By hydro i did not mean pumped storage hydro but ordinary dam hydro. It does not technically store energy but it is a very effective on demand power producer because you can turn it on or off at will (provided there is enough water in the reservoir).

Also, it is very good for intermittent generation, because when you stop it, you can fill up the water in the reservoir and give yourself potential energy for the next time you start it up. It does in a way store energy, it stores the energy of rivers, not of electricity.

Of course whether you can access it depends on your environment. You have to have convenient rivers to dam up, and you have to have no water shortages. In a case of water shortage the decision to let water out or not is usually made based on water needs, not electricity needs.

Hydro has very specific geographical requirements and in countries like Germany, all almost all potential for hydro power has already been put to use and yet it provides only a fraction of the electricity generation here.

Hydro only plays a large role world-wide in countries with low population densities such as Norway.

The geographical requirements are way too big for hydro, destroys nature, the possibility of disasters.