The Nordic countries generally still wants to increase their wind and solar power, but the big issue during winters is when there's cold air high pressure systems we get neither sun nor wind, having an energy storage that can hold up to 5 days worth of energy should help us nudge past them.
Hydro-energy exist (mainly Sweden and Norway, but I think some in Finland as well), but it's fairly built out so stable non-fossil power needs to be nuclear, or wind/sun + storage (that hasn't been good enough so far).
Interconnectors also exist (and more are planned), which means, for example, that Norway can buy wind energy from the UK when it’s cheap and abundant, in preference to using stored energy from their hydro lakes.
That way they effectively get more out of existing hydro lakes, which in Norway is already a very significant storage capacity.
Electricity became a lot more expensive in Norway after building several interconnectors to UK and mainland Europe. Importing high prices from the failed energy politics of UK and Germany which both have among the most expensive electricity in the world.
This has been a huge debate, and the general concensus seems to be that joining ACER and building inrerconnectors to mainland Europe was a big mistake.
Electricity prices don't go up because you have access to expensive power, it goes up because you don't have enough cheap power so you have to buy the expensive power.
It seems like Norway just wouldn't have power if they weren't connected to other sources, not that they'd have more cheap power.
Norway could power itself fully with domestic hydro. But it chose not to, as the power companies make more money by importing foreign power when it's cheap and exporting hydro when it's not.
Wind does better in the winter.
See eg here for Canada monthly stats: https://www150.statcan.gc.ca/t1/tbl1/en/tv.action?pid=251000...
Also, wind does better at night than day, which may be related or not.
https://suomenuusiutuvat.fi/en/wind-power/wind-power-in-cold...
The largest planned hydro storage projects are using decommissioned mines, and those are going to run out quickly.
Or just use a large lake. You're not going to noticeably affect the water levels of a large lake. You might pump 10 billion litres of water, which is .02% of the volume of Mjøsa.
Then you have to deal with the problem of sea water corroding everything it touches.
> You might pump 10 billion litres of water, which is .02% of the volume of Mjøsa.
It's not the amount of water that you pump, it's the amount * the elevation delta. Where are you planning on getting the elevation delta from?
Neither of these challenges is technically insurmountable, but this is a field where capex + opex/KWH is everything.
Elevation delta is not hard to find in Norway! A typical pumped storage facility uses 100m of delta; I imagine Norwegian ones would use more.
> but this is a field where capex + opex/KWH is everything.
And pumped storage is significantly cheaper for seasonal storage than any proposed alternatives.
The original post is efficient for heat storage, but converting low grade heat to electricity is not efficient.
Most projects seek 200-600m. This map doesn't even consider pumped hydro <200m: https://maps.nrel.gov/psh
> And pumped storage is significantly cheaper for seasonal storage than any proposed alternatives.
Based on what? Cost is particularly variable for pumped hydro. It can be one of the cheaper options when stars align. But you need 1) a suitable geography that minimizes the cost of damming or digging a resivoir with sufficient head 2) available for development without too much backlash 3) Near enough grid resources to minimize infrastructure and line losses. I'm surely leaving pieces out.
It can be cheap, but it has far more hoops to jump than alternatives like batteries, hot sand and other "storage-in-a-building" designs which can be built where needed and using fairly standard industrial construction.
This sounds pretty cheap if it works out:
That said, there's been a fair bit of talk here in Norway recently about tax incentives blocking hydro owners from upgrading old generators, improving efficency. Apparently a lot of currently unused power available if they "just" did that.
Are there extant succesful examples of pumped hydro in cold regions?
There's some pumped hydro at Niagara falls in Canada, which is far enough North that it should see a bit of a that/freeze cycle but is still a relatively mild climate.
Don't know anything about what issues this does/doesn't present to them, just happen to know it exists.
Or concretely Niagara Falls goes from an average low of -6.44 C in February to 21.0 C in July. Barcelona an average low of 4 C in January to 20.2 C in August (according to the internet).
But yes, it's warmer than Finland, just cold enough to see something of a freeze that cycle.
This is a terrible handwave. How many days per year, in the middle of winter, in a cold country, are you OK with having no power?
FTA:
> The project will cut fossil-based emissions in the Vääksy district heating network by around 60% each year, by reducing natural gas use bu 80% and also decreasing wood chip consumption.
* Energy can also be carried northward from other areas in the same country or neighboring countries, where there are more sunlight hours or more wind.
* Geothermal energy sources, e.g. https://www.rehva.eu/rehva-journal/chapter/geothermal-energy...
* Increase in solar panel farm area
* Improvements in panel efficiency (which continue)
* Improvement in energy use efficiency
... in some combination, and with decent storage, might get even the Nordic countries to cover their needs.
2. We have no geothermal sources sufficient for production of electricity, it can only be used to slightly reduce primary energy use during winter, but it will raise electricity use during winter.
3. Helps not at all, because 0 times however large number you like is still 0.
4. Likewise.
5. Improvements in efficiency do not help you stay alive when it's -30°C.
The option up here really truly is "do we use fossil fuels, or do we use nuclear". Renewables do not help. They are nice to have, and it makes sense to build them because they complement the reduced output of nuclear in summertime, and because the lower cost/kWh can help some industry, but that's all.
As for nuclear, the challenge is finding companies that are able and willing to build it. Areva and Rosatom both failed at the "able" part. And a power company (I think it was Fortum) recently stated that they would consider building new nuclear reactors with German electric prices but not with Finnish prices.
There is more to that than a power company asking for subsidies. Finland is a small country. Olkiluoto 3 alone generates >10% of the electricity. Newer reactors would likely be smaller but still ~10% of the total. Finnish power companies are too small to take risks like that on their own. They can't build new reactors at their own risk, in order to sell the power in the market. Before a reactor gets built, the power company needs long-term commitments from industrial users and utility companies to buy power for a guaranteed price. Such commitments would make sense for the buyer with German electricity prices but not with Finnish prices.
Finland was very very wise and savvy to get a fixed price contract for Olkiluoto 3. The final cost was far far far above its price, and France ended up paying that price. I'm not sure if you'll see a builder go down that route any time soon again.
If that's the case, then why does the indistry demand the repeated renewal of the Price-Anderson Nuclear Industries Indemnity Act?
Show me your Monte Carlo simulation where wind (which is negatively correlated to solar) and 8 hours of battery storage are factored in, along with small amounts of gas peaking plants.
That's the failure of European union
As for latter Sweden, doesn't currently have capacity for it and I don't think they have been very interested in increasing it, currently Finland often benefits from the fact that there isn't enough transport capacity between Southern and Northern Sweden electric grids so Finland gets some cheap electricity from there.
Texas having their own grid is not a failure of American federalism.
This very favorable scaling is why natural geothermal retains heat even though the input energy was delivered gradually over as much as millions of years.
If you assume a modern house with a heat load of 1800kWh per year (fairly standard for a new build medium sized home where I live, in Northern Europe) that means you'd need a tank roughly 50m3, or 10,000 gallons for Americans. In terms of insulation you'd need around 50cm of XPS foam, and it would be buried a meter below ground.
It's nothing terribly complicated in terms of construction or engineering. Of course you'd pay more upfront, but then your heating bills would be practically zero. In warmer climates it would be much simpler, you could probably get away without burying it.
1800 kWh is very little. We use around 12000 kWh and our neighbours' new house uses around 8000 kWh annually and most of that is heating. I'm not sure how many houses can hit 1800.
Changing to a different central source of heating (i.e. storage) seems orthogonal.
But going with larger structures probably means aggregation (fewer of them are built, and further apart). Assuming homes to be heated are staying where they are, that requires longer pipes. Which are harder to insulate. Because geometry.
The conversion to electricity loses energy, but I assume the loss is negligible in transmission, and then modern heat pumps themselves are much more efficient.
And the average high and low in February in 26°F and 14°F according to Google, while modern heat pumps are more energy-efficient than resistive heating above around 0°F. So even around 14–26°F, the coefficient of performance should still be 2–3.
For electricity-to-heat conversion, heap pumps are indeed much more efficient relative to resistive heating, yes. About 4 times more efficient.
In absolute terms, though - that is still only 50% of "Carnot cycle" efficiency.
https://en.wikipedia.org/wiki/Coefficient_of_performance
Similarly, heat-to-electricity conversion is about 50% efficient in best case:
https://en.wikipedia.org/wiki/Thermal_efficiency
So, in your scenario (heat->electricity conversion, then transmission, then electricity->heat conversion), overall efficiency is going to be 50% * 50% = 25%, assuming no transmission losses and state-of-art conversion on both ends.
25% efficiency (a.k.a. 75% losses) is pretty generous budget to work with. I guess one can cover a small town or a city's district with heat pipes and come on top in terms of efficiency.
Alternately, if you are going to deliver the heat at low temperature to a district heating system, you might as use a topping cycle to extract some of the stored energy as work and use the waste heat, rather than taking the second law loss of just directly downgrading the high temperature heat to lower temperature.
High temperature storage increases the energy stored per unit of storage mass. If the heating is resistive, you might as well store at as high a temperature as is practical.
Gas-fired heat pumps have been investigated for heating buildings; they'd have a COP > 1.
I am interested if there are any cheap small scale external combustion engines available (steam? stirling? ORC?)
> [250MWh] held in a container 14m high and 15m wide
According to Gemini 3.0 Pro, lifepo4 is 1.5-3.5x more dense than this, which isn't bad. 250MWh is a lot of capacity for such a small land footprint. At 2MW it can power ~2000 homes for ~5 days while taking up the land footprint of ~1 home.
What's the price? And how does the price scale with capacity?
Peltier modules can be used to generate electricity, but they are crazy inefficient.
An efficient steam turbine is largely inaccessible to hobbiests and I am scared of steam/pressure. Though I did look at repurposing a car turbo for this purpose. There were additional issues with regulating the amount of heat you wanted to extract (load matching) and recycling waste heat.
I wondered if it was possible to use a Sterling engine, but you can't buy anything other than very small toys online and I don't have the facilities to machine my own.
Haha, would love to get something working, but I suppose I'm not smart enough to figure out an effective way to get that heat back out as usable/controlled electricity.
Most of our electrical production is based on a solution found several hundred years ago, we just made it really big and worked out how to control the heating and pressure of the steam well.
Thermal electricity generation really benefits from scale and extremes. The Carnot efficiency is proportional to the temperature differential between hot and cold. Even so-called "low quality" heat from a standard nuclear rector design is far hotter than anybody should deal with at home and it only gets ~1/3 efficiency. And dealing with small turbines is really inefficient too.
This is where batteries and solar really shine. They scale so well, and are extremely economical and electrically efficient.
Heat storage works well when you get beyond the scale of individual homes, but it's hard to make it work. I'd love to see something related to heat pumps in the future for homes, but district heating, such as could be accomplished by converting natural gas systems to heat delivery, are probably required for it to make sense.
Back-of-the-napkin math felt promising. A 1kg block of sand heated to 500 degrees Celsius should contain about 100Wh of electricity. Scaling that capacity up is easy, as it's just about adding sand or temperature (+ an effective method of transporting heat across the sand - maybe sand + used motor oil?).
Assuming 80% efficiency, tariff arbitrage (buy electricity during off-peak hours and use it during high-price hours) would pay off very quickly. In my area (Australia) it would be a matter of months - but the low real-world efficiency and lack of parts make it impossible.
It could work for heating during winter, though perhaps an AC/heatpump with the condenser a couple metres underground would be better value for money.
There's a video of people doing this on YouTube. They use the ground as their heat source. https://youtu.be/s-41UF02vrU
I assume that because there is no current market for small sterling generators nobody wants invest in tooling to make one and because there are no small sterling generators there is no market for them.
Specifically, does the need for heavy insulation and the active heating of the sand make the ground a less effective or even problematic insulator? Could excavating and building a below-ground foundation for a high-temperature device like this be more complex and expensive than an above-ground silo? How would permafrost conditions affect this design?
I point again to Standard Thermal for an idea tailored to true seasonal storage. I wait for more news from them, particularly on their very low cost resistive heater technology.
Also the capex from sand battery goes to (mostly) local construction, while when buying chemical batteries all the money goes to china.
More directly this is a very cold area. Enough it might effect battery storage enough to be a real problem.
Why did we go to the moon when we have perfectly good vacuum chambers here at home.
The implied "my way is better" in these responses is usually the bad take on "what made this better than my way" as a question which nobody really can answer unless the OP is the engineer.
"Why does Finland not deploy ubiquitous small nuclear reactors every 25 meters and make a heated road to the north you can drive over as well as get power from if you have a power adapter for finnish plugs"
> "The installation will supply heat to the Vääksy district heating network and is expected to lower fossil-based emissions by approximately 60% annually, primarily through an estimated 80% reduction in natural gas consumption and reduced reliance on wood chips."
https://www.pv-magazine.com/2025/11/25/finlands-polar-night-...
> "This latest project will use locally available natural sand, held in a container 14m high and 15m wide."
and how a news outlet about energy could get such a fundamental unit wrong.
But given that later in the article it does revert to correct units (and the numbers are plausibly proportional), I assume it's just a typo. Strange that it hasn't been corrected even now.
"...It follows Polar Night Energy completing and putting a 1MW/100MWh Sand Battery TES project into commercial operations this summer..."
between this and salt battery which one is the future???
- embrace nuclear
- embrace North Africa, admitting them as member states, and doing massive solar there, and doing massive grid expansion to carry it north. And then in top of that, will their way to sufficient storage like the rest of us.
We'll see what they choose :D
I also see no reason to admit North African states into the EU before an agreement can be reached about transporting solar. The geopolitical risks have always been about other states severing the link during a conflict with you, and less about the parties to the deal reneging. So whether Morocco or Algeria is part of the EU is quite immaterial to the risk profile.
This kind of thing really does need simulation modelling to be reasoned about properly. The one thing I am confident in saying is that these single sentence just-so stories about what is and isn't a good idea are going to be wrong, because the fundamental principle is statistical diversification, which needs to be approached through simulation rather than through words.
It's helpful to have two flavors of storage; one short term and efficient (batteries), one long term with low capex (hydrogen, thermal). The last is the most undeveloped but there are promising ideas.