by Len Morse

Created on: September 27, 2010

Wind turbines, those giant towers that look like a cross between a pinwheel and a jet engine, can be seen cropping up in regions of flat land all over the world. Many of them together, sometimes hundreds, are known as a wind farm, but it is not uncommon to see only a few or just one in a particular location.

Most people are aware that wind turbines are used to create electricity from wind energy, which is becoming quite the popular alternative power source in many countries, but many folks may wonder about how the “wind-to-electricity” transformation physically happens. Wind farm energy shows great potential, and the more we know about it, the more likely we are to decrease or even negate our dependency on environmentally hazardous fossil fuels like coal and oil.

== Turbine Effectiveness Variables ==

Wind moves across the blades and causes them to turn, much like the propellers of an airplane, but it’s not that simple. According to the European Wind Energy Association (EWEA), there are three basic variables that help influence how well a turbine does its job.

• Wind Speed: Turbines produce more electricity with stronger breezes. Average wind speeds usually range from about 13 to 33 feet (4 to 30 meters) per second, depending on location.

• Air Density: More dense air, found at or near sea level, rotates the blades more effectively than “lighter” air, which is at higher altitudes. Thus, the best elevation to build a wind farm is along the coast or off shore.

• Blade Specifications: Obviously, this is the one variable that engineers can control. Longer, slimmer, and lighter turbine blades can increase energy production. In his detailed May 5, 2010 article, Windpower Engineering Editor Paul Dvorak stresses the importance of turbine blades being as light as possible, yet durable enough to withstand high winds without breaking. Current blades range from 130-300 feet (40-90 meters), but future prototypes may be as big as 435 feet (145 meters).

== Wind to Electricity ==

The actual transition from wind to electricity occurs in an enclosed unit called a nacelle on top of the turbine, behind the blades. Traditionally, the turning blades rotate a low-speed shaft and a high-speed shaft, which are attached via two gears of different sizes. Depending on the wind speed, the low-speed shaft rotates 30-60 times per minute, and the high-speed shaft rotates approximately 1000-1800 times per minute. The back end of the high-speed shaft is attached to the generator, which creates electricity from these rotations.

However, according to a 2008 article on Metaefficient.com, nacelle technology in newer and larger turbines successfully eliminates the gears, creating a more efficient conversion.

The turbine generator’s direct current (DC, flowing in one direction only) electricity goes through a grid-interactive inverter (or “grid-tie inverter”) that transforms it into alternating current (AC, can flow in both directions) electricity that is used by utility grids. Grid-tie inverters can be used in private homes as well as commercially.

== Summary ==

In 2009, the European Union’s total wind energy saved more than 100 million tons of Carbon Dioxide, or the equivalent of removing 25% of gas-fueled cars off EU roads. That is no small feat, and if both wind energy popularity and turbine manufacturing prowess continue to increase globally, it seems that it’s only a matter of time before many more governments will be able to considerably lessen traditional fuel use.

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