Converting low-temperature waste heat into hydrogen energy through four different organic cycle setups: A comparative techno-economic analysis

A large amount of low-temperature heat is wasted in industrial processes and energy conversion systems, which can be converted into useful energy by utilizing various technologies. Hence, the present study provides a comparison among four low-temperature organic cycles to convert such waste heat into hydrogen energy. Partial evaporating organic Rankine cycle (PEORC), organic flash cycle (OFC), trilateral cycle (TLC), and organic flash regenerative cycle (OFRC) are compared at the optimal operating point from thermodynamic and economic viewpoints. A thermoelectric generator is employed in the four cycles to recover the heat lost during the condensation process into electricity. The total electricity generated by each cycle is converted into hydrogen through a proton exchange membrane electrolyzer. Exergy efficiency ( ), specific cost of hydrogen production ( ), and levelized cost of hydrogen (LCOH) are the output parameters in the comparative analysis. The OFRC-based system has the highest (30.77%) and the second-lowest LCOH (4.66 ). The PEORC-based system brings about an acceptable (27.39%), the lowest LCOH (4.08 ), and the lowest (157.8 ). The TLC-based system causes the second-highest (30.21%) and the second-lowest (169.1 ). The OFC-based system has the weakest performance among the four configurations.