Re: Alternative to Solar
" There's probably not much elevation change along the E. River to get a decent head of water in either direction "
The East River isn't really a river and it is pretty much all always at sea level, as is the Hudson off Manhattan. But elevation isn't needed, there's about a 3 knot reversing current all day and all night, from tidal changes in the "flooded estuary" which is what all the waters surrounding NYC actually are. Most of the time, you can actually observe a tidal bore going up the Hudson twice daily, as the incoming ocean waters push up and inland.
Enclosed turbines are fine for stream generators, but this ain't no stream. (G)