What is Fuel?

   Fuel, except for atomic energy, is carbon formed by the action of the sunlight on growing plants. When carbon is burned, energy in the form of heat is released. The four commonest forms of fuel, in the order of their appearance on the stage of history, are wood, coal, gas, and petroleum. Out of these basic forms of fuel man has learned to develop a multitude of refined forms, such as charcoal from wood, coke from coal, washed or purified gas from natural gas, and gasoline from petroleum.
   The ability of various peoples to use fuel differs. In the world today the advanced nations are the ones that burn enormous quantities of coal, gas, and oil. The "backward" countries are relatively poor in the use of these fuels. As the standard of living in a society improves, greater amounts of fuel are used to provide food, clothing, shelter, and other consumer products, as well as transportation, warmth in the win­ter, and air conditioning in the summer. The increase in productivity of American farmers since World War I is significantly related to their increased use of fuel, especially gasoline.
   Fuel, as carbon in any of its multitudinous forms, is not the only source of energy. Electricity from water power is another source.
   Atomic energy may soon replace carbon as a fuel. One pound of uranium can produce five million times as much energy as one pound of coal.