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Finland’s radical answer to renewable energy’s biggest headache: The world’s largest sand battery
sanitationhttps://www.cnbc.com/2026/07/25/finland-sand-battery-renewable-energy-storage.html
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eickerA giant thermal battery storing heat instead of electricity is exactly the kind of engineering we need more of. It won’t replace lithium batteries or solve every energy problem, but district heating is a huge source of emissions in cold countries. Sometimes the smartest climate tech isn’t flashy AI: it’s hot rocks and good physics. 💪😎✌️
joelthelionAnd the best part is, it’s not actually complex or expensive technology. Essentially it’s a big box with crushed stone in it.
Exactly. That’s what makes it so compelling. No scarce minerals, no exotic chemistry, no billion Euro manufacturing plants. Sometimes the best solutions are the simplest ones.
Not to take away from the achievement, but how long can heat be stored though? Isn’t pumped hydro a better solution?
Apparently long enough for a Finnish town. The technologies aren’t really competitors: They’re complementary technologies for different jobs.
That’s enough to provide the 5,000 residents of Pornainen with nearly one month of heat demand through the summer — and roughly one week of demand in the winter.
from the article
So, basically it eliminates heating needs over summer, which is amazingly useful. But it doesn’t do much for winter.
That sounds crappy, but it’s probably a good 10-20% reduction in heating emissions, which is nothing to sneer at.
It does do something important in the winter: smooth out the irregularities on renewables. It’s not like you charge it up in September and then just expect it to carry you through to March. It means that your renewables just have to cover the demand some time this week, not at the exact moment the town wants the power. If there’s a high-pressure front that means you’ve got minimal wind for Monday through to Thursday, it’s fine, you just extract power from the battery and then re-heat when the wind picks up at the weekend
That does sound interesting. I’m curious though what the heat loss is while stored (I.e how much energy is lost over time with no energy being pulled)
They’ve got a quote from an Oxford uni professor of energy and climate policy in there who says it can store heat effectively for weeks. The manufacturer claims that it maintains about 80% of its “charge” if left for a month
One of the cool things about this design is that the bigger it is, the better it gets at storing heat. The square-cube law is in effect here, since heat can only be lost by leaving the silo at the outside whereas heat can be stored throughout the whole volume
I think pumped hydro is already maxed out in many locations, and a lot more complex/expensive if you only need to store heat (and not electricity).
Also, some of us live in, for example, the Netherlands. Pumping two meters of water floods half the country.
And turning a valley into a lake is pretty terrible for the ecology. Adding pumps to existing hydroelectric dams is a great thing, but making new ones is… Hard to sell
A_norny_mousseLand of sauna, folks: crushed rocks and heat.
It’s a decent size. Only 13m tall and 15m diameter, and it can heat 5,000 homes for a week in winter or a month in summer. Very impressive, and can imagine something that compact working in urban environments too. For example, in the basement of a new apartment block.
See Drake Landing in Alberta 2012. They used sand storage to heat 52 houses with 97% efficiency. Worked for years, then they ripped it all out and switched to gas.
Toronto downtown office buildings are cooled by lake water in summer, cutting AC electricity by 75% and eliminated AC brown outs, since 2005.
I thought it was like pumped hydro but using sand! Now I’m disappointed. Still cool though, but storing heat is not a long-term solution, is it?
DiplomjodlerYes it is. The heat from the sand battery can be used throughout the winter. All you need is good insulation.
I think of it as a simpler alternative to pumped hydro when all you need is heat. It kind of dumb to waste the great pumped hydro resources that can store electricity on heating stuff. So, this can cover their heating needs during bad weather, and they can used pumped hydro for the rest.
Removing industrial and transportation, heating represents is more than half of the energy use in Finland. Being able to store it and use later - particularly in district heating applications - is definitely a long-term solution
ValmondIIRC it can store heat for months.
what’s the source for the $25/kWh claim? that’s about 100x more than I was expecting.
that’s about 100x more than I was expecting.
That’s the construction cost. If the cycle life is 1000, then you would get $0.025/kWh.
Probably that not just any sand will do. Similar with building concrete/cement the sand used is important, even desert countries often have it shipped in because desert sand isnt the right type.
Psssh I know some contractors in Florida that could build these sand batteries for 1/10th the cost. Probably with performance correlating with price too, that’s a bargain
It should only get cheaper with time though. How much degradation can you expect with sand. I do wonder what is the ROI on this kind of thing.
OP why did you add this into your title when the article doesn’t say that anywhere in the text?
Yeah the article doesn’t actually say that at all. That appears to be pulled straight out of OP’s ass.
However, if that’s the installed cost, and per kW, then that’s insanely cheap. Solar where I am is about $2500 per kW capacity installed. $25 per kW would be dirt cheap.
discharged via heat exchangers to warm water for the local district heating network.
It needs certain infrastructure to work.
You could also use it to generate electricity. That’s 20-40% efficient. With negative prices in summer these days that would still be interesting.
Sounds like interesting tech. But as another poster noted, to be useful it needs to be able to deliver the heat to homes, which requires a steam pipe system. Not necessarily a dealbreaker, but definitely a big up front cost that communities would need to consider.
Also, it makes sense that the battery basically just consumes electricity that would otherwise go to waste. But I think it could be an even better system if the sand were heated more directly by the sun for additional heat storage during winter.
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It’s interesting piece of technology, but it’s not ‘radical’. The company behind the storage has done their homework and they seem to be well engineered, but the “technology” itself is pretty much as old as bonfires, people have used hot rocks to heat up tents for ‘a while’.
But sand has pretty good thermal properties and size of these new iterations of old tech makes them pretty decent solution for energy storage with renewables. I’ve been following various ‘sand battery’ products for our own house, but the main problem with all of them tends to be the size required. In practise for our own house we’d need a sand battery roughly the size of 6m storage container (with heat pumps and all the other hardware) and that’d be so expensive that the investment wouldn’t pay itself back in my lifetime.
The main material could be smashed/pulverized glass. The stoage of direct renewable electricity to heat makes the cost (Overall, including climate responsibilities) more appealing when considered along the same lines as Solar panels, or concentrated solar - using a FPS converter that can utilized that direct heat to generate heat back into electricity makes the project a bit of a challenge, but overall a pragmatic solution for long term use cases. Build up in tight spaces and consider alternate uses like wind sheilds and parking spaces when it comes to space conformance. 🤔 I hear aircrete is an insulation thats already prevalent in europe is this true?
As in sand. Glass is recyclable material, it makes no sense to use that for this kind of application since sand is already everywhere. Also at least some flavours of glass can melt on temperatures used on these which I’d imagine could cause problems.
At least here in Finland it is not. It could be, but it’s not really widely available right now. Maybe in the future, but that would need at least some changes on how things are built.
My parents were planning to build a cabin around a Russian stove (massive stone chimney with beds and a ton of thermal mass) for overnight heat, but ended up in an RV instead when their retirement coincided with the housing collapse.
That style stoves are pretty common around here on older buildings. We have one and it really helps during winter and cuts down the electricity bill, at least as long as we have enough firewood to keep that thing going.
You need district heating for this to work. Not every place has that, so it’s costly to install in places. You could use it to generate electricity, but then there are losses in the conversion.
I’d wager most places in Finland have district heating. Certainly true of Estonia and Finland is even further north.
Now individual homes here in Estonia usually aren’t connected to district heating, and not all apartment buildings are, but most are and more are joining because it turns out maintaining your own heating system is a burden most buildings don’t want to deal with (nobody usually even wants to head the association)
For Finland, 46% of heating is done with district heating, with it being as high as 90% in the bigger cities.
Germany: ~15%
France: ~6–8%
Netherlands: ~5–7%
USA: <1%
yeah, well usually district heating is a thing in places where heating is major energy consumer. Russia, Nordic countries, Canada and so on.
More temperate places don’t have district heating, since the heating need isn’t intense enough to warrant it.
The network is expensive to build, but the vast economies of scale make the actual on going heating more efficient and cheaper. Whatever the heating source might be. Be it fuel burning boiler or industrial scale heat pumps.
versant-owned website. boo