While we may view Earth as our home base, it is also a powerful source for interesting types of energy. Geothermal energy involves extracting the energy of the surface heat right beneath our feet. Bioenergy involves using renenewable energy from biological sources, like plant materials. These two energy sources are becoming more prevalent as new technologies are developed. This book looks at these important energy sources, how they are harvested, and what they may mean for the future of our energy.