For my advanced volcanology class, we were encouraged by my professor to attend a Volcanological Society of Sacramento (VSSAC) meeting. Of course, he is one of the head members of the organization and the meeting meets on the second floor of the geology building on campus. The presentation was given by a geologist named Tom Box. He gave a wonderful talk, The Nature, Development, and Preservation of a Unique Resource on "The Geysers". If "The Geysers" are unknown to you, it is the world's largest producing geothermal plant and is located near prime wine country in the California Coast Ranges. He was a on-site geologist for several decades. The geothermal area was found in the late 1840's and used as a destination resort for many years. Commerical steam power started slowly in the 1960's, didn't become a big producer until the 1970's, and reached its peak in the 1980's. Currently, the plant has a extensive ground water injection program, which might explain the continuous microquakes in the area (see diagram above, cluster of small earthquakes outlines "The Geysers" region).
Other geothermal plants in California include locations at the Salton Sea and Coso Volcanics.
I really enjoyed the talk and greatly improved my knowledge of geothermal power as a clean natural resource. This presentation brought to my mind, we as a society need to focus on alternative resources, instead of beating around the "bush" for more decades by using coal and foreign oil.