— World Economic Forum (@wef) January 3, 2017
Iceland is about to tap into water as hot as lava. Several kilometres below ground, a drilling rig named Thor will soon penetrate the area around a magma chamber, where molten rock from the inner Earth heats up water that has seeped through the seafloor. This water – up to 1,000°C and saturated with corrosive chemicals – will eventually be piped up to the surface and its heat turned into usable energy.
It is a huge engineering challenge, and one which may usher in a new age of geothermal power production. Existing geothermal projects around the world need waters heated to less than 300°C, so why go to this extra effort and expense?
The answer is simple: water at the most extreme temperatures exists in a state described as “supercritical”, where it behaves as neither a true liquid, nor a true gas, and is capable of retaining a phenomenal amount of energy. Supercritical water can generate up to ten times more power than conventional geothermal sources.