Learning the basics of wind power

Wind mills and turbines may seem a bit unsightly, but they play a crucial part in both history and in modern-day farming. Wind power has been used for thousands of years to pump water and grind grain. The following information will give us a greater appreciation of this force of nature.

Wind power has been used for thousands of years to pump water and grind grain. Its use in milling grain was once so common that all machines with blades turned by the wind became known as windmills, even though they were and are used for purposes other than milling. The traditional form of the windmill, often associated with the Netherlands, used large cloth sails that were reefed like the sails of a ship when stormy weather threatened, and the upper structure was swivelled by hand to keep the arms facing into the wind. These windmills were quite inefficient.

As a result, wind power did not become popu­lar outside Europe until much more efficient windmill designs were introduced. In the middle of the 19th century, a new type of windmill to serve a different purpose appeared on the scene. These windmills had slow-turning, mul­tiple blades made of wood or galvanized steel. The new mills performed admirably, pumping underground water from bores and wells, or surface water from dams, rivers and creeks. Thousands of them appeared on farms and stations, particularly in the United States, Aus­tralia and New Zealand.

1. The Savonius rotor was developed in 1920 by S. J. Savonius, a Finn, and is similar in design to ventilators still used on the roofs of industrial buildings. The main weakness­ of this device is that it operates at a low rotational­ speed and therefore requires substantial gearing to generate electricity. It also quickly loses efficiency if the rotational speed is not controlled. The Savonius presents­ a large, unbroken expanse of metal to the wind so the supporting tower has to be very strong. Its main application­ is for water pumping in low-wind areas.
2. The Darrieus rotor, invented by the Frenchman G. J. M. Darrieus in the 1920s, resembles a two or three bladed egg beater. Because it swings on a vertical axis, it does not have to swivel into the wind every time the wind shifts direction. The rotor needs to be "kick-started" by a small motor after a windless spell, so it is not ideal for regions of intermittent wind as the constant use of a starter motor would greatly increase operating costs.

The 1920s saw the next major development in harnessing the wind. High-speed windmills capable of generating electricity were introduced, bringing the promise of cheap power to remote areas. Sub­sequent refinements have shown that wind power is a productive source of electricity in regions with strong, regular winds. In practice, though, the relatively high establishment costs make windmills a realistic choice only for those in remote regions not already connected to the electricity grid. Wind turbines are most commonly used in a hybrid system with solar photovoltaic panels; the panels supply electricity during extended periods of little or no wind.