Hot Dry Rock (HDR) Resources
Hot dry rock receives heat from magma. The temperatures are in the range of 150°C to 290°C which are available at a depth of about 5 km.
Similar to oil well technology, the recovery of heat from HDR is done by drilling a deep hole in the rock and then cracking it to form cavity or fractures. The fracturing of rock can be done by :
- Hydraulic fracturing using high pressure water.
- Nuclear explosion.
- Chemical explosion by detonating the explosives.
In order to recover geothermal heat , water is pumped into the fractured well (injection well) and withdrawn from another well called production well located at a distance apart. The mixture of water steam obtained from production well can be used for power generation.
This technology is still under development in India.