cbreezen, hydro requires massive water flow from rivers taking water from very large areas. I suspect (not sure) PR simply does not have the geography for it. If it did, someone would have built one as a first source of power.
Although I'm an engineer, I don't have the background to make a solid call on this. Frankly, it requires knowledge from several disciplines to do a complete analysis, plus all the political factors that must be weighed. But, with the knowledge of power systems I have, I don't see any way other than to repair their existing system. After repairs, they will be far better off than before due to the very poor condition of the poles, lines, metering systems and transformers that were there pre-storm. So, that will become the foundation for future changes - say, to wind and/or solar.
The reason I'm so negative is due to the existing debt PR has, and their doubtful ability to pay off even more debt on top of that. The banking vultures were there eating at them before the storm! I have not read how it is proposed for even the existing infrastructure repairs to be paid for.
If one had a competent company come in and do all the studies, propose the changes and win a contract - if it's not a pay-in-full contract, they will want ownership of a piece of Puerto Rico. And, therein lies the rub - with so much existing debt, plus new debt for repairs and/or upgrades, there may not be any privately owned Puerto Rico left for the citizens!
I wish it could, but I don't think any grassroots efforts can even make a dent toward paying for this work. We're talking several hundred million dollars (of the cuff), and that does not include helping to pay for all the other damages (homes, crops, etc.). Sorry I can't be more positive.
I doubt if Puerto Ricans want billionaires like Bezos or Musk owning their souls, either.