Design and thermodynamic analysis of sustainable hybrid system based on solar tower and helium gas cycle for green hydrogen and ammonia production

Abstract

Sustainable energy-based hybrid energy plants hold significant potential for addressing environmental issues and advancing towards a carbon-free future. This research primarily aims to design and evaluate a solar-powered combined cycle for power, hydrogen (H₂), and ammonia (NH₃) production. This innovatively designed multiple generation system composed of a solar tower (ST), a Brayton cycle (BC) with helium (He) as the fluid, a transcritical Rankine cycle (tRC) powered by carbon dioxide (CO₂), organic Rankine cycle (ORC), thermoelectric generator (TEG), a Proton Exchange Membrane (PEM) electrolysis and a NH₃ reactor. Thermodynamic analyzes are performed to determine the performance of the entire plant and subsystems. The research analysis revealed that the total net power generation capacity is 4938.15 kW and, the net power production of the sub-systems helium BC, tCO₂ RC, ORC and TEG is computed as 4482.03 kW, 100.1 kW, 286.32 kW, and 69.75 kW respectively. Moreover, according to thermodynamic analysis results, H₂ and NH₃ production rates are 1.7 kg/h and 78 kg/h, respectively. The energetic efficiency of the system is 26.71 % and the exergetic efficiency is 26.16 %. The total exergy destruction in the plant is 13811.39 kW. The highest exergy destruction among the system elements is in the solar tower with 85.3 % (11782.66 kW) of the total exergy destruction. Additionally, the levelized energy cost (LEC) for the system is $0.007 $/kWh and the sustainability index (SI) is 1.37325373.