H2 processes with CO2 mitigation: Thermo-economic modeling and process integration
Within the challenge of greenhouse gas reduction, hydrogen is regarded as a promising decarbonized energy vector. The hydrogen production by natural gas reforming and lignocellulosic biomass gasification are systematically analyzed by developing thermo-economic models. Taking into account thermodynamic, economic and environmental factors, process options with CO2 mitigation are compared and optimized by combining flowsheeting with process integration, economic analysis and life cycle assessment in a multiobjective optimization framework. The systems performance is improved by introducing process integration maximizing the heat recovery and valorizing the waste heat. Energy efficiencies up to 80% and production costs of 12.5-42$/GJH2 are computed for natural gas H2 processes compared to 60% and 29-61$/GJH2 for biomass processes. Compared to processes without CO2 mitigation, the CO2 avoidance costs are in the range of 14-306$/tCO2,avoided.The study shows that the thermo-chemical H2 production has to be analyzed as a polygeneration unit producing hydrogen, captured CO2, heat and electricity.