Wind Large Scale
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Wind PowerA wind turbine is a machine which converts the kinetic energy from wind power into mechanical energy and, ultimately, useful electrical energy for the national grid. The kinetic energy is extracted from the wind by means of an aerodynamic rotor, which is connected to a generator to produce electricity. This generator is then connected to the grid to provide electricity for homes, offices and industry. There are a wide range of wind power turbine technologies available, from micro through to large commercial wind turbines. Wind turbines can also be classed by the orientation of the axis of rotation to the direction of the wind – horizontal axis machines and vertical axis machines. This page concentrates on the larger horizontal axis wind turbines, which are by far the most common. For an overview of micro wind turbines please click here or please go to our SWIFT wind turbine page. Since the 1980’s wind turbine manufacturers have been producing wind turbines with a capacity in excess of 100 kW. The scale of commercially available wind turbines increased to over 1 MW by the late 1990’s, and to 5 MW by 2006. The reason for the increasing capacity is the greater efficiency of the system and the improved economies of scale. The picture below shows how the scale of available wind turbines has increased over the past 2 decades.  Figure 1 – Wind Turbine Power output scale Large wind turbines are now available from 100 kW to over 5,000 kW. Those belonging to the lower end of this scale are typically installed individually on small farms or businesses, whilst the top end of this scale are used in off-shore wind farms. Turbines ranging from 1 to 3 MW are typically used on industrial sites or in modern on-shore wind farms. The amount of power a wind turbine can generate depends on the rating of the wind turbine and the wind regime in which it is to operate. The ‘rating’ is the maximum amount of power the turbine can generate after a certain wind speed (typically 25mph). The power that a wind turbine can generate varies according to the cube of the wind speed, so that doubling the wind speed will produce eight times as much power. It is therefore important to ensure that wind farms are installed on tall towers on windy sites with exposure to the prevailing wind directions. That said, wind farm developers must choose sites carefully in order to ensure that whilst there is enough wind to make the project commercially viable, there will also be the least possible adverse impact on the local environment. Factors that need to be considered in the early stages of a wind farm project are the visual impact, noise pollution and shadowflicker impact on local residents, the impact of construction and operation on protected areas and important or protected flora and fauna, and the impact of the development on aviation, television signals and other communications. These negative impacts must be weighed up against the positive impacts, such as reduced levels of carbon dioxide emissions and the creation of local jobs. The results are compiled in an Environmental Impact Assessment (EIA) which is submitted to the local council along with a planning application. A suitable wind farm site will therefore:
These are only guidelines and much investment and research will be needed to quantify the impact of a wind farm. If a site has been carefully chosen and planning consent is granted for the wind farm, it can then be constructed and will operate for up to 20 years. After this period, the owner of the wind farm may decommission the project and return the land to its original state or re-power the project with new turbines for a further 20 years. Wind farms therefore offer a sustainable source of energy which will last for as long as the wind blows. |
