Product Selection and Supply Chain Optimization for Fast Pyrolysis and Biorefinery System

This study determines the optimal plant sizes, locations, and product distributions for an integrated fast pyrolysis biorefinery supply chain using a mixed-integer nonlinear programming (MINLP) model. Hydrogen, liquid fuels, commodity chemicals, and lignin are considered as the potential biorefinery products. The proposed approach is illustrated through a case study of Minnesota, where forest residue is selected as the biomass feedstock. The decisions about biomass supply (roadside chipped forest residue and raw forest residue), facility selection, and product distribution are explored in this case study. The total converted bio-oil is 1.1 million metric tons per year and the total cost is $330 million for the base case. Impacts of marketing prices on product selections are investigated. Compared to upgrading of phase separated bio-oil, whole bio-oil upgrading is preferable in terms of economics. Hydrogen and liquid fuel prices have greater influence on the annualized profit than the commodity chemical price

Natural Gas and Cellulosic Biomass: A Clean Fuel Combination? Determining the Natural Gas Blending Wall in Biofuel Production

Natural gas has the potential to increase the biofuel production output by combining gas- and biomass-to-liquids (GBTL) processes followed by naphtha and diesel fuel synthesis via Fischer–Tropsch (FT). This study reflects on the use of commercial-ready configurations of GBTL technologies and the environmental impact of enhancing biofuels with natural gas. The autothermal and steam-methane reforming processes for natural gas conversion and the gasification of biomass for FT fuel synthesis are modeled to estimate system well-to-wheel emissions and compare them to limits established by U.S. renewable fuel mandates. We show that natural gas can enhance FT biofuel production by reducing the need for water–gas shift (WGS) of biomass-derived syngas to achieve appropriate H₂/CO ratios. Specifically, fuel yields are increased from less than 60 gallons per ton to over 100 gallons per ton with increasing natural gas input. However, GBTL facilities would need to limit natural gas use to less than 19.1% on a LHV energy basis (7.83 wt %) to avoid exceeding the emissions limits established by the Renewable Fuels Standard (RFS2) for clean, advanced biofuels. This effectively constitutes a <i>blending</i> limit that constrains the use of natural gas for enhancing the biomass-to-liquids (BTL) process