8.5 billion gallons per second
Well over half of the planet is water and the use of tides and currents for the production of electricity could be endlessly renewable. The world’s first field of underwater turbines, using currents of the East River, will be in New York City.
I was promoting ‘current’ turbines during the 1980s and 90s with TR International, including an integrated rapid deployable port with Baker Engineering.
There are 1000s of low impact power generation sites.