This 'Binary' or dual closed loops system confuses most...

This 'Binary' or dual closed loops system confuses most everybody initially Darkie. Probably because it is so clever and beautiful, yet simple once you grasp it.
Below is a link to a page of a 'Fact Sheet' on the GDY website.
It shows a diagramatic layout of the typical plants to be used. You can see 'Loop 1' and Loop 2'.
L1, the water recirculating endlessly down Hab.1. Getting heated to 240C odd in the granites. Then back to the top where it passes through the heat exchanger and gives up it's heat to the turbine fluid. Water I think in the trial 1MW unit but more likely a speacial low boiling point mixture in the real thing.
No matter. That becomes pressurised vapour or steam and drives the turbine and generator.
The 'exhaust' from this is not discharged to atmosphere but condensed in air cooled towers before being pumped around this second loop, endlessly also. So nothing is lost.

Coming back to the first loop, down around the well. The water down in the granite is under very high pressure, something like 400psi. It is kept that way right around the #1 loop and never turns to steam because of the pressure.
There is no leakage from the underground reservoir. If there was leakage it would not be at this high pressure.

See if you can pick this up in the diagram, (scroll down to P2.) with its explanation.

http://www.geodynamics.com.au/IRM/content/report_presentation.html