Economic Evaluation of Lignocellulosic Biofuel Manufacturing Considering Integrated Lignin Waste Conversion to Hydrocarbon Fuels

Although lignin accounts for 20%-25% of the total weight of dry lignocellulosic feedstock, it is largely wasted in the lignocellulosic ethanol industry due to the challenging nature of decomposing lignin polymers. In fact, through a series of chemical processes, lignin can be converted into hydrocarbon biofuels with a very low oxygen content; thus making them suitable to be combined with conventional fossil fuels for transportation fuel applications. In this paper, we present a framework to guide biofuel manufacturers seeking to extend traditional lignocellulosic biofuel manufacturing processes to process lignin waste and convert it to hydrocarbon biofuels. Additionally, we conducted an economic viability assessment on such integrated production processes by comparing to the baseline case based on the NREL 2011 bio-ethanol process design. The findings show that using lignin waste, the integrated manufacturing processes can produce 16 million gallons of hydrocarbon fuel in addition to the 67 million gallons of ethanol compared to the baseline case. In addition, the economic evaluation shows that the production cost per unit energy produced increases by only 3.97%, which indicates the integrated production scheme has great potential to be economically viable.