There are two classes of systems that go by the name "geothermal". The article is opining about the deep "High Temp" thermal systems that are found in places l

There are two classes of systems that go by the name "geothermal". The article is opining about the deep "High Temp" thermal systems that are found in places like the Geysers field in California, in Iceland, and in New Zealand. Those use heat in a primary way to power heat engines to generate electricity. You are talking about the other class of geothermal. That class is also known as "ground source heat pumps" for HVAC. Just like a reverse-cycle air-conditioner can heat as well as cool by exchanging heat with the outside air, ground source heat pumps do the same by exchanging heat with relatively shallow underground media. Typically, those have much higher heat capacities than air, which is the competition. Nobody attempts to run heat engines with such Low Temp resources as encountered in ground source heat pump applications...