Abstract :
Where will our future cities find the energy to keep industry going, to transport goods and people, to keep our homes and offices adequately lighted and comfortable all year round, and to operate such vital equipment as communication systems, computers, refrigerators, and other apparatus without which our everyday life would seem intolerable? In the United States, the energy for these many end uses traditionally has come from such sources as coal, petroleum, natural gas, and hydroelectric power, although the share of each of these elements in the energy pie has been changing over the years. The use of petroleum, for example, went up from 14 percent in 1920 to 46 percent in 1973, while the contribution of coal over that same period shrank from 78 to 18 percent.
