Innovative hybrid biomass-MCFC- Graz cycle systems for sustainable power and synthetic fuels: A thermodynamic and environmental analyses

This study investigates a hybrid biogas-driven energy system integrating a Graz cycle, molten carbonate fuel cell, and methanol–methane synthesis units with internal CO 2 recycling. The configuration enables simultaneous production of electricity and renewable fuels within a thermodynamically consistent and carbon-neutral framework. Comprehensive thermodynamic, exergoeconomic, and environmental analyses were conducted to assess overall performance. Results indicate that the integrated system achieves a maximum exergy efficiency of 54.82 %, with maximum net electrical power of 10.773 MW. The total product cost varies between 131.14 and 193.89 $/GJ, depending on operating conditions, while CO 2 emissions are reduced by more than 80% relative to conventional biogas-fired systems. The sustainability index reaches 1.5–2.2, confirming a high degree of reversibility and resource efficiency. These results demonstrate that the Graz–MCFC hybrid platform provides an effective pathway toward clean power generation and carbon-neutral synthetic fuel production from renewable biogas. • A novel biogas-driven hybrid system integrating GT–MCFC–Graz cycle is proposed. • •Internal CO 2 recycling enables near-zero-emission multi-generation. • •Coupling with PEM electrolysis supports hydrogen-based fuel synthesis. • •Maximum exergy efficiency of 54.82% and net power of 10.77 MW achieved. • •CO 2 emissions reduced by over 80% compared to conventional systems.