This comes from an email from Paul Biggs (firstname.lastname@example.org) to the excellent Greenie Watch blog. While windmills are an absurd way to produce electricity, this shows they may be even more ridiculous than I thought.
"The October edition of Which? Magazine [in the UK] reported on domestic wind turbines in an article entitled 'Wind turbine blows cold.' Which? installed one in a house and monitored it from December 2007 to June 2008. The result was that it used more electricity than it generated. This is because the turbine includes an "inverter" that converts the energy into electricity to go into the mains, and the inverter needs power which it draws whether the wind is turning the turbine or not. If the 'greens' want to 'save the planet' with domestic wind turbines, then they will have to make sure that they live somewhere very windy. Given the energy used and costs involved in manufacturing, installing, maintaining, plus eventual decommissioning - there may not be anywhere that is windy enough!"