Is it possible to install a water turbine in an underground river to generate power?

Question

I dont know how fast the water flows but it would be in a system of underground cinotes.Like in Cancun Mexico. I know that the turbines used on some dams only spin around 180 rpm. What is the minimum speed needed to produce usable current on a 120/240 volt system 3 phase?

Answer 1

It is possible, but there would have to be quite a bit of usable power in the flowing water to make it practical for commercial use. That is, if the water is flowing slowly, it would have to be very deep to be of practical use.

There are 2 ways to overcome slow flow:
1. Gear up the turbine into the generator.
2. Make a generator with enough poles so ~1 RPM would produce 60 Hz.

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Answer 2

Output will be a function of mass flow of the stream and the pressure buildup that can be achieved at the turbine inlet. The speed of the turbine will depend on the design of the wheel, which is a function of the pressure drop.