Questions about the physics of turbine operation

[Jdetterline]

I'm no physicist, or grammar specialist so please go easy on me for my first posting here. I've been seeing a lot about wind turbines and hydro turbines. But I had an idea that I thought would be very obvious yet I can't find a topic on it when doing a quick search. And that is this; what would be the downside of connecting multiple alternators to one shaft on either a wind or water turbine? Keep in mind this would include making a longer shaft from the blades on the turbine to accommodate spacing out gears or whatever so that you can space out belts to make room for different alternators. I'm just wondering if the resistance is that great when you connect more than one via a belt, or why hasn't anyone done this already? Or maybe the real problem here is that I just haven't found the link? Thanks for reading.

 

[Bob S]

You can add as many alternators as you want, but one alternator is sufficient to get close to the theoretical maximum energy output limit of 59% on a horizontal axis wind turbine, for example. Energy out will never exceed energy in. Read about Betz' Law for wind turbines at

http://en.wikipedia.org/wiki/Betz'_law

Bob S

 

[Jdetterline]

Okay thanks Bob. I'll have to read that. I guess in my simple mind I was envisioning 4 12V alternators producing 48V. Or whatever Voltage an alternator produces and mulitiplying that by 4.