Exergy estimate of a novel hybrid solar-gas power and organic Rankine cycle-based hydrogen-production system

Abstract

This study proposes a novel hybrid solar-gas power and hydrogen-production system, which is comprised by the solar tower thermal system, gas-steam turbine combined cycle and organic Rankine cycle-based hydrogen-production system. Based on the Ebsilon code, the operation processes of the hybrid system are simulated. The results show that the output power and electric efficiency of the hybrid system are 103.9 MW and 41.3%, and the daily hydrogen output is 62.2 kg. The operation simulation results of the hybrid system reveal that the gas-steam combined cycle and solar island can both achieve stable operations, and the power generation section and hydrogen-production device can both work effectively, which means the hybrid system is technically feasible. The exergy estimate results of the hybrid system show that the combustion chamber and solar receiver have the two largest exergy destructions, which are 56.5 MW and 45.3 MW. That means the performances of the two components can be further improved. For the hydrogen-production system, the exergy destructions of the proton exchange membrane electrolyzer, turbine, condenser and evaporator of the organic Rankine cycle are 0.156 MW, 0.111 MW, 2.338 MW and 1.891 MW, and the corresponding exergy efficiencies are 51.2%, 92.6%, 80.7% and 79.5%, respectively.