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Heat pumps can't take the cold? Nordics debunk the myth
(techxplore.com)
This is a most excellent place for technology news and articles.
Shallow geothermal is basically dead in most of the world because it's too much hit and miss, the geology is simply too complex and involved (and underground) to predict. There's also a fuckton of issues with water ingress, minerals that like to expand when getting wet and such. You can't really take Iceland as an example for countries not straddling a continental rift.
Deep geothermal is utterly reliable but for the longest time drilling that deep was just too expensive. Plasma deep drilling is a solution but it's still in its infancy.
that's not the geothermal we are talking about, geothermal heat pumps
https://www.energy.gov/energysaver/geothermal-heat-pumps
Those are ground source heat pumps.
Seriously by that nomenclature we'd also have aerothermal heat pumps.