It has some top level supporters, the wholesale geothermal heat pump. The Environmental Protection Agency has been a big fan of this technology for a long time, and many electricity producers offer incentives to homeowners to encourage the installation of the units.
Geothermal units work just like standard air heat pumps work - they take advantage of the energy of outside air to either heat or cool the inside space.
This can be, when it works okay, a really efficient way of heating and cooling, making the best possible use of electricity. The trouble is that the six hundred percent efficiency that you see when you compare heat pumps if not always achieved (not even usually achieved in some places)
The main heat pump problem is when the outside temperature drops significantly. Then it is not possible to take heat from the cold outside air in order to heat our homes, so the heating unit switches to old fashioned and inefficient electrical resistance heating.
Geothermal heatpumps put an end to this problem because the temperature below ground remains fairly stable. The only disadvantage is that you need to dig down (or out - there is a horizontal configuration that does not need to go so deep). That is what the grants offered by some energy companies are for!