[ncmncm]

Nobody said tidal power was hydro power. But, for completeness, I will say it now: tidal is also hydro.

It is distinguished from common hydro power by drawing, ultimately, on planetary body kinetic energy rather than insolation.

[oneoff786]

Well that’s not correct. You can say whatever you want but that isn’t the common definition of the term.

[ncmncm]

Language is tricky, and cannot be made less tricky without loss of most of its value.