Installation raising steam from geothermal heat - has concentric inlet and steam outlet pipes with water boiled in preformed fissure

摘要

A large diameter hole is drilled into the earth to a depth at which there is solid rock at a high temperature. Water is forced down the hole at high pressure to crack the rock and produce a large fissure in it. A small diameter tube is then inserted centrally in the hole and water is pumped through it. It enters the fissure and is evaporated. The steam produced rises through the annular space between the central tube and the outer bore.