Further to my investigation into the maintenance and lifespan of offshore wind turbines I find some disturbing information revealing that all is not as is publicised in the MSM.
The Media has been regurgitating that the lifespan of a turbine will be 20 years. Perhaps not, going by this statement.
Recently, Sandy Butterfield, a former chief wind turbine engineer at the National Renewable Energy Laboratory (NREL) in Colorado, was quoted as stating that the wind industry expects today's gearboxes to last 7–11 years. This markedly contrasts with the 20-year design lifetime of the wind turbines. And the implications for the industry are huge, since changing a gearbox is typically a lengthy and extremely costly exercise.
Replacing a wind turbine gearbox involves primarily the gearbox cost itself, which typically represents around 10% of the total wind turbine cost. On top of this expense, must be added its transportation to site, crane rental and mobilisation cost, and the man-hours spent on the replacement. It means that the value can quickly reach about €200,000 – €500,000, depending on the turbine size and the wind farm's location.
Not quite what we are led to believe. Of course they are now attempting to build direct drive turbines in order to do away with a gearbox completely.
Some manufacturers have chosen to move to direct drive to reduce the number of moving parts in the wind turbine more exposed to wear. But this has led to wind turbine specific generator designs that are usually more expensive and often come together with a long-term maintenance contract with the Original Equipment Manufacturer (OEM), which does not necessarily meet the operations and maintenance (O&M) concept of flexibility expected by customers.
So now they are going to be even more expensive to build. Though at least one manufacturer is trying a different tack to the conventional thinking on turbine design. Alstom Pure Torque system