I have access to this decorative windmill. It’s been in place for decades, spins freely in the wind, and has made millions of revolutions in its lifetime. Its RPM’s are impressive even in relatively low wind.
What are your thoughts on how I should harness this energy?
You can’t realistically do it. Even is you find a tiny enough generator the amount of power would be so small it would barely light a led in a high wind.
Try turning a bike generator by hand, it takes a lot to generate a little power.
Search on diy wind turbine and start from scratch.
https://www.rwu.edu/news/news-archive/how-build-your-own-wind-turbine
Agreed. The “impressive RPM” mentioned in the OP won’t matter, because it’s about angular momentum, not specifically angular frequency. You would certainly be putting in more energy to build it than you’d conceivably get out. At best this would be a “fun learning experience in your garage” project.
Counterpoint: even lighting an LED with a tiny working windmill is pretty neat.
As long as we’re all clear that that’s the only thing OP can expect, sure. If OP is wondering how much they can knock off their energy bill with this project, the answer is jack shit.
Counter counter point: It is neat, IF it works.
Or you can do what my neighbors did and just buy one.
Tried to find a link to the wind powered lawn ornament but couldn’t. You will have to satisfy your windy lust with this.
https://campingguider.com/portable-wind-turbine-for-camping/