Pulp mill integration with alcohol-to-jet conversion technology

This study examines the integration of commercial liquid fuels production from biomass using the alcohol-to-jet pathway into a conventional kraft pulp mill operation. Mill assets including feed handling and supply chain infrastructure, power and recovery systems, and potential equipment retrofitting opportunities are utilized by a fuel production unit through lignocellulosic ethanol fermentation and alcohol-to-jet processing. Potential economic benefits of integrating the energy recovery system (recovery boiler) of the pulp mill with the biomass pretreatment systems are evaluated through energy and mass balances of the integrated facility. Process variations explored within this model include the use of hemicellulose pre-extraction or black liquor fractionation, modifications to digester operations and the scale of a mill retrofitting project. The production of liquid fuels is found to provide a relative reduction in energy use compared to pulp production. With the low energy costs provided by this design, maintaining a high yield throughout the conversion process and the reduction of capital costs offer the best opportunities for further improving economics. Although the economic viability of a realistic biorefinery is not directly evaluated in this study, the aim is to identify technical barriers and opportunities for development of integrated strategies for implementing proven biofuels production technologies.