Exploring the hybrid route of bio-ethanol production via biomass co-gasification and syngas fermentation from wheat straw and sugarcane bagasse: Model development and multi-objective optimization

Abstract

Biomass co-gasification and syngas fermentation is one of the least trotted paths in the Indian biofuel production scenario. The aim of the research here is to develop an equilibrium model of biomass co-gasification and syngas fermentation in Aspen plus. Two Indian lignocellulosic biomass namely wheat straw and sugarcane bagasse have been selected as feedstock for this co-gasification process followed by the syngas fermentation. The process shows promising results in terms of ethanol production and energy usage. The effects of gasification process parameters on overall process performance have been analysed. Empirical regression equations were constructed to account for the effects of biomass ratio, which is the ratio of the masses of wheat straw and sugarcane bagasse, gasification temperature and equivalence ratio over ethanol yield, lower heating value of syngas, cold gas efficiency, overall system efficiency, and CO2 emission using response surface methodology. Finally, a multi-objective optimization has been conducted to maximize the ethanol production and overall system efficiency, and to minimize the CO2 emission of the system. Results suggest that the wheat straw and sugarcane bagasse ratio of 4:1, 919.5oC temperature and 0.15 equivalence ratio is the optimum point with an ethanol production rate of 20.917 tonnes/hr, overall efficiency of 52.184%, and a minimum CO2emission of 32669.862 kg/h.