> > and larger blades raise cut in speeds > That is not necessarily true, it depends on the allowed degree of pitch ... I think you are correcting a different

> > and larger blades raise cut in speeds > That is not necessarily true, it depends on the allowed degree of pitch ... I think you are correcting a different matter here. Blade diameter in practice dominates the amount of power a which turbine can be designed to generate at lower windspeeds, aerodynamic design choices have to work with whatever diameter is provided. Increasing diameter involves significant expense and the entire reason it is payed is to raise cut in / raise generation at lower speeds / increase capacity factor. > Suffice to say that wind power is generally installed for 20-30 year life-span Not in recent years. 15 year contracts for windfarms are the current norm. I've read this often while following industry news and it can be observed from querying the different times [1] > after that they become un-economical to operate both due to increased maintenance costs Its not known to be the case that they'll become uneconomical. It may just be more economical to upgrade them, there is uncertainty involved which is the manufacturers bet. Its a great commercial advantage of wind farms (and solar) that they can be relatively quickly online and make a profit on investment in 15 years rather than seeking 30 or 40 or 50 year supply contracts as some competing technologies do because of higher construction costs. [1] https://duckduckgo.com/?q=industry+contract+for+wind+15+year https://duckduckgo.com/?q=industry+contract+for+wind+15+year