Harnessing wind energy was one of man's earliest achievements. Small windmills pumped water in ancient Syria and sailing ships used windpower to first circumnavigate the globe. The modern use of wind turbines originated in the 17th Century where the Renaissance Dutch used wind power to recover hundreds of thousands of acres of land by draining the Rhine River delta. The classic Dutch windmill design predominated for 300 years, pumping water, grinding grain and sawing wood until the multibladed American Farm Windmill was developed in the middle of the 19th century. These machines covered the continent, pumping water on every farm and in every town until rual electrifacation (and rust) brought about their demise in the middle of the 20th century.
Advances in the fields of aerodynamics and composite materials have made modern electric power generating wind turbines a reality. These machines range in size from a meter to a hundred meters in rotor diamater and from a hundred watts to a thousand kilowatts in power output. Wind turbines suitable for residential or village scale wind power range from 500 watts to 50 kilowatts. These machines fall into three categories:
Utility interconnected winturbines generate power which is syncronous with the grid and are used to reduce utility bills by displacing the utility power used in the household and by selling the excess power back to the electric company. These machines are economically attractive where there is a good wind resource and where the local power costs are in excess of 15 cents per kilowatt hour.
Wind turbines for remote homes (off the grid) generate DC current for battery charging.
Wind turbines for remote water pumping generate 3 phase AC current suitable for driving an electrical submersable pump directly.
