;)
Readers may remember Gordon Hughes' report about the lifetimes of real-world industrial wind turbines and the finding that this is much shorter than assumed in government cost projections. The reasons for the short lifetimes centre on wear and tear on the turbine blades and on the gearboxes.
In that vein, you may be interested in this recording from a forum for windfarm operators in which some of these problems are discussed in fairly plain terms. Having listened, you realise that the factors affecting performance are legion, including not only wear and tear, but dirt build-up on the blades, icing. These factors can severely impact upon performance, and because they tend to unbalance the blades they then increase wear and tear on the mechanical parts of the turbine. But icing is even more serious, as the last speaker on the recording notes:
The icing issue in Northern Europe is huge...there was a [wind] park in Northern Sweden...and it iced up for 21 days....you are talking about a complete shutdown...do the maths...everything else becomes insignificant...there will be huge PR problems...you are looking at if we will invest in wind farms or wind energy ever again.