Hence we are essentially mining geothermal energy in the same way that we mine fossil fuels. The main problem with geothermal, of course, is lack of easily accessible surface sites. Turbines on Old Faithful would probably not be well received. Only real source of loss is turbine friction. US has large reserves.
Heat engine driven electricity is possible.
Also very viable for space heating needs. The potential of this resource is enormous but so far no technology exists to extract energy in a commercially useable way.