Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Using non-renewable resources as a source of energy has many problems - they are scarce, finite, pollute air, soil and water, contribute to the global climate change, as well as many other environmental issues. Even nuclear power, which traditionally was seen as relatively clean, has its risks, as was vividly demonstrated in 2011 by the disaster at the Fukushima NPP in Japan. One of the possible sources of safe and environmentally friendly alternative energy is geothermal energy, generated from the thermal or heat energy produced and stored in Earth. Learn more about the geothermal energy, its advantages and drawbacks, economic aspects and more in this book.