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In the third millennium, developing countries will confront significant environmental problems such as ozone depletion, global warming, the shortage of fossil resources, and greenhouse gas emissions. This research looked at a multigenerational system that can generate clean hydrogen, fresh water, electricity, heat, and cooling. The system's components include Rankine and Brayton cycles, an Organic Rankine Cycle (ORC), flash desalination, an Alkaline electrolyzer, and a solar heliostat. The proposed process has been compared for two different start-up modes with a combustion chamber and solar heliostat to compare renewable and fossil fuel sources. This research evaluated various characteristics, including turbine pressure, system efficiency, solar radiation, and isentropic efficiency. The energy and exergy efficiency of the proposed system were obtained at around 78.93% and 47.56%, respectively. Exergy study revealed that heat exchangers and alkaline electrolyzers had the greatest exergy destruction rates, at 78.93% and 47.56%, respectively. The suggested system produces 0.04663 kg/s of hydrogen. Results indicate that at the best operational conditions, the exergetic efficiency, power, and hydrogen generation of 56%, 6000 kW, and 1.28 kg/s is reached, respectively. Also, With a 15% improvement in the Brayton cycle's isentropic efficacy, the quantity of hydrogen produced increases from 0.040 kg/s to 0.0520 kg/s., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Due to the ubiquitous, cost-effective, and environmentally friendly characteristics of renewable energies, employing renewable energy sources has become an inevitable part of new-designed energy systems. In this regard, the present study proposes a multi-generation system with the potential of power, cooling, and freshwater production by utilizing geothermal and solar energies at the same time. The proposed system consists of two evaporators operating at above and below zero temperatures and a humidification and dehumidification desalination system for freshwater production. Along with the parametric evaluations based on thermodynamic and exergoeconomic perspectives, two-objective optimizations are conducted by employing the NSGA-II method. The results show that cooling capacity and energy efficiency increase by an increment of the temperature of the flashing separator, evaporator 1 and 2. Besides, increasing the temperature of evaporator 2 leads to lower hydrogen and net electricity production. The results indicate that the exergy-cost case of optimization correspondingly leads to exergy efficiency and overall unit cost of products of 20.82% and 0.144 $/kWh. Also, the maximum value of cooling is produced in the energy-cost optimization, when the objective function is the energy efficiency, which is equal to 848.9 kW with a 48.16% improvement compared to the base state. • Using solar-geothermal energy to produce power, cooling, and freshwater. • Evaluation of the proposed system by parametric study and two-objective optimizations. • Outputs at the base case are 548.4 kW electricity, 569.1 kW cooling, and 3.436 m3/day freshwater. • Based on energy-cost optimization, the overall unit cost of products is obtained 0.146 $/kWh. • Based on exergy-cost optimization, energy and exergy efficiencies are obtained 21.91% and 20.82%. [ABSTRACT FROM AUTHOR]

• A novel hybrid biomass-solar triple combined power cycle is proposed. • Solar energy is used for hydrogen production employing PEM electrolyzer. • The hydrogen is utilized as the co-feed in post-firing stage of the gas turbine. • Multi-objective optimization based on power cost and CO 2 emissions is performed. • Significant reduction in CO 2 emissions is achieved by integration of hydrogen post-firing. Utilization of hybrid renewable resources in supplying clean energy is a new idea which helps to fulfill individual drawbacks of each renewable source. In this work, an innovative triple combined power cycle driven by hybrid biomass-solar energies is proposed, analyzed and optimized from the exergy, economics, and environmental standpoints. In order to fulfill the intermittent nature of solar energy, it is used for hydrogen production (via Proton Exchange Membrane (PEM) electrolyzer supplied by electricity from Photovoltaic-Thermal (PVT) panels) which is injected into a post-firing combustion chamber of the gas turbine. The proposed system consists of a biomass fueled gas turbine combined with a closed Brayton cycle and a Rankine cycle as the bottoming cycles. To examine the system performance, thermoeconomic evaluation is carried out and multi-objective optimization is performed to find the optimum operating conditions based on Levelized Cost Of Electricity (LCOE) and CO 2 emission. The results revealed that, incorporation of solar-based hydrogen production with the biomass-based gas turbine results in a significant decrease in CO 2 emissions and biomass consumption as well as increase in power generation capacity. However, it brings about a decrease of exergetic efficiency (due to the large exergy destruction in PVT and PEM electrolyzer) and an increase of LCOE (due to the additional expenditures imposed by PVT panels and PEM electrolyzer). Under the best operating conditions based on multi-objective optimization, the proposed triple combined cycle attains exergy efficiency of 30.44% with a LCOE of 61.37 $/MWh, and CO 2 emission of 0.4579 kg/kWh. [ABSTRACT FROM AUTHOR]