If you're generating power from a flowing water source with a moderate head, a Pelton wheel is a good choice.
Example of a Pelton wheel that receives water through a pipe. While the penstock may be set up to provide either a precipitous or sloping fall, it should be of as large a diameter as possible, have minimum bends, and hold down flow friction to the least amount.
ILLUSTRATION: POPULAR SCIENCE
This 25-ton Pelton wheel is designed for installation in a 30,000-hp. unit. It turns at 171 r.p.m. and has a 1,008' head.
A 12" Pelton wheel with reducer and gatevalve throttle.