Most places where pumped hydro is viable already have it. The growth potential is limited.
Hydrogen is a more interesting option. Not necessarily for energy storage, but as a fuel for use cases where electricity can't be used (like fertilizer or methanol rather than cars or heating).
Hydrogen is a more interesting option. Not necessarily for energy storage, but as a fuel for use cases where electricity can't be used (like fertilizer or methanol rather than cars or heating).