Updated: UK wind industry claims micro-wind is working

The British Wind Energy Association (BWEA) has questioned the validity of a new report released today showing that many micro wind turbines are generating just a fraction of the energy promised by manufacturers.

The study from renewables consultancy Encraft assessed electricity output from 26 building-mounted wind turbines and found that on average they provided only five to 10 per cent of the energy claimed by manufacturers. The worst performer generated just 41 watt-hours a day, not even providing enough electricity to power the turbine's own electronics.

Matthew Rhodes, managing director of Encraft, told The Telegraph that there was a need for wind turbine manufacturers to provide clearer information on which sites are suitable for on-site turbines.

"While we expected the trial results to be somewhat below manufacturer claims, we have been taken aback by the magnitude of the discrepancy, and are disappointed that the results of the trial suggest that micro wind is suited only to tall buildings and coastal sites," he said.

However, the BWEA questioned the validity of research based on 26 sites, many of which did not boast suitable wind profiles.

"In fact, the study corroborates what the industry has been saying for years, " said BWEA spokesman Nick Medic. "Namely, that you need to place turbines in locations where there is wind. You wouldn't put a hydro-generator in a place with insufficient water pressure and the same applies with wind. The problem is that this type of research could be picked up by the anti-wind lobby to try and justify its position."

Speaking to BusinessGreen.com Encraft's John Bradshaw, said that the study had not been intended to undermine a microgeneration industry that the company openly supports, but added that it did reveal a tendency for manufacturers to overstate the output from turbines.

"We were disappointed that the performance was not as good as expected," he said. "The fact is that some of the standards used by manufacturers to predict energy output are pretty inaccurate, particularly at lower speeds."

Medic dismissed suggestions that wind turbine manufacturers were guilty of " over-selling" their turbines, knowingly installing them in locations that are not suitable for wind turbines.

He said that the BWEA had recently developed new standards designed to help installers better assess the likely returns for micro wind turbines based on a locations wind profile. "Our members are very scrupulous in their advertising and encourage customers to undertake wind readings over a period of time before deciding to install," he added.

But Bradshaw said there was an urgent need for manufacturers to improve their techniques for measuring expected outputs or risk alienating customers. "A lot of the manufacturers' calculations are done in wind tunnels or using computer models and they are not proving accurate when turbines are installed," he said.

The BWEA's figures show there are 1,000 building mounted turbines in operation in the UK and the sector is expected to continue grow as more properties in rural and coastal locations look to install the technology.

"There are now a plethora of case studies out there that show you can get a good return on investment, you can get payback periods of less than four years and you can generate enough energy to sell power back to the grid, given a good wind profile," Medic said.