There was always a lot of talk round here about a rumour that the amount of carbon put into the foundations of a turbine released more carbon than it saved over its lifetime. I'm back with the book "How Bad are Bananas?" by Mike Berners-Lee. On page 153, he has a table which suggests that a 660kW turbine like this should have paid back the carbon released in its manufacture, transportation and installation in 145 days. That's less than half a year. This turbine has been in for more than 20 years. The rumour is not true. The source of the information is this paper.
