OPTIMIZATION OF GAS-TURBINE COMBINED CYCLES FOR SOLAR-ENERGY AND ALTERNATIVE-FUEL POWER-GENERATION

Power generation with combined cycles of gas turbines and bottoming steam cycles can be an attractive option for solar energy or alternative-fuel heat sources. It is shown how basic thermodynamic principles can be used to establish energetically optimal operating conditions, and to evaluate power generation efficiency, for realistic power plants. A comparison with performance data from commercial, combined-cycle power plants shows accurate predictions both for overall efficiency and for optimized operating conditions. Heat-to-electricity conversion efficiencies for temperatures that are easily achieved in solar towers or biomass plants can be close to 50%. An illustrative example is presented for overall energetic optimization of a solar-driven, combined-cycle power plant.