"Drilling a deep geothermal well several kilometres into the ground to exploit these resources is very similar to drilling an oil or gas well. The difference is that an oil or gas well delivers a commodity that guarantees a significant return on investment. The hot water flowing from a geothermal well provides a lower return on investment, making it less attractive to investors.
In countries like the UK, Spain, France, Germany and the East Coast of the US, where geothermal resources remain largely untapped, exploration risk is still high due to a lack of available data from deep wells. This is not an enticing prospect for investors, who remain unwilling to provide the capital investment needed to drill – trapping the industry in a difficult cycle to break out of.
Geothermal energy’s synergies with shale gas production could offer a way out. For a geothermal resource to be viable, you need both heat and permeable rock to pump water through. You often also need to improve the heat transfer from the ground to the power plant by using pressurised water to shear the rock – a broadly similar process to that used in the shale gas industry."