Even if this was technologically feasible, maybe the cost would be prohibitive. It would be much cheaper to not build the dam in the first place or close it, or just build alternative energy sources (solar, wind, etc.)
I want to make a case for the e-bikes: they are less strenuous than the traditional bikes but require a good degree of cardiovascular exercise. This is a good incentive for older people
No, it's not simple. Changing most of a country car fleet, drastically reducing traffic, changing the infrastructure, changing the population mindset, overcome the cultural wars (this is the most important thing to change). From outside, it seems that this is part of the (new) US mythology. This is really difficult to change.