The main results. of the simulation study of a double-flash geothermal plant, including a steam-CO2 reboiler-based separation process, are presented. Dynamic models of two-phase, H2O-CO2 components are derived, and their use for dynamic simulation and operating point optimization is discussed. Control system issues are then considered. On one hand, the simulator is used as an aid to design and test standard level and pressure control loops, whose actual performance would otherwise be difficult to predict due to the high degree of interconnection of the plant components. On the other hand, the control concept for the innovative parts of the plant is discussed, recognizing that the control problem and the operating point optimization problems have to be tackled simultaneously. A simple, yet effective, solution for this problem is proposed.