Hot rock heat mining could provide energy at competitive prices, according to a recent study by the Massachusetts Institute of Technology.

The power cost is expected to vary from site to site, depending mainly on geological conditions, experts said. The overall cost of building hot rock power plants will go down as the industry develops, they said.

How existing geothermal energy compares to other renewable energies per kilowatt hour (Source: the International Energy Agency):

Geothermal: €0.01 to 0.09 (2 to 12 U.S. cents)

Biomass: €0.01 to €0.12 (2 to 16 U.S. cents)

Wind: €0.02 to €0.09 (3 to 12 U.S. cents) Solar: €0.13 to €0.36 (18 to 50 U.S. cents)

Hydro: €0.01 to €0.12 (2 to 16 U.S. cents)

An Australian hot rock power plant could produce electricity at an estimated cost of 4.5 Australian cents (€0.03; 3.8 U.S. cents) per kwh, according to Queensland-based Geodynamics Limited.

The cost of hot rock power production in Europe has yet to be determined. In general it is expected to be more expensive than wind energy, but cheaper than solar energy, said Juerg Baumgaertner, a manager at a European Union geothermal research project in the French town of Soultz-sous-Forets.