Anne Sinclaire made some interesting environmental claims in her letter of 2nd December. I teach my MSc students to be sceptical of environmental claims and test evidence.
The balance of energy production and embedded energy is part of life cycle assessment, a subject I teach.
The claim that “industrial” wind turbines take more energy out of the environment in their production is false.
My evidence comes from the Ecoinvent database (www.ecoinvent.org).
The embedded energy (from construction and maintenance) of onshore turbines of 0.75 to 4.5 MW capacity is 3.5% to 6% of output. With a continuous loading of 50%, to takes between 120 and 210 days to generate the manufacturing energy.
Putting very small turbines on roofs reduces their efficiency hugely, because the atmospheric boundary layer reduces the wind speed closer to the ground.
Hence, taller turbines are more efficient. I have no data on the embedded energy in rooftop turbines, but their location puts them at an operational disadvantage.
The aesthetics of locating large, effective turbines is indeed challenging, but their use is essential in reducing harms from fossil fuel use. Anne Sinclaire offered her own solution.
The Stroud valleys are not ideal. Apart from aesthetic matters, the turbines would generate more on hill tops!
Dr Adrian Williams