|The repair to the (13 year old ?) turbine has been:|
1. A new set of rotor blades due erosion of the surface. The old blades could have been used, a bit less efficient, but it was appropriate to exchange while big cranes were on site.
2. A new nacelle (the housing on the tower). The fault was a crack in the yaw (steer in to the wind) bearing which required the nacelle to be removed. Once again, it was appropriate to replace the nacelle with a reconditioned unit while big cranes were on site.
3. The old blades were removed and the new blades were fitted to the existing generator (the big circular thing on the ground in the photos) which includes the blade turning mechanism.
4. A major part of this type of turbine is in the concrete hut and this was not replaced.
'All transported by mega-trucks from The Netherlands, and installed by Dutch engineers.'
Mega-trucks are used for all sorts of construction activity. Some obviously think that wind turbines should sprout, organically, from the ground and should justify this fantasy.
'I wonder if it has actually produced enough energy to pay for all this, either in terms of electricity sales, or in terms of CO2 saving?'
It has. Energy payback for wind turbines is around 1 year compared with typical lifetimes of 20+ years (site dependent), i.e. 20 times more energy produced than consumed. DTI/DBERR quote onshore wind and nuclear as similar lifetime CO2 costs, with overlapping and different assumptions.
The 'nympy' turbine has operated for less than 20 years - it is middle-aged rather than old-aged. In that time various developments of the technology have improved the longevity. If left un-repaired, it could have operated for some time yet. However, health and safety and maximising efficiency of production dictated this scale of repair. The turbine can now be expected to operate for at least another 20 years, with appropiate periodic small-scale maintenance.
I suppose that some drive cars until they (the car) suffer serious breakdown and then abandon them rather than perform appropriate and timely maintenance to maximise safe and effective operation ?