Energy is the ability to do work. It surrounds us in all aspect of life. However, the ability to harness it and use it, as economically as possible, is the challenge before mankind. Alternative energy refers to energy sources, which are not based on the burning of fossil fuels or the splitting of atoms. The renewed interest in this field of study comes from the undesirable effects of pollution both from burning fossil fuels and nuclear waste by products. Fortunately, there are many means of harnessing energy that have less damaging impacts on the environment.
One example wind power. Wind energy is a clean and renewable source of electric power and is also the world's fastest growing energy source.
More then five thousands years ago, the Egyptians used the wind to sail ships on the Nile. Later, people built the first turbines and used the wind to grind grain. These machines looked like paddle wheels and were used in Persia as early as 200 BC.
By the fourteenth century, the Dutch had taken the lead in improving the design of windmills. They invented propeller type blades and used wind power to drain the marshes and lakes of the Rhone River delta. In America, Early European settlers used windmills to grind wheat and corn, to pump water, and to cut wood at sawmills. By the early twentieth century, small windmills were used for pumping water and electric power generation in Europe, the United States, Africa, and elsewhere. In addition to thousand of small wind electric generators, a few larger systems were built in North America and Europe.
In the 1970's, the increase in oil and fossil fuel prices helped wind power return as an economical alternative energy source. Governments all around the world, especially in North America and Europe, instituted research and development programs. These efforts led to the development of modern wind turbines, which have dramatically reduced the cost of generating electricity from wind power.
A wind turbine works the opposite of a fan. Instead of using electricity to make wind, like a fan, wind turbines use wind to make electricity. The wind turns a blade, which spins a shaft, which connects to a generator and makes electricity. Modern wind turbines fall into two basic groups, the horizontal axis and the vertical axis design.
Horizontal axis wind turbines have blades that spin in a vertical plane like airplane propellers. The blades have a special shape so that when wind passes over them, it moves more rapidly over one side. This creates a low pressure behind the blade and a high-pressure area in front of it. The difference between these two pressures causes the blades to spin.
The blades of a vertical axis wind machine work on the same principles as horizontal axis machine. The shape of the blades causes the pressure to differ when the wind blows over them. This causes the assembly to spin. In a vertical axis machine, however, the blades spin in a plane that is parallel to the ground like an eggbeater.
Wind turbines are made in a variety of sizes, and therefor power ratings. The largest machine, such as the one built in Hawaii, has propellers that span more than the length of a football field and stands twenty stories high. It also produces enough electricity to power fourteen hundred homes. A small home sized wind machine has rotators between 8 and 25 feet in diameter. It stand upward of 30 feet and can supply the power needs of an all electric home or small business.
Wind energy is also a partial solution to environmental problems. The electric Power Research Institute has stated that " Alone among the alternative energy technologies wind power offers pollution free electricity that is nearly cost competitive with today's conventional sources". In 1991, for example, California's wind power plants offset the emission of more than 2.8 billion pounds of carbon dioxide. These same wind plants offset sixteen million pounds of nitrogen oxide, sulferdioxide, and particles. It would take a forest of one hundred and seventy five million trees to provide the same air quality.
The environment, however, is not the only benefit wind turbines offer. Wind energy is already one of the most cost competitive renewable energy technologies, at about three to five cents per kilowatthour. These costs are competitive with the direct operating cost of many conventional forms of electricity. In the future, prices are expected to drop even further. This will provide low cost electricity to homes, businesses, schools and manufacturing plants.
Although wind power does have relatively little impact on the environment, there are some drawbacks. For instance, there is concern over the noise produced by the rotator blades and aesthetic impacts. Also, birds have been killed by flying into rotators. Most of these problems have been resolved or greatly reduced through technological development or by properly siting wind plants. Another challenge to using wind as a source of power is that it is intermittent and it does not always blow when electricity is needed. Wind cannot be stored and therefor it cannot be used to meet the timing of all electricity demands. Further, good wind sites are often located in remote locations far from areas of electric power demand. Finally, wind resource development may compete with other uses for the land and those alternative uses may be more highly valued then electricity generation.
Wind power has an expansive future according to experts. In the 1990's wind energy was the fastest growing source of electricity in the world. However, the majority of this growth has been in Europe.
The U.S. Department of energy recently announced that it hopes to power at least 5% of the nation's electricity with wind by 2020. The department also wants to increase federal use of wind energy to 5% by 2010
Although the world may never be able to fulfill all of its energy needs through renewable energy sources, it is a goal worth trying to achieve. And people are working toward that goal. Many advances in the field of wind generated power have been made in recent years, and research efforts continue to press forward on numerous other alternative energy fronts.