this post was submitted on 11 Jul 2023
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There is already some geothermal in continental Europe. Most of it is used as aquifere heat storage thou. Basicly a big ground water bubble in great depths, so it is already decently hot(that is often 2000m down or so). Then hot water is produced at the surface and pumped down and when needed it is pumped up again. Thanks to being down deep enough, it stays warm for a long time. The big advantage is that the amount of heat able to be stored.
Currently one is under construction in Hamburg, which has a capacity of 5GWh. The district heating consumption of Hamburg for one year is 4GWh and currently heating half a million housing units, so a big part of the city.
Yep. It doesn't even have to be very deep. Helsinki is using some old "oil caves" (oil storage caverns excavated into granite, depth 80 m) to store some 10 GWh of heat for extraction during winter. Apparently, granite is an excellent insulator. They pump the heat from sewage (cooling the sewage and heating the cavern) during summer...
...but that wouldn't be classified as natural geothermal, and not primary production but seasonal storage.
But it works. But only on large scale. I ran the calculations for a private little project and the results looked bad. With anything related to thermal storage, it has to be big (energy loss scales with the square of volume, storage with the cube of volume).