In Iceland and a few other countries, geothermal energy delivers a large part of the energy used for heating or cooling through geothermal heat pumps. But you may be surprised to learn that there are hundreds and thousands of buildings in the U.S. that are also hooked up to such systems. Geothermal energy is also applied at larger scales for electricity generation in various countries and, faced with rising energy demand, there has been renewed interest in developing this sustainable resource more aggressively.
But what is geothermal energy and how is it developed? Professor Roland Horne, who leads the geothermal institute at Stanford University, gives a lecture on existing and future geothermal energy systems in this Woods Institute Energy Seminar from 2007. While some of the statistics he cites are a few years out of date, his discussion remains relevant and provides an introduction to this potentially important future energy source.