I thought it worth responding to Glenn's and David's posts on the above this
exact point has happened in New Zealand where we used to have more than 200
geysers at Wairakei, Rotorua and a few other smaller geothermal fields and
now have less than seven. The ground at Wairakei is sinking at the rate of
1mm each year and so many thousands of tonnes of steam are removed that a
neighbouring valley can no longer be called Wairakei Geyser Valley because
there are no geysers. it is a joke to call it a Thermal Valley.
At Ngawha in the far North of my country the thermal activity is
dramatically reducing as steam is removed for power generation using and
ORMAT Sytem. This closed system using isopentane is reducing the viability
of the springs and pools at Ngawha and costing people their livelihood.
NZ has sacrificed short-term energy gains for its long term natural wonders.
Other countries are following.
Even so, geothermal systems are used to generate electricity in Italy, NZ,
USA, Eastern Russia, Indonesia, Philippines and some S. American countries.
Invariably geothermal geologists report a stabilising of the groung and
activity by the removal of energy as steam. So now people can live and work
in previously dangerous areas.
As Glenn noted, geothermal energy is only potentially available in
relatively few areas. Iceland may be able to get much of its energy
needs from it, but not most other countries. Geothermal development
risks disrupting hot springs and geysers, thus disrupting tourist
revenue and unusual biological systems.
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