sentences:  Exploration involves finding vast blocks of "hot rocks" with fracture systems that could generate electricity through water being injected, circulated through the fractures, and being returned to surface as steam which could then be used to rotate steam turbines.There are vast deep-seated granite systems in Central Australia that have high temperatures at depth and these are being drilled by companies such as Panax Geothermal, Geodynamics Ltd, Petratherm, Green Rock Energy and Pacific Hydro to depths of more than four kilometres.South Australia has been described as "Australia's hot rock haven" and this renewable energy form could provide an estimated 6.8% of Australia's base load power needs by 2030.