Finland warms up the world’s largest sand battery, and the economics look appealing
Finland warms up the world’s largest sand battery, and the economics look appealing | TechCrunch
Adding little bit extra context here.
In Finland large number of homes are heated by district heating. This means there is heat plant or combined heat and power (CHP) plant, which heats water to around 70C - 110C (158F - 230F) and that is distributed to homes.
In this system heat batteries are useful, and near all CHP plants in Finland have done heat battery in last few years. These heat batteries are just 7-store high insulated water storage. Usefulness to store just water is that system is relatively simple. Water in - water out. This makes it that the turbine in CHP can be run more freely towards electricity price, not the network heat demand.
Plain heat plants generally don't yet have these, because the buffer created by heat battery is not that much needed. But if these sand batteries can store heat longer, and because they might be cheaper to build, it can make sense.
Source: I work in company that owns 19 district heating networks.
I heard that the electrolytic medium used in this battery is coarse and gets everywhere
it’s hard to get any cheaper than the crushed soapstone now housed inside an insulated silo in the small town of Pornainen. The soapstone was basically trash — discarded from a Finnish fireplace maker.
Hell yeah. I'm glad that this works with that kind of sand, and is being done without the kind we're running out of.
we are running out of sand??
Like everything else...if you want to get into the details (which are important)...It's complicated
They report about 10/15% loss when doing heat -> heat. Cost per Kilowatt of storage about 25 euro, compared to 115 if lithium batteries were used.
It's a pretty neat system:
However, heat stores are subject to scaling laws which don't favour sand on the large scale, at least unless it's underground (and then you have to keep groundwater out to avoid vaporizing it). Large thermal stores benefit from storing heat in water, and placing the water deep underground, so the boiling point rises. If local rock has low thermal conductivity, even better.
For comparison Helsinki (.fi) has a 10 GWh underground thermal store. Where I live, Tallinn (.ee) will soon get a 1 GWh surface thermal store. And Vantaa (.fi) will soon complete a whopping 90 GWh thermal store that's located 100 m underground, so their water will boil at 140 C instead of the usual 100 C. Boiling points up to 300 C are attainable in practise, then the curve starts leveling out.
That's so cool, thanks for the info!
100MWh from that one little silo, that's incredible.
What a stupidly simple yet clever idea.
Here's the operator's website https://polarnightenergy.com/
this shit is so cool. it’s like those potential-energy-battery ideas with the stacked blocks, but ACTUALLY efficient!!
efficient because heat is used for heat. (district heating system). getting electricity from heat is relatively inefficient. Stacked blocks are relatively efficient but concerns over wind resistance.
Conversions tend to be inefficient, but in this case you can use only the best kinds of conversions.
They’ll use cheap electricity to heat up the sand, which is approximately 100% efficient. Then, the heat is stored for a while, and that’s when some of it will leak through the walls. Not a whole lot though, because of insulation and a small surface to volume ratio. Eventually, the heat is used to heat up water, which is another highly efficient conversion.
If you convert another form of energy back to electricity, you tend to lose a lot of it as heat. Physics just loves to use heat as the final destination for all sorts of energies, so it only makes sense to aim for utilizing it instead of treating it as a byproduct.
Pornainen’s battery is charged using electricity from the grid
How so, do they use heater resistors or a heat pump?
Electricity may be cheap sometimes but still, heater resistors aren't the most efficient.
