Politecnico di Torino - Corso Duca degli Abruzzi, 24 - 10129 Torino, ITALY

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Regenerative reheating geothermal system

geothermal expansion processgeothermal flash plantsGeothermal regenerative reheatinghigh enthalpy geothermicsturbine isoentropic efficiency


This innovative regenerative re-superheating geothermal plant configuration improves the efficiency of existing plants by introducing a two-stage expansion process and the inclusion of the re-superheater (evaporator-superheater) between the two stages.

Technical features

Compared to the single-flash configuration of a conventional plant,  the the expansion process is separated into two stages and incorporates a  resuperheater (evaporator-superheater) between the two stages. The essential aspect of the system and process consists of superheating steam obtained through a regenerative process, and directly using the steam which is separated at the piezometer headsteam in a backpressure turbin,e where it is expanded to a pressure, generally higher than the atmospheric one. The steam at the exhaust of the backpressure turbine is heated using the liquid’s heat, separated at the piezometer headsteam and sent to a second steam turbine for expansion up to the condenser pressure. The reheating increases both the enthalpy jump and the isoentropic efficiency of the expansion process.
TRL 5/6: prototype plant

Possible Applications

  • Geothermal power plant upgrade to improve plant efficiency.
  • Geothermal power plant upgrade to reduce energy production costs.


  • Significant increase in energy production in comparison with existing technologies without  changes in power plant configuration;
  • Compliance with silica solubility constraints in re-injection geothermal fluid;
  • Simplified plant design;
  • Reduction of erosion phenomena in turbine due to the presence of liquid droplets.