The UK placed as the 7th country to harness an awesome 2GW capacity last February 9, 2007. Still, the remaining wind power giant with a 20. 6 GW installed capacity is Germany (British Wind Energy Association, 2004). Many numbers of wind farms are built over the country and these are classified as either offshore or onshore wind farms. The difference between the two lies mainly in the locations where the wind turbines are located and operated. The number of installed offshore wind farms in UK has been impressive that it comprised about one-third of Europe’s total offshore wind resources.
By virtue of Electricity Act 1989, the Non-Fossil Fuel Obligation (NFFO) has directed the first development of UK offshore wind power industry through harnessing electricity from renewable (non-fuel) sources. This lead to two wind farms construction, namely the Blythe Offshore and Gunfleet sands. The series of dialogues between the British Wind Energy Association (BWEA) and the Crown State resulted to more granted permissions to start and precede the offshore wind development in April 2001.
But the process of getting consent from the Crown State was not easy because the probable cause of CO2 emissions has to be checked. Until, a decision came up to permit high-capacity environmentally-friendly wind farm (Wind power in the United Kingdom, 2004). Among the installed offshore wind farms in UK, London Array and Triton Knoll have the largest generated power so far. Like offshore wind farms, onshore wind farm development became difficult in terms of receiving planning permissions.
In the country, onshore wind farms generate much power than offshore farms do. Based on March 2006 report by BWEA, a peak supply of 6000 MW is forecasted on onshore wind farms by 2010, which is about 5% of the country’s electricity requirement. Among the installed onshore wind farms over the country, the Hadyard Hill generates the highest power of about 120 MW from 52 wind turbines (British Wind Energy Association, 2006). For the list of built and proposed offshore and onshore wind farms in UK, see Appendix A and Appendix B, respectively.
Among the classical wind machines, windmill harnessed wind energy that can be used traditionally in grinding grains and wheat, pumping water, and sawing woods. It is often found in large farm and ranch buildings like post mills, smock mills, and tower mills. The efficiency of windmill is based on the technology utilized, for instance the number and sizes of blades used, because the cost lies mainly not in the source of energy which is the wind (Schefter, 1982) A sample of windmill is shown in Figure 2-2. Since before 7th century, the first windmills have been built in Persia.
These windmills have rectangular shaped blades which are helpful in harnessing wind energy for grinding corn and pumping water in the farm. In Europe, windmills are often built on top of castle towers and used to grind cereals. Unlike in United States, windmills were primary used in water pumping and distribution along vast areas of farms. This helped the development of rail transportation by supplying pumped water on steam locomotives. Windmills were transformed due to design modification and technological advancement.
It is presently called as wind turbines or wind generators which are primarily used in converting wind energy into electricity, not just to grind cereals and pump water. Wind turbines harnessed wind energy and converted it to electrical power in a simple mechanism. The wind turbine operates like an electric fan, but in the opposite way. Instead of producing wind, wind turbines used it to cause its blades around its rotor to rotate continuously. The rotor is connected to the main shaft which turns the gear box to spin and generate electrical energy (generator) (Kirchen, 2006).
The generated electrical energy travels until it reaches the transformer where the conversion into high-voltage electricity happens. Then, the electricity will be transmitted via the power utility grid tower and distributed by power lines into residential, commercial and industrial locations within the range of service (BBc News, 2007) (Figure 3-1) Figure 3-1. Wind Power Generation [howturbineswork] The design of wind turbines are greatly affected by nature of the wind, local topography, and materials to be used for its construction.
The design size of the wind turbine blades and rotor depends on how strong and how much wind can be resisted. The height of the wind turbine is affected by topography based on wind availability. To get or harnessed more wind kinetic energy, the wind turbine must have greater height or to be placed in greater elevation. Wind turbine design can be onshore, offshore, or even aerial based on the locations where they are installed. Moreover, wind turbine can be classified with respect to the axis about which the blades pivot: horizontal-axis wind turbine (HAWT) and vertical-axis wind turbine (VAWT).
The common design of wind turbine is the HAWT. It can stand up to 20-storey high. It has blades like the airplane propellers that can vary in number from more than three (Wind Turbine, 2006). The location of the rotor atop can either be placed in front (windward side) or behind (leeward side) dependent on the direction of the wind available in a location. Figure 3-2 illustrates a model of HAWT. The pole or tower of HAWT can be made of concrete or steel for greater resistance to buckling and torque due to earthquake forces and other ground disturbances.
Unlike the HAWT, the design of VAWT has its axis of blades rotation perpendicular or almost perpendicular to the wind direction. Physically, it looks like a giant egg beater. Regardless of the direction of the wind, it can still generate power by its specially designed blades capable of rotation either clockwise or counterclockwise. Its main rotor and bearings can be placed near the ground surface for easy accessibility, usually for reasons of repair and maintenance. Figure 3-3 demonstrates an example of VAWT.