Wind Energy
The use of wind energy as a renewable energy resource involves harnessing the power contained in moving air. Wind energy represents a vast source of energy that has already been harnessed for hundreds of years. The UK has the largest potential wind energy resource in Europe and wind power is currently one of the most developed and cost-effective renewable energy technologies.
Wind turbines can be situated either onshore or offshore. Offshore wind is just beginning to be developed, but has enormous potential.
How it works
Turbines catch the wind’s energy using propeller-like blades (usually three blades), which are mounted on a shaft to form a rotor. The blades use aerodynamic forces (‘lift’ and ‘drag’), in a similar fashion to an airplane wing, to produce mechanical power. This power rotates the blades and the shaft. The shaft is connected to a generator, normally via a gearbox, which produces electricity. The rotor blades and shaft are connected to the nacelle, which contains the gearbox and other power/mechanical components and sits at the top of the wind turbine tower. The nacelle can rotate freely, allowing the wind turbine blades to align with the direction of the wind and helping them to extract as much energy as possible.
Wind turbines are mounted on a tower to optimise energy capture. This is because, in general, wind is stronger, more consistent and less turbulent the higher off the ground it is.
Wind turbines can be used as stand-alone devices for applications such as water pumping or battery charging in areas where there is no access to the main electricity grid, or they can be connected to a utility power grid. Wind generators range in size from kilowatt-sized machines (suitable for domestic buildings) to large multi-megawatt devices (1 megawatt = 1,000 kilowatts) for use in the national electricity grid.
Electricity will not be generated when there is no wind. This means that there are some technical challenges with incorporating this form of generation into the electricity network to provide power as needed. However, wind farms are distributed throughout the UK so the changes in power from individual turbines will be evened out; if the wind drops in one area of the UK it is still highly likely to be present in others. On a small scale, storage devices, such as batteries, can be used.
Conventional back-up power, usually from coal or gas, is required at all times on the electricity grid in case of sudden power outages at any power station. The National Grid Company has estimated that the extra amount of conventional back-up needed to cope with an increasing level of wind generation is likely to be small. Intermittency will also become less of an issue through other factors, such as new large-scale energy storage technologies.