Actually I think it is the opposite. This is very low speed at 10-20 rpm. A non-vortex hydro plant runs way faster with 1-2 meters of head, some fast enough tha

Actually I think it is the opposite. This is very low speed at 10-20 rpm. A non-vortex hydro plant runs way faster with 1-2 meters of head, some fast enough that a high-pole-count generator can be directly driven.