Warwick Trials on building mounted turbines

UK Field Trial of Building Mounted Wind Turbines Shows Very Poor Results

(From New Energy Focus, 1-14-2009)
Small wind turbine manufacturers have been heavily criticized for “exploiting” customers’ enthusiasm, after trials found that building-mounted wind turbines performed far below standards claimed by makers.

The report, carried out by energy consultants Encraft and supported by the British Wind Energy Association and the Micropower Council, also raised concerns that “aggressive and over-optimistic” marketing by suppliers of building-mounted wind turbines could damage the credibility of the wind industry as a whole.

Matthew Rhodes, managing director of Encraft, said that the firm was “taken aback” by the discrepancy between manufacturers’ claims and actual performance, and added that Encraft was “saddened” by the response of parts of the industry who would rather keep the data a secret.

He said: “The gap between average expectation and reality is much larger than people could reasonably expect – in fact the average performance of a building-mounted wind turbine in situ is between 5-10% of manufacturers’ claims.”Many wind experts have indeed been warning for years that building-mounted wind, randomly sited on the homes of the most enthusiastic customers will not work, but they have been ignored,” he added.

Warwick Wind Trials

The Warwick Wind Trials report, which was released yesterday at an industry event hosted by Encraft, tested 26 wind turbines from five manufacturers in variety of good and bad locations over the course of a year.

The report found that on average the small turbines were only operating at a capacity factor of 0.85%, compared to a large wind turbine’s 10-30% average, and were generating a mean of 214Wh a day – enough to power just five low-energy light bulbs.

However the report did admit that the results may have been affected by the turbines in the strongest sites being turned off for most of the year-long trials, after local residents complained about the noise.

When the averages were adjusted to take this into account, the capacity factor went up from 0.85% to 4.15%, however Encraft argued that this was still well below customers’ reasonable expectations.

The Leamington Spa-based consultancy said that the turbines, from Ampair, Windsave, Zephyr, StealthGen and Eclectic, each produced around £33.39’s worth of electricity a year on average: “Buyers should beware”, said the report.

Mr Rhodes continued: “The failure of some, not all, of the companies promoting building-mounted micro wind has not been in design or manufacture, it has been in failing to market their products ethically.

“The failure of some, not all, of the companies promoting building-mounted micro wind has not been in design or manufacture, it has been in failing to market their products ethically.” Matthew Rhodes, Encraft

“Under pressure to make a quick return on investment, customer enthusiasm to do something to help the environment, and lack of familiarity with wind technology, has been exploited,” he added.

The report conceded that manufacturers’ claims may have been correct in perfect laboratory conditions, but warned that failing to inform customers of the variations in wind speeds and environment could affect the wind industry’s credibility overall.

The report stated: “The technology is likely to make a tangible contribution to energy and carbon saving only on the most exposed sites and tallest buildings.” It continued: “The combination of this reality, aggressive and over-optimistic marketing by some suppliers, and the enthusiasm and credulity of the market has potentially led to an unfortunate outcome where the wind industry as a whole is in danger of suffering from a setback in credibility.”

The report also stressed that the poor results experienced in this study apply only to current models of building-mounted wind turbines and should not be applied to large-scale wind which, it said, is “an excellent and highly effective choice” for non-urban environments.

The trial results are available here http://www.warwickwindtrials.org.uk/