Data-driven optimization of a biomass–geothermal system for power and green ammonia production

This study presents a hybrid biomass–geothermal energy system for simultaneous power generation and ammonia production. The system integrates biomass conversion via gasification or anaerobic digestion, a gas turbine cycle, a geothermal-assisted organic Rankine cycle (ORC), thermoelectric generation, water electrolysis for hydrogen production, and catalytic ammonia synthesis. An optimization framework combining surrogate-based modeling and a metaheuristic algorithm is developed to determine optimal operating conditions. The system’s performance is evaluated in terms of net power output, thermodynamic efficiency, product cost, and environmental impact under a gate-to-gate boundary. The developed framework enables the evaluation of multi-generation energy systems and supports decision-making for sustainable energy planning. The optimization results demonstrate that the proposed integrated system can achieve a maximum net power output of 16.34 MW, an exergy efficiency of 48.43%, a minimum product cost of 19.03 $/GJ, and a minimum emission index of 0.4005 kg/kWh under scenarios. Comparative analysis shows that the digester-based configuration outperforms the gasifier-based system due to higher methane content and improved combustion characteristics. Overall, the results indicate that the proposed hybrid system offers a promising pathway for sustainable power and green ammonia production with improved thermodynamic and environmental performance.