Petroleum, gas and coal are called nonrenewable energy or fossil fuels. Although uranium is not fossil fuel, but if extracted and used, it wont be made again in short period of time.

The renewable source of energy is an energy thatcouldberegenerated in short period of time.

Although generating electricity from renewable source (wind, solar. Biomass, etc) have no adverse impact on environment, but the overall use of this energy has decreased since its peak in 1996. Its production became only 6 quads in 2002. Each quad is equal to 5.9 quadrillion Btu.

People used wood to generate heat hundreds of years ago. In the past about 90 percent of energy source was wood.

Low price of fossil fuel and its convenience attracted people to switch from wood to fossil fuels.

This cheap prices of fossil fuel prevented people to use the renewable source of energy. Attracting the power industry to shift to renewable fuel as source for electricity production needs legislation. Finally, in short term while cheap fuel is in hand, possibility to increase renewable energy is not in sight in the United States.

Renewable energy in other countries, where sun shines most of the year or at windy areas, is proving economical. But in U.S.A where there are clouds and days are quiet (no wind area) and dams are made to control floods, demand increase for renewable energy is not proved to be commercial. In 2002 about 5.9 Quadrillion BTu (Quads) of energy produced was  in the form of renewable energy.