Paul Thomsen, spokesperson for Ormat Technologies, provided the book’s chapter on geothermal, discussing his company’s power plants that are a field-proven, mature commercial product operating worldwide.
The first geothermal project was about 1905 in Italy. A farmer drilled a well, hot water came out, which turned to steam and the concept of putting a steam turbine on that to produce electricity was created. Soon we had flash technology, where water comes out of the ground, turns to steam and you put a turbine on it. And there are projects like that in Northern California at the geysers; there are projects like that in Iceland, in Africa – but they tend to be unique anomalies.
Ormat Technologies became a company in 1965. Our chairman decided that there were probably more stable ways to produce electricity and started to work on a heat exchanger and a turbine design utilizing what’s called the organic Rankine cycle. The cycle simply creates a secondary loop; where there are deviations in temperature, you can heat a working fluid which does the vaporizing, which builds pressure and turns a turbine. He first implemented this on a solar project in Mali, Africa. It was technically a success, but commercially not that attractive, so he turned towards geothermal.