cmon bhp, page-6

vivonne - I understand your enthusiasm, however the Lihir project is sited on a volcano (from memory)- the geothermal power generation is via Hot Wet Rock technology, as employed in other volcanic provinces (eg Nth Island New Zealand). In general terms: ground waters within the volcanic setting are at elevated temps, there tends to be substantial porosity within the volcanic rock pile and the hot 'brines' are generally near surface - tapping these 'brines' for heat transfer & power generation is relatively easy compared to Hot Dry Rock settings (as proposed by GRK and the likes). Target depths are much deeper, porosity can be quite low (GRK are targeting a buried granite which MAY have a fracture/joint network that MAY be further fractured - ie they have to engineer/enhance the permeability/fluid flow pathway before a suitable circulatory cell can be established... as well as supply the fluid - there are still a lot of maybes & considerable capex...). Having said that though, IMO they are certainly worth a punt. ;-)

Also on a few minor points - Geothermal energy is not strictly/necessarily a renewable energy (not on our timescale anyway)- you are effectively mining the ground for heat and eventully this resource will be depleted - it will take thousands of yrs for further radiogenic decay in the buried rock to generate more heat...and in this context it can be viewed as a natural nuclear reactor.
dyor & don't take my word for it.