Carbon Neutral Fuels and Chemicals from Standalone Biomass Refineries

Abstract

The urgency to eliminate man-made greenhouse gas emissions and achieve energy security/independence by all countries justifies an energy policy that considers the major role of renewable biomass as a source of organic feedstock for producing adequate organic chemicals and biofuels on a sustainable basis and economically. This paper investigates a three-stage thermochemical process to convert wet biomass into a tailored mix of syngas for producing green methanol, hydrogen, and Fischer-Tropsch products. The three-stage thermochemical process involves the torrefaction of wet biomass using hot carbon monoxide gas, pyrolysis of torrefied biomass to produce biochar, and final gasification of the pyrolysis gases by auto thermal reforming up to 1400o C temperature. The proposed process is suitable to utilize a wide variety of biomass materials such as freshly harvested biomass without field drying, agro waste, forest/plantation litter, organic municipal solid wastes, sludge from sewage water treatment plants, solid biomass rejects from anaerobic digesters, bagasse from sugar or first-generation ethanol plants, organic solid rejects from second-generation ethanol plants, waste glycerides from biodiesel plants, industrial organic waste, etc. The proposed process offers valorization of biomass so that the net income of farmers is enhanced a fewfold by selling freshly harvested biomass. The economic analysis found that carbon-neutral hydrogen, methanol, etc can be produced below the prevailing costs of such products derived from fossil crude oil or natural gas without considering carbon credits. It is feasible in a standalone biomass refinery to use any biomass as only one bulk raw material/feedstock without any harmful emissions to water bodies or the atmosphere except carbon neutral carbon dioxide gas if not sequestrated.