Thermo-economic-environmental analysis of a hybrid green hydrogen system driven by a solar dish Stirling engine combined with a supercritical CO₂ Brayton cycle for enhanced performance and effective waste heat recovery

AbstractThis study evaluates the energy performance, economic viability, and potential CO₂ emission reductions of an integrated Solar Dish Stirling Engine-Supercritical CO₂ Brayton system Proton Exchange Membrane Electrolyzer (SDS-SCO₂B-PEME). The proposed hybrid system (Solar Dish Stirling engine (SDS), an sCO₂ Brayton cycle, an electrolyzer, a power converter, and a hydrogen storage tank (HST)) leverages efficient waste heat recovery to enhance performance and enable efficient green hydrogen production. MATLAB/Simulink® is employed for thermo-economic and environmental (3E) modeling to evaluate key parameters, including dish area, power output, efficiency, heat loss, levelized cost of hydrogen (LCOH), and annual CO₂ mitigation. Results show that increasing the cycle temperature from 400 °C to 800 °C reduces the total plant dish area from 1.42 km2 to 1.12 km2, boosts power output from 70 kW to 90 kW, and reduces heat loss from 320 kW to 50 kW. Hydrogen production increases from 1200 kg to 1800 kg as condenser air temperature rises from 0 °C to 50 °C. Cycle efficiency peaks at 60% with a CO₂ flow rate of 5 kg/s and a pressure ratio of 2. Moreover, the results from the economic model confirmed the cost-effectiveness of the formulated system, with the Levelized Cost of Energy (LCOE) of 0.1126 $/kWh, and the LCOH value of 4.053 $/kg. Environmentally, the proposed system can reduce CO₂ emissions by 16.0 Mt. compared with oil and 12.8 Mt. compared with natural gas, which indicates the strong potential for large-scale decarbonization in solar-rich regions. The obtained findings highlight the system's potential for sustainable and high-efficiency hydrogen production.