Factors affecting the success of a wind turbine are :reliability, windspeed, swept area, cost and efficiency. I found a Quiet Revoluiton QR5 turbine at the botanic gardens in Edinburgh and I am checking out these criteria.
There is a good rule of thumb that says a wind turbine should be 30 feet above any obstruction within 300 feet. Windspeed is highly critical for energy production since the energy depends on the cube of the windspeed. There is hardly any wind for turbines sited below the ‘canopy layer’ of the tree tops. For more details check the Carbon Trust wind siting tool. The company state that “Please note that the minimum recommended average wind speed for a QR5 is 5m/s.” But they were willing to sell one to go on this site, maybe just for “demonstration purposes”?
Reliability is very important since the kilowatt hours of energy generated will depend on the hours the turbine is available. The QR5 is out of action so far as I am aware due to problems with the blade attachments. Vertical axis turbines do have intrinsic fatigue problems which along with the problems of starting and stopping, and the problems of putting them on proper towers have made them a poor choice for wind energy.
The turbine is a nice size (5m high x 3.1m in diameter) but in relation to its cost it will not produce much energy even on a good 5 m/s site. The turbine alone costs £25,000. It does not matter how efficient it is it can never produce more than about 12,000 kWh per year at a 5m/s site, and the manufacturers claim 7,500 kWh per year. A HAWT of similar size and a fraction of the cost would do the same.
Nice ornament? Or a big waste of money, and another big embarrassment to the small wind industry?