A few interesting facts about modern wind turbines

Wind turbines are a great source of renewable energy. However, due to their location, they are also exposed to a great deal of brutal weather. Here are some facts about wind turbines:

Modern electricity-generating windmills (wind turbines) use a completely different design than windmills used for pumping water.

• A number of refinements have emerged over decades of use:  the blades have an aerodynamic design similar to that of airplane propellers; a durable, lightweight material (such as fibreglass or special timbers) is used for the propellers; and there are just two or three blades to the propeller.
• Wind turbines are subject to stresses that can destroy them if they are not care­fully designed and built. In particular, they have an upper limit and must have a way of automatically protecting themselves from damage by strong winds.
• Some have propellers that are pushed to one side, out of the wind. Others are designed so that the whole propeller tilts backwards, reducing the area of propeller exposed to the wind and thereby slowing down the blades. Both methods are reliable and effective.
• Domestic-use wind turbines have propeller diametres (the diametre of the circle swept by the blade tips) ranging from one to seven metres (three to 22 feet), and they produce between 50 watts and 10 kilowatts of power; the larger the diametre, the greater the electricity output.
• Most models are designed to run for many years with little or no attention. Lubrication is required infrequently, and most turbine parts are moisture-proof and non-corrosive.
• The supports on which the turbines are mounted are usually made of steel, and many are designed to hinge at the base so that the turbine can easily be lowered to the ground for inspection and maintenance.

Extreme winds push against the blades of a turbine­, tilting the propellers backwards so that they are no longer exposed to the wind's full force.

• The propellers "feather" harmlessly until the wind speed drops, when the propellers­ automatically resume their usual position.
• A furling turbine's propellers are offset from the main pivot axis.
• As wind speed rises, the blades turn edge-on into the wind, reducing their speed, while the tail stays inline with the wind direction.
• The weight of the tail restores the blades to normal when the wind dies down.

As you can see, wind turbines are an obvious source of renewable energy in certain windy areas. However, there are definite risks in building and maintaining turbines, especially because of the stress caused by the weather.