Electric power is the use of electric energy to do work. It lights, heats, and cools many homes. Electric power also runs television sets, refrigerators, vacuum cleaners, and many other home appliances. Electric power operates machinery in factories. Escalators, elevators, and computers and other business machines in stores and offices use electric power. Electric power drives many trains and subway systems. On farms, electric machinery performs such tasks as pumping water, milking cows, and drying hay.

Huge electric generators in power plants produce almost all the world's electric power. The majority of these plants burn coal, oil, or natural gas to run the generators. Most other plants drive the generators by means of nuclear energy or the force of falling water. Wires carry the electric current from power plants to the cities or other areas where it is needed. The electric power is then distributed to individual consumers.

Electric power is measured in units called watts. For example, it takes 100 watts of electric power to operate a 100-watt light bulb. Ten 100-watt bulbs require 1,000 watts, or 1 kilowatt. The amount of energy used is expressed in kilowatt-hours. A kilowatt-hour equals the amount of work done by 1 kilowatt in one hour. If you burn ten 100-watt bulbs for one hour or one 100-watt bulb for 10 hours, you use 1 kilowatt-hour of electric energy.

The world's electric power plants can produce more than 3 billion kilowatts of electric power at any given time. The United States leads all other countries in generating capacity. American power plants can generate nearly 800 million kilowatts. Canadian plants can produce more than 100 million kilowatts.