Generating geothermal energy using multiple working fluids

A geothermal system comprising:

• a closed loop geothermal well comprising:
• a surface inlet wellbore,
• a surface outlet wellbore, and
• an interconnecting wellbore fluidly coupled to and interconnecting the surface inlet wellbore to the surface outlet wellbore, the interconnecting wellbore residing in a target geothermal subterranean zone;
• a first heat transfer working fluid residing inside and configured to circulate in the geothermal well;
• and
• a second working fluid configured to circulate in the geothermal well from the surface inlet wellbore to the surface outlet wellbore, the second working fluid residing upstream of the first heat transfer working fluid and the second working fluid comprising a fluid density greater than a fluid density of the first heat transfer working fluid;
• wherein circulating the second working fluid comprises pushing, with the second working fluid, the first heat transfer working fluid toward a surface outlet of the surface outlet wellbore to collect energy from the mobilized first heat transfer working fluid received at the surface outlet.

A power production system, comprising:

• an electrical grid;
• an intermittent power production source electrically coupled to the electrical grid;
• a closed loop geothermal system electrically coupled to the electrical grid, the closed loop geothermal system comprising:
• a geothermal well comprising a surface inlet and a surface outlet,
• a heat exchanger fluidly coupled to the surface outlet and electrically coupled to the electrical grid, the heat exchanger configured to output electricity generated by movement of a first heat transfer working fluid pushed by a second working fluid circulated, in the geothermal well, downhole to convert a gravitational potential energy of the second working fluid into kinetic energy of the first heat transfer working fluid, the second working fluid comprising a greater density than the first heat transfer working fluid and residing upstream of the first heat transfer working fluid;
• and
• a controller operatively coupled to the electrical grid, the intermittent power production source, and the closed loop geothermal system, the controller configured to determine, based on a power output of the intermittent power production source, a power requirement of the electrical grid for a selected period of time and configured to switch the closed loop geothermal system between charging cycles and discharging cycles to provide, together with the intermittent power production source, a dispatchable energy output to the electrical grid.