The link to a picture of a Kaplan that I saw in another thread today looks a whole lot like an old Jet Ski pump (I have several laying around). I'll try to take a picture of one later today. The ones I have are about 5" in diameter and designed for axial flow. They have an aluminum housing with 15~17 degree impeller and drive shaft. Having the pump, housing and drive shaft already there it would be pretty easy to hook up an alternator, and keep it completely dry. For that matter the entire WET portion could be completely sealed so that it would hold pressure/vacuum.
I don't know the first thing about water power so I don't have any insight into the practical mechanics of what really works.
Is this a totally hair brained idea, or might it have some merit?
Put it in the right section for you. TW