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[Display omitted] • A novel system for production and storage of H 2 with net-zero carbon emissions is developed. • High-temperature fuel cells and biogas upgrading unit are efficiently integrated. • Waste heat of the fuel cells is recovered in the Cu-Cl unit for hydrogen production. • Integrated process can generate 108 kmol/h liquid hydrogen and 18.88 MW power. • A hybrid method of the GA and artificial intelligence tools is applied for optimization. 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 CO 2 emissions is necessary. Hydrogen (H 2) 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 CO 2 emissions. A high-temperature fuel cell is utilized to reduce CO 2 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. [ABSTRACT FROM AUTHOR]

• A comparison between energy communities modelled as aggregation of prosumers. • A multi-objective optimization of the design and operation of energy communities. • Demand Side Management as a powerful tool for improving the energy community design. • Reduction in the cost of energy and CO 2 emissions of 14% and 24%, respectively. • Community demand management enhances the exploitation of renewable energy sources. This paper focuses on three different configurations of energy communities (ECs) modelled as aggregations of local prosumers of renewable electric and thermal energy. The goal consists in improving the economic performance of the ECs while contributing to address the issue of climate change and fulfilling the existing energy demands or demands modified with smart strategies. Accordingly, type and size of the energy conversion and storage units of the prosumers included into ECs (design) and their operation are optimized with a bi-objective approach, considering investment and operation costs, and greenhouse gas emissions, both direct due to fuel burning, and indirect due to life cycle, as objectives to minimize. Moreover, two strategies of demand side management (DSM) are considered: a price-based demand response program applied downstream of the design optimization, and a new DSM model, which adapts the electricity demand to the renewable energy sources locally available, applied upstream of the design optimization. It results that the proposed DSM can ensure a better balancing between generation and demand profiles, thereby decreasing the stress on the electricity grid. Globally, ECs can reduce their energy expenditure of 14% and the overall CO 2 -equivalent emissions of 24% compared to the reference case of the simple consumers. [ABSTRACT FROM AUTHOR]