A comparison of two schemes for pure hydrogen injection into a syngas-fueled SOFC: Thermoeconomic and environmental-based investigations

Abstract

The solid oxide fuel cells (SOFCs) driven by bio-syngas from biomass gasification are among the novel technologies for efficient and clean electricity generation. One challenge facing these systems is the shortage of biomass resources in some seasons and locations. One solution to mitigate this challenge is hybridizing these systems with other forms of renewable energies for decreasing the biomass consumption. The present work proposes integration of biomass driven SOFC with wind energy, in which the extra hydrogen is produced using the wind turbines and is used as a co-feed fuel for the SOFC. The hydrogen is supposed to be produced using an alkaline electrolyzer driven by electricity from the wind turbines. Two structural configurations are developed regarding how the extra hydrogen is injected into the basic biomass fueled SOFC. In one system the produced hydrogen is mixed with syngas fuel before the anode entry, while in the other system the hydrogen is burnt in afterburner of the SOFC for more power generation in the integrated gas turbine. Practical feasibility of these hybrid configurations are appraised based on thermodynamics laws, after which their economics and environmental features are investigated. Finally, tri-objective optimization is employed for finding the best operating conditions of the two configurations. According to the obtained results, injecting the extra hydrogen into the anode of the SOFC yields 8.3 % more electricity compared to the other configuration. As a result of more electricity generation, it yields 5.4 % less environmental emissions and 7.9 % less unit electricity cost.