20 ms·

Giant 'sand battery' holds a week's heat for a whole town

289 points by aa_is_op 3y ago

xnx 3y ago
Large-scale ‘sand battery’ goes online in Finland https://news.ycombinator.com/item?id=32006791 https://news.ycombinator.com/item?id=32006791 2 years ago | 287 comments A sand battery could transform clean energy https://news.ycombinator.com/item?id=33465272 https://news.ycombinator.com/item?id=33465272 1 year ago | 143 comments
gorpy7 3y ago
This is great technology, simple and effective. I’ve spent many hours reverse engineering to see how effective and expensive it might be. I’ve found it’s very cost effective but heat can be hard to calculate. i like that they did a prototype. i think i’ll do one at some point. for an individual house it makes more sense to improve my insulation but i think ill still build a small version for fun.
- dragontamer 3y ago
  IceBear went out of business with the opposite tech: tanks of water storing the cold generated from excess AC cycles. Cheap electricity can make cold, and then a fan can convert the cold water into cold air during peak hours when electricity was costlier. Fans still took electricity to run, but it'd only be a few hundred watts to run air-conditioning rather than kilowatts of power.
  - 0cf8612b2e1e 3y ago
    How long ago was this? The idea seems simple enough and would really benefit from the increasing glut of renewables. Even better, unlike a sand battery, you can potentially cycle it for several months of summer, by offsetting consumption by just a few hours feels like it could be economically viable. Then again, the competition is general purpose batteries which can be used all year and probably require less maintenance.
    - llm_trw 3y ago
      Just because something seems like should work doesn't mean it will. Air conditioners are simple and cheap to install. An insulated swimming pool in the basement is not.
      - dragontamer 3y ago
        1 cubic meters of water chilled 10C below ambient is 40MegaJoules of energy. Or in other words: 11kW-hrs of cooling, comparable to an entire Tesla Powerwall. We aren't talking about entire swimming pools here. Just a few cubic meters of water. Shift the temperature delta as you see fit but... It's actually very space efficient.
        pi-e-sigma 3y ago
        Typical residential air conditioning is using 4kW of power. So your 40MJ of energy would be used up in 40MJ/4kW=10000 seconds, or just 3 hours. And its only theoretical, because it assumes 100% efficiency in storage and conversion
        llm_trw 3y ago
        It's odd how often battery enthusiasts don't understand the difference between energy and power.
        nimos 3y ago
        Air conditioners have a COP of about 3 though. So really its more like 3.5kwh of storage. If you want to go lower temperature to store more then your COP drops.
        dragontamer 3y ago
        The temperature delta is the hard part for me to estimate here. I know that IceBear left the water around 45F, so take that for what you will. Either way, we aren't talking about entire swimming pools here. Just a small, single digit number of cubic meters of water.
  - abkfenris 3y ago
    My local power company worked with a bunch of businesses in my town to install these rather than upgrade the dead end line for a few peak periods.
  - ZeroGravitas 3y ago
    IceBear was competing directly with ever cheaper PV. It's a tech for time shifting cheap overnight energy to the expensive daytime. Installing PV gives you cheap power directly and correlates with air-con demand.
    - dragontamer 3y ago
      Nope. You still need aircon at 7pm after the sun begins to set and while solar is losing power. Cooler temperatures aren't until 10pm or so, hours after sunset.
- logtempo 3y ago
  it's how "rocket stove" works: https://en.wikipedia.org/wiki/Rocket_stove https://en.wikipedia.org/wiki/Rocket_stove Since you burn the wood really fast, you need to delay that heat release. That's where sand comes in as a cheap and good enough material. There are also systems that heat water and store it in a tank, which also make sense if you want hot water in your house too.
  - zdragnar 3y ago
    Sand is actually pretty bad. Gravel is a little better, clay is best. Sand is really only useful here because that much clay is usually significantly more expensive and would take forever to dry out. Source: researched the shit out of and have built a rocket stove.
photonbucket 3y ago
I'm curious about "why sand", is it better at holding heat than say water?
- dragontamer 3y ago
  Probably not. But sand doesn't freeze (or perhaps, sand doesn't melt) under normal temperatures. That's probably more important for an icy region.
  - tonyarkles 3y ago
    Probably not relevant to the specific problem at hand because sand that's getting heated to 600 degrees is going to quickly boil off any residual moisture. As a warning, though, so that people don't experience the pain I got to experience, a pile of sand is really good at holding onto water internally and freezing when it gets cold. We had to replace our sewer line a while back and for various reasons were taking care of filling the hole and redoing the concrete ourselves. The sand guys left a big pile in the driveway for us and as soon as winter came the whole pile turned into a single giant rock despite having been out in the hot sun previously. Exactly to your point, though, one of the great things about using sand for this application instead of water is that you can probably just shut the thing off for maintenance without having to worry about draining all of the sand out. If it freezes up due a bit of residual moisture content it's not going to expand nearly the same way that a silo full of water would, and it should be easy enough to thaw out just by putting some heat into it.
- Waterluvian 3y ago
  It’s probably less likely to turn into gas, increase in pressure, and explode the silo.
- christkv 3y ago
  Can store a lot more heat by volume. Water has other bad properties. The higher the temperature the higher the pressure.
  - 3y ago
Karellen 3y ago
Something similar, but more for industrial processes: Can a Simple Brick Be the Next Great Battery? | John O'Donnell | TED https://www.youtube.com/watch?v=X6Wgd4v_yW8 https://www.youtube.com/watch?v=X6Wgd4v_yW8
- fy20 3y ago
  This is basically how houses in central Europe work. The walls and floors are built with masonry (bricks or concrete) and wrapped in a thick layer of insulation. This results in a building with a very high thermal mass. The result is that it takes a long time for the inside of the building to change temperature. The other day we had a warm sunny spring day (5C / 40F), so I opened all the windows and did some spring cleaning. I set the thermostat to 16C as I didn't want the heating coming on while I was doing this. I forgot about this, and the next day when I woke up wondered why the temperature in the house was only 20.5C (68F) as usually we have it set to 22C (72F) - then I remembered I effectively turned off the heating 18 hours ago, and forgot to turn it back on.
tamimio 3y ago
It isn’t a totally new concept, in CSP (concentrated solar power) plants, a molten salt is used to store the heat as well.
- yeknoda 3y ago
  novelty is secondary to implementation
  - defrost 3y ago
    CSP Pilot plant broke ground 12 years ago: In 2012 Vast Solar commenced its 1.2 MW Performance Validation Project which was supported by funding from the then Australian Solar Institute. This CST project was completed on 22 October 2019. https://arena.gov.au/projects/csp-pilot-plant/ https://arena.gov.au/projects/csp-pilot-plant/ Scaled up second stage is being built out now (2024): Vast said on Friday that it has partnered up with global design and manufacturing firm Contratos y Diseños Industriales (CYD) to take the next step forward on its VS1 project, the 30MW/288MWh plant in South Australia. (Aug 2023): https://reneweconomy.com.au/australias-biggest-solar-thermal-plant-takes-big-step-forward-with-digital-twin/ https://reneweconomy.com.au/australias-biggest-solar-thermal...
- Qwertious 3y ago
  It isn't totally new, nothing under the sun etc etc, but honestly it's closer to a hot water tank than it is to CSP. Which makes sense, since the original conception of PNE was a hot water tank IIRC. CSP stores heat as a means to produce electricity, the PNE sand battery stores heat as a means to provide heat. CSP's molten salt was heated by pumping it through (solar) heated pipes, which meant it had to have the correct fluid properties etc. The PNE sand is heated in-place via electricity which means it can be basically any old crap, as long as it's inert at 600 degrees or less. In other words, CSP differs drastically by the energy input method, the energy output method, and the composition and requirements of the storage medium. Basically all of the PNE tech is centuries old, the point is that together in this specific configuration they're an incredibly cheap heat storage medium - resistive heating, insulation, sand, all cheap.
100k 3y ago
There's some interesting companies in this space. https://gofourth.com/ https://gofourth.com/ - focusing on grid storage, uses graphite (carbon) and liquid tin for heat transfer https://antoraenergy.com/ https://antoraenergy.com/ - industrial heat and electricity https://rondo.com/ https://rondo.com/ - industrial heat You can find interviews with their founders on the Volts podcast.
pfdietz 3y ago
NREL's ENDURING sand battery, storing heat at 1200 C in quartz sand. Round trip efficiency using turbines is estimated at ~53%. https://arpa-e.energy.gov/sites/default/files/2021-03/07%20Day1-Zhiwen%20Ma_NREL.pdf https://arpa-e.energy.gov/sites/default/files/2021-03/07%20D... The IP has been licensed by Babcock and Wilcox, who are the source of the nifty compact fluidized bed heat exchanger.
- chiph 3y ago
  It's an interesting concept. Cheap. Doesn't take up a lot of space. Could be driven by a solar furnace. My concern is whether the cyclone particle separator will do a good enough job - gas turbine blades don't like being blasted with grit. I expect they'd need a heat exchanger to be sure to get only clean gas driving the turbines.
  - pfdietz 3y ago
    > Could be driven by a solar furnace. Perhaps more interestingly, it could be driven by combustion of an e-fuel as a backup in case the sand becomes depleted.
  - hanniabu 3y ago
    > Cheap. Until patents are involved
Animats 3y ago
This new sand battery is expected to stand 13 m (42.7 ft) tall and 15 m (49.2 ft) wide, providing an output power of 1 MW and a capacity of 100 MWh. That's impressive. It's close to the energy density of fuel oil. Or did I calculate that wrong?
- noqc 3y ago
  100 MWh is 8 tons of "oil", according to a google search. Oil is probably about the density of water, so 1 cubic meter is about 1 ton of oil, and this structure is about 2000 cubic meters, so oil has 200 times the fuel density of this battery. It's still pretty good though.
  - reaperman 3y ago
    “Oil” is 10-15% less dense than water. So yes, “about” the density of water, for napkin purposes. This would be diesel or heating oil. Gasoline is 30% less dense than water though.
  - logtempo 3y ago
    your number is good, as it's the heavier from all oil. Don't work for all type of oil though. https://en.wikipedia.org/wiki/API_gravity https://en.wikipedia.org/wiki/API_gravity Light crude oil has an API gravity higher than 31.1° (i.e., less than 870 kg/m3) Medium oil has an API gravity between 22.3 and 31.1° (i.e., 870 to 920 kg/m3) Heavy crude oil has an API gravity below 22.3° (i.e., 920 to 1000 kg/m3) Extra heavy oil has an API gravity below 10.0° (i.e., greater than 1000 kg/m3)
bicebird 3y ago
I was thinking of ways to get around the peak solar generation being when you don't need it for heating and genuinely really heartening to hear about solutions like this. The article doesn't mention the costs or complexity in building each unit but definitely implies it's cheaper than storing it batteries, which makes sense if it's essentially a heating element buried in sand. Wonder what the smallest viable size would be, could you have one for each street / block of flats? One of the comments mentions burying them for better insulation which I'm assuming they didn't want to do just for the prototypes?
- llm_trw 3y ago
  >The article doesn't mention the costs or complexity in building each unit but definitely implies it's cheaper than storing it batteries, which makes sense if it's essentially a heating element buried in sand. Batteries are more expensive than nuclear power so yes, anything else is better. The issue is that we can't both electrify everything and use legacy heating applications. Going back the the 20th century idea of central heating/cooling is great until you realize the costs involved with adding all the plumbing to buildings which were never designed with it in mind.
- noqc 3y ago
  Peak solar is peak A/C usage in the summer, which is typically more expensive than heating. In colder times more energy is used at night, but I think less energy is still used at night in the winter than in the day in summer.
  - fbdab103 3y ago
    That does not seem right. A hot day in summer might be 35C->20C (95F->68F). Winter is going to be more like -10C->20C (15F->68F) twice the temperature gradient to overcome.
    - lstodd 3y ago
      That does not seem right. -10С to +20C .. I can't even think of a place with such a swing. Harsh continental climate winter is maybe -30C to -20C or so.
ionwake 3y ago
Sorry to a noob can someone explain this please. They are just heating up sand right?
- loeg 3y ago
  Yep.
- Ekaros 3y ago
  Yep, combined with district heating that works with simple heat exchangers, it is pretty decent system. So you either pump power to sand or take heat from it and put it heating network.
gorpy7 3y ago
Ben_bai said it pretty well. water is good but it can cause rust, pressure, freeze, leak, etc. sand avoids most of this. the big thing is that sand can be heated much much hotter and this helps make up for its shortcomings relative to water. they likely charge and discharge with air blowing thru stainless steel network of pipes thru the sand. this would require special tuning. as someone else mentioned, the thing with water is that the temp is uniform everywhere because water transfers heat within its volume easily. sand doesn’t, so you need pipes spaced out right. i’ve wondered about insulation but, i think you can step it out with refractory bricks first then a mineral insulation, then something like perlite or fiberglass. the hot air would interface with heat exchanger to transfer the heat to whichever fluid that would go on to heat the home/s. since the sand can be heated to 1700F or more, a kiln or quartz heating element that can exceed this temp is needed. last, a thermally isolated heat temp tolerance fan would be required. i guess a slew of sensors in the sand and at the exchanger unit and output, i can imagine wanting sensors everywhere for tuning sake.
- lancewiggs 3y ago
  MGA Thermal uses tiny aluminium droplets in carbon matrix material to do heat storage with 1: constant temperature storage and 2: at much higher temperatures and energy density that allows for steam generation etc.
- Valgrim 3y ago
  Some Youtube folks tried a much simpler approach: Take a large metal bucket or barrel. Put a heating element and a simple oven thermostat on the bottom. Fill with sand. Connect to a solar panel or other enrgy source. The air between the sand particles seem to actually provide a bit of convection and insulation. The thermostat turns the circuit off before getting too hot for the heating element. The heat accumulated during the day is slowly released over time directly through the metal.
  - immibis 3y ago
    Any system that involves an electrical solar panel connected to a low-temperature electrical heater is likely to be better served with a solar hot water panel, by about a 10:1 ratio.
anonu 3y ago
It feels that Europe is so far ahead the US in matters of environmental sustainability. Why is that? Is it more dense than the US, so they need to be more careful with resources?
- Gigachad 3y ago
  Less politically radicalised maybe? America should have all the tech and resources required to pull this stuff off, but it just doesn’t happen.
  - yurishimo 3y ago
    It's mostly centered around cost. Fuel (of all types) is so cheap in the US that efficiency was not an ultra high priority for most people. Ironically, the US has now gotten extremely competent at drilling for natural gas and the price is going to stay pretty much fixed where it is for the next 50+ years. Most of the waste from the early days has also been reduced and funneled into new petrochemical production processes that used to be reliant on oil. If you are going to stay in one place for a long time, renewable solutions to problems like hot water and residential electricity are worth the investment, but with the migratory nature of the US worker, it's often cheaper for a household to pay for fuel for 5~ years rather than invest in a renewable solution that they will never reap the monetary benefits from. From what I've experienced since moving from the US to Europe in 2022, it's a lot more common for people to stay in the same houses for an extended period of time. Especially here where I live in the Netherlands, you can commute to work almost anywhere in the country in about 2 hours by car. This allows people to keep the family home.
- gregwebs 3y ago
  Much of the US has access to cheap natural gas. And a good amount of oil. The greater the cost of energy the more it drives innovation in energy usage as well as incentivizes projects that would have a longer pay back period where energy is cheaper. Although Norway has abundant energy but socialized the profits and is using them to advance their usage of renewables and electrification. In the US we privatize the gains and only socialize the losses.
- 3y ago
chmod775 3y ago
Reminds me of Berlin's water heat storage tank: https://www.energy-storage.news/vattenfall-starts-filling-up-200mw-thermal-storage-tower-in-berlin/ https://www.energy-storage.news/vattenfall-starts-filling-up... It's specifically intended to store surplus energy from renewables for later use.
heyalexej 3y ago
Here's a smaller scale water battery that heats an entire house year round. The water tank itself is placed in the center of the house across all 3 floors and actually makes for a quite nice design element as well. The energy is generated in the warm seasons and the volume of water is large enough to last through the entire winter. It's a German vid but subtitles are quite accurate. https://www.youtube.com/watch?v=MBLiNHsod8Y https://www.youtube.com/watch?v=MBLiNHsod8Y
- WithinReason 3y ago
  You don't even need water, you can just transfer the heat to the soil under your house
- AnthonyMouse 3y ago
  Doesn't this suffer the problem that you're then putting heat into the device, which is in your house, during the warm season when you want your house to stay cool?
  - defrost 3y ago
    Think of the water tank as being in but insulated from the house. In the hot summer the hot air within the house is cooled by heat pumping the heat into the water tank which is slowly over weeks bought up from cold to mean summer tempreture. In the winter the heat is extracted from the water and transfered to the house. The house and the water mass are out of phase by six months.
  - mythhabit 3y ago
    It's a large enough volume of water, that adding insulation is feasible.
    - AnthonyMouse 3y ago
      But then why put it in the house and not e.g. in the ground?
at_a_remove 3y ago
I've been obsessed, mildly, with Feolite. It could be brought back for these sorts of applications to great effect. It's got the volumetric heat capacity of water and the ability to withstand much greater temperatures without any annoying phase transitions. It was very popular in the UK, where they went in early on charging for electricity on a rate varying by hour. The basic formula is easy, but there's a lot of secret ingredients to get the heat capacity way, way up. Speaking of home uses and phase transitions, they have made inroads into making materials with a phase transitioned tuned to household temperatures. Say you have aimed for seventy-two Fahrenheit. The temperature gets higher than that? The material melts, absorbing ambient heat. Then, as the temperature dips below seventy-two Fahrenheit, it freezes, releasing heat. It would make a fantastic sort of "heat capacitor," designed to deal with rapid, small-scale temperature fluctuations, while larger heat batteries could deal with fluctuations over days, weeks, and so on. Only problem is that these phase transition materials tend to be terrifyingly flammable, so far. Like soaking all of your drywall panels in candle wax before putting them up.
turtlebits 3y ago
You can DIY this on the cheap by connecting solar panels directly a $10 hot water heating element and burying it in sand. You will need to pair the right spec element with your panels No charge controller, inverter or battery needed.
- scotty79 3y ago
  Heating element from pyrolytic oven would be better.
m463 3y ago
I get that sand is inexpensive and simple and I like the idea - especially since it scales to an entire town (!) But I can't help but think of one "technology" that could make a scheme like this MUCH more effective. a phase change. for example, it takes 1 calorie for water to go from 30 to 31 degrees F, but but it take 80 calories to go from solid at 32 to liquid at 32 F. A project I remember reading about that was really interesting was a house constructed with logs that had a resin that phase changed around room temperature. The idea was that the logs would be heated by sunlight, and the resin in the logs would absorb lots of energy without easily going above room temperature. Then at night, they would slowly solidify and give off heat at room temperature. This would be a cool way to stabilize house temperatures without needing equipment. EDIT: it was called the enertia house I'm uncertain of the history, it seems there are a lot of different "enertia house" search hits. Here's one explaining the idea: https://enertia.net/howitworks.html https://enertia.net/howitworks.html
- jessriedel 3y ago
  There's a pretty cool coffee mug based off the idea too https://joeveo.com/pages/the-temperfect-mug https://joeveo.com/pages/the-temperfect-mug
  - ImPostingOnHN 3y ago
    Coffee Joulies work off the same concept https://www.baristamagazine.com/coffee-joulies-engineered-solution-cooling-coffee/ https://www.baristamagazine.com/coffee-joulies-engineered-so...
  - londons_explore 3y ago
    Dunno what 'wax like substance' they use, but if I were designing it I would use sodium acetate (vinegar+baking soda). By adjusting the amount of water in the mixture, you can fine-tune the phase change temperature to whatever the customers like for their coffee. It also boils above 100C so when the customer puts it in the microwave it won't burst unless they boil the cup dry. And when the customer does break it, it's non toxic and food safe.
- 3y ago
latchkey 3y ago
Good buddy of mine in Vietnam has been working on a company around this as well: https://www.alterno.group/ https://www.alterno.group/
petters 3y ago
Storing heat in huge water tanks has been done for a long time in Sweden
froddd 3y ago
The fact I find most fascinating is that they have a local district heating system reusing heat produced from local industry. That’s efficiency on another level.
- apexalpha 3y ago
  I think that's pretty common, no? Here in NL our district heat comes from a chemical refinery a few clicks away. For them the heat is an annoying waste product.
  - m4rtink 3y ago
    Here in Brno, Czech Republic, 25% of the city wide heating is provided by the municipal waste incinerator. There are also a few cities that get heat into their networks from nuclear power plants and something similar is planned in the future for Brno as well.
locallost 3y ago
Would it make sense to actually store it underground, or are the gains minimal when compared to the costs? In general, I'm impressed that there's so much research and investment in this field (storing excess renewable energy). I think most people don't realize how much and that the problem of the sun not shining and wind not blowing all the time will be solved much more quickly than most people think is possible.
- nimos 3y ago
  https://en.wikipedia.org/wiki/Drake_Landing_Solar_Community https://en.wikipedia.org/wiki/Drake_Landing_Solar_Community There was an experimental community in Alberta, Canada doing this. Seems to be relatively successful as pilot project.
helpfulContrib 3y ago
[dead]
onetimeuse92304 3y ago
100MWh = 3.6 * 10^11 joules sand's heat capacity = 830 J/kg degree C sand battery size is "13m tall and 15m wide". Assuming most voluminous possible shape that's 13m * 15m * 15m = 2925 cubic meters of sand (100% fill, no account for insulation, etc.) Dry sand density is about 1600kg/m3 Total weight of sand would be 2925m3 * 1600kg/m3 = 4.7Mkg (4.7kt) 4.7Mkg of sand has a heat capacity of 830J/kg * 4.7Mkg = 3.9 * 10^9 joules / degree C (it takes this much energy to heat up entire battery by one degree C) So from this, we get that 100MWh of energy would heat up the battery by (3.6 * 10^11 J) / (3.9 * 10^9 J/C) or about 100C. If we include a different shape (a cylinder), and account for a thick insulation needed, this becomes closer to 200C of temp diff. I guess it checks out... It is going to be more difficult to estimate heat loss. But sand is quite expensive so my question is, why sand and not water? Water has 5 times higher specific heat per weight, about 3 times per volume. Water is way cheaper than sand and much easier to find, transport and extract energy from. The only real problem with water is you can only heat it up to 100C.
- ametrau 3y ago
  They heat the sand to 600c. But you could just use more water. I don’t get it also.
  - dgacmu 3y ago
    Interesting! Wonder if it's also due to ease / lower risk of containment. And sand doesn't expand if you accidentally let it freeze, which is again nice from an "it won't rupture" perspective. As to cost, the article does note that they're reusing crushed soapstone from a local byproduct, so maybe that helps reduce the cost? That said, their FAQ says it's about heat capacity: https://polarnightenergy.fi/sand-battery https://polarnightenergy.fi/sand-battery > Why do you use sand? > Many solid materials, such as sand, can be heated to temperatures well above the boiling point of water. Sand-based heat storages can store several times the amount of energy that can be stored in a water tank of a similar size; this is thanks to the large temperature range allowed by the sand. So, it saves space and it allows versatile use in many industrial applications. So perhaps they're also specifically targeting future applications where they would need to supply > 100C heat.
nimos 3y ago
Been curious if you can't do this with houses generally. Set a temperature range of say 21-25c. Drive the temperature up when there is excess wind/solar (was primarily thinking of EU) then let it fall off. Obviously works better the better insulated a house is. Has the advantage of turning everything in your home into a thermal battery with the only real cost being furnace controller, potentially even just software. At one point I meant to do the math to figure out the rough storage/efficiency for an average home but never got around to it.
- darkerside 3y ago
  Real estate is precious. You really want a massive heat battery taking up a lot of living space?
  - nimos 3y ago
    I'm not suggesting adding anything. Homes have lots of stuff in them. Everything in your house becomes a thermal battery - tables, chairs, beds, walls, counters, clothes and so on. Just allow a range of temperatures and when energy is very low cost drive the indoor temperature to the upper range. Ideally you have a brick/stone home with good exterior insulation.
    - darkerside 3y ago
      Sure, I do that sometimes. The effect rounds to zero, but better than nothing?
ametrau 3y ago
It’s more of a sand heat sink. It’s heated up in various ways then the heat is used when it’s needed.

289 points by aa_is_op 3y ago

xnx 3y ago

Large-scale ‘sand battery’ goes online in Finland https://news.ycombinator.com/item?id=32006791 https://news.ycombinator.com/item?id=32006791 2 years ago | 287 comments A sand battery could transform clean energy https://news.ycombinator.com/item?id=33465272 https://news.ycombinator.com/item?id=33465272 1 year ago | 143 comments

gorpy7 3y ago

This is great technology, simple and effective. I’ve spent many hours reverse engineering to see how effective and expensive it might be. I’ve found it’s very cost effective but heat can be hard to calculate. i like that they did a prototype. i think i’ll do one at some point. for an individual house it makes more sense to improve my insulation but i think ill still build a small version for fun.

dragontamer 3y ago
IceBear went out of business with the opposite tech: tanks of water storing the cold generated from excess AC cycles. Cheap electricity can make cold, and then a fan can convert the cold water into cold air during peak hours when electricity was costlier. Fans still took electricity to run, but it'd only be a few hundred watts to run air-conditioning rather than kilowatts of power.
- 0cf8612b2e1e 3y ago
  How long ago was this? The idea seems simple enough and would really benefit from the increasing glut of renewables. Even better, unlike a sand battery, you can potentially cycle it for several months of summer, by offsetting consumption by just a few hours feels like it could be economically viable. Then again, the competition is general purpose batteries which can be used all year and probably require less maintenance.
  - llm_trw 3y ago
    Just because something seems like should work doesn't mean it will. Air conditioners are simple and cheap to install. An insulated swimming pool in the basement is not.
    - dragontamer 3y ago
      1 cubic meters of water chilled 10C below ambient is 40MegaJoules of energy. Or in other words: 11kW-hrs of cooling, comparable to an entire Tesla Powerwall. We aren't talking about entire swimming pools here. Just a few cubic meters of water. Shift the temperature delta as you see fit but... It's actually very space efficient.
      - pi-e-sigma 3y ago
        Typical residential air conditioning is using 4kW of power. So your 40MJ of energy would be used up in 40MJ/4kW=10000 seconds, or just 3 hours. And its only theoretical, because it assumes 100% efficiency in storage and conversion
        llm_trw 3y ago
        It's odd how often battery enthusiasts don't understand the difference between energy and power.
      - nimos 3y ago
        Air conditioners have a COP of about 3 though. So really its more like 3.5kwh of storage. If you want to go lower temperature to store more then your COP drops.
        dragontamer 3y ago
        The temperature delta is the hard part for me to estimate here. I know that IceBear left the water around 45F, so take that for what you will. Either way, we aren't talking about entire swimming pools here. Just a small, single digit number of cubic meters of water.
- abkfenris 3y ago
  My local power company worked with a bunch of businesses in my town to install these rather than upgrade the dead end line for a few peak periods.
- ZeroGravitas 3y ago
  IceBear was competing directly with ever cheaper PV. It's a tech for time shifting cheap overnight energy to the expensive daytime. Installing PV gives you cheap power directly and correlates with air-con demand.
  - dragontamer 3y ago
    Nope. You still need aircon at 7pm after the sun begins to set and while solar is losing power. Cooler temperatures aren't until 10pm or so, hours after sunset.
logtempo 3y ago
it's how "rocket stove" works: https://en.wikipedia.org/wiki/Rocket_stove https://en.wikipedia.org/wiki/Rocket_stove Since you burn the wood really fast, you need to delay that heat release. That's where sand comes in as a cheap and good enough material. There are also systems that heat water and store it in a tank, which also make sense if you want hot water in your house too.
- zdragnar 3y ago
  Sand is actually pretty bad. Gravel is a little better, clay is best. Sand is really only useful here because that much clay is usually significantly more expensive and would take forever to dry out. Source: researched the shit out of and have built a rocket stove.

photonbucket 3y ago

I'm curious about "why sand", is it better at holding heat than say water?

dragontamer 3y ago
Probably not. But sand doesn't freeze (or perhaps, sand doesn't melt) under normal temperatures. That's probably more important for an icy region.
- tonyarkles 3y ago
  Probably not relevant to the specific problem at hand because sand that's getting heated to 600 degrees is going to quickly boil off any residual moisture. As a warning, though, so that people don't experience the pain I got to experience, a pile of sand is really good at holding onto water internally and freezing when it gets cold. We had to replace our sewer line a while back and for various reasons were taking care of filling the hole and redoing the concrete ourselves. The sand guys left a big pile in the driveway for us and as soon as winter came the whole pile turned into a single giant rock despite having been out in the hot sun previously. Exactly to your point, though, one of the great things about using sand for this application instead of water is that you can probably just shut the thing off for maintenance without having to worry about draining all of the sand out. If it freezes up due a bit of residual moisture content it's not going to expand nearly the same way that a silo full of water would, and it should be easy enough to thaw out just by putting some heat into it.
Waterluvian 3y ago
It’s probably less likely to turn into gas, increase in pressure, and explode the silo.
christkv 3y ago
Can store a lot more heat by volume. Water has other bad properties. The higher the temperature the higher the pressure.
- 3y ago

Karellen 3y ago

Something similar, but more for industrial processes: Can a Simple Brick Be the Next Great Battery? | John O'Donnell | TED https://www.youtube.com/watch?v=X6Wgd4v_yW8 https://www.youtube.com/watch?v=X6Wgd4v_yW8

fy20 3y ago
This is basically how houses in central Europe work. The walls and floors are built with masonry (bricks or concrete) and wrapped in a thick layer of insulation. This results in a building with a very high thermal mass. The result is that it takes a long time for the inside of the building to change temperature. The other day we had a warm sunny spring day (5C / 40F), so I opened all the windows and did some spring cleaning. I set the thermostat to 16C as I didn't want the heating coming on while I was doing this. I forgot about this, and the next day when I woke up wondered why the temperature in the house was only 20.5C (68F) as usually we have it set to 22C (72F) - then I remembered I effectively turned off the heating 18 hours ago, and forgot to turn it back on.

tamimio 3y ago

It isn’t a totally new concept, in CSP (concentrated solar power) plants, a molten salt is used to store the heat as well.

yeknoda 3y ago
novelty is secondary to implementation
- defrost 3y ago
  CSP Pilot plant broke ground 12 years ago: In 2012 Vast Solar commenced its 1.2 MW Performance Validation Project which was supported by funding from the then Australian Solar Institute. This CST project was completed on 22 October 2019. https://arena.gov.au/projects/csp-pilot-plant/ https://arena.gov.au/projects/csp-pilot-plant/ Scaled up second stage is being built out now (2024): Vast said on Friday that it has partnered up with global design and manufacturing firm Contratos y Diseños Industriales (CYD) to take the next step forward on its VS1 project, the 30MW/288MWh plant in South Australia. (Aug 2023): https://reneweconomy.com.au/australias-biggest-solar-thermal-plant-takes-big-step-forward-with-digital-twin/ https://reneweconomy.com.au/australias-biggest-solar-thermal...
Qwertious 3y ago
It isn't totally new, nothing under the sun etc etc, but honestly it's closer to a hot water tank than it is to CSP. Which makes sense, since the original conception of PNE was a hot water tank IIRC. CSP stores heat as a means to produce electricity, the PNE sand battery stores heat as a means to provide heat. CSP's molten salt was heated by pumping it through (solar) heated pipes, which meant it had to have the correct fluid properties etc. The PNE sand is heated in-place via electricity which means it can be basically any old crap, as long as it's inert at 600 degrees or less. In other words, CSP differs drastically by the energy input method, the energy output method, and the composition and requirements of the storage medium. Basically all of the PNE tech is centuries old, the point is that together in this specific configuration they're an incredibly cheap heat storage medium - resistive heating, insulation, sand, all cheap.

100k 3y ago

There's some interesting companies in this space. https://gofourth.com/ https://gofourth.com/ - focusing on grid storage, uses graphite (carbon) and liquid tin for heat transfer https://antoraenergy.com/ https://antoraenergy.com/ - industrial heat and electricity https://rondo.com/ https://rondo.com/ - industrial heat You can find interviews with their founders on the Volts podcast.

pfdietz 3y ago

NREL's ENDURING sand battery, storing heat at 1200 C in quartz sand. Round trip efficiency using turbines is estimated at ~53%. https://arpa-e.energy.gov/sites/default/files/2021-03/07%20Day1-Zhiwen%20Ma_NREL.pdf https://arpa-e.energy.gov/sites/default/files/2021-03/07%20D... The IP has been licensed by Babcock and Wilcox, who are the source of the nifty compact fluidized bed heat exchanger.

chiph 3y ago
It's an interesting concept. Cheap. Doesn't take up a lot of space. Could be driven by a solar furnace. My concern is whether the cyclone particle separator will do a good enough job - gas turbine blades don't like being blasted with grit. I expect they'd need a heat exchanger to be sure to get only clean gas driving the turbines.
- pfdietz 3y ago
  > Could be driven by a solar furnace. Perhaps more interestingly, it could be driven by combustion of an e-fuel as a backup in case the sand becomes depleted.
- hanniabu 3y ago
  > Cheap. Until patents are involved

Animats 3y ago

This new sand battery is expected to stand 13 m (42.7 ft) tall and 15 m (49.2 ft) wide, providing an output power of 1 MW and a capacity of 100 MWh. That's impressive. It's close to the energy density of fuel oil. Or did I calculate that wrong?

noqc 3y ago
100 MWh is 8 tons of "oil", according to a google search. Oil is probably about the density of water, so 1 cubic meter is about 1 ton of oil, and this structure is about 2000 cubic meters, so oil has 200 times the fuel density of this battery. It's still pretty good though.
- reaperman 3y ago
  “Oil” is 10-15% less dense than water. So yes, “about” the density of water, for napkin purposes. This would be diesel or heating oil. Gasoline is 30% less dense than water though.
- logtempo 3y ago
  your number is good, as it's the heavier from all oil. Don't work for all type of oil though. https://en.wikipedia.org/wiki/API_gravity https://en.wikipedia.org/wiki/API_gravity Light crude oil has an API gravity higher than 31.1° (i.e., less than 870 kg/m3) Medium oil has an API gravity between 22.3 and 31.1° (i.e., 870 to 920 kg/m3) Heavy crude oil has an API gravity below 22.3° (i.e., 920 to 1000 kg/m3) Extra heavy oil has an API gravity below 10.0° (i.e., greater than 1000 kg/m3)

bicebird 3y ago

I was thinking of ways to get around the peak solar generation being when you don't need it for heating and genuinely really heartening to hear about solutions like this. The article doesn't mention the costs or complexity in building each unit but definitely implies it's cheaper than storing it batteries, which makes sense if it's essentially a heating element buried in sand. Wonder what the smallest viable size would be, could you have one for each street / block of flats? One of the comments mentions burying them for better insulation which I'm assuming they didn't want to do just for the prototypes?

llm_trw 3y ago
>The article doesn't mention the costs or complexity in building each unit but definitely implies it's cheaper than storing it batteries, which makes sense if it's essentially a heating element buried in sand. Batteries are more expensive than nuclear power so yes, anything else is better. The issue is that we can't both electrify everything and use legacy heating applications. Going back the the 20th century idea of central heating/cooling is great until you realize the costs involved with adding all the plumbing to buildings which were never designed with it in mind.
noqc 3y ago
Peak solar is peak A/C usage in the summer, which is typically more expensive than heating. In colder times more energy is used at night, but I think less energy is still used at night in the winter than in the day in summer.
- fbdab103 3y ago
  That does not seem right. A hot day in summer might be 35C->20C (95F->68F). Winter is going to be more like -10C->20C (15F->68F) twice the temperature gradient to overcome.
  - lstodd 3y ago
    That does not seem right. -10С to +20C .. I can't even think of a place with such a swing. Harsh continental climate winter is maybe -30C to -20C or so.

ionwake 3y ago

Sorry to a noob can someone explain this please. They are just heating up sand right?

loeg 3y ago
Yep.
Ekaros 3y ago
Yep, combined with district heating that works with simple heat exchangers, it is pretty decent system. So you either pump power to sand or take heat from it and put it heating network.

gorpy7 3y ago

Ben_bai said it pretty well. water is good but it can cause rust, pressure, freeze, leak, etc. sand avoids most of this. the big thing is that sand can be heated much much hotter and this helps make up for its shortcomings relative to water. they likely charge and discharge with air blowing thru stainless steel network of pipes thru the sand. this would require special tuning. as someone else mentioned, the thing with water is that the temp is uniform everywhere because water transfers heat within its volume easily. sand doesn’t, so you need pipes spaced out right. i’ve wondered about insulation but, i think you can step it out with refractory bricks first then a mineral insulation, then something like perlite or fiberglass. the hot air would interface with heat exchanger to transfer the heat to whichever fluid that would go on to heat the home/s. since the sand can be heated to 1700F or more, a kiln or quartz heating element that can exceed this temp is needed. last, a thermally isolated heat temp tolerance fan would be required. i guess a slew of sensors in the sand and at the exchanger unit and output, i can imagine wanting sensors everywhere for tuning sake.

lancewiggs 3y ago
MGA Thermal uses tiny aluminium droplets in carbon matrix material to do heat storage with 1: constant temperature storage and 2: at much higher temperatures and energy density that allows for steam generation etc.
Valgrim 3y ago
Some Youtube folks tried a much simpler approach: Take a large metal bucket or barrel. Put a heating element and a simple oven thermostat on the bottom. Fill with sand. Connect to a solar panel or other enrgy source. The air between the sand particles seem to actually provide a bit of convection and insulation. The thermostat turns the circuit off before getting too hot for the heating element. The heat accumulated during the day is slowly released over time directly through the metal.
- immibis 3y ago
  Any system that involves an electrical solar panel connected to a low-temperature electrical heater is likely to be better served with a solar hot water panel, by about a 10:1 ratio.

anonu 3y ago

It feels that Europe is so far ahead the US in matters of environmental sustainability. Why is that? Is it more dense than the US, so they need to be more careful with resources?

Gigachad 3y ago
Less politically radicalised maybe? America should have all the tech and resources required to pull this stuff off, but it just doesn’t happen.
- yurishimo 3y ago
  It's mostly centered around cost. Fuel (of all types) is so cheap in the US that efficiency was not an ultra high priority for most people. Ironically, the US has now gotten extremely competent at drilling for natural gas and the price is going to stay pretty much fixed where it is for the next 50+ years. Most of the waste from the early days has also been reduced and funneled into new petrochemical production processes that used to be reliant on oil. If you are going to stay in one place for a long time, renewable solutions to problems like hot water and residential electricity are worth the investment, but with the migratory nature of the US worker, it's often cheaper for a household to pay for fuel for 5~ years rather than invest in a renewable solution that they will never reap the monetary benefits from. From what I've experienced since moving from the US to Europe in 2022, it's a lot more common for people to stay in the same houses for an extended period of time. Especially here where I live in the Netherlands, you can commute to work almost anywhere in the country in about 2 hours by car. This allows people to keep the family home.
gregwebs 3y ago
Much of the US has access to cheap natural gas. And a good amount of oil. The greater the cost of energy the more it drives innovation in energy usage as well as incentivizes projects that would have a longer pay back period where energy is cheaper. Although Norway has abundant energy but socialized the profits and is using them to advance their usage of renewables and electrification. In the US we privatize the gains and only socialize the losses.
3y ago

chmod775 3y ago

Reminds me of Berlin's water heat storage tank: https://www.energy-storage.news/vattenfall-starts-filling-up-200mw-thermal-storage-tower-in-berlin/ https://www.energy-storage.news/vattenfall-starts-filling-up... It's specifically intended to store surplus energy from renewables for later use.

heyalexej 3y ago

Here's a smaller scale water battery that heats an entire house year round. The water tank itself is placed in the center of the house across all 3 floors and actually makes for a quite nice design element as well. The energy is generated in the warm seasons and the volume of water is large enough to last through the entire winter. It's a German vid but subtitles are quite accurate. https://www.youtube.com/watch?v=MBLiNHsod8Y https://www.youtube.com/watch?v=MBLiNHsod8Y

WithinReason 3y ago
You don't even need water, you can just transfer the heat to the soil under your house
AnthonyMouse 3y ago
Doesn't this suffer the problem that you're then putting heat into the device, which is in your house, during the warm season when you want your house to stay cool?
- defrost 3y ago
  Think of the water tank as being in but insulated from the house. In the hot summer the hot air within the house is cooled by heat pumping the heat into the water tank which is slowly over weeks bought up from cold to mean summer tempreture. In the winter the heat is extracted from the water and transfered to the house. The house and the water mass are out of phase by six months.
- mythhabit 3y ago
  It's a large enough volume of water, that adding insulation is feasible.
  - AnthonyMouse 3y ago
    But then why put it in the house and not e.g. in the ground?

at_a_remove 3y ago

I've been obsessed, mildly, with Feolite. It could be brought back for these sorts of applications to great effect. It's got the volumetric heat capacity of water and the ability to withstand much greater temperatures without any annoying phase transitions. It was very popular in the UK, where they went in early on charging for electricity on a rate varying by hour. The basic formula is easy, but there's a lot of secret ingredients to get the heat capacity way, way up. Speaking of home uses and phase transitions, they have made inroads into making materials with a phase transitioned tuned to household temperatures. Say you have aimed for seventy-two Fahrenheit. The temperature gets higher than that? The material melts, absorbing ambient heat. Then, as the temperature dips below seventy-two Fahrenheit, it freezes, releasing heat. It would make a fantastic sort of "heat capacitor," designed to deal with rapid, small-scale temperature fluctuations, while larger heat batteries could deal with fluctuations over days, weeks, and so on. Only problem is that these phase transition materials tend to be terrifyingly flammable, so far. Like soaking all of your drywall panels in candle wax before putting them up.

turtlebits 3y ago

You can DIY this on the cheap by connecting solar panels directly a $10 hot water heating element and burying it in sand. You will need to pair the right spec element with your panels No charge controller, inverter or battery needed.

scotty79 3y ago
Heating element from pyrolytic oven would be better.

m463 3y ago

I get that sand is inexpensive and simple and I like the idea - especially since it scales to an entire town (!) But I can't help but think of one "technology" that could make a scheme like this MUCH more effective. a phase change. for example, it takes 1 calorie for water to go from 30 to 31 degrees F, but but it take 80 calories to go from solid at 32 to liquid at 32 F. A project I remember reading about that was really interesting was a house constructed with logs that had a resin that phase changed around room temperature. The idea was that the logs would be heated by sunlight, and the resin in the logs would absorb lots of energy without easily going above room temperature. Then at night, they would slowly solidify and give off heat at room temperature. This would be a cool way to stabilize house temperatures without needing equipment. EDIT: it was called the enertia house I'm uncertain of the history, it seems there are a lot of different "enertia house" search hits. Here's one explaining the idea: https://enertia.net/howitworks.html https://enertia.net/howitworks.html

jessriedel 3y ago
There's a pretty cool coffee mug based off the idea too https://joeveo.com/pages/the-temperfect-mug https://joeveo.com/pages/the-temperfect-mug
- ImPostingOnHN 3y ago
  Coffee Joulies work off the same concept https://www.baristamagazine.com/coffee-joulies-engineered-solution-cooling-coffee/ https://www.baristamagazine.com/coffee-joulies-engineered-so...
- londons_explore 3y ago
  Dunno what 'wax like substance' they use, but if I were designing it I would use sodium acetate (vinegar+baking soda). By adjusting the amount of water in the mixture, you can fine-tune the phase change temperature to whatever the customers like for their coffee. It also boils above 100C so when the customer puts it in the microwave it won't burst unless they boil the cup dry. And when the customer does break it, it's non toxic and food safe.
3y ago

latchkey 3y ago

Good buddy of mine in Vietnam has been working on a company around this as well: https://www.alterno.group/ https://www.alterno.group/

petters 3y ago

Storing heat in huge water tanks has been done for a long time in Sweden

froddd 3y ago

The fact I find most fascinating is that they have a local district heating system reusing heat produced from local industry. That’s efficiency on another level.

apexalpha 3y ago
I think that's pretty common, no? Here in NL our district heat comes from a chemical refinery a few clicks away. For them the heat is an annoying waste product.
- m4rtink 3y ago
  Here in Brno, Czech Republic, 25% of the city wide heating is provided by the municipal waste incinerator. There are also a few cities that get heat into their networks from nuclear power plants and something similar is planned in the future for Brno as well.

locallost 3y ago

Would it make sense to actually store it underground, or are the gains minimal when compared to the costs? In general, I'm impressed that there's so much research and investment in this field (storing excess renewable energy). I think most people don't realize how much and that the problem of the sun not shining and wind not blowing all the time will be solved much more quickly than most people think is possible.

nimos 3y ago
https://en.wikipedia.org/wiki/Drake_Landing_Solar_Community https://en.wikipedia.org/wiki/Drake_Landing_Solar_Community There was an experimental community in Alberta, Canada doing this. Seems to be relatively successful as pilot project.

helpfulContrib 3y ago

[dead]

onetimeuse92304 3y ago

100MWh = 3.6 * 10^11 joules sand's heat capacity = 830 J/kg degree C sand battery size is "13m tall and 15m wide". Assuming most voluminous possible shape that's 13m * 15m * 15m = 2925 cubic meters of sand (100% fill, no account for insulation, etc.) Dry sand density is about 1600kg/m3 Total weight of sand would be 2925m3 * 1600kg/m3 = 4.7Mkg (4.7kt) 4.7Mkg of sand has a heat capacity of 830J/kg * 4.7Mkg = 3.9 * 10^9 joules / degree C (it takes this much energy to heat up entire battery by one degree C) So from this, we get that 100MWh of energy would heat up the battery by (3.6 * 10^11 J) / (3.9 * 10^9 J/C) or about 100C. If we include a different shape (a cylinder), and account for a thick insulation needed, this becomes closer to 200C of temp diff. I guess it checks out... It is going to be more difficult to estimate heat loss. But sand is quite expensive so my question is, why sand and not water? Water has 5 times higher specific heat per weight, about 3 times per volume. Water is way cheaper than sand and much easier to find, transport and extract energy from. The only real problem with water is you can only heat it up to 100C.

ametrau 3y ago
They heat the sand to 600c. But you could just use more water. I don’t get it also.
- dgacmu 3y ago
  Interesting! Wonder if it's also due to ease / lower risk of containment. And sand doesn't expand if you accidentally let it freeze, which is again nice from an "it won't rupture" perspective. As to cost, the article does note that they're reusing crushed soapstone from a local byproduct, so maybe that helps reduce the cost? That said, their FAQ says it's about heat capacity: https://polarnightenergy.fi/sand-battery https://polarnightenergy.fi/sand-battery > Why do you use sand? > Many solid materials, such as sand, can be heated to temperatures well above the boiling point of water. Sand-based heat storages can store several times the amount of energy that can be stored in a water tank of a similar size; this is thanks to the large temperature range allowed by the sand. So, it saves space and it allows versatile use in many industrial applications. So perhaps they're also specifically targeting future applications where they would need to supply > 100C heat.

nimos 3y ago

Been curious if you can't do this with houses generally. Set a temperature range of say 21-25c. Drive the temperature up when there is excess wind/solar (was primarily thinking of EU) then let it fall off. Obviously works better the better insulated a house is. Has the advantage of turning everything in your home into a thermal battery with the only real cost being furnace controller, potentially even just software. At one point I meant to do the math to figure out the rough storage/efficiency for an average home but never got around to it.

darkerside 3y ago
Real estate is precious. You really want a massive heat battery taking up a lot of living space?
- nimos 3y ago
  I'm not suggesting adding anything. Homes have lots of stuff in them. Everything in your house becomes a thermal battery - tables, chairs, beds, walls, counters, clothes and so on. Just allow a range of temperatures and when energy is very low cost drive the indoor temperature to the upper range. Ideally you have a brick/stone home with good exterior insulation.
  - darkerside 3y ago
    Sure, I do that sometimes. The effect rounds to zero, but better than nothing?

ametrau 3y ago

It’s more of a sand heat sink. It’s heated up in various ways then the heat is used when it’s needed.