Rstuart,

If you want a citation, you can simply look at the link you provided. Everyone talks about potential, but no one has claimed commercial viability.

Presently the biggest operating plant in the world for the hot rock technology is the Landau plant. Considering that it generates 20GWhr p.a. at the subsidised rate this covers the operating costs of the plant not any of the capital investment.

After 30 years of development, there is little to show for it. The logistics of supplying water for cooling and for losses in the rock fissures, and power lines out would require substantial investment on top of any plant.

JJ,

Only parts of the system are closed.

Considering that they are pumping high pressure water into the rock fissures, there are losses. (about 7 to 15% of water injected) and considering the volume of water, this is considerable, making it the most water hungry power generation technology available.

http://www.science.org.au/nova/116/116key.html
http://geoheat.oit.edu/bulletin/bull23-4/art4.pdf

I would suggest more than skim reading the promotional information before posting.