Good Energy’s information on wind power, how we use it, and how you can use it
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Wind farms are becoming an increasingly common sight dotting the UK landscape, which makes sense, as we are the windiest country in Europe. One 2.5MW wind turbine in a good location could produce enough electricity to meet the annual needs of over 1,400 households, (BWEA)
How do wind turbines work?
Wind turbines harness the wind’s energy to generate electricity. Wind turns the blades, which turn a turbine in a generator to make an electrical current. This electrical energy is converted from DC (direct current) electricity coming out of the generator into AC (alternating current) electricity, and a transformer is used to convert the electricity to the right voltage to be exported to the local electricity grid.
Most wind power turbines consist of rotor blades which rotate around a horizontal hub. The hub is connected to a gearbox and generator, which are located inside the nacelle. The nacelle houses the electrical components and is mounted at the top of the tower. This type of wind turbine is referred to as a ‘horizontal axis’ machine.
The rotor diameters of horizontal axis wind turbines range up to 80 metres, while micro wind turbines can have a rotor diameter of just 2 meters. Typically, wind turbines have three blades but some designs have, two or just one. The blades are made of fibreglass-reinforced polyester or wood-epoxy. They rotate at 10-30 revolutions per minute at constant speed, although an increasing number of machines operate at a variable speed.
Power is controlled automatically as wind speed varies and machines are stopped at very high wind speeds to protect them from damage. Most have gearboxes although there are increasing numbers with direct drives. Sensors are used to monitor wind direction and the tower head is turned to line up with the wind as its direction changes.
Towers are usually cylindrical, made of steel and generally painted light grey however some towers are constructed from a steel lattice framework. Towers range from 10 meters for small scale wind turbines to 75 meters for large scale wind turbines.
Commercial wind power turbines range in capacity from around 100 kilowatts to over 2 megawatts. The crucial parameter is the diameter of the rotor blades - the longer the blades, the larger the area ’swept’ by the rotor and the greater the energy output. At present the average size of new machines being installed is now super megawatt, 1.3-2.3MW, and there are larger machines on the market. The trend is towards moving to these larger wind turbines as they can produce electricity at a lower price.
The most important factor affecting the performance of wind power is the windiness of the site. Most wind turbines start operating at a speed of 4-5 metres per second and reach maximum power at about 15 m/s. The power available from the wind is a function of the cube of the wind speed. Therefore a doubling of the wind speed gives eight times the wind power output from the turbine. All other things being equal, a turbine at a site with an average wind speed of 5 meters per second (m/s) will produce nearly twice as much power as a turbine at a location where the wind averages 4 m/s. Another factor affecting performance is the availability of the equipment. This is the capability to operate when the wind is available - an indication of the turbine’s reliability. This is typically over 98% for modern wind power machines.
And a third factor affecting performance is wind turbine arrangement. Turbines need to be positioned very precisely to ensure they gain the maximum energy from the wind. This is so they harness the available wind power resource to the best of their ability without causing ‘wind shadow’ or introducing turbulence to the wind that will then blow through the surrounding turbines. This may reduce productivity and increase wear on the wind turbines.
Onshore wind power is currently the most economical way to generate wind power, and is becoming cheaper.
Offshore wind power provides a plentiful resource which, although currently more expensive than onshore wind, is still more economical than other forms of renewable generation. (BWEA) The report ‘Building a Low Carbon Economy’ (Committee on Climate Change, December 2008) states that onshore and offshore wind together can deliver 30% of the UK’s electricity supply by 2020.
Microwind power turbines are increasingly being used to power homes across the UK. www.generateyourown.co.uk offers wind turbines ranging from 2.5kW to10kW in size, and their carefully chosen installers can often accommodate requests for larger turbines too.
Why choose wind power?
Electricity from wind emits no carbon dioxide. Wind is also plentiful, and free. Wind farms are relatively simple to construct and, although they may occupy a large area of land in total, only a small foundation at the foot of each turbine is needed, and the rest can stay as it is, for example it can continue to be used for grazing livestock. So, if a wind farm is decommissioned, the land can be returned to its previous state much more easily than if it had a power station built on it.
Wind power: fact and fiction
- Wind Power Fiction: To generate the energy we need, countless wind turbines will litter the countryside
- Wind Power Fact: Government legislation requires the UK to generate 15% of our electricity from renewable sources by 2020. By installing just 3,500 more modern wind turbines – probably 2,000 onshore and 1,500 offshore - we could get around 8% of the UK’s electricity from clean wind energy by 2010.
- Wind Power Fiction: Building a wind farm uses more energy than it will make in its lifetime.
- Wind Power Fact: Actually, an average wind farm will pay back the energy used to build it in around 3 – 5 months. This is shorter than a fossil-fuelled power station, which will take around 6 months.
- Wind Power Fiction: Wind power is very pricey
- Wind Power Fact: Wind power is getting cheaper. Onshore wind power currently costs around 3-4p per kWh. This isn’t a lot more than new coal (2.5-4.5p) and is cheaper than new nuclear (4-7p). Statistics suggest that by sometime after 2010, wind power will challenge gas for position as cheapest energy source.
- Wind Power Fiction: Wind farms have a negative effect on tourism.
- Wind Power Fact: There is no evidence to suggest this. The UK’s first commercial wind farm at Delabole, which is owned by Good Energy, received 350,000 visitors in its first ten years of operation. We regularly hold wind fairs at Delabole to inform people about the benefits of wind energy and to show what wind farms are like close up.
The facts above all come from the British Wind Energy Association (BWEA). You can find more by visiting http://www.bwea.com/energy/myths.html
How does wind power fit into the puzzle?
A common misconception is that wind power can be unreliable. However, figures suggest that if we look not just at sources of electricity, but also at the way it’s distributed, we could really profit from this unlimited resource. Scotland already has 32% of its domestic electricity needs met by wind power, and claims it will surpass 50% by 2020 (Guardian).
For the most reliable wind electricity, however, we should look to creating a pan-European network so that a windy day in the UK or Denmark could, for example, export wind energy at times of surplus supply and import from other renewable energy sources across the continent (Guardian).
Good Energy and wind power
We’re big fans of wind energy. Most of the renewable electricity we generate and buy comes from wind turbines of all different sizes, including those at our own wind farm in Delabole, Cornwall. We’re currently investing in repowering Delabole to more than double its output - see our generation pages.
If you’re thinking about generating your own wind power at home, we can help you every step of the way, from choosing your wind turbine to getting paid for the wind power you generate. Visit www.generateyourown.co.uk for information on microwind, grants and funding, installation and Good Energy generation schemes.
If you’re already making energy from wind - large or small scale - visit www.goodenergygeneration.co.uk to see how Good Energy can help make sure you a great deal for your power.
Help grow the wind power industry by switching to Good Energy
Switching your home or business from your standard electricity supplier to Good Energy means that all the electricity you use will be supporting independent renewables around the UK, including the wind power schemes we generate and buy from. We are the UK’s only 100% renewable electricity supplier and fight for renewable energy every day. Switching to Good Energy is the first step in supporting wind power.
The next step? Generating your own.
