More renewable electric generation along with less fossil-fueled generation is needed in order to reach net-zero greenhouse gas (GHG) electricity. My home state (California) does not consider nuclear generation or medium to large hydroelectric generation “renewable,” although I do. California defines the two excluded “non-renewable” electricity sources as “zero-carbon resources.”
Hydro power is also a bit strange in other respects, whether it’s small medium or large. First of all it serves several masters. In addition to needs by the electric grid it responds to needs for water.
This post is mostly about medium to large hydro generation, specifically those that have dams, and thus reservoirs.