Home wind turbines dealt a blow 

The energy from some micro power equipment would not operate a lightbulb, says official study

Home wind turbines are significantly underperforming and in the worst cases generating less than the electricity needed to power a single lightbulb, according to the biggest study of its kind carried out in Britain.

An interim report revealed that homeowners could be being misled by the official figures for wind speeds because they are consistently overestimating how much wind there is – sometimes finding that real speeds are only one third of those forecast. In the worst case scenario, the figures indicate that it would take more than 15 years to generate enough ‘clean’ energy to compensate for the manufacture of the turbine in the first place.

The study, supported by government and the British Wind Energy Association on behalf of the industry, is a setback for hopes of a big uptake in micro-wind turbines to help slash the carbon emissions from big power generation.

But the environmental consultancy running the project, Encraft, said there was noticeable disparity between poor results in urban and suburban areas – such as the west London area where Conservative leader David Cameron hopes to put up a turbine – and far better ones in high-rise and coastal locations.

Other research, however, shows that seven out of 10 people say seeing turbines reminds them to save energy, said Matthew Rhodes, Encraft’s managing director. ‘There is no doubt that microgeneration as a whole has a critical role to play in delivering a low carbon and secure energy future for the UK.

‘Micro wind turbines are part of this mix, but they need to be installed in a responsible and appropriate manner.’

The association said technology and predictions of wind speeds were improving, but turbines should not be written off in built-up areas. ‘Consumers need to exercise common sense: these will be more effective where it’s most windy,’ added Charles Anglin, its communications director.

Encraft, based in Warwickshire, launched the trial in 2006 and is now monitoring speeds and power generation at five rural, eight suburban and 11 urban sites, including six on blocks of flats. Most trial sites only began working last year, but the results of nearly 64,000 operating hours ‘reasonably indicate’ their performance, said Rhodes.

Results from 15 sites show only three generated more than 400 watt-hours of electricity a day; two at 875wh and the single site which reached 1,790wh.

Windspeed indicators confirmed that the official data used to assess how good a site is for a wind turbine are too high: wind speeds were one third to two thirds of what was forecast, said Rhodes.

The trial will add to pressure for tougher standards for installing micro-turbines, said Rhodes. Greenpeace and the Conservatives said ‘feed-in tariffs’ which allow homeowners to sell spare electricity to the national grid to help repay their costs would ensure that people opted for the best technology, which also includes solar panels and ground source heat pumps.

The average national windspeed is 5.6 metres per second, compared to a recommended 4-5m/s minimum for a micro-turbine.
Wind power facts

· Roof-mounted equipment similar to that which was installed at his west London home by the Conservative party leader, David Cameron, costs from £1,500.

· Domestic turbines can either be free-standing or fitted to the roof of your house or an outbuilding. The larger, free-standing turbines can cost up to £20,000.

· The government wants 20 per cent of the United Kingdom’s energy to come from renewable sources within the next 15 years. Homeowners can apply for 30 per cent grants towards wind turbines.

· You must apply for planning permission before having a turbine installed.

· Turbulence is the main obstacle to success. The higher the building’s location, and the higher the turbine, the better. Buildings and trees cause erratic wind speeds.

By Juliette Jowit, environment editor

The Observer

6 January 2008