Hydrogen production using solid oxide electrolyzer integrated with linear Fresnel collector, Rankine cycle and thermochemical energy storage tank

Hydrogen has been hailed as a fuel due to growing energy requirements, as well as environmental considerations. So far, no research has been conducted on the simultaneous use of linear Fresnel collector and solid oxide electrolyzer cell with thermochemical storage tanks to produce hydrogen. In this paper, a newly developed system with the purpose of producing a constant flow of hydrogen using solar energy is proposed. The system includes four main subsystems. These subsystems include linear Fresnel solar collectors, solid oxide electrolyzer cell, Rankine power generation cycle, and thermochemical energy storage unit. Modeling of subsystems is done using MATLAB and Aspen HYSYS software. The system is studied from the perspective of the first and second laws of thermodynamics. Also, the effect of thermal energy storage with different periods on the overall performance is investigated. Four thermal energy storage scenarios and their effect on energy and exergy efficiency, solar fraction, thermochemical storage tank dimensions, and auxiliary heater load variations are presented as results. The system is capable of producing 50.4 kg of hydrogen per hour. Results show that the Rankine cycle has the capability to provide 42.78% of the electrical power consumed by the electrolyzer. Also, with the increase of thermal energy storage period up to one year, the energy and exergy efficiencies will reach to 20.17% and 13.73%, respectively. In this case, 0.83 of the energy required for the system, is supplied by the solar energy.