There are many geothermal advocates. Geothermal energy is nearly inexhaustible. The available resource is greater than the amount of oil the world has used and has left. A geothermal plant has a very small geographically footprint (MW/acre) compared to other energy sources. Geothermal produces continuous (baseload) power at a very low cost. When done right geothermal produces minimal greenhouse gases.
At the low end, the California Geysers produce electricity for 3-3.5 cents/kWhr, while some geothermal resources need 6-12 cents/kWhr. Credit Suisse (2009) calculated that geothermal power costs 3.6 cents/kWhr, versus 5.5 cents/kWhr for coal.
Geothermal has a capacity factor (average output/maximum output) of 0.84 (nuclear is 0.90, wave energy is 0.6, wind is 0.4, solar is 0.20)