Wind as a resource in the UK

The UK has 40% of the total European wind resource, the most in Europe. This is a massive untapped potential. Wind energy is the most technically and economically developed renewable technology; it is an entirely natural and renewable energy source which produces no harmful emissions or waste products.

The UK’s wind resource is theoretically sufficient to provide 8 times the country's electricity needs; however, at present wind power only provides a modest 0.6% of electricity supply. This is poor when compared with Denmark's 18%, and places the UK at the bottom of the European renewable energy league.

Image: Horns Rev, Danish west coast.

Wind turbines require a site with uninterrupted wind supply, and need to be away from obstacles by at least ten times the height of an obstacle, alternatively a taller tower can be used.

The first commercial wind farm in the UK, was built in 1991 at Delabole (below) in Cornwall, and used 400 kilowatt (kW) turbines.

Image: Delabole Wind Farm, Cornwall

Grid connection

Currently in the UK there are over 1100 grid-connected turbines installed, this produces over 767 megawatts of electricity and meets the needs of nearly half a million households each year, to put this into context it is estimated that there are over 215,000 households in Cornwall.

The power produced by a small wind turbine can be stored at the site in a battery (suitable for remote or off the grid locations). For turbines greater than 2kW the power can be transferred to the national grid. For grid connected systems, power goes into the normal electrical supply; any excess can be sold to the national grid, using a special inverter and controller which convert DC electricity to AC at a quality and standard acceptable to the grid.

Image: Goonhilly Downs wind farm has been in operation since 1993 and consists of 14 wind turbines with a height of 30m and an output of just 400KW each. The energy produced powers about 4500 Cornish homes.

Environmental issues

Energy and CO2 savings

The energy produced and greenhouse gas savings depend on the size of wind turbine and the windspeed at the site. On average in Cornwall the following would be the savings at well exposed sites around the county:

*including sales of carbon credits at £70/tonne, and Climate Change Levy

This table makes the assumption that all the electricity produced is replacing purchased electricity at £58/MWh. For smaller users the cost of purchased electricity is higher and for larger users tends to be lower.

Every unit of electricity generated from a wind turbine displaces one that would otherwise be generated from fossil fuels, and thus prevents the emission of several greenhouse gases, including carbon and sulphur dioxides and nitrous oxide. Wind turbines in the UK currently prevent the emission of well over one and a half million tonnes of CO2 each year.

Meeting the Government's targets (8% by 2010) for wind energy would result in the production of over 16.7 billion units of clean green electricity, sufficient to power 4 million households each year while saving the emission of over 14.4 million tonnes of carbon dioxide into the atmosphere.

Noise

Thanks to improved technology noise from wind turbines is no longer the issue that it used to be. The noise produced by a typical wind farm would not be noticeable in most residential areas in the UK. Noise from the blades is now minimised by careful attention to the design and manufacture of the blades. Any noise from the gearbox and generator is contained by sound insulation and isolation materials. When standing next to a turbine, it may be possible to hear a swishing sound from the rotation of the blades; the whirr of the gearbox and generator may also be audible. However, as distance from the turbine increases, these effects are greatly reduced.

Image: The Michelin tyre factory in Dundee has two 2MW wind turbines installed in 2006, which provide around 8GWh pa, around 1/3 of the electricity needed by the plant. Saves 7,200 tpa CO2.

Birds

By locating wind turbines away from important migration and nesting habitats bird fatalities are small and infrequent.

Cost

The cost of wind energy is affected by many factors. For a new onshore wind farm in a good location the cost would be 3-4 pence per unit, competitive with new coal (2.5-4.5p) and cheaper than new nuclear (4-7p). The price of electricity generated from a wind turbine has fallen by a factor of 4 since the first wind farm started operating in the UK in 1991.

Due to the large number of providers the costs of installing a domestic scale turbine are competitive. Pay back times for the investment vary according to the local wind speed at the site. Approximate costs for domestic turbines are:

• Up to 1 kW = £1,500
• 1-1.5 kW turbine = £2 – 5,000
• 6-8 kW turbine = £15 – 25,000
• 2 MW = £2 million

Wind turbines once installed require very little maintenance, only needing checking twice a year. For the larger machines this should be undertaken by specialist contractors of which there are a number in Cornwall (see below). They will check mechanical and electrical systems safely and keep the turbine operating efficiently. In a turbulent environment turbines might need more frequent replacement of the gear box, which suffers more wear in those circumstances.

Examples of wind installers in Cornwall:

• Aeolus Power www.aeoluspower.co.uk
• Microgeneration Ltd www.microgeneration.com
• Natural Generation www.naturalgen.co.uk

Image source: Ecotricity. This 2MW wind turbine was installed in 2005 and is Europe’s most visible wind turbine. The turbine produces around 3.5 GWh pa, providing electricity for around 1,000 homes and local businesses.