Multi-objective optimization of an innovative integrated system for production and storage of hydrogen with net-zero carbon emissions

Global energy consumption has been exponentially increasing, leading to the depletion of conventional energy sources and a considerable increase in greenhouse gas emissions. The exploitation of sustainable energy sources and the development of innovative methods for mitigation of CO2 emissions is necessary. Hydrogen (H2) as a versatile and green fuel can be produced and stored in liquid form using sustainable energy sources through innovative methods. In this paper, a novel optimal hybrid structure is proposed for hydrogen production and storage with net-zero CO2 emissions. A high-temperature fuel cell is utilized to reduce CO2 emissions and supply the heat and power needed to produce and liquefy hydrogen. The hybrid configuration employs an electro-thermochemical unit for hydrogen production, molten carbonate fuel cells, a hydrogen liquefaction process, and a biogas upgrading by water scrubbing. A robust combination of meta-heuristic algorithms and artificial intelligence is developed to optimize the investment return period and energy/exergy efficiencies. The fuzzy Bellman-Zadeh, LINMAP, and TOPSIS techniques are also used to make decisions in multi-objective optimization. This innovative configuration generates 108 kmol/h liquid hydrogen, 18.88 MW power, 54 kmol/h oxygen, and 3258 kmol/h hot water. Pinch, sensitivity, exergy, and economic assessments are implemented to evaluate the performance of the hybrid structure. The thermal and exergy efficiencies of the proposed configuration are obtained to be 78.21 % and 64.83 %, respectively. The greatest portions of destructed exergy are resulted from the fuel cells-gas turbine hybrid system (63.63 %), electro-thermochemical unit (25.96 %), and biogas upgrading technology (6.23 %). The returns period on investment, the prime price of electricity, and the net benefit are computed as 4.854 years, 0.0420 US$/kWh, and 15.73 million US$/years, respectively, based on the energy potentials of Newfoundland and Labrador, Canada.

Automated summary

Global energy consumption is rapidly increasing, resulting in the depletion of traditional energy sources and a significant rise in greenhouse gas emissions. It is crucial to utilize sustainable energy sources and innovative approaches to mitigate CO2 emissions. This study proposes a novel hybrid structure for hydrogen production and storage with zero CO2 emissions. The design incorporates a high-temperature fuel cell for CO2 reduction and the generation of heat and power for hydrogen production and liquefaction. The hybrid configuration employs electro-thermochemical units, molten carbonate fuel cells, hydrogen liquefaction processes, and biogas upgrading technologies. Meta-heuristic algorithms and artificial intelligence are developed to optimize investment return period and energy/exergy efficiencies. Fuzzy Bellman-Zadeh, LINMAP, and TOPSIS techniques are used for decision-making in multi-objective optimization. The proposed configuration produces 108 kmol/h of liquid hydrogen, 18.88 MW power, 54 kmol/h of oxygen, and 3258 kmol/h of hot water. Performance evaluations based on pinch, sensitivity, exergy, and economic assessments show thermal efficiency of 78.21% and exergy efficiency of 64.83%. The largest portions of exergy destruction come from the fuel cells-gas turbine hybrid system (63.63%), electro-thermochemical unit (25.96%), and biogas upgrading technology (6.23%). The return period on investment, prime price of electricity, and net benefit are computed as 4.854 years, 0.0420 US$/kWh, and 15.73 million US$/years, respectively, using the energy potentials of Newfoundland and Labrador, Canada.