Routine maintenance shouldn't be the issue. Wind turbines have moving parts that will require regular maintenance and periodic replacement. The same is true of any other power plant, factory or piece of mechanical or electronic equipment. Stuff wears out. But if you want to keep the thing operating, you can. This is why B-52's are still flying and antique cars are still on the road.
At some point, major components fail, repair is too expensive, and it makes sense to retire the old unit and build new if the technology is still relevant. But on a wind turbine, everything, including the blades, would seem to be easily replaceable as a matter of routine maintenance except the tower itself. Current designs have very tall, skinny towers, but I'd be surprised if these are designed to be scrapped in 20 years. If so, surely there are sturdier designs that could be used.
Do not confuse the issue with logic.
Nobody subsidizes renovation.
After twenty years of being an obnoxious neighbor, there is no political will to renovate a wind turbine. Therefore there is no government subsidy.
Without subsidy, it doesn’t happen.
They are essentially helicopter transmissions scaled up. I wouldn’t trust my life to a twenty year old helicopter transmission I don’t think.
Fatigue Life of Wind Turbine Structural Components
https://pdfs.semanticscholar.org/55d2/b3390dfc2995c0c52e39c2ce7f6189e43c40.pdf
Retiring worn-out wind turbines could cost billions that nobody has
https://www.energycentral.com/news/retiring-worn-out-wind-turbines-could-cost-billions-nobody-has
“Could some engineer clue me in on why 20 years is a limit?”
Me too. I agree with you. Something else is up.
Perhaps it is to hard to take the heads off to repair and they trash them in the process?
https://nawindpower.com/wisconsin-public-service-says-goodbye-to-lincoln-wind-farm
This is not because the turbines are too old. These are small V47 660kw turbines and there are only 14 of them. The “farm” is not viable economically. Current wind turbines have 100ish meter rotors and are rated at about 2-3mw and the wind farms are more like a 100 turbines. Iowa has many such wind farms.
There are plenty of websites dealing with wind power and the rapidly advancing technology and the rapidly falling price.
We see both damaged blades and repaired/new blades being trucked on the loop around our town on a frequent basis. One truck even missed a turn and wound up downtown; that was an afternoon of chaos! '-)
~~~~~~~~~~~~~~
BUT -- when you consider that without huge government subsidies wind turbines are a losing proposition -- maintaining them for a long lifetime makes zero economic sense.
The “longevity issue” is most likely couched in the tax write-offs. These companies are operating by “depreciating” these “assets” over 20 years, so they arbitrarily “assign” a useful life of 20 years because that’s what the IRS allows them. They don’t want the “tax consequences” of having to recapture their depreciation, so they simply scrap them at the end of their “IRS useful life,” which evidently is 20 years. This isn’t about wind energy being a good bet economically, it’s simply about making money any way that they can.
They don’t want them to last for a long time.
They get subsidy on new units for a period of time. When they fail, they replace them with new ones so they can continue to get the subsidy.
The Wind Turbine thing is like the rest of the alternative energy. NOT that practical is you are honest about the economics.
It is because the engine that powers and turns the windmill blades can only last so long. Maybe if they actually let the wind turn the blades they would last longer.
But there is no money in long lasting windmills. Replacing them requires production and installation and as such generates more revenue from government funds.