So if you have a long cell with an ion-gradient along it, I guess you have to have the turbines attached to something right? Or else the protons will just push it around rather than spin it? And then there is still the issue of protons just flowing around the turbine rather than through it. It may be possible, but to my layman intuition it sounds way harder to get right than a membrane.

I wonder if maybe an intermediate step could be just channels and turbine. But no pump. If the amount of protons surrounding membrane varies over time, the cell can open the channels when there are many protons outside, and close the channels when there are few (forcing equalization through turbines).

Or maybe it can use acid protolysis to create protons?