Exergoeconomic evaluation of a new carbon-free hydrogen and freshwater production system based on biomass gasification process

Abstract

This article is based on the conceptual-thermodynamic design and exergoeconomic investigation of a new poly-generation system driven by a biomass fuel (i.e. wood). In the proposed energy system, a Rankine power process, a gasification process, a desalination process (i.e. multi-effect desalination, MED) and a water electrolyzer (i.e. solid oxide electrolyzer cell, SOEC) are installed in a hybrid form. Electric energy, fresh water and hydrogen gas are the useful output products of the proposed energy system. The proposed energy system indicates an innovative framework for the carbon-free production of these products, which introduces an environmentally friendly and efficient schematic. The findings of the research indicated that the proposed energy system is capable of producing more than 1.8 MW of electric power. Other useful output products of the proposed energy system include hydrogen fuel and fresh water, which were calculated as 0.0036 kg/s and 9.92 m3/h, respectively. It was also calculated that the proposed energy system can achieve energetic and exergetic efficiencies equal to 37.1% and 17.8%, respectively. The total unit exergy cost of the products and the exergy destruction rate of the proposed energy system were equal to 15.9$/GJ and 8640 kW, respectively. Parametric analysis is also presented in order to identify the input variables affecting the performance of the energy system. Further, the behavior of the system under four different types of biomass was evaluated and compared.