Windmills: Converting Cheap, Clean Wind power to Electricity

Windmills produce clean electricity. They are ultimately powered by the sun because it is the heat of the sun and the rotation of the Earth that creates wind. However, the power provided generally does not come in steady flows, but in bursts and gusts. This means that wind systems must be flexible using batteries or relying on backup sources to supply consistent power to a single dwelling or across a grid.

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The history of windmills shows they have provided useful power in Europe as far back as Medieval times. The Crusaders probably brought back ideas about using wind power while in the Middle East. The Persians had been using wind for centuries for pumping water and grinding grain.

The most famous windmills are those found in Holland. Dutch windmills were used to pump water out of flooded regions. The system of windmills was essential for maintaining the integrity of the dike system that kept the North Atlantic from taking over large areas of the Netherlands. Windmills are also a famous landmark in the American west, where they were used to pump water and for early electrification.

Windmills for making electricity were first made in the early 1900s. They produced direct current electricity (DC). Appliances were made specifically to run on DC. Today AC is used because it is safer than DC and can be transported over long distances. Modern windmills are more properly called "wind-turbines". These are usually Horizontal Axis Wind Turbines (HAWT). They consist of rotor blades connected to a horizontal shaft, which in turn, is hooked directly to an electrical generator. A HAWT is more efficient than turbines utilizing vertical axis designs. However, for large turbines variable pressures on the blades at different heights can cause severe stress on the blades and bearings.

Vertical Axis Wind Turbines (VAWT) come in some very interesting designs. Since the shaft is straight up and down, the sails or blades do not have to be constantly adjusted to deal with variable wind directions. Because rotors have to come back against the wind, this type of turbine is not as efficient as the HAWT.

Using Wind Turbine Power

Windmills can be sited on residential property. There are two ways to use wind turbine generated power. The first requires the generator be hooked to a series of batteries. In this configuration some kind of monitoring system is put in place to cut off power flow in case the batteries become fully charged. The power is then used by local appliances directly from the batteries in a closed system.

The alternative is to hook into the power grid. In this case an agreement must be made with the power provider to take the power generated. Most states and countries require that utilities accommodate local power generation, reducing the consumer's electrical costs by his own power generation. This is usually done at the meter. Excess production can usually be sold directly to the power company for a cost close to what it would cost the company to produce the power itself. This involves some extra equipment.

Most residential windmills are equipped with an AC 60 cycle generator. To hook to the grid a converter will change the power from AC to DC. Then it must be fed through an inverter so that the voltage and frequency are matched to the grid. Generated power is then usually used locally and the excess fed back to the grid. A two way meter or a second meter is necessary for this to be tracked. As a safety measure a monitoring device spills the extra electricity if the grid is not live in order to protect linemen in the case of maintenance.

Because massive amounts of wind energy cannot be easily stored, wind power is usually supplemented by other forms of power generation within a grid.

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