HDR Prospects in Italy and Turkey

Abstract

Exploitation of hydrothermal systems is the only commercial way to extract sizable heat quantities from the interior of the earth. The number and location of such systems endowed with high temperature fluids is however limited. To increase substantially recovery of the immense amount of existing terrestrial heat one has to look for a way to extract it from otherwise tight rocks by creating artificially a fractured underground reservoir and circulating fluids therein to capture some of the available heat (HDR). HDR research and experimentation is underway in several countries around the world and has led to significantly increased knowledge and progress in this field. The concept of HDR has evolved to include artificial stimulation of rocks with latent fractures, adjoining hydrothermal fields or aquifers. Technical challenges to a successful HDR development include: creation of a large underground heat exchanger; control of the fluid flow balance; optimization of heat depletion of the reservoir. HDR systems tapping high temperature rocks at moderate depth have a stronger chance of being economic. Italy and Turkey, as well as Greece are the European countries where this last condition is better fulfilled.