Integrated biomass-fueled power system with helium cycle and CO2-to-methanol synthesis: A multi-objective optimization for sustainable energy and carbon mitigation

This study presents an advanced hybrid energy system that combines biomass digestion, a gas turbine, a closed-loop helium cycle, and a methanol synthesis unit to achieve efficient power generation and carbon dioxide utilization. A comprehensive thermodynamic, exergoeconomic, and environmental (4E) analysis is conducted to assess system performance under varying operational conditions. Multi-objective optimization—utilizing artificial neural networks and a genetic algorithm—seeks to simultaneously maximize exergy efficiency and minimize both CO₂ emissions and unit product cost. Results show that the optimal configuration achieves an exergy efficiency of 39.8 %, a unit product cost of $96.5/GJ, and CO₂ emissions of 1.29 kg/kWh. The helium cycle enhances thermal recovery from the gas turbine exhaust, increasing net power output by 15.3 %. Meanwhile, the methanol synthesis unit effectively captures and converts CO₂ using hydrogen from a PEM electrolyzer, reducing environmental impact by 18.7 %. Parametric analyses reveal key trade-offs among thermal efficiency, hydrogen production, and methanol yield. Compared to conventional biomass systems, this integrated approach offers a scalable, cost-effective, and environmentally sustainable solution for low-carbon power and fuel production.