No, the 20 year number is a distraction. A well designed wind turbine, constructed to spec can last much longer without any major revision. It might also not (t

No, the 20 year number is a distraction. A well designed wind turbine, constructed to spec can last much longer without any major revision. It might also not (there will be early failures, as well as super long successes). It's more like buying an router for the office, deprecating it in 3 years but running it for 7. The 3 years is the 20 off the windmill. How long it will actually last depends more on circumstances than on it actually being ok to keep on going. Major reasons to repower are new tech, as in your network. Upgrading from 100Mbit to 1Gbit is a bigger reason to upgrade a commodity like a windmill or a router. That it still being under warranty. Putting a 3.4 MW where you had a 900Kw is good value for money. Especially if maintance costs are lower, yields are higher, it's quieter and can do more regarding grid stability etc. For the router to fail after 4 years is ok. Next day new one arrives. For a windmill to fail after 25 years is ok, two months later you have a new one. For a nuclear powerplant to fail in year 65, means you don't have a country left ;) (NL here)