Nuclear Energy
Nuclear Energy, energy released during the splitting or fusing of atomic nuclei. The energy of any system, whether physical, chemical, or nuclear, is manifested by the system’s ability to do work or to release heat or radiation. The total energy in a system is always conserved, but it can be transferred to another system or changed in form. Until about 1800 the principal fuel was wood, its energy derived from solar energy stored in plants during their lifetimes. Since the Industrial Revolution, people have depended on fossil fuels—coal, petroleum, and natural gas—also derived from stored solar energy. When a fossil fuel such as coal is burned, atoms of hydrogen and carbon in the coal combine with oxygen atoms in air. Water and carbon dioxide are produced and heat is released, equivalent to about 1.6 kilowatt-hours per kilogram or about 10 electron volts (eV) per atom of carbon. This amount of energy is typical of chemical reactions resulting from changes in the electronic structure of