چكيده به لاتين
Hydrogen is a carbon-free energy carrier that can be used in various industries. Currently, more than 95% of the world hydrogen demand is being produced from methods based on fossil-fuels. However, in the recent years, researchers proposed numerous new methods that use water-splitting process to produce hydrogen from dissociation of water molecules. These methods include water electrolysis, thermochemical cycles, electrochemical cells, utilization of special algae, etc. Copper-Chlorine (Cu-Cl) thermochemical cycle is one of the most promising types of these options. This cycle utilizes both heat and electricity, and based on its required temperature, it can be integrated with various energy sources like solar energy. In this study, thermodynamic, economic, and environmental analyses of a solar-powered hydrogen production system based on four-step Cu-Cl cycle is proposed and optimized. Waste heat recovery potential of the Cu-Cl cycle is investigated at first to find an optimal heat exchanger network for both thermal and economic perspectives. Afterwards, a new standalone plant is proposed that connects a solar power tower subsystem using high-temperature molten salt with a four-step Cu-Cl cycle and a supercritical steam Rankine cycle. By optimizing the current model using NSGA-II algorithm, the system is compared to another hydrogen production system based on steam methane reforming considering technical, economic, and environmental aspects of design. Moreover, another solar-powered system is proposed in this study that uses gas turbine and pressurized cavity receiver in its solar subsystem. The system is used to produce various outputs including steam, electricity, hydrogen, and oxygen. The optimization results indicated that the first system that utilizes high-temperature molten salt has an energy efficiency, exergy efficiency, and LCOH of 28.6%, 29.42%, and 18.14 $/kg H2, respectively. It was observed that if hydrogen of a plant is produced from both SMR and solar-powered Cu-Cl cycle, while the ratio of solar hydrogen to all of the plant required hydrogen increases from 0 to 1, the LCOH and GWP changes from 1.33 $/kg H2 and 11.24 kg CO2 eq./kg H2 to 17.98 $/kg H2 and 0.628 kg CO2 eq./kg H2, respectively.
