Energy is ubiquitous. From giant machines like airplanes and trains to small gadgets like bulbs and watches, the modern lifestyle is sustained by consuming various forms of energy. The broader scope of “energy” includes various other forms. For example, in Physics, kinetic energy is defined as the energy an object possesses due to its motion. Sustainable Economics, however, focuses on the sustainability issues associated with particular energy forms that are identified as resources and hold economic value, such as coal, oil, and hydropower.