I was recently given a link to a website (apparently a blog really) that is an absolute must read.
The site owner has built his own hydroelectric system (including the turbine) described and documented it along with hundreds of other topics in the most informative and readable writing I have seen in a long time.
There is just too much to mention it all here but as examples, look at his model Wankel engine rebuild, his notes on imperial/metric measurements and say, his article on making a 12V 20Amp supply.
I guarantee that once you have read the first few paragraphs of his experiences you will be hooked!
There is lots of engineering content so its not off topic here, my only regret is it might keep you out of the workshop for a bit… but you will learn something.