Investigation of an integrated thermochemical hydrogen production and high temperature solar thermochemical energy storage and CO2 capture process

Depletion of fossil fuels and their environmental impacts are significant issues of today. While the increasing energy demands have led researchers to explore new areas. Hydrogen is one of the most promising alternatives that could provide clean energy from renewable sources. Hydrogen production using solar energy has been investigated; however, hydrogen storage and novel processes that rely less on external energy are still a literature gap. For the first time, a novel integration of the zinc-sulfur-iodine hydrogen production system with heliostat solar collector and thermochemical energy storage is proposed in this study. The proposed system allows for the production of clean hydrogen, reduced need of external energy, and improved process efficiency. Three scenarios for the H-2 production are discussed where exergy efficiency, solar fraction, storage tank dimensions, auxiliary heater load, and thermal efficiency are evaluated. Simulations are performed with System Advisor model/ Aspen Plus, and results show a solar fraction of 75.46% as 0.5 mol/s H-2 is produced and 2.3 mol/s CO2 is captured. Further, employing the storage system decreases required heat of the ZnSI system by half to 4710 kW and increases efficiency to 17.54%. The exergy and thermal efficiency of the system are obtained as 65.87% and 28.90%, respectively.