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Wind Energy Information
We have been utilising wind energy for hundreds of years – Holland is well known for its windmills used to grind grain into flour, the UK had a few, and in the US many isolated farms had a windmill to pump water.
Now we are using wind turbines to generate electricity - the UK has the largest potential wind energy resource in Europe. Wind power is currently one of the most developed and cost-effective renewable energy technologies. It is estimated that 1% – 3% of the energy from the sun is converted into wind energy – about 50-100 times more energy than is converted into biomass by all the plants on earth through photosynthesis!
Onshore wind power generators - how they work
Most turbines have three blades mounted on a shaft to form a rotor which catches the wind’s energy. Using the same lift and drag airflow forces that aircrafts use, the turbine blades move as low pressure forms on their downside. This low pressure pocket pulls the blade towards it and thus produces mechanical power. As the blades and shaft rotate, the shaft which is connected to a generator is then able to produce electricity. The generator is contained within the nacelle at the top of the turbine. The nacelle can rotate freely aiding the blades’ alignment with wind direction.
Wind turbines will generally be built to be well above ground level as this is where the stronger wind is.
Turbines may be stand-alone – as a means for water pumping or battery charging in areas where there is no access to the power grid. Sizes can range in power output from kilowatt sized from a home wind generator – to multi-megawatt for national electricity grid use.
If there is no wind – no power will be generated. As more turbines are introduced across the country this should not prove much of a problem nationally as there will always be wind somewhere. For home wind power generators – it may be advisable to use a turbine alongside other sources of electricity – to connect to the grid if possible – and to use a battery to store excess power for calmer days.
Backup power to support periods of lack of wind will probably be provided by coal and gas, though as new large energy storage facilities are developed there will be less need for backup.
According to the Dti wind turbines stand to be responsible for nearly 2 million tonnes reduction in carbon emissions by 2010. They do have some carbon footprint themselves mostly down to the manufacturing process – however the average wind farm will pay back this energy within 3-5 months and with a 20-25 year lifetime turbines will produce far more energy than they consume.
Offshore wind power generators - how they work
Offshore wind developments are major projects – facing huge challenges technically and practically. However, the UK is basically a series of smallish islands which have good access to available strong and constant offshore winds. Offshore wind gives better output and more consistent generation than onshore wind turbines can hope to achieve. Also, luckily for the UK, the sea is relatively shallow around the land masses allowing for turbine foundations to be driven into the seabed rather than attempting to accomplish a complicated floating system of turbines.
Offshore wind farms are essentially the same as onshore farms only larger and the electricity is transported not underground or overhead, but via undersea cables. The projects’ sheer scale requires special arrangements in terms of dock space, transport of parts and timing of installation – waiting for calm weather conditions. There are some great pictures that gives an idea of the scale of an offshore wind turbine at the BBC News site.
