Using wind energy to power our appliances is nothing new. Wind has been used as a source of energy for many years. The Babylonians and Chinese used wind power to irrigate crops as early as 4000 years ago. Of course boats have long been powered by the wind in their sails. In Europe during the middle ages windmills were used to grind corn.
So wind energy is really an ancient technology. But how does it work? The earth’s atmosphere is heated by the sun but this does not happen evenly. Rather certain areas of the atmosphere become warmer than others. The warmer sections rise. When this happens more air blows in to replace them. This is felt as wind.
Wind energy can be harnessed by building a tall tower on top of which sits a large propeller. The wind causes the propeller to move which in turn powers a generator. This produces electricity. When many of these towers are built together it is called a wind farm. The amount of energy that can be produced depends on the size of the propellers, the number of towers and the amount of wind available.
For this reason wind farms are only built in areas that have strong winds that blow most of the time. There are some boats and caravans that are fitted with wind generators. These generators keep their batteries charged, but this is wind energy on a very small scale.
Wind farms are ideally suited to places along the coast, at the summit of rounded hills, open plains and gaps in mountainous regions. These areas will have winds that are strong and dependable. To make wind energy a viable proposition they need to blow rapidly and steadily. There are some farms which use wind energy to supply electricity to homes such as those in Los Angeles.
Propellers need to be big so that bigger volumes of air can be harnessed. Propeller blades can be angled to either a "fine" or "coarse" pitch. This means that they can deal with different wind speeds. The generator and propeller have the ability to turn into the direction the wind is coming from. There are wind farms that use vertical turbines to harness wind energy. In this case they don’t have to turn and face into the wind.
Towers for harnessing wind energy are very tall. This helps them reach to the area of the atmosphere where the wind is the strongest. It also makes it possible to free up as much land as possible for farming activities in low-lying areas.
Wind energy has several advantages and disadvantages. Clearly wind is free and farms don’t require any fuel to run. Wind farms also do not generate and waste products or greenhouse gases and frees up land for farming. They are ideally suited to remote areas and can also act as tourist attractions.
On the down side wind energy is unpredictable. Coastal land is also very expensive and this is the best site for wind farms. Wind farms are not aesthetically pleasing. They can also be harmful to migrating birds who follow strong wind channels. Wind generators are also noisy. When several towers are placed together they can be intrusive. If you live near a wind farm it might mean a poor television reception too!
