Wind TurbinesWind turbines harness wind energy and use it to generate electricity. The UK is a windy country that has 40% of all the wind energy in Europe blowing over it, making the UK an excellent country for having wind turbines. Households can make use of wind energy to generate electricity by installing small systems known as “micro-wind turbines” or “small-wind turbines”.
How wind turbines workMost wind turbines use blades that are shaped similar to aircraft wings to harness the energy in the wind. Horizontal Axis Wind Turbines: Horizontal axis wind turbines have their blades attached to a central hub that is free to rotate. As the hub rotates it drives an electricity generator. The stronger the wind the faster the hub rotates and the greater the amount of electricity that is generated. Usually the blades, hub and generator sit at the top of a mast where they are free to rotate through 360°. A ‘tailvane’ moves the unit so that the hub is always facing into wind. With the hub facing into wind the blades are positioned to best harness the energy from the wind. As the wind passes over the blades lift is generated in the same way that an aircraft wing generates lift. Lift is an energy force and this causes the blades to move. The hub that the blades are connected to rotates, providing power to drive the generator which then generates electricity. Vertical Axis Wind Turbines: Vertical axis wind turbines have their main rotor shaft set vertically. The generator and gearbox are usually set on the ground and the rotor blades rotate around the shaft. As wind blows over the rotor blades lift is generated and the blades spin around the main shaft. The spinning shaft drives the generator and electricity is generated. With this type of unit the turbine blades do not have to be pointed into wind.
Electricity generated can be used to:
Any excess electricity generated can be supplied back to the National Grid and sold to an electricity supplier.
Types of wind turbines used to provide electricity for the homeRoof mounted: these wind turbines are small enough to be mounted on the roof of your home, garage or any other suitable structure that has unobstructed wind flow over it. There are a range of sizes and power outputs available, typically between 1kW to 2kW. Mast Mounted: are usually larger than the roof mounted turbines and have greater power outputs ranging from 2kW to 6kW. They are mounted on top of masts, erected in a suitably exposed location at your property that has unobstructed air flow.
ConsiderationsCheck that your property has enough land – the distance between the proposed turbine and your nearest neighbour should be at least 200 metres. Check that your home is in a windy area – for wind turbines to be effective you need your home to be in an area where the average wind speed is at least 5 metres per second (m/s). Micro-wind turbines work best in exposed locations – the best locations are on top of hills, on the coat, or shorelines of estuaries and large rivers. The turbines work best when they are able to catch clear airflow and therefore need to be positioned away from buildings, hedges, trees, hills, solid fences and other large objects. This is because as the wind hits obstructions turbulence is created that can affect the efficiency of wind turbines. It is best to position a micro-wind turbine at least 75 metres away from any obstructions. When positioning a wind turbine it is also important to take into consideration the prevailing winds. Make allowances for fluctuations in wind speed – the amount of electricity that a turbine generates will vary from day to day depending on the amount of wind. Some days the air maybe completely still, meaning that the turbine will be unable to generate electricity. On still air days you will need an alternative source of electricity. However, when the wind turbine is generating surplus electricity this can be used to charge batteries or sold back to the National Grid. Selling surplus electricity to the National Grid will provide you with some additional income and enable someone else to make use of the green electricity that you have generated. Wind turbines should be at least 10 metres above any obstructions – the height of the turbine is important because friction causes airflow to be slower and more turbulent the closer to the ground it is. Check to see if you need planning permission – most micro-wind systems need to have planning permission from the local authority. It is important that you obtain this permission before you install your system.
Advantages of micro-turbinesSave money – rising fuel costs make wind turbines an attractive option. Once you have purchased and installed your wind turbine the electricity produced is free. Furthermore with the feed in tariff you will receive 19.9 pence for every kilowatt of electricity produced and a further three pence for every kilowatt sold back to the National Grid. Reduce your carbon footprint – the electricity generated by wind turbines is green renewable energy that does not release any carbon dioxide or other pollutants. Wind power is a completely renewable energy – the UK is very rich in wind energy and wind turbines are an effective way of harnessing this energy in order to generate electricity.
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