Re: A small question
Whilst there's a huge amount of geothermal power available, individual sites have limited lifetimes of about 20-50 years before their heat reservoir is depleted - rocks hold a lot of heat, but are lousy conductors. A good geothermal prospect not only needs hot rocks, but it needs expansion room to drill new boreholes when the older ones become less productive.
Australia's geothermal potential is mostly deep (4km) wells sunk into dry, ancient granites that are hot because of radioactive decay of high concentrations of uranium. If they can get it to work they will be exploiting the same sort of rocks as found in West Cornwall.
The Rosemanowes Quarry experiments in the 1980s produced large amounts of hot water but couldn't overcome huge losses of water between the injection and extraction wells. Modern fracking and horizontal drilling technologies might make this possible again. A 10MWe/50MWh pilot has been planned at Union Downs for Redruth for some time now and drilling should begin later this year. A second plant has also been approved at Eden.