Sweden had (I believe it is finished now) a subsidy for heat pumps over a few years. It was a limited offer and not really a large part of the cost, but it pushed many to make the shift. That a heat pump was economically beneficial over time was never in question, it was just a matter of getting people to do the investment (cost to own vs. cost to buy). Guess the subsidy worked as planned.
All types of pumps are used: water/water heat, air/water heat, air/air heat, and exhaust heat.
There is also a relatively close-to-surface magma layer that runs down from Iceland under Norway, Sweden, S and SW Finland, and down into the Baltics. So there is quite hot rock if you are prepared to drill down. Not sure how much this has been exploited, but Finland has more experience than almost any country in drilling Pre-Cambrian rock.
Sandvik is the leading company. You can't be me, I'm taken
