The United States depends on fossil fuels, like oil and coal, for energy. According to experts these sources will exhaust by the year 2050. Fossil fuels also pollute the environment. So we need to search for alternative energy sources which are reliable and renewable.
Wind power is the force of the wind harnessed by windmills and wind turbines that convert it into electricity. Because wind is a clean and renewable source of energy, modern wind turbines are being installed in many countries to supplement more traditional sources of electric power, such as burning coal. After the oil crisis of the 1970s, many countries launched programs to develop modern wind turbines. While many of these programs failed, Denmark was successful in developing one. Countries such as the United States have adopted this technology to develop wind energy resources. Design improvements have helped increase the world's wind energy generating capacity by nearly 150 percent since 1990.
In 1997, for example, the world market for wind energy reached billion. One major disadvantage of wind mills is that it is not so efficient as other power generation technologies.
Hydroelectric power is the energy produced by running or falling water that is used for driving machinery, especially for generating electricity. The development of hydroelectric power requires storage lakes, dams, bypass canals, and the installation of large turbines and electric generating equipment. Worldwide, hydroelectric power represented 19 percent of the total energy generated in 1998, the most recent year for which data are available. In many countries, hydroelectric power is the dominant source of electric power. Canada, the largest producer of hydroelectric power in the world, generated 340.3 billion kilowatt-hours in 1999, about 60 percent of the nation's electric power. Hydroelectric-power generation in the United States increased from about 16 billion KWH in 1920 to 305.6...