Many people associate geothermal energy with watching dramatic geyser eruptions or relaxing in a steaming natural hot spring. However, heat from within the Earth can also be used to generate electricity and heat buildings. Readers learn about the past, present, and future of geothermal power through this informative book. Topics covered include how geothermal heat is created and brought up to Earth's surface, the surface features, such as lava flows, hot springs, geysers, and fumaroles, that are signs of it, and how geothermal heat pumps and geothermal power plants work. The need for renewable energy sources such as geothermal energy is addressed, as is the need to manage geothermal resources sustainably.