Pondless hydromechanical storage system

A method of operating a power system, comprising:

• producing a fluid from a first subterranean formation at a first zone of a well;
• flowing the fluid through an impeller section of an electrical submersible generator installed in the well;
• generating electricity using the electrical submersible generator;
• and
• injecting the fluid into a second subterranean formation at a second zone of the well.

A system comprising:

• a well intersecting a first subterranean formation and a second subterranean formation;
• an electrical submersible generator installed in the well;
• a packer coupled to the electrical submersible generator, the packer located between the first and second subterranean formations, and sealing against a casing string of the well;
• wherein the electrical submersible generator is configured to:
• generate electricity when a fluid flows in the well from the first subterranean formation to the second subterranean formation;
• and
• pump the fluid from the second subterranean formation to the first subterranean formation.