Analysis and multi-objective evolutionary optimization of Solar-Biogas hybrid system operated cascade Kalina organic Rankine cycle for sustainable cooling and green hydrogen production

A novel cascade system of Kalina and Organic Rankine cycle for cooling and green hydrogen production was proposed. The cascade system is designed to utilizes the heat effectively with heat recovery components for sustainable cooling and green hydrogen. The proposed system consists of a solar-biogas hybrid heat source, Kalina and ORC power generation system, dual evaporator vapor compression cooling system and solid oxide electrolyser. The system's performance is evaluated based on the availability of low-temperature heat sources (90 to 150 °C) and medium-grade heat sources (190–280 °C). It is assessed for its capability to provide cooling only or in combination with hydrogen production, and their efficient utilization is compared from energetic, exergetic, environmental, and economic perspectives. To optimize this innovative system, a multi-objective evolutionary approach is employed, considering operating conditions as constraints and incorporating performance metrics for all criteria as objectives. Utilizing multi-objective decision-making techniques, diverse optimal points are pinpointed within the trade-off space, enabling real-time adaptive responses to changes in weather, energy demands, and biogas availability. The net present value analysis demonstrates that, assuming a hydrogen selling price of $6 per kilogram and cooling costs of $4 per KW the payback periods are calculated to be 2 years for the ORC-VCRS cycle and 3 years for the integrated Kalina topping with bottoming ORC cycle. The multi-objective optimization results indicate that the optimum operating conditions for the cascade system involve boiler, absorber, and condenser temperatures set at 196 °C, 110 °C, and 25 °C, respectively. Under these conditions, the system achieves an energy utilization ratio of 0.76, an exergy efficiency of 21.56 %, and a total cost of $58,677.