Most electricity is produced from what are called “fossil fuels”​—oil, coal and natural gas. These fuels are burned at power-generating plants in huge furnaces. The furnace heats a water boiler to produce a superheated steam. The steam then rushes at 1,000 miles an hour into a huge turbine, and spins its bladed wheels. In hydroelectric plants, falling water, instead of steam, is used to turn the turbine. The turbine then drives a generator to produce electricity.

Over 80 percent of the electricity in the United States is produced in steam-turbine plants, while hydroelectric facilities generate most of the rest. The first steam-turbine electric plant went into operation ninety years ago in New York city. Today there are some 3,400 power plants throughout the country.

Actually the steam-turbine process of producing electricity is rather inefficient In the conversion process only about one third of the energy of the coal, oil or gas is turned into electricity. The other two thirds of the energy escapes in the form of waste heat and other pollutants. Also, up to 20 percent of the generated electricity is lost in its transmission from the power plant to the place of use.

The fossil fuel consumption of electric power plants staggers comprehension. A large coal-fired plant may burn over 600 tons of coal an hour! Coal is used to generate nearly half the electricity in the United States, and falling water, natural gas and oil produce most of the rest.

As industry grew, however, man needed more power to drive newly invented machines. Fossil fuels laid away in the earth ages ago were utilized. Coal was dug up and used in increasing volume. By 1910 it was the energy source for three quarters of man’s power needs.

In 1970, oil provided about 43 percent, natural gas about 33 percent, and coal some 20 percent of the country’s total energy needs.