Wind turbines (UK domestic)

Wind turbines have been on the United Kingdom's domestic market many years, but their popularity and public awareness is now increasing substantially.

Claims about their efficiency and productivity are under some debate due to the disparity of manufacturer's forecasts with case study results. The prime problem is that they are routinely being installed in areas with wind speeds much too low to realise a useful level of energy return. Wind-powered electricity generation requires wind speeds above those found in the great majority of inhabited areas.

Planning permission
In England planning permission has been granted to only 50% of applications while in Scotland more than 90% are being approved.

The regulations are expected to change in 2007 with wind turbines coming under the same permitted development rights as satellite dishes. A consultation period on the proposed changes ended on June 27, 2007.

Wind-speed
Many of the manufacturer's examples rely on assumptions about average wind speed which, in practice, is very variable. This is particularly important because power input to a wind turbine is proportional to the cube of the wind-speed. Consequently halving the wind speed reduces input power by a factor of eight, not by a half.

The change in output power is greater than this factor of 8, since wind generators only begin to generate at a 8 meters per second. They are also resricted by high winds, wind at more than 25 mtrs per second will stop the turbine Thus wind speed in the locality is a critical factor.

It is therefore important that local average wind-speed is determined, and that buildings or other natural features that may disrupt the smooth flow of the wind are taken into account before purchasing. Most built up areas in Britain do not have sufficient windspeed for productive generation. The presence of other buildings in built-up areas make wind speeds even lower. Only some of the more exposed rural locations may have promise.

In unsuitable areas, one alternative suggested may be to form a cooperative, such as the Baywind Energy Co-operative, to provide a larger-scale turbine to serve the local community. While there are few of these in the UK, they are common in other countries, notably Denmark, where around 5% of the population are involved in such schemes. However it is generally better to place turbines in more suitable high wind speed areas, which are not generally centres of population.

Example costs
The following example costs are taken from manufacturer's literature. See the section above regarding the importance of wind-speed in these examples.

Refer to bettergeneration.co.uk for an index of domestic turbines.


 * Windsave turbine WS1000 (1 kW)
 * Claimed average output: 500 kwH per year
 * Note: 2 years warranty, expected working life of 10 years
 * Materials: £1,600
 * Installation: Included
 * Tax: Included
 * 30% Clear Skies Grant: £500
 * Total Costs: £1,100


 * Swift turbine (1.5 kW)
 * Claimed average output: 2000 kwH per year
 * Materials: £3,500
 * Installation: £1,950
 * Tax: £272
 * 30% Clear Skies Grant: £1,700
 * Total Costs: £4,022


 * Stealthgen by Eclectic Energy (0.4 kW)
 * Claimed output: 660 kwH per year
 * Materials: £875
 * Installation: not included, estimate £800
 * Tax: Included
 * Grant: not currently available
 * Total costs: £1,675