What I don't get is when people say that the round trip efficiency of Sand is low compared to Li Batteries. My take is WHO CARES?! If you lose 30%-50% of generated renewable power storing it in Sand that's STILL 50%-70% power you would otherwise have lost because you don't have storage. And if Sand is MUCH cheaper than Li batteries and not subject to the scalability issues of batteries then it's better than nothing.
I get your point and it does have merit. But by the same logic, the efficiency of the renewable power source wouldn't matter either. Looking at it in reverse, a lower round-trip efficiency means lost power that you wouldn't lose if you used a Li-ion battery, improving your energy independence.
@@ipp_tutor Yes, but With Sand batteries you don't have to Ramp up production on Li, Cobalt, Manganese, and every other substance we would need to electrify everything and keep pumping out Batteries. The cost of mining, transport, pollution, discard, recycle of any Chemical battery (even if we switch the Na instead of Li) will Always be more than building a Big insulated tank and filling it with sand.
@@jonjohns8145Why not just convert excess supply into hydrogen injected into existing natural gas system with a capped limit where safety wouldn't be an issue.
14:00 pro tip. you don't have to just go up LOL you can also go down with it! 10 stories underground 3 stories above ground AND less wall support issues and collapse problems. so the acerage is way less than shown here by a huge amount! also you build a 50 storey building they go down like 20 stories in the basement to anchor it etc. well you can build your sand silo and bury it right next to the foundation and heat it from there forever. run electric in heat and hot water comes out
This also solves the spillage issue, and doesn't have the potential to poison local soils because the stuff is solid. Although, you have to wonder what benefits sand has over local earth given that you don't need to excavate anything to do traditional, residential geothermal storage.
I first learnt about sand batteries in Bill Millisons 'Permaculture Designers Manual' printed in 1988. They called it an 'energy store' and it is used as low grade heat for heating houses, green houses, hot wateretc, which is what this type of heat is best for, and which incidentally is the energy most people need/ use.
They have been called "heat stores" for decades. Some people in hot climates pump the hot air from their roof spaces during the day into a bed of rocks under their houses to use as heat during the night. Pumping air is very cheap, and rocks are excellent thermal stores. Others use 'trombe walls' to the same effect either storing energy in the wall, or a rock bed underneath. Trombe walls can also cool houses!
Just imagine that you have a factory where every machine has a steam engine, but the heat is provided by portable and replaceable sand batteries that's charged at a central heating location. This enables each machine to operate independently for a few hours before their batteries needs to be replaced. The batteries themselves to back to the charging station until they get hot enough again. At the very least, this would make for some very whimsical steampunk setup. It doesn't even have to be that elaborate. It'd be awesome enough to just pull a hot cylinder full of sand from the fireplace, put it in some huge automaton and watch it come to life.
I am a big believer in thermal energy. This was true even before I knew anything. I had a house that utilized a wood burning enclosed burn chamber in our mud room that burned wood very efficiently and heated a ceramic tile wall in the house. There was a ceiling fan near by to aid in distribution of the heat and that wall would stay warm for days. Think if you had something similar that heated sand with excess solar electricity then circulated air through steel piping in the sand to heat the wall. I feel too many people discount ideas such as these with arguments about efficiency. Once installed there is virtually no maintenance. This can be built with off the shelf equipment that would make repairs such as a blower motor easy to do. This type of system could last the entire lifespan of the home and could be self powered by the same solar system. Upfront costs, yes, but after that, you could have supplemental heat for life. The cost for this is not too much compared to the propane cost reduction it could provide. If I could reduce my propane by 30%, that’s like $500 a year, every year, forever!
Passive buildings sometimes use thermal mass such as winter sun hitting walls or floors of which cement to heat up during the day and release that heat at night. This works at residental scale
That can be a medium for storing heat in a system with a heat pump. Whether something natural like stone would be best for a cold storage isn't known to me, but natural safe materials at temperatures which don't explode, even when water is applied, would be great.
We have water batteries here in Germany in some residential buildings. Those are basically huge tanks filled with regular water which is heated during the summer by solar panels and the heat is then stored and used during the winter to heat the building. It´s pretty simple. However producing electricity from heat is a bad idea, the loses are to great. However the overall efficiency of thie mentioned idea is way higher since the energy is stored in between seasons. The idea is fantastic because it´s rather cheap and technologically easy.
There’s absolutely a case for residential heating use, if oversize your solar panel system and capture the excess energy in the sand battery, throughout the year. That can be used to heat your home through the winter.
I live in the desert southwest of the US, and that would be a wonderful application for our region. PLENTY of sun here, even in the winter. Such a system wouldn't have to be huge (as Ricky stated home systems would need to be) as our heating requirements are modest through the winter months. Even so, we do *have* heating requirements, as well as the need for hot water (of course). I would love to have a system like that for our home.
This is already being done here in Germany with water heat storing tanks. Also good thinking on your part. It´s efficiency is fantastic because sun energy is abundant in the summer and it´s used in the winter.
You mentioned a "cold battery". Check out Ice Bear by Thule Energy Storage. This is daily thermal energy storage (DTES). Before refrigeration was invented people would harvest winter time ice from a lake and store it in an "ice house" so they would have ice in the summer time. This is seasonal thermal energy storage (STES). For winter home heat I use PV-direct to heat water in an uninsulated tank when the sun shines that at night heats the house (DTES). I am still trying do decide between sand or water or other for (STES). Thank you for a most informative video.
Cold batteries are already in use. There is one under Helsinki, a huge pool of cold water, and it's a part of a pretty extensive district cooling system. They have also district heating but the cooling system is also quite widespread and has been there for 20 years.
I've also seen an old ice house design from somewhere in the middle east, where they can't just store the ice. It used the expansion of air descending through a chimney into a larger chamber to make ice. My father used to work at a historic cliff dwelling in New Mexico where that mechanism occurred naturally, keeping the caves at about 65 F even when the temp outside was in the hundreds.
@@Nurk0m0rath For the cooling chimney, what's the process which does the cooling and is that cooler air just becoming the ambient air for their living area? It's not stored anywhere of course.
@@markhathaway9456 I'm no physicist but I understand the cooling effect is created by reverse compression. When the air is drawn into the chimney (or cracks in the cliff) and compressed, then hits a larger chamber, it slows and expands, becoming colder. I'm none too clear on the details of how it works though. I've been trying to remember where I saw that design and the closest I can think of is that it might have been in one of those features about ancient advanced technologies.
I saw the polar night thing when they first installed it, seemed genius, so i built a small scale one using an approx. 1 cub yard of sand and a small wood stove. it has worked 2 winters now, but i still haven't worked out all the issues yet. i need to move more heat from the wood stove to the sand instead of heating my shop to 80+ degrees. I burn a small fire for approx 5-7 hrs per day, and the heat radiates off the insulated sand box at night and does a good job keeping my 1200 sq ft shop toasty warm all winter. saves a truckload of firewood compared to just the woodstove i had. plan to connect solar panels to it soon!
Most uses with the heat pump are indoor-outdoor, but if you create heat-cold storages, then it might be more effective when the indoor-outdoor temperatures are less extreme. Also, if you have solar panels on the roof, you might want to cool them by bleeding the heat off and directly into your storage system.
Outstanding video! I've got 5120 watt-hours of LiFePO4 storage, and many hours of wasted solar energy each day. I'm thinking of building a sand battery, using it as a solar dump load. Yours is the best video on this topic so far. Absolutely brilliant and thanks for sharing.
This is totally doable, though if you have access to the grid the easier dump is to just throw it onto the grid with a cheap micro-inverter. In your case, however, I would spend the bucks on adding more main battery storage to improve your overnight margin and give you some bad-weather bridging capability first, before worrying about energy dumps. One thing you are going to hit up against is, well, the weather. On hot days we have a ton of excess solar but no real overnight heating needs. On cloudy days or cold winter days we generally do not have enough solar so there isn't any excess to dump in the first place. That's a bit of a problem actually. One has to have excess production during the days or weeks where the dump can actually provides a useful service. -- In anycase, if you are going to do a dump I recommend doing it through a satellite battery instead of directly from the main system. That's what I do. I have a 48V main system (10kWh) and a small 24V satellite battery. I have a DC-to-DC which dumps any excess energy when the main system is full over to the 24V satellite battery. This way I can transfer excess energy at 1000W but my actual "dump" doesn't have to be 1000W, and I can control WHEN I actually dump to the actual dump independent of when the excess energy was being produced (which can be quite important actually). I then have a timer which turns on the actual dump from the 24V satellite battery at an opportune time for when the dump is useful. The actual dump device can be anything. It can be a sand battery, a small A/C or heat pumps, or a cheap little grid-tied micro-inverter if one has access to the grid, it can help the water heater, Etc. -Matt
I think DIYers will build sand batteries. You could probably build some rudimentry heating system using nothing but reclaimed bits and pieces and some tinkering
People do but it is harder than it looks. One can use a water-heater's thermal element (electric backup element) for heating it up, but getting the heat out of the sand battery is actually not entirely trivial. Basically you need something that can tolerate the heat and you need airflow to get the heat out again. An open-ended steel pipe with a fan on one end to push air through, and then some fins (like a piece of a radiator) to disperse the heat in the air because you don't want a blast of hot air at 500C. Regulating the output is the hard part. You can't just duct it to the house (not at 500C). One mistake and the whole house burns down.
On most videos you'll see on the subject, there's usually a lot of physical effort involved, and it doesn't really last past half a day. They work, but there's a human in the loop, and it's not a small part. An electrically-heated sand battery might require less effort, but there's usually not a reason to do that unless the electricity isn't coming from the grid, otherwise, you might as well turn on your normal electric heater. So far, I haven't seen anyone do anything beyond a proof of concept or proof that it works for the room they intend to heat. Also, almost none of them do any sort of heat regulation, but that's usually because they're trying to heat a large room as quickly as possible. I've never seen one try to do a hot water system.
We have water batteries here in Germany. It´s just a huge insulated water tanks placed underground with a coil in it and some plumbing. Solar energy during the summer is being stored all the way up to the winter. It´s overall efficiency is better than with Li-ion batteries and it´s cheaper. Doesn´t get as hot as with Sand but is cheap and works.
Hello! I discovered your channel a while ago, and I think it’s fantastic. I really appreciate how you analyze different ideas, essentially checking them for physical or chemical feasibility. That inspired me to share one of my own ideas with you, to see if you think it’s feasible. Some time ago, I gifted Saudi Arabia an idea for creating a hydrogen cycle. Here’s a rough breakdown of the concept: First, the brine left over from reverse osmosis is used to generate energy in an osmotic power plant. That energy, in turn, is used to produce hydrogen. As a third step, the brine could be utilized to extract rare earth elements. Finally, the remaining salt could be used for chemical or food processing. I'm really looking forward to hearing your thoughts on this! By the way, I just wanted to add that your channel is great, with incredibly interesting topics. Although I only discovered it a month or two ago, I have to say it’s full of fascinating content. Keep up the excellent work!❤
I was watching a video yesterday and the discussion included talk about homes with heating and cooling provided with the help of a heat pump. In France they're called a pompe à chaleur. The heat pump heats one storage unit with the heat from the other which is kept cold. The heat and cool of these two units help regulate the temperature of the home, cooling or heating as necessary. It's mostly for air temperature, not heating water, though that might be possible too. If you lived in a place where the average temperature was higher than you desire, the typical operation would be to cool the air in your home, while heating water. We know heat pumps work, so it's an idea for our times.
A dual phase sand tank with separate cold and hot sides sounds kind of brilliant. You'd be able to do all kinds of amazing things with having both a chilled battery and a heat battery. Throw in some heat exchangers and suddenly your steel plants are powering your industrial freezers. The concrete plant down the street can cool the freezer of every local restaurant. If we think in terms of districts and communal sourcing rather than individualized solutions, economy of scale works in *everybody's* favor. It makes little sense for an individual house to power it's own hot water tanks when it would cost orders of magnitude less overall to do so for an entire city, plus there would never be any chance of running out of hot water.
I'm pretty sure you'd quickly run into huge losses if you try to run very hot or very cold water through long runs of pipe. A city-wide system would (I surmise) have far greater losses than using heat pumps for individual freezers and water heaters. Industrial freezers (and heat pumps generally) are already extremely efficient. With a good modern unit, you get about 3x more cooling than the amount of energy you put in. This is because heat pumps MOVE heat, rather than generating it.
When people picture sand spread across idyllic beaches and endless deserts, they understandably think of it as an infinite resource. But as we discuss in a just-published perspective in the journal Science, over-exploitation of global supplies of sand is damaging the environment, endangering communities, causing shortages and promoting violent conflict. Sand is not the answer as it is used in so many everyday projects in economies around the world and numerous countries are already in short supply. The negative consequences of over-exploiting sand are felt in poorer regions where sand is mined. Extensive sand extraction physically alters rivers and coastal ecosystems, increases suspended sediments and causes erosion. I suppose the west could replace it with the garbage they produce to replace the sand; which of course would never be called exploitation of the poor and lead to world wide social unrest.
@@edgelord6560 There are two major sand Deserts. One is the Sahara located in the Middle East/Northern Africa and the other is the Gobi located in China. The first is one of the most politically unstable areas in the world and the second belongs to a country that has to support 25% of the worlds population. So you want the USA to depend on China even more let alone the area that already controls the majority of easily obtained oil.
@@edgelord6560 Sand is the most abundant solid substance on the planet, but we also use it more than anything else. The only two things that are consumed more than sand is air and water. We use about 50,000,000,000 tons of sand every year. That is a quantity large enough to cover the entire state of California. Cut out California on a map and then go ahead and try to copy and paste in on other parts of the world. This is the problem of big numbers. But essentially, it’s impossible for us to conceptualize things in the billions that we consume by the dozen.
@@anthonycarbone3826Doesn't America have deserts of its own? Seems to me that there are plenty of deserts in those cowboy movies you consistently sent around the world. Or are they are protected in national parks and can't be touched?
@@Debbie-henri Much of the desert land in the USA is controlled by the Federal Government in Parks and other Federal Land Management. You do understand taking all of the sand destroys the surface ecology for both humans and wild life. Do you really think the tree huggers are going to stand by and allow real destruction of animal habitat and National Parks. This is not something that is underground and out of the public's notice. Plus deserts are prone to flash floods and without the sand the floods will cause even more irrevocable erosion which sets off a chain reaction of even more dire consequences for everything living in the area.
It's good that you mentioned the Northern parts, like Canada or Northern Europe, that's where it can be most useful. I too do not see the use of it much outside the district heating of places in colder climates, because in the Northern places you mentioned we will not get much sun from mid October - start of March, so all we have left of renewables is wind... and we have the MOST need of energy in those winter months when we cannot survive without heating and it is a huge chunk of energy we use. Lithium batteries are not the best storage medium to take in sun in August or September and then store it for December-February when it will be most needed. And even solving winter heating here makes a lot of sense because it is a huge chunk of our energy needs. Probably best options to keep energy gained during summer to the winter month are either convert it to hydrogen or such solutions as the sand batteries for heat.
The picture at 4:00 is designed to appear like the entire thing is buried, but that would not be the case. All of the ancillary equipment would be in a shed next to the home, on top of the tank. You never want to bury something you may need to service later. But rusty old tanks are abundant and cheap. So long as its not capable of building pressure of any sort? Its harmless. As is exhaust tubing that can be easily bent at the local muffler shop. We are now seeing All-in-one hybrid and off-grid solar charge controller/Inverters that have 30/50 amp/240V "Smart Load" circuits built in. That would enable you to dump a crap ton of excess solar energy into such a thermal battery, every time the electrical batteries are full. The Grid is becoming more and more reluctant to pay consumers for their energy. Storing it as thermal energy just makes way too much sense. Heck if I lived in the south? I'd be freezing a thermal mass instead.
The problem with using the heat directly is that the most sand exists where we don't need the heat! Turns out, Phoenix and Las Vegas aren't clamoring for heat for most of the year. Yes, we still need hot water, but maybe electricity is still the best use. That said, the "negative heat' aspect is interesting. But I don't think it's grid-capable.
you would need a way to be pulling the heat out of the batteries at least on average at the rate the heat is being put in, since the data center heat output would be fairly steady and it doesnt need any of that heat back. buffering in sand batteries might let the heat be coupled to consumers better.
Data centers already recycle waste heat to some degree. The real problem though is that the "heat" you get out of a data center really isn't all that hot, and it is really really difficult to extract useful work out of something that isn't all that hot.
One missing point in this video is that the Li Ion batteries are Day storage, Sand Batteries can be used as seasonal storage, as Sand keeps the heat very long and is able to keep the heat from summer and move it to winter. On a limit, but much more than any other electrical battery system today!
Great idea! Reminds me of Drake Landing Solar Community in Alberta, Canada, a neighborhood which stores so much energy in the summer that they can use it to heat all winter.
@@markhathaway9456 They store a heat in a large underground area all summer, and it stays warm enough to provide heat all winter. You can't easily insulate something this well for a single house, but you can for a neighborhood. (Heat escapes based on the size of the surface area but the total amount of heat/energy stored is based on the size of the volume.)
Could be an interesting use for all the unused office space in major cities. I imagine weight would restrict the number of floors able to be used, but buildings could easily have lower floors converted to thermal storage to help reduce heating and cooling cost, while also reducing the required occupancy rate. Especially if the building was able to store more energy than it used and was able to sell excess to surrounding office buildings.
One thing to remember when comparing the cost per kwh of a battery vs heat storage is that the electricity from the battery can be used with a heat pump which can have 400 to 500 precent efficiency in converting electricity to heat but also can be used for cooling. But in really cold environments, the sand battery seems like 8t could be a good idea.
But the heat could come from concentrated solar which is 95% efficient at catching sun rays instead of 20-25% photovoltaic with also a lot less copper silver silicon etc
I have been using sand batteries for 4 years in a greenhouse it works responsibly good. I use a solar collector in a circut using pex pipe. I’m considering using solar to run heating elements so I can obtain higher sand temperatures.
1 huge advantage is that a sand battery, if done right, can hold temperature for many months, you can charge it in the summer and heat your home in winter with it, when solar is at its lowest output.
My biggest concern is what do you do with it during summer? It's not going to take all summer to charge it. I live in a part of Africa where energy and electricity overall is very scarce. But it's also very hot here most of the year. Can really say it only gets cold 2 months of the year here. So my question is, what application is there during the other 9-10 months of the year. I'm curious to see how one could use the sand battery as an alternative to air conditioning
@@abarairenji4483 hot running water, no need to ever use a boiler or whatever again. But it's more catered to northern climates, that have 3-6 months of need for heating.
@@nikm3r true, hot running water would be an ideal solution. I was thinking of converting back to electricity. Yes you lose about 50% energy when doing this but considering it's in a region where the grid only powers about 35-40% of residents, I don't think that energy loss is too bad right?
@@abarairenji4483 it would really depend on how cheap solar + regular batteries vs solar + sand battery + turbine to turn the heat back to electricity would be in your area of the world. Do the math! I just saw your name btw, nice!
Cooling provided with heat is actually possible with ´absorption chillers ´ which were generally used in the oil and gas industry where excess gas was burnt to provide heat to run absorption chillers.
Many houses are build on sand. The grounding down of the basement could do the thermal insulation, so summer heat could be stored in the ground of your cellar; warm air rises upwards in winter hugging the whole house. Today some think about cooling the house in summer by tubes digged in the still cool gardens sand. Half a century ago I was fascinated by a zero energy house witch stored the summer sun in a iron tube containing ten thousand liters of water, positioned vertical in the middle of the house, reaching from the basement to the roof where tubes collect hot water directly from installed thermal sun collectors. The stored energy was told to be enough for a winter. I later never heard anything about, maybe oil or gas was easier to use in existing habiations.
Another great video with fantastic informative points like the energy -> heat ration vs the heat -> energy ratio where I had no idea. This and many other reasons is why I love the channel 🎦🎦
I love the concept of a sand battery it's old tech that has been provent o work in small applications so if can use modern tech to refine it the possibilities and environmental benefits are enormous. I can't wait to see where this leads
Good quality sand is becoming scarce in any places due to its use in construction. The world has been on a construction boom the last few decades and sand is a key ingredient in concrete. This could eventually be a problem if sand batteries become popular.
Sand is up there with water as the most consumed commodity by mankind, good point. One of the drawbacks of dams for electricity is that it stops sand from mountain glacier grinding to get to the ocean, who would have thought way back! Sand battery sand would be reusable though..
All these thermal mass batteries such like, sand batteries, gravel batteries, stone batteries, brick (masonry) batteries, water batteries and even ground heat batteries, all have a common liver line, they are very cheap and a handy man can do 80% of the functionality for the 20% of the cost (the Pareto principle) on their own, and not to speak about the long term maintenance savings.
A cold battery is know as ice storage which has been around for years. They used to be recharged at night when electrical rates were low. Now they are recharged in the day and are depleted at night when there is no cheap solar to power HVAC equipment.
What if you could compact and spread out sand (ideally black sand) basically it would be very easy to heat up the sand during the day by spreading it out thin and exposing it to sunlight. Then compact it quickly to store the heat in. Then during the night you would extract the heat to heat homes. Then right before the sun comes up at the coldest time before morning, you would again spread out the sand to cool it down to night time temps. Then in the day you can use that for air conditioning, no?
If you want to store cold, liquid nitrogen would probably be better because of the phase change (14:40). You're also have an absolute limited of 300 degrees of temperature difference because it's impossible to store below absolute zero.
All refrigeration, which includes air conditioning, is using heat to make cold. Nearly all installations use electricity to create that heat but there are gas refrigerators that use heat directly. So, refrigeration and air conditioning should be included in what can be powered with this technology. This make a big, difference to the ROI as air conditioning is powered during hot weather where the days are longest and the sun shines brightest. For new builds the structure could be above a sand heat reservoir in the ground. In this way the efficiency could be further improved.
YOU DEFINITELY WANT TO READ THIS POST: I met a guy who as a young student invented a way of cheaply and ecologically heating a house and all of its hot water while he was attending New England Technical Institute in Warwick, Rhode Island in the 1980s. He won an award for his idea. His idea is to build a concrete compost pit and run copper water pipes in coils in the compost pit for heating water running through the copper pipe, and having the pipe feed from the home and return back to the home to heat up radiators or radiant hot water flooring, as well as tap water. Compost reaches surprisingly high temperatures. I think it's around 175°. If you're taking a hot shower you probably want your water around 100°. You'll have ample hot water from the compost pit. Any transmission lost between the house and the compost pit would not have a practical impact on heating the home or heating the tap water enough so that you don't need a conventional hot water heater. Running a water pump requires a lot of electricity, so it would be an excellent idea to compliment the system with rooftop solar. But even if you cannot compliment this system with solar power, it is still much more efficient than burning fossil fuels to heat the water or using electric radiators. My wife and I are planning to buy some land in Vermont to build an ultra-ecological, ultra-efficient, low-maintenance home using alternative building materials. This compost heating design will be central to our home heating and hot water systems. I had wondered about the potential for a sand battery to explode when exposed to liquid water. Thanks for confirming my suspicion. That doesn't mean it's the worst thing. Fossil fuel storage containers also explode. Pick your poison.
@KK-dv3wh An energy efficient home in a cold climate with a 120-day heating season needs about 83 million joules per day. Since the compost energy is coming mostly from food calories, we can convert joules to food calories, with 4184 joules per calorie that's about 20,000 calories per day worth of food that you would need to compost. This doesn't include heating water, which depending on hot water use can rival space heating use. Even if the home were twice as efficient as one of the best modern homes, it would require more food than 5 people require in a day. We use fuel and electricity to heat homes because they are much cheaper and much less valuable than food. Food waste is free, but unless you're wasting 10 peoples worth of food every day you're not making enough to provide for your heating needs. And this is why this idea hasn't gone anywhere since the 80's
Granted, composting is great for making soil-amendant for gardening. And, if you want an early start to the growing season you can build a hot-bed composter to capture some of that compost heat to germinate in the late winter and early spring. So composting is great, but for home heating, look to heat pumps. If you're feeling creative and inventive, look into organic PCMs to store heat when your heat pump is most efficient and use it in the cooler parts of the night.
One thing that is really hard to quantify is the cost to downstream users. The beauty of batteries is that users all already are set up to use power. If you want to bring a huge sand battery to share heat then every home or business needs to be set up tp directly use heat. Perhaps that happens in some areas of the world - but none that I know. Also, how much heat would be lost in distribution? How much would it cost to prepare infrastructure to move around that much heat without huge losses? So many more factors to consider! Thanks for the good video and view of something new!
Umm as mentioned in the video it can be used for district heating, so you have a plant that provides hot water in a given area, nothing needs to change in the infrastructure outside of the plant, sure if you're running your own heating that's not gonna help much but it doesn't mean there are no use cases where it doesn't fit in perfectly
Building codes. Most of Europe has district heating. Most of North America doesn't. If cities start planning to add this infrastructure, then you absolutely could see this in the future. Although most systems only change in response to scarcity or drastic disturbance.
I can’t remember the show but instead of sand they froze a like a 4’ square box of water at night when energy was cheap to help the a/c during the day. Pretty sure it was a library or public building and in California
I really hope a private version is made, not just the commercial variety, we should have the option to get a sand battery, even if it's a community one.
Sand batteries are great for off grid systems. There are plenty of times off grid solar is wasting the energy it captures because the batteries are full. Load dumping into a sand battery at that time, for warming your house / workshop on cold, no sun days makes plenty of sense. So along with pumping water to head or compressing air, sand batteries are a great way of storing excess power cheaply.
This brings up a question for greenhouses in the winter. Would it be better to have a separate sand battery to heat the greenhouse or would it be better to integrate it into the flooring cement the greenhouse? And would it be better just to run pipes within the sand battery to increase the floor heat or would it be better to use a heat exchanger to heat the air?
I watched a interesting interview with Robin Zeng (founder of CATL). He had some interesting points about grid storage batteries. It's really worth a watch. One of the points he discussed is the electronics and all other parts involved with battery storage have to be super reliable because there are so many of them for grid storage system.
Off hand, additional installation cost and maintenance access would probably be the primary reasons not to put the tank under ground. Digging/excavating a big enough hole can be expensive. If placed underground, you also might have issues with sinking, groundwater infiltration, seismic instability, etc. If there is any issues with the tank, maintenance and repair of the tank would be a lot more expensive and time consuming. Having said all that ... placing it underground might have some advantages, such as the tank being more insulated by the surrounding ground and other advantages.
Peltier devices would pair nicely with sand storage. Efficiency would be awful but no moving parts for maintenance. Heat one sand battery and cool another during surplus and then reverse for generation
Efficiency would be more than awful but I agree on the low maintenance. Efficiency is kinda the crux of the matter, though... if one is over-producing so much that one can still get something useful out of multiple stages of an extremely inefficient dump, its better to do something more direct with that overproduction than stuff it into a sand-battery.
for a home it is much better to use a huge tank of water right in the middle or your basement and maybe the first floor and constructing the stairway around it. of course you need some insulation around the water tank. due to the fact that an insulation is not perfect anyway some heat always leaks out. however, this "heat loss" is not lost at all, because the tank is in the middle of your house. that means that this thermal leakage is already heating your house a tiny bit. you can also implement two different tube coils inside at the top and bottom and extract and put in the heat very flexible because on the upper end it will always be warmer than at the bottom. this way you can heat the top end up with thermal solar panel to max. 40 degrees C because that is warm enough for your house heating system and then you switch over to put the additional heat at the bottom of the tank. for extraction you could do a similar thing. if the tank is very hot on the top, like 95°C, you take the heat out of the bottom or a mixture out of it to go with the right temperature in your heating. if the whole tank is getting colder, you could extract it only on the top of the tank. this installation lasts practically forever. and while having a basement is expensive, it is still very nice for a big hobby room, fitness room, party room, storage room, etc.
My only question is this: What kind of sand do the batteries take? For example, does it take rough/course sand that is used in construction and concrete or the fine and smooth sand from oceans and African deserts?" If it’s the latter, could that help reduce brine from our oceans when we desalinate our waters? . I figure this product of theirs would incredibly valuable if it contributes to solving this problem of Brine.
Hot and cold sand batteries? Now you’re getting into some interesting territory here. You’re also going to be able to collect condensation for drinking water in such a system, because you need hot and cold to absorb water from the air. On top of that you’re using excess energy that would have been wasted to get it. Pushing the idea further with more tweaking and you have a steam engine that barely runs out of water and fuel and has the potential to become an engine that runs on the atmosphere around it.
I think for ''Cold" battery, just freezing water would be great. Use solar during day to make a bunch of ICE and at night air can circulate through the ice cubes and cool your house.
I see a few problems here:- How exactly are we gonna transfer energy in n out ? Suppose we are using a steam driven turbine to take heat out it won't be abt to take all the energy. Like we will only be abt to exhaust 1000° C energy to 100° C energy coz steam can't exist below 100°C or so. Will the hardware used to heat up the system be efficient enough to transfer all the heat to the sand ?
2:30 can't we redirect the demand better so it can be used for energy intensive processes? 2:52 i just wondered why there are no Solarpanels on the roof?
Sand is "GeoThermal Where-ever You Want It" ... that's the best way to think of it. Use Sand Battery systems the same way you'd use GeoThermal. It's a bank; deposit when you have excess, withdraw when you need to top off the energy budget. Keep in mind that in North America, 25% of energy is for heating and cooling. Also keep in mind that transmission losses are averaged at 30%. So every kilowatt of electricity use for Hot/Cold, you reduce electrical generation demand by 325w. Over a thousand homes, that becomes significant.
I am building a passive house with radiant floor heating. I have to insulate under the slab-on-grade and this got me thinking. What if I dig a bit deeper, insulate, then put down a layer of sand with the Pex piping in the middle of the sand layer, followed by the concrete flooring above. Would the sand battery under the slab make the entire flooring more efficient? Should the PEX go in the sand or the slab? Has anyone done this? Someone must have, but I can't find any information about it. Please tell me your thoughts.
It could work, but get a “open-minded” mechanical engineer to do some heat loss heat gain computation, you’d need to ensure it doesn’t overheat ( which is a different problem, even in very cold climates) I did something like that but using earth tubes that were charged/ recharged and it worked fine 👍🏿
What about heating the sand with concentrated solar power, and using it to produce desalinated water? Would it have any advantage over other desalination methods?
I have heard of building techniques that regulate temperature by piping to areas far below surface. It also reminds me of traditional kim chee making where they bury jars of veggies to ferment at a constant temperature underground. This seems like something that could be very useful if integrated into new home construction. Not sure about the safety concerns living over a heat storage but I see potential.
@@markhathaway9456 I can’t remember what I had for breakfast today so don’t rely on my recall from half a century ago but they were a cupboard full of heavy brick sized thermal blocks with electrical elements sandwiched within. Air was blown through holes and came out all toasty through floor grilles.
Is it 1100 Deg C or Deg F? At 3:15 your graphic conflicted with your statement. Which one is correct and please let's stop with dual units all together-- Pick one and stick with it- we can handle it.
Am building an earth battery ( sand) for my off grid cabin can you tell me where I can find a source for electric pv heat and hvac I am running cooling by running pipe away from the sand too cool only
Maximizing efficiency is great, but economics still rules. If a sand battery can be built, on a per watt basis, for some fraction of the cost of a Li-On battery, then it is going to have an advantage, even if it only has a 65% roundtrip efficiency. This sand battery technology also would seem to have a big advantage for longer duration electricity production than a Li-On battery, which could prove to be useful for overcoming longer lulls in renewable energy production.
65% rountrip efficiency is likely better than Hydrogen, which we should also be pursuing at scale. California already has a glut of renewable electricity during the day.
If the heat is coming from Photovoltaic panels those also have low efficiently. Would it be more economical to us evacuated solar tubes to heat sand, then use it for home heating and electricity?
@@ricza7345 Have you seen the latest hybrid solar PVT? The panels also run tubing for water serving two purposes. Cooling the panels(which dont like extreme heat) and heating water. Ive seen this idea used in Europe.
They are comparing apples to oranges here. The current project has no reelectrification step. You basically pay $60/kwh just for the heat storage capabilities, while the battery system returns electricity at $150/kwh. The system is too expensive for just heat, because you are paying more than just the renewable energy production, like grid fees and taxes. Even if the electricity price was zero because of taking overproduction, you would still pay 10 cents for getting it into the storage. You can turn 1 kwh of electricity into 4 kwh of heat with a heap pump. Here you convert 1 kwh of electricity to maybe 0,85 kwh of heat, after it was moved from the storage through the district heating and into your home.
Pretty good video, thanks for the details on the subject of sand batteries. It's great that low quality and can be used for this instead of beach/ocean sand etc
That's the biggest "gotchya" to this entire discussion...GSHP (ground-source heat pumps) are already better than the best sand batteries. The sun already heats the earth, such that the energy needed can be moved around (through heat pumps) to warm and cool your home, as needed. With that work done, heating water with a heat pump is also very easily done. My home has an air-source heat pump and hot water heater with a heat pump on top of it. My summer vacation place is going to use a ductless mini-split for all the same reasons. The sand battery is going to have limited application for metro areas with existing hot water radiator networks.
Why not use one or more Fresnel screens to focus sunlight to heat the sand? The screens are relatively cheap and can produce up to 2000F or more at focal length. After an initial start-up, the system can maintain itself even on mildly cloudy days. It's possible to not only heat living space, but also produce electricity from sunlight.
Generally the way it is done is with reflectors... rheostats. A curved mirror focuses the sunlight onto a tube filled with your heat exchange liquid. That liquid is pumped through the tube along all the reflectors and then goes through a heat exchanger in the actual sand-battery (or whatever).
Cold battery is an interesting idea. But for that you could use water, the phase change of going to ice would store a massive amount of energy, much more than you could get with an equivalent volume of sand without going to super low temperatures which would kill efficiency.
An idea occurred to me for another of your videos. What if you convert that heat to light, Sodium Light and then to electricity? And you could reclaim the heat from the Air Conditioning unit.
You state that this wouldn't work very well during the summer (other than your "cool battery" you mention later on). However, this would work great in the summer as well for "passive" cooling. Using a large radiator of sorts above the home, create an updraft through the home cooling from conduit that's in the ground. Even if not using it to "directly" cool the home, use this cooler air as the ambient "outside" air for an airconditioner to transfer heat into out of the home, making the aircon far more efficient. The pumping would almost be not needed for this type of loop as convection would keep hot liquid at the top of the draft tower/vent.
Seems like a wet battery full of ice would be an easier 'cold battery' due to the whole issue of massive amounts of energy being needed or lost in order to cause a phase change.
A cold battery makes a ton of sense. Use a ground source heat pump to cool large sand battery. Run a hydronic loop through the battery to your fan coils using a mixing valve to control the temperature of the water. You would want to cool the battery down as low as can be done efficiently by your heat pump. And size it to last overnight on your hottest night. The hope would be that your solar array would be enough to charge your DC batteries and cool the sand battery far enough to make it overnight. This is made easier by the fact that the hottest nights are generally preceded by the longest sunniest days.
I like your idea about using it to cool as well. It sounds like you are thinking of having more than one temperature bank. You could draw heat from one for your heating needs and sink heat to the other for your cooling needs. Keeping strategic temperature ranges in each would allow you to use passive heat transfer for most applications. At the lower temperature ranges you could also use hydronics for a passive transfer medium, and heat pump for active transfers. It would be interesting to see what the net difference between heat needs and heat waste is in our homes. If we had staged temperature batteries we could capture waste heats and use them to preheat the thermal medium in the higher temp stages so that they require less energy. Heat Needs: Dryers, Stoves, Ovens, Water Heaters, Home Heat - Air, Home Heat - Radiant Floors, Side Walk Snow Melting Coils, Roof Snow Melting Coils, Swimming Pools (maybe not in San Diego, but up hear in the North), Green Houses, Cold Lithium Batteries, etc. Heat Wastes: Fridges, Freezers, Chilled Water Dispensers, Air Conditioning, Freeze Dryers, Green Houses, Hot Lithium Batteries, etc. I'm thinking three to five stages, one really hot, and two at the opposite ends of the useful heat pump temperature spectrum. Perhaps two more, one at the freezing and boiling point of water, since it is probably the best passive medium. That would complicate the waste electrical power side of the equation a little bit more, but I wonder if it is worth it. I think of two exotic waste cases. The fictional Stillsuit worn on Arrakis (I loved that episode by the way), and the intricate thermal management of a real Tesla vehicle. Questions: 1. It sounded like you were saying that they use sand as insulation too, which makes me wonder if we use much better thermal insulation, how long do you think we can we store heat. Can we save passive summer heat and use it in the winter? What about the opposite, save the absence of heat from the winter to sink heat to in the summer? 2. What are your thoughts about using deserts and glaciers to moderate the climate on mega scales? For instance, what if we tugged a huge iceberg from one of the poles to the California coast and moved the ice inland to Death Valley. It could take several years to complete, but the resulting ice melt would be inland where it is desperately needed, while lowering temperatures and not raising the sea level. (I got this idea from the movie: Brewster's Millions) I'm waiting for you and Matt Ferrell to collaborate on an episode. You, him, and Grady Hillhouse produce my favorite channels.
Based on what you said in your video on a 100-ton sand battery heating 100 homes in Europe, an average home would only need 1 ton of sand to heat that home. One ton of sand equals 22 cubic feet.
Solar Roof PV directly into the AC chiller pump fan system means that when the sun shines heating the building the most, the AC working hardest, all the solar PV energy used directly without being stored in batteries, especially with micro-inverters on the PV panels making AC directly in each panel //
There are several on the market that can directly take solar DC string voltages to run the A/C. You don't even have to go through a DC-AC conversion stage. However, this is not really ideal because homes take a while to heat up from the sun. On a hot day, our solar system starts producing significant amounts of energy as early as 8am, but the A/C in our house doesn't usually have to kick in until roughly noon, or even 1pm. And in a similar vein, one generally wants the A/C to run well into the evening, long after the solar has stopped producing.
When it comes to heat energy storage, besides cost of the storage medium, volumetric heat capacity is an important consideration. For instance silicon dioxide has a 1.855 J/(cm³*K) But sodium chloride is 9.04 J/(cm³*K). This means sodium chloride can store more than 4.5× as many joules of energy for each degree of temperature rise in a cubic cm. Yet both cubes have the same surface area to lose heat over. In other words, for each joule a cubic cm of silicon dioxide stores, a cubic cm of sodium chloride rises in temperature by less than 1/4.5 that of the silicon dioxide. And how fast heat is lost given the same surface area and insulation is proportional to temperature. Bulk sodium chloride and sand have similar cost so per cubic meter, so its volumetric heat capacity should take on a more important role in consideration.
The large capacity for storing heat comes from the max temperature, which is easy to achieve through resistive heating coils. But on the cool side, it seems to me that you would have to get much colder than freezing to have a similar cooling capacity. Is there technology that can achieve very cold temperatures efficiently with electricity? On the topic of usefullness if used only for heat. I remember a video on this topic that mentioned very northern locations that don't get much sunlight in winter. The heat battery was useful there because they could be heated during the summer, and would hold their heat for months into the winter.
it they want to make cool sand battery, they should make cold and hot sand battery together, moving the heat to the hot battery when cooling the cold battery.
Check out Batsand for a domestic solution when you come back to this. Also Antora, both for their high temp heat and also their interesting IR PV heat to electricity solution.
The problem I see is that, even if you do use the heat directly, you are still heating your home with resistive heat, just indirectly or delayed. Resistive heat is crap efficiency wise. They'd need to adapt heap pump technology or something to this use to up the efficiency.
So the bigger (or hotter) the better. But how efficient will it be if you scale it down to 10%? Like a 7' tall and 2' - 3' diameter. I don't need to heat a 100 houses, just my own house (cuz, I like to try things and not want to compete with natural gas which cost $ 2.5 - $5/GJ or $0.009 - $0.018/kwh, by selling heat to the neighborhood)
What I don't get is when people say that the round trip efficiency of Sand is low compared to Li Batteries. My take is WHO CARES?! If you lose 30%-50% of generated renewable power storing it in Sand that's STILL 50%-70% power you would otherwise have lost because you don't have storage. And if Sand is MUCH cheaper than Li batteries and not subject to the scalability issues of batteries then it's better than nothing.
I get your point and it does have merit. But by the same logic, the efficiency of the renewable power source wouldn't matter either. Looking at it in reverse, a lower round-trip efficiency means lost power that you wouldn't lose if you used a Li-ion battery, improving your energy independence.
@@ipp_tutor Yes, but With Sand batteries you don't have to Ramp up production on Li, Cobalt, Manganese, and every other substance we would need to electrify everything and keep pumping out Batteries. The cost of mining, transport, pollution, discard, recycle of any Chemical battery (even if we switch the Na instead of Li) will Always be more than building a Big insulated tank and filling it with sand.
Better than nothing is often the wrong way to go. Also t here are far superior media than sand, and quite inexpensive as well.
@@jonjohns8145Why not just convert excess supply into hydrogen injected into existing natural gas system with a capped limit where safety wouldn't be an issue.
Exactly
14:00 pro tip. you don't have to just go up LOL you can also go down with it! 10 stories underground 3 stories above ground AND less wall support issues and collapse problems. so the acerage is way less than shown here by a huge amount! also you build a 50 storey building they go down like 20 stories in the basement to anchor it etc. well you can build your sand silo and bury it right next to the foundation and heat it from there forever. run electric in heat and hot water comes out
This also solves the spillage issue, and doesn't have the potential to poison local soils because the stuff is solid.
Although, you have to wonder what benefits sand has over local earth given that you don't need to excavate anything to do traditional, residential geothermal storage.
Water ingress is a huge issue for below-ground-level structures, so it really isn't as straight-forward as one might think.
Going up is cheaper than going down.
I first learnt about sand batteries in Bill Millisons 'Permaculture Designers Manual' printed in 1988. They called it an 'energy store' and it is used as low grade heat for heating houses, green houses, hot wateretc, which is what this type of heat is best for, and which incidentally is the energy most people need/ use.
Let's call them "thermal batteries", so people won't think they compete with electrical batteries.
They have been called "heat stores" for decades. Some people in hot climates pump the hot air from their roof spaces during the day into a bed of rocks under their houses to use as heat during the night.
Pumping air is very cheap, and rocks are excellent thermal stores.
Others use 'trombe walls' to the same effect either storing energy in the wall, or a rock bed underneath.
Trombe walls can also cool houses!
Battery? Do these stores electricity?🤔🤨
Just imagine that you have a factory where every machine has a steam engine, but the heat is provided by portable and replaceable sand batteries that's charged at a central heating location. This enables each machine to operate independently for a few hours before their batteries needs to be replaced. The batteries themselves to back to the charging station until they get hot enough again. At the very least, this would make for some very whimsical steampunk setup. It doesn't even have to be that elaborate. It'd be awesome enough to just pull a hot cylinder full of sand from the fireplace, put it in some huge automaton and watch it come to life.
I am a big believer in thermal energy. This was true even before I knew anything. I had a house that utilized a wood burning enclosed burn chamber in our mud room that burned wood very efficiently and heated a ceramic tile wall in the house. There was a ceiling fan near by to aid in distribution of the heat and that wall would stay warm for days. Think if you had something similar that heated sand with excess solar electricity then circulated air through steel piping in the sand to heat the wall. I feel too many people discount ideas such as these with arguments about efficiency. Once installed there is virtually no maintenance. This can be built with off the shelf equipment that would make repairs such as a blower motor easy to do. This type of system could last the entire lifespan of the home and could be self powered by the same solar system. Upfront costs, yes, but after that, you could have supplemental heat for life. The cost for this is not too much compared to the propane cost reduction it could provide. If I could reduce my propane by 30%, that’s like $500 a year, every year, forever!
I stopped consuming any media concerning the development of battery technologies a decade ago. I'm glad I did. None of them went anywhere
Passive buildings sometimes use thermal mass such as winter sun hitting walls or floors of which cement to heat up during the day and release that heat at night. This works at residental scale
That can be a medium for storing heat in a system with a heat pump. Whether something natural like stone would be best for a cold storage isn't known to me, but natural safe materials at temperatures which don't explode, even when water is applied, would be great.
I have contemplated creating a sand battery for personal home heating, using Sun tracking mirrors to heat the battery. Thank you for the video
We have water batteries here in Germany in some residential buildings. Those are basically huge tanks filled with regular water which is heated during the summer by solar panels and the heat is then stored and used during the winter to heat the building. It´s pretty simple. However producing electricity from heat is a bad idea, the loses are to great. However the overall efficiency of thie mentioned idea is way higher since the energy is stored in between seasons. The idea is fantastic because it´s rather cheap and technologically easy.
There’s absolutely a case for residential heating use, if oversize your solar panel system and capture the excess energy in the sand battery, throughout the year. That can be used to heat your home through the winter.
I live in the desert southwest of the US, and that would be a wonderful application for our region. PLENTY of sun here, even in the winter. Such a system wouldn't have to be huge (as Ricky stated home systems would need to be) as our heating requirements are modest through the winter months. Even so, we do *have* heating requirements, as well as the need for hot water (of course). I would love to have a system like that for our home.
This is already being done here in Germany with water heat storing tanks. Also good thinking on your part. It´s efficiency is fantastic because sun energy is abundant in the summer and it´s used in the winter.
You mentioned a "cold battery". Check out Ice Bear by Thule Energy Storage. This is daily thermal energy storage (DTES).
Before refrigeration was invented people would harvest winter time ice from a lake and store it in an "ice house" so they would have ice in the summer time. This is seasonal thermal energy storage (STES).
For winter home heat I use PV-direct to heat water in an uninsulated tank when the sun shines that at night heats the house (DTES).
I am still trying do decide between sand or water or other for (STES).
Thank you for a most informative video.
Cold batteries are already in use. There is one under Helsinki, a huge pool of cold water, and it's a part of a pretty extensive district cooling system. They have also district heating but the cooling system is also quite widespread and has been there for 20 years.
I've also seen an old ice house design from somewhere in the middle east, where they can't just store the ice. It used the expansion of air descending through a chimney into a larger chamber to make ice. My father used to work at a historic cliff dwelling in New Mexico where that mechanism occurred naturally, keeping the caves at about 65 F even when the temp outside was in the hundreds.
Actually yoy can get cold from heat since fridge works on heating and gasifing things.
@@Nurk0m0rath For the cooling chimney, what's the process which does the cooling and is that cooler air just becoming the ambient air for their living area? It's not stored anywhere of course.
@@markhathaway9456 I'm no physicist but I understand the cooling effect is created by reverse compression. When the air is drawn into the chimney (or cracks in the cliff) and compressed, then hits a larger chamber, it slows and expands, becoming colder. I'm none too clear on the details of how it works though. I've been trying to remember where I saw that design and the closest I can think of is that it might have been in one of those features about ancient advanced technologies.
I saw the polar night thing when they first installed it, seemed genius, so i built a small scale one using an approx. 1 cub yard of sand and a small wood stove. it has worked 2 winters now, but i still haven't worked out all the issues yet. i need to move more heat from the wood stove to the sand instead of heating my shop to 80+ degrees. I burn a small fire for approx 5-7 hrs per day, and the heat radiates off the insulated sand box at night and does a good job keeping my 1200 sq ft shop toasty warm all winter. saves a truckload of firewood compared to just the woodstove i had. plan to connect solar panels to it soon!
Check out videos on using a Rocket stove to make and direct the heat you want to store.
using geothermal to heat and cool your house you basically are using the ground as a cold battery in the summer
Most uses with the heat pump are indoor-outdoor, but if you create heat-cold storages, then it might be more effective when the indoor-outdoor temperatures are less extreme. Also, if you have solar panels on the roof, you might want to cool them by bleeding the heat off and directly into your storage system.
Outstanding video! I've got 5120 watt-hours of LiFePO4 storage, and many hours of wasted solar energy each day. I'm thinking of building a sand battery, using it as a solar dump load. Yours is the best video on this topic so far. Absolutely brilliant and thanks for sharing.
@jxpat watch this video
This is totally doable, though if you have access to the grid the easier dump is to just throw it onto the grid with a cheap micro-inverter. In your case, however, I would spend the bucks on adding more main battery storage to improve your overnight margin and give you some bad-weather bridging capability first, before worrying about energy dumps.
One thing you are going to hit up against is, well, the weather. On hot days we have a ton of excess solar but no real overnight heating needs. On cloudy days or cold winter days we generally do not have enough solar so there isn't any excess to dump in the first place.
That's a bit of a problem actually. One has to have excess production during the days or weeks where the dump can actually provides a useful service.
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In anycase, if you are going to do a dump I recommend doing it through a satellite battery instead of directly from the main system. That's what I do. I have a 48V main system (10kWh) and a small 24V satellite battery. I have a DC-to-DC which dumps any excess energy when the main system is full over to the 24V satellite battery.
This way I can transfer excess energy at 1000W but my actual "dump" doesn't have to be 1000W, and I can control WHEN I actually dump to the actual dump independent of when the excess energy was being produced (which can be quite important actually).
I then have a timer which turns on the actual dump from the 24V satellite battery at an opportune time for when the dump is useful. The actual dump device can be anything. It can be a sand battery, a small A/C or heat pumps, or a cheap little grid-tied micro-inverter if one has access to the grid, it can help the water heater, Etc.
-Matt
I think DIYers will build sand batteries. You could probably build some rudimentry heating system using nothing but reclaimed bits and pieces and some tinkering
People do but it is harder than it looks. One can use a water-heater's thermal element (electric backup element) for heating it up, but getting the heat out of the sand battery is actually not entirely trivial. Basically you need something that can tolerate the heat and you need airflow to get the heat out again. An open-ended steel pipe with a fan on one end to push air through, and then some fins (like a piece of a radiator) to disperse the heat in the air because you don't want a blast of hot air at 500C.
Regulating the output is the hard part. You can't just duct it to the house (not at 500C). One mistake and the whole house burns down.
On most videos you'll see on the subject, there's usually a lot of physical effort involved, and it doesn't really last past half a day. They work, but there's a human in the loop, and it's not a small part. An electrically-heated sand battery might require less effort, but there's usually not a reason to do that unless the electricity isn't coming from the grid, otherwise, you might as well turn on your normal electric heater. So far, I haven't seen anyone do anything beyond a proof of concept or proof that it works for the room they intend to heat.
Also, almost none of them do any sort of heat regulation, but that's usually because they're trying to heat a large room as quickly as possible. I've never seen one try to do a hot water system.
We have water batteries here in Germany. It´s just a huge insulated water tanks placed underground with a coil in it and some plumbing. Solar energy during the summer is being stored all the way up to the winter. It´s overall efficiency is better than with Li-ion batteries and it´s cheaper. Doesn´t get as hot as with Sand but is cheap and works.
Hello! I discovered your channel a while ago, and I think it’s fantastic. I really appreciate how you analyze different ideas, essentially checking them for physical or chemical feasibility. That inspired me to share one of my own ideas with you, to see if you think it’s feasible.
Some time ago, I gifted Saudi Arabia an idea for creating a hydrogen cycle. Here’s a rough breakdown of the concept: First, the brine left over from reverse osmosis is used to generate energy in an osmotic power plant. That energy, in turn, is used to produce hydrogen. As a third step, the brine could be utilized to extract rare earth elements. Finally, the remaining salt could be used for chemical or food processing.
I'm really looking forward to hearing your thoughts on this! By the way, I just wanted to add that your channel is great, with incredibly interesting topics. Although I only discovered it a month or two ago, I have to say it’s full of fascinating content. Keep up the excellent work!❤
I was watching a video yesterday and the discussion included talk about homes with heating and cooling provided with the help of a heat pump. In France they're called a pompe à chaleur. The heat pump heats one storage unit with the heat from the other which is kept cold. The heat and cool of these two units help regulate the temperature of the home, cooling or heating as necessary. It's mostly for air temperature, not heating water, though that might be possible too. If you lived in a place where the average temperature was higher than you desire, the typical operation would be to cool the air in your home, while heating water. We know heat pumps work, so it's an idea for our times.
A dual phase sand tank with separate cold and hot sides sounds kind of brilliant. You'd be able to do all kinds of amazing things with having both a chilled battery and a heat battery. Throw in some heat exchangers and suddenly your steel plants are powering your industrial freezers. The concrete plant down the street can cool the freezer of every local restaurant. If we think in terms of districts and communal sourcing rather than individualized solutions, economy of scale works in *everybody's* favor. It makes little sense for an individual house to power it's own hot water tanks when it would cost orders of magnitude less overall to do so for an entire city, plus there would never be any chance of running out of hot water.
I'm pretty sure you'd quickly run into huge losses if you try to run very hot or very cold water through long runs of pipe. A city-wide system would (I surmise) have far greater losses than using heat pumps for individual freezers and water heaters. Industrial freezers (and heat pumps generally) are already extremely efficient. With a good modern unit, you get about 3x more cooling than the amount of energy you put in. This is because heat pumps MOVE heat, rather than generating it.
When people picture sand spread across idyllic beaches and endless deserts, they understandably think of it as an infinite resource. But as we discuss in a just-published perspective in the journal Science, over-exploitation of global supplies of sand is damaging the environment, endangering communities, causing shortages and promoting violent conflict. Sand is not the answer as it is used in so many everyday projects in economies around the world and numerous countries are already in short supply. The negative consequences of over-exploiting sand are felt in poorer regions where sand is mined. Extensive sand extraction physically alters rivers and coastal ecosystems, increases suspended sediments and causes erosion. I suppose the west could replace it with the garbage they produce to replace the sand; which of course would never be called exploitation of the poor and lead to world wide social unrest.
We can use only river sand for construction. That's why there's a shortage but desert sand is almost unlimited
@@edgelord6560 There are two major sand Deserts. One is the Sahara located in the Middle East/Northern Africa and the other is the Gobi located in China. The first is one of the most politically unstable areas in the world and the second belongs to a country that has to support 25% of the worlds population. So you want the USA to depend on China even more let alone the area that already controls the majority of easily obtained oil.
@@edgelord6560 Sand is the most abundant solid substance on the planet, but we also use it more than anything else. The only two things that are consumed more than sand is air and water.
We use about 50,000,000,000 tons of sand every year. That is a quantity large enough to cover the entire state of California. Cut out California on a map and then go ahead and try to copy and paste in on other parts of the world. This is the problem of big numbers. But essentially, it’s impossible for us to conceptualize things in the billions that we consume by the dozen.
@@anthonycarbone3826Doesn't America have deserts of its own? Seems to me that there are plenty of deserts in those cowboy movies you consistently sent around the world. Or are they are protected in national parks and can't be touched?
@@Debbie-henri Much of the desert land in the USA is controlled by the Federal Government in Parks and other Federal Land Management. You do understand taking all of the sand destroys the surface ecology for both humans and wild life. Do you really think the tree huggers are going to stand by and allow real destruction of animal habitat and National Parks. This is not something that is underground and out of the public's notice. Plus deserts are prone to flash floods and without the sand the floods will cause even more irrevocable erosion which sets off a chain reaction of even more dire consequences for everything living in the area.
Idk if you slowed down your speech, but this was a lot more understandable than usual 😅 You're awesome. Thanks for everything!
Correction...( 3:16)
1100 degrees Fahrenheit....
660 Celsius
( at least according to your own text, on-screen)
I've never been inside a hot Pyramid, so yeah sand is fantastic at cooling as well
It's good that you mentioned the Northern parts, like Canada or Northern Europe, that's where it can be most useful. I too do not see the use of it much outside the district heating of places in colder climates, because in the Northern places you mentioned we will not get much sun from mid October - start of March, so all we have left of renewables is wind... and we have the MOST need of energy in those winter months when we cannot survive without heating and it is a huge chunk of energy we use. Lithium batteries are not the best storage medium to take in sun in August or September and then store it for December-February when it will be most needed. And even solving winter heating here makes a lot of sense because it is a huge chunk of our energy needs. Probably best options to keep energy gained during summer to the winter month are either convert it to hydrogen or such solutions as the sand batteries for heat.
The picture at 4:00 is designed to appear like the entire thing is buried, but that would not be the case. All of the ancillary equipment would be in a shed next to the home, on top of the tank. You never want to bury something you may need to service later. But rusty old tanks are abundant and cheap. So long as its not capable of building pressure of any sort? Its harmless. As is exhaust tubing that can be easily bent at the local muffler shop. We are now seeing All-in-one hybrid and off-grid solar charge controller/Inverters that have 30/50 amp/240V "Smart Load" circuits built in. That would enable you to dump a crap ton of excess solar energy into such a thermal battery, every time the electrical batteries are full. The Grid is becoming more and more reluctant to pay consumers for their energy. Storing it as thermal energy just makes way too much sense. Heck if I lived in the south? I'd be freezing a thermal mass instead.
The problem with using the heat directly is that the most sand exists where we don't need the heat! Turns out, Phoenix and Las Vegas aren't clamoring for heat for most of the year. Yes, we still need hot water, but maybe electricity is still the best use.
That said, the "negative heat' aspect is interesting. But I don't think it's grid-capable.
It could be use to store excess heat from data centers to improve the efficency.
I think data centers could give the heat to a local central heating system?
you would need a way to be pulling the heat out of the batteries at least on average at the rate the heat is being put in, since the data center heat output would be fairly steady and it doesnt need any of that heat back. buffering in sand batteries might let the heat be coupled to consumers better.
Data centers already recycle waste heat to some degree. The real problem though is that the "heat" you get out of a data center really isn't all that hot, and it is really really difficult to extract useful work out of something that isn't all that hot.
Meanwhile in Australia, they tell us glass will be more expensive because the world is running out of sand.
It is conceivable that the stored heat from a sand battery could be used to generate electicity by means of a stirling engine.
One missing point in this video is that the Li Ion batteries are Day storage, Sand Batteries can be used as seasonal storage, as Sand keeps the heat very long and is able to keep the heat from summer and move it to winter. On a limit, but much more than any other electrical battery system today!
Great idea! Reminds me of Drake Landing Solar Community in Alberta, Canada, a neighborhood which stores so much energy in the summer that they can use it to heat all winter.
Exactly
It’s not a theory (any longer) but a proven solution that should be highlighted 🎉
And, how do they store it for long-term use ?
@@markhathaway9456 They store a heat in a large underground area all summer, and it stays warm enough to provide heat all winter. You can't easily insulate something this well for a single house, but you can for a neighborhood. (Heat escapes based on the size of the surface area but the total amount of heat/energy stored is based on the size of the volume.)
Could be an interesting use for all the unused office space in major cities. I imagine weight would restrict the number of floors able to be used, but buildings could easily have lower floors converted to thermal storage to help reduce heating and cooling cost, while also reducing the required occupancy rate. Especially if the building was able to store more energy than it used and was able to sell excess to surrounding office buildings.
One thing to remember when comparing the cost per kwh of a battery vs heat storage is that the electricity from the battery can be used with a heat pump which can have 400 to 500 precent efficiency in converting electricity to heat but also can be used for cooling. But in really cold environments, the sand battery seems like 8t could be a good idea.
But the heat could come from concentrated solar which is 95% efficient at catching sun rays instead of 20-25% photovoltaic with also a lot less copper silver silicon etc
I have been using sand batteries for 4 years in a greenhouse it works responsibly good. I use a solar collector in a circut using pex pipe. I’m considering using solar to run heating elements so I can obtain higher sand temperatures.
I have been thinking of that
How do warm the battery and where is it? In the greenhouse itself?
1 huge advantage is that a sand battery, if done right, can hold temperature for many months, you can charge it in the summer and heat your home in winter with it, when solar is at its lowest output.
My biggest concern is what do you do with it during summer? It's not going to take all summer to charge it. I live in a part of Africa where energy and electricity overall is very scarce. But it's also very hot here most of the year. Can really say it only gets cold 2 months of the year here. So my question is, what application is there during the other 9-10 months of the year.
I'm curious to see how one could use the sand battery as an alternative to air conditioning
@@abarairenji4483 hot running water, no need to ever use a boiler or whatever again. But it's more catered to northern climates, that have 3-6 months of need for heating.
@@nikm3r true, hot running water would be an ideal solution. I was thinking of converting back to electricity. Yes you lose about 50% energy when doing this but considering it's in a region where the grid only powers about 35-40% of residents, I don't think that energy loss is too bad right?
@@abarairenji4483 it would really depend on how cheap solar + regular batteries vs solar + sand battery + turbine to turn the heat back to electricity would be in your area of the world. Do the math!
I just saw your name btw, nice!
@@nikm3r hehe, thanks.
Appreciate you taking the time to educate me a little. 👍
"I don't like sand. It's coarse and rough and irritating and it gets everywhere."
the worst is the weight! but at least you don;t have expansion, boiling, or leak problems like water, and it works more steady.
it's over, I have the high ground!
Not like you. You're everything soft and smooth.
@traybern Kramer, a Jedi? I doubt it.
If we could develop a bull shit batteries we could make them super cheaply in Washington DC.
Yes, I've known a few people who've gotten great mileage from their bullshit! 👍
Cooling provided with heat is actually possible with ´absorption chillers ´ which were generally used in the oil and gas industry where excess gas was burnt to provide heat to run absorption chillers.
Many houses are build on sand. The grounding down of the basement could do the thermal insulation, so summer heat could be stored in the ground of your cellar; warm air rises upwards in winter hugging the whole house. Today some think about cooling the house in summer by tubes digged in the still cool gardens sand.
Half a century ago I was fascinated by a zero energy house witch stored the summer sun in a iron tube containing ten thousand liters of water, positioned vertical in the middle of the house, reaching from the basement to the roof where tubes collect hot water directly from installed thermal sun collectors. The stored energy was told to be enough for a winter. I later never heard anything about, maybe oil or gas was easier to use in existing habiations.
Another great video with fantastic informative points like the energy -> heat ration vs the heat -> energy ratio where I had no idea. This and many other reasons is why I love the channel 🎦🎦
Agreed!
I love the concept of a sand battery it's old tech that has been provent o work in small applications so if can use modern tech to refine it the possibilities and environmental benefits are enormous. I can't wait to see where this leads
Good quality sand is becoming scarce in any places due to its use in construction. The world has been on a construction boom the last few decades and sand is a key ingredient in concrete. This could eventually be a problem if sand batteries become popular.
Yeah I'm hoping that the _cheap_ sand will work just as well for this - but he didn't mention.
Sand is up there with water as the most consumed commodity by mankind, good point. One of the drawbacks of dams for electricity is that it stops sand from mountain glacier grinding to get to the ocean, who would have thought way back! Sand battery sand would be reusable though..
Parrot fish are always happy to make more 😊
All these thermal mass batteries such like, sand batteries, gravel batteries, stone batteries, brick (masonry) batteries, water batteries and even ground heat batteries, all have a common liver line, they are very cheap and a handy man can do 80% of the functionality for the 20% of the cost (the Pareto principle) on their own, and not to speak about the long term maintenance savings.
A cold battery is know as ice storage which has been around for years. They used to be recharged at night when electrical rates were low. Now they are recharged in the day and are depleted at night when there is no cheap solar to power HVAC equipment.
What if you could compact and spread out sand (ideally black sand) basically it would be very easy to heat up the sand during the day by spreading it out thin and exposing it to sunlight. Then compact it quickly to store the heat in. Then during the night you would extract the heat to heat homes. Then right before the sun comes up at the coldest time before morning, you would again spread out the sand to cool it down to night time temps. Then in the day you can use that for air conditioning, no?
If you want to store cold, liquid nitrogen would probably be better because of the phase change (14:40). You're also have an absolute limited of 300 degrees of temperature difference because it's impossible to store below absolute zero.
All refrigeration, which includes air conditioning, is using heat to make cold. Nearly all installations use electricity to create that heat but there are gas refrigerators that use heat directly. So, refrigeration and air conditioning should be included in what can be powered with this technology. This make a big, difference to the ROI as air conditioning is powered during hot weather where the days are longest and the sun shines brightest.
For new builds the structure could be above a sand heat reservoir in the ground. In this way the efficiency could be further improved.
YOU DEFINITELY WANT TO READ THIS POST:
I met a guy who as a young student invented a way of cheaply and ecologically heating a house and all of its hot water while he was attending New England Technical Institute in Warwick, Rhode Island in the 1980s.
He won an award for his idea.
His idea is to build a concrete compost pit and run copper water pipes in coils in the compost pit for heating water running through the copper pipe, and having the pipe feed from the home and return back to the home to heat up radiators or radiant hot water flooring, as well as tap water.
Compost reaches surprisingly high temperatures. I think it's around 175°. If you're taking a hot shower you probably want your water around 100°. You'll have ample hot water from the compost pit.
Any transmission lost between the house and the compost pit would not have a practical impact on heating the home or heating the tap water enough so that you don't need a conventional hot water heater.
Running a water pump requires a lot of electricity, so it would be an excellent idea to compliment the system with rooftop solar. But even if you cannot compliment this system with solar power, it is still much more efficient than burning fossil fuels to heat the water or using electric radiators.
My wife and I are planning to buy some land in Vermont to build an ultra-ecological, ultra-efficient, low-maintenance home using alternative building materials. This compost heating design will be central to our home heating and hot water systems.
I had wondered about the potential for a sand battery to explode when exposed to liquid water. Thanks for confirming my suspicion. That doesn't mean it's the worst thing. Fossil fuel storage containers also explode. Pick your poison.
how much compost would a home have to generate to meet its heating needs?
@KK-dv3wh An energy efficient home in a cold climate with a 120-day heating season needs about 83 million joules per day. Since the compost energy is coming mostly from food calories, we can convert joules to food calories, with 4184 joules per calorie that's about 20,000 calories per day worth of food that you would need to compost. This doesn't include heating water, which depending on hot water use can rival space heating use. Even if the home were twice as efficient as one of the best modern homes, it would require more food than 5 people require in a day. We use fuel and electricity to heat homes because they are much cheaper and much less valuable than food. Food waste is free, but unless you're wasting 10 peoples worth of food every day you're not making enough to provide for your heating needs. And this is why this idea hasn't gone anywhere since the 80's
Granted, composting is great for making soil-amendant for gardening. And, if you want an early start to the growing season you can build a hot-bed composter to capture some of that compost heat to germinate in the late winter and early spring. So composting is great, but for home heating, look to heat pumps. If you're feeling creative and inventive, look into organic PCMs to store heat when your heat pump is most efficient and use it in the cooler parts of the night.
@@Spencergolde I imagined it must be a stretch, thanks for the details.
@@KK-dv3wh ,
That's a good question. I have no idea. That's about as much information as he gave me in a random conversation at a Dunkin' Donuts.
One thing that is really hard to quantify is the cost to downstream users.
The beauty of batteries is that users all already are set up to use power. If you want to bring a huge sand battery to share heat then every home or business needs to be set up tp directly use heat.
Perhaps that happens in some areas of the world - but none that I know.
Also, how much heat would be lost in distribution? How much would it cost to prepare infrastructure to move around that much heat without huge losses?
So many more factors to consider!
Thanks for the good video and view of something new!
which is why it is more interesting to use the heat to generate steam to run a turbine to create electricity
Umm as mentioned in the video it can be used for district heating, so you have a plant that provides hot water in a given area, nothing needs to change in the infrastructure outside of the plant, sure if you're running your own heating that's not gonna help much but it doesn't mean there are no use cases where it doesn't fit in perfectly
Building codes. Most of Europe has district heating. Most of North America doesn't.
If cities start planning to add this infrastructure, then you absolutely could see this in the future. Although most systems only change in response to scarcity or drastic disturbance.
In Alaska, they do use radiator/district heat. They also have underfloor piping as well as typical radiators.
I can’t remember the show but instead of sand they froze a like a 4’ square box of water at night when energy was cheap to help the a/c during the day. Pretty sure it was a library or public building and in California
There was one in Texas too, I think
I really hope a private version is made, not just the commercial variety, we should have the option to get a sand battery, even if it's a community one.
Sand batteries are great for off grid systems. There are plenty of times off grid solar is wasting the energy it captures because the batteries are full. Load dumping into a sand battery at that time, for warming your house / workshop on cold, no sun days makes plenty of sense.
So along with pumping water to head or compressing air, sand batteries are a great way of storing excess power cheaply.
This brings up a question for greenhouses in the winter. Would it be better to have a separate sand battery to heat the greenhouse or would it be better to integrate it into the flooring cement the greenhouse? And would it be better just to run pipes within the sand battery to increase the floor heat or would it be better to use a heat exchanger to heat the air?
I watched a interesting interview with Robin Zeng (founder of CATL). He had some interesting points about grid storage batteries. It's really worth a watch. One of the points he discussed is the electronics and all other parts involved with battery storage have to be super reliable because there are so many of them for grid storage system.
Why would it take up any Acers? Couldn't you put the tank under ground?
Off hand, additional installation cost and maintenance access would probably be the primary reasons not to put the tank under ground. Digging/excavating a big enough hole can be expensive. If placed underground, you also might have issues with sinking, groundwater infiltration, seismic instability, etc. If there is any issues with the tank, maintenance and repair of the tank would be a lot more expensive and time consuming. Having said all that ... placing it underground might have some advantages, such as the tank being more insulated by the surrounding ground and other advantages.
Or just use the sand that’s already there
Peltier devices would pair nicely with sand storage. Efficiency would be awful but no moving parts for maintenance. Heat one sand battery and cool another during surplus and then reverse for generation
Efficiency would be more than awful but I agree on the low maintenance. Efficiency is kinda the crux of the matter, though... if one is over-producing so much that one can still get something useful out of multiple stages of an extremely inefficient dump, its better to do something more direct with that overproduction than stuff it into a sand-battery.
for a home it is much better to use a huge tank of water right in the middle or your basement and maybe the first floor and constructing the stairway around it.
of course you need some insulation around the water tank. due to the fact that an insulation is not perfect anyway some heat always leaks out.
however, this "heat loss" is not lost at all, because the tank is in the middle of your house. that means that this thermal leakage is already heating your house a tiny bit. you can also implement two different tube coils inside at the top and bottom and extract and put in the heat very flexible because on the upper end it will always be warmer than at the bottom. this way you can heat the top end up with thermal solar panel to max. 40 degrees C because that is warm enough for your house heating system and then you switch over to put the additional heat at the bottom of the tank. for extraction you could do a similar thing. if the tank is very hot on the top, like 95°C, you take the heat out of the bottom or a mixture out of it to go with the right temperature in your heating. if the whole tank is getting colder, you could extract it only on the top of the tank.
this installation lasts practically forever. and while having a basement is expensive, it is still very nice for a big hobby room, fitness room, party room, storage room, etc.
One company which produces absorption chillers, which perhaps is still operational is ´Carrier Ibara ´ based in Japan.
My only question is this:
What kind of sand do the batteries take? For example, does it take rough/course sand that is used in construction and concrete or the fine and smooth sand from oceans and African deserts?"
If it’s the latter, could that help reduce brine from our oceans when we desalinate our waters? . I figure this product of theirs would incredibly valuable if it contributes to solving this problem of Brine.
Hot and cold sand batteries? Now you’re getting into some interesting territory here. You’re also going to be able to collect condensation for drinking water in such a system, because you need hot and cold to absorb water from the air. On top of that you’re using excess energy that would have been wasted to get it. Pushing the idea further with more tweaking and you have a steam engine that barely runs out of water and fuel and has the potential to become an engine that runs on the atmosphere around it.
Man Thank you for all those precise/precious datas 🙏🙏🙏
I'm actually planning on building one at my home
I think for ''Cold" battery, just freezing water would be great. Use solar during day to make a bunch of ICE and at night air can circulate through the ice cubes and cool your house.
That heat could be used for saunas even in the summer, or heating swimming pools.
I see a few problems here:-
How exactly are we gonna transfer energy in n out ?
Suppose we are using a steam driven turbine to take heat out it won't be abt to take all the energy. Like we will only be abt to exhaust 1000° C energy to 100° C energy coz steam can't exist below 100°C or so.
Will the hardware used to heat up the system be efficient enough to transfer all the heat to the sand ?
2:30 can't we redirect the demand better so it can be used for energy intensive processes?
2:52 i just wondered why there are no Solarpanels on the roof?
Sand is "GeoThermal Where-ever You Want It" ... that's the best way to think of it. Use Sand Battery systems the same way you'd use GeoThermal. It's a bank; deposit when you have excess, withdraw when you need to top off the energy budget.
Keep in mind that in North America, 25% of energy is for heating and cooling. Also keep in mind that transmission losses are averaged at 30%. So every kilowatt of electricity use for Hot/Cold, you reduce electrical generation demand by 325w. Over a thousand homes, that becomes significant.
Wait, why are sand battery silos built upwards and not downwards (into the ground)? Wouldnt that help with thermal insulation?
I am building a passive house with radiant floor heating. I have to insulate under the slab-on-grade and this got me thinking. What if I dig a bit deeper, insulate, then put down a layer of sand with the Pex piping in the middle of the sand layer, followed by the concrete flooring above. Would the sand battery under the slab make the entire flooring more efficient? Should the PEX go in the sand or the slab? Has anyone done this? Someone must have, but I can't find any information about it. Please tell me your thoughts.
It could work, but get a “open-minded” mechanical engineer to do some heat loss heat gain computation, you’d need to ensure it doesn’t overheat ( which is a different problem, even in very cold climates)
I did something like that but using earth tubes that were charged/ recharged and it worked fine 👍🏿
Thank you, Kori. I'll see how open-minded of a mechanical engineer I can find :) @@koriifaloju2051
What about heating the sand with concentrated solar power, and using it to produce desalinated water? Would it have any advantage over other desalination methods?
I have heard of building techniques that regulate temperature by piping to areas far below surface. It also reminds me of traditional kim chee making where they bury jars of veggies to ferment at a constant temperature underground. This seems like something that could be very useful if integrated into new home construction. Not sure about the safety concerns living over a heat storage but I see potential.
Lithium battery $150/Kwh, Polar night Energy $85/Kwh, Batsand $2/Kwh. The insane potential of DIY sand battery.
How about using absorption chillers to cool the home during summer?
Why is the Sand Battery built above ground and not below? Curious.
What goes around comes around!
My first home I bought in 1965 was heated in exactly this way - thermal blocks.
How were the blocks heated? How long did they hold the heat? What were the blocks made of?
@@markhathaway9456 I can’t remember what I had for breakfast today so don’t rely on my recall from half a century ago but they were a cupboard full of heavy brick sized thermal blocks with electrical elements sandwiched within. Air was blown through holes and came out all toasty through floor grilles.
Is it 1100 Deg C or Deg F? At 3:15 your graphic conflicted with your statement. Which one is correct and please let's stop with dual units all together-- Pick one and stick with it- we can handle it.
Am building an earth battery ( sand) for my off grid cabin can you tell me where I can find a source for electric pv heat and hvac
I am running cooling by running pipe away from the sand too cool only
Maximizing efficiency is great, but economics still rules. If a sand battery can be built, on a per watt basis, for some fraction of the cost of a Li-On battery, then it is going to have an advantage, even if it only has a 65% roundtrip efficiency. This sand battery technology also would seem to have a big advantage for longer duration electricity production than a Li-On battery, which could prove to be useful for overcoming longer lulls in renewable energy production.
65% rountrip efficiency is likely better than Hydrogen, which we should also be pursuing at scale. California already has a glut of renewable electricity during the day.
If the heat is coming from Photovoltaic panels those also have low efficiently. Would it be more economical to us evacuated solar tubes to heat sand, then use it for home heating and electricity?
@@ricza7345 Have you seen the latest hybrid solar PVT? The panels also run tubing for water serving two purposes. Cooling the panels(which dont like extreme heat) and heating water. Ive seen this idea used in Europe.
They are comparing apples to oranges here. The current project has no reelectrification step. You basically pay $60/kwh just for the heat storage capabilities, while the battery system returns electricity at $150/kwh. The system is too expensive for just heat, because you are paying more than just the renewable energy production, like grid fees and taxes. Even if the electricity price was zero because of taking overproduction, you would still pay 10 cents for getting it into the storage. You can turn 1 kwh of electricity into 4 kwh of heat with a heap pump. Here you convert 1 kwh of electricity to maybe 0,85 kwh of heat, after it was moved from the storage through the district heating and into your home.
Pretty good video, thanks for the details on the subject of sand batteries. It's great that low quality and can be used for this instead of beach/ocean sand etc
3:23 insert heat pump comment here
Totally
That's the biggest "gotchya" to this entire discussion...GSHP (ground-source heat pumps) are already better than the best sand batteries. The sun already heats the earth, such that the energy needed can be moved around (through heat pumps) to warm and cool your home, as needed. With that work done, heating water with a heat pump is also very easily done. My home has an air-source heat pump and hot water heater with a heat pump on top of it. My summer vacation place is going to use a ductless mini-split for all the same reasons. The sand battery is going to have limited application for metro areas with existing hot water radiator networks.
Very interested in this system for home heating and cooling in the prairies of Canada for residential purposes. We have -40C to +40C over the year.
Why not use one or more Fresnel screens to focus sunlight to heat the sand? The screens are relatively cheap and can produce up to 2000F or more at focal length. After an initial start-up, the system can maintain itself even on mildly cloudy days. It's possible to not only heat living space, but also produce electricity from sunlight.
Generally the way it is done is with reflectors... rheostats. A curved mirror focuses the sunlight onto a tube filled with your heat exchange liquid. That liquid is pumped through the tube along all the reflectors and then goes through a heat exchanger in the actual sand-battery (or whatever).
Cold battery is an interesting idea. But for that you could use water, the phase change of going to ice would store a massive amount of energy, much more than you could get with an equivalent volume of sand without going to super low temperatures which would kill efficiency.
An idea occurred to me for another of your videos. What if you convert that heat to light, Sodium Light and then to electricity? And you could reclaim the heat from the Air Conditioning unit.
You state that this wouldn't work very well during the summer (other than your "cool battery" you mention later on). However, this would work great in the summer as well for "passive" cooling. Using a large radiator of sorts above the home, create an updraft through the home cooling from conduit that's in the ground. Even if not using it to "directly" cool the home, use this cooler air as the ambient "outside" air for an airconditioner to transfer heat into out of the home, making the aircon far more efficient.
The pumping would almost be not needed for this type of loop as convection would keep hot liquid at the top of the draft tower/vent.
Seems like a wet battery full of ice would be an easier 'cold battery' due to the whole issue of massive amounts of energy being needed or lost in order to cause a phase change.
A cold battery makes a ton of sense. Use a ground source heat pump to cool large sand battery. Run a hydronic loop through the battery to your fan coils using a mixing valve to control the temperature of the water.
You would want to cool the battery down as low as can be done efficiently by your heat pump. And size it to last overnight on your hottest night.
The hope would be that your solar array would be enough to charge your DC batteries and cool the sand battery far enough to make it overnight. This is made easier by the fact that the hottest nights are generally preceded by the longest sunniest days.
I love the idea. Undecided with Matt did a good video about sand batteries not long ago, for more information.
I like your idea about using it to cool as well. It sounds like you are thinking of having more than one temperature bank. You could draw heat from one for your heating needs and sink heat to the other for your cooling needs. Keeping strategic temperature ranges in each would allow you to use passive heat transfer for most applications. At the lower temperature ranges you could also use hydronics for a passive transfer medium, and heat pump for active transfers.
It would be interesting to see what the net difference between heat needs and heat waste is in our homes. If we had staged temperature batteries we could capture waste heats and use them to preheat the thermal medium in the higher temp stages so that they require less energy.
Heat Needs: Dryers, Stoves, Ovens, Water Heaters, Home Heat - Air, Home Heat - Radiant Floors, Side Walk Snow Melting Coils, Roof Snow Melting Coils, Swimming Pools (maybe not in San Diego, but up hear in the North), Green Houses, Cold Lithium Batteries, etc.
Heat Wastes: Fridges, Freezers, Chilled Water Dispensers, Air Conditioning, Freeze Dryers, Green Houses, Hot Lithium Batteries, etc.
I'm thinking three to five stages, one really hot, and two at the opposite ends of the useful heat pump temperature spectrum. Perhaps two more, one at the freezing and boiling point of water, since it is probably the best passive medium. That would complicate the waste electrical power side of the equation a little bit more, but I wonder if it is worth it. I think of two exotic waste cases. The fictional Stillsuit worn on Arrakis (I loved that episode by the way), and the intricate thermal management of a real Tesla vehicle.
Questions:
1. It sounded like you were saying that they use sand as insulation too, which makes me wonder if we use much better thermal insulation, how long do you think we can we store heat. Can we save passive summer heat and use it in the winter? What about the opposite, save the absence of heat from the winter to sink heat to in the summer?
2. What are your thoughts about using deserts and glaciers to moderate the climate on mega scales? For instance, what if we tugged a huge iceberg from one of the poles to the California coast and moved the ice inland to Death Valley. It could take several years to complete, but the resulting ice melt would be inland where it is desperately needed, while lowering temperatures and not raising the sea level. (I got this idea from the movie: Brewster's Millions)
I'm waiting for you and Matt Ferrell to collaborate on an episode. You, him, and Grady Hillhouse produce my favorite channels.
Based on what you said in your video on a 100-ton sand battery heating 100 homes in Europe, an average home would only need 1 ton of sand to heat that home. One ton of sand equals 22 cubic feet.
Solar Roof PV directly into the AC chiller pump fan system means that when the sun shines heating the building the most, the AC working hardest, all the solar PV energy used directly without being stored in batteries, especially with micro-inverters on the PV panels making AC directly in each panel //
There are several on the market that can directly take solar DC string voltages to run the A/C. You don't even have to go through a DC-AC conversion stage. However, this is not really ideal because homes take a while to heat up from the sun. On a hot day, our solar system starts producing significant amounts of energy as early as 8am, but the A/C in our house doesn't usually have to kick in until roughly noon, or even 1pm. And in a similar vein, one generally wants the A/C to run well into the evening, long after the solar has stopped producing.
Ammonia cycle refrigeration would work great with this sand battery system.
When it comes to heat energy storage, besides cost of the storage medium, volumetric heat capacity is an important consideration.
For instance silicon dioxide has a 1.855 J/(cm³*K) But sodium chloride is 9.04 J/(cm³*K).
This means sodium chloride can store more than 4.5× as many joules of energy for each degree of temperature rise in a cubic cm. Yet both cubes have the same surface area to lose heat over. In other words, for each joule a cubic cm of silicon dioxide stores, a cubic cm of sodium chloride rises in temperature by less than 1/4.5 that of the silicon dioxide. And how fast heat is lost given the same surface area and insulation is proportional to temperature.
Bulk sodium chloride and sand have similar cost so per cubic meter, so its volumetric heat capacity should take on a more important role in consideration.
The large capacity for storing heat comes from the max temperature, which is easy to achieve through resistive heating coils. But on the cool side, it seems to me that you would have to get much colder than freezing to have a similar cooling capacity. Is there technology that can achieve very cold temperatures efficiently with electricity?
On the topic of usefullness if used only for heat. I remember a video on this topic that mentioned very northern locations that don't get much sunlight in winter. The heat battery was useful there because they could be heated during the summer, and would hold their heat for months into the winter.
So why not use an inverter to boost up the power on either end?
it they want to make cool sand battery, they should make cold and hot sand battery together, moving the heat to the hot battery when cooling the cold battery.
Check out Batsand for a domestic solution when you come back to this. Also Antora, both for their high temp heat and also their interesting IR PV heat to electricity solution.
The problem I see is that, even if you do use the heat directly, you are still heating your home with resistive heat, just indirectly or delayed. Resistive heat is crap efficiency wise. They'd need to adapt heap pump technology or something to this use to up the efficiency.
So the bigger (or hotter) the better. But how efficient will it be if you scale it down to 10%? Like a 7' tall and 2' - 3' diameter. I don't need to heat a 100 houses, just my own house (cuz, I like to try things and not want to compete with natural gas which cost $ 2.5 - $5/GJ or $0.009 - $0.018/kwh, by selling heat to the neighborhood)
You can use that heat for Absorption chilling units.