Why do windmills have a lifespan instead of being repairable/upgradeable?
In: Engineering
Many are upgradeable — it is called “repowering” the turbine. It is the blades that tend to have a firm lifespan (20-30 years), because they are fibers (glass or carbon) suspended in a resin matrix. Over decades of loading and unloading, that material has degraded and can no longer sustain the loads. So the blade is scrapped and landfilled. New research is being done that will allow blades to be recycled, but to keep running past 20-30 years, the turbine would need new blades.
Keep in mind that there is NO engineered material that doesn’t eventually break down due to fatigue. The design goal is to have them last as long as it makes sense financially—to expand the material beyond 30years would require such groundbreaking material work that the cost would be infeasible, so no one does it. As one of my professors used to say — any one can build a bridge that doesn’t fall down; it takes an engineer to build a bridge that barely doesn’t fall down. Our goal is to meet the demands of the project without vastly over engineering the thing.
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