SUMMARYThis paper discusses some potential low-temperature thermochemical and hybrid cycles for nuclear-based hydrogen production and considers them as a sustainable option for hydrogen production using nuclear process/ waste heat and off-peak electricity. We also assess their thermodynamic performance through energy and exergy efficiencies. The results show that these cycles have good potential and become attractive due to their high overall efficiencies 50% based on a complete reaction approach. The copper-chlorine cycle appears to be a highly promising cycle for nuclear-based hydrogen production in this regard.

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Geothermal-based hydrogen production, which basically uses geothermal energy for hydrogen production, appears to be an environmentally conscious and sustainable option for the countries with abundant geothermal energy resources. In this study, four potential methods are identified and proposed for geothermal-based hydrogen production, namely: (i) direct production of hydrogen from the geothermal steam, (ii) through conventional water electrolysis using the electricity generated through geothermal power plant, (iii) by using both geothermal heat and electricity for high temperature steam electrolysis and/or hybrid processes, and (iv) by using the heat available from geothermal resource in thermochemical processes. Nowadays, most researches are focused on high-temperature electrolysis and thermochemical processes. Here we essentially discuss some potential low-temperature thermochemical and hybrid cycles for geothermal-based hydrogen production, due to their wider practicality, and examine them as a sustainable option for hydrogen production using geothermal heat. We also assess their thermodynamic performance through energy and exergy efficiencies. The results show that these cycles have good potential and attractive overall system efficiencies over 50% based on a complete reaction approach. The copper-chlorine cycle is identified as a highly promising cycle for geothermal-hydrogen production.