Geothermal or Heat Pumps
Like Tidal Power, Geothermal Energy is in the initial stages of development. The basis is that as you descend into the ground the earth gets warmer, a fact known to miners for centuries. The temperature slowly rises with depth but stays more or less constant at a given depth. The earth is a huge heat sink and can keep giving energy for eternity, the same as nuclear, but without any radiation.
The term Heat Pump is just beginning to enter into the lexicon of climate aware citizens. Air Source Heat Pumps are beginning to be installed but are large and expensive. As well as Ground Source there is a growth of Air Source appliances, which are said to work well even Norwegian Winters. Bristol, described in an article in The Economist dated 2nd December 2023 is extracting heat from the waters of their harbour to heat 2.500 city centre flats.
For a single domestic dwelling you cannot drill a bore hole too deep, because of the cost. My partner’s home in the USA needs supplementary heating on the very chilly days but works very well cooling in the summer. Large buildings will have to go very deep (5000 meters) to get to temperatures that can create steam for heating the total building. A competition for SMRs.
Iceland is operating a Direct Air Capture plant with geothermal energy for its power source, but that country is well known for its geysers.
Further reading: https://www.hephaeet.com/