Thermodynamic analysis of a net zero emission system with CCHP and green DME production by integrating biomass gasification

A net zero emissions system with biomass gasification based CCHP and green DME production is proposed and evaluated via the analysis methods of parametric, thermodynamic and economic. The H2/CO ratio and the steam-to-biomass ratio on the mole fractions, the calorific value of syngas, the DME yield, and the energy outputs of the district energy production subsystem are investigated. The parametric analysis shows that as the H2/CO ratio raised, the mole fractions of H2 increased and the mole fraction of CO decreases. With the increasing of the steam-to-biomass ratio from 0 to 0.35, the mole fraction of H2 increased from 16.2% to 34.3%. Moreover, the thermodynamic analysis demonstrates that, the cold gas efficiency of 93.8%, synthetic DME efficiency of 59.9%, carbon efficiency of 37.1%, and the carbon dioxide reduction of 15,280 tons/a are achieved for the overall proposed system. The total thermal efficiencies of proposed system in summer, winter and transition days are 83.8%, 84.3%, and 75.7%, respectively. Additionally, the economic analysis indicates that the gasifier has the largest capital cost rate of 35.27%, and the major operating cost rate results in labor & supervision of 35.7%. For the proposed system, with the bio-DME price varying from 0.5Pbio-DME to 1.25Pbio-DME, the net annual income drops from 10.88 to 4.38 MUSD, and the payback period will range from 2.8 to 11.3 years.