Environmental Engineering Reference
In-Depth Information
Injection Well
Extraction Well
Power Plant
Fracture Zone
fig. 13.8
An enhanced geothermal system.
geothermal power and transporting it to Maui and Oahu
by undersea cable, but had no real use on the Big Island
itself with its small population and lack of industry. We
gave them a use which they hoped would make the resi-
dents enthusiastic about the project. Unfortunately it all
came to naught when the cost of the undersea cable was
found to have been greatly underestimated.
The new thing in geothermal is the program aimed at
developing the technology to allow the mining of heat
energy from hot dry rock at depths of
ve to ten thousand
feet (
to
km) in regions where drilling to that depth is
not too dif
.
An injection well and an extraction well are drilled to the
desired depth. Water is pumped down the injection well
where it is heated to a high temperature, taken back to the
surface through the extraction well, turned to steam to
drive an electrical generator, and
cult. The basic idea is shown in
Figure
.
finally sent back down
the injection well to be used over and over again. This
