The basic wind story looks pretty promising. If an average house uses around 10,000 kWh a year, then a 5 – 15 kW turbine can made a sigficant contribution to this. A 10 kW turbine, for example, would cost around 20,000 pounds and payback in 15 years. A turbine operates in winds over 10 mph and typically produces in an average year 30% of its potential output. This suggests that if it runs successfully for 30% of the year (say 100 days) it should produce 100 x 24 x 10 kWhs = 24,000 kWhs. This seems much higher than the sites are indicating.
But theory aside, we need to check out practical case studies from people who have done it. Good starting points seem to be:
- CAT has a 15 kW turbine
- West Beacon Farm near Loughborough has two 25kW turbines. They apparently welcome visits (Prof. Marmont on 01509 610 033).
However, the big snag for Hedgerely Wood seems to be the height the tower needs to be. 100 ft seems to be typical for these small systems. Worse still, they say that the bottom of the blades need to be at least 10 feet above anything within 300 feet. This means that the turbine is going to be visible whether we put it near the house or at the top of the wood. And in an area designated for outstanding natural beauty, I can see that being a near impossible problem.
So first indications suggest that it may be that wind is not going to be part of our equation.