Exergoeconomic and environmental analyses with multi-objective optimization of a novel flare-gas-driven multigeneration system integrated with post-combustion desulfurization and carbon capture

The rising global energy demand and growing environmental concerns highlight the need for sustainable and efficient energy management. A significant challenge is the flaring of associated gas at crude oil wells, especially in the Middle East, which wastes energy and increases greenhouse gas emissions. This study proposes a multigeneration energy system for the recovery and utilization of flare gas in Ahvaz, Iran, integrating electricity, heating, cooling, freshwater, and hydrogen production. The system couples flare gas combustion with a supercritical CO2 recompression cycle, a regenerative steam Rankine cycle, a single-effect absorption refrigeration cycle, reverse osmosis desalination, and a proton exchange membrane electrolyzer. Environmental impacts are mitigated through flue gas desulfurization and carbon capture. Simulation results show a net power output of 31.48 MWe, heating and cooling loads of 18.43 MW and 2.36 MW, and desalinated water production of 33.24 kg/s. The system achieves energy and exergy efficiencies of 45.21 % and 24.85 %, with an exergy cost of 0.2908 $/kWhe. Multi-objective optimization using NSGA-II improves the energy and exergy efficiencies to 49.60 % and 26.85 % while reducing the total cost rate by 5.43 %, demonstrating the system's potential for sustainable energy management and environmental benefits.