a solar panel or your wind wall?