A model of an integrated hydrothermal liquefaction, gasification and Fischer-Tropsch synthesis process for converting lignocellulosic forest residues into hydrocarbons

Abstract

The aim of this work was to develop a model of an integrated biomass-to-liquid process, consisting of hydrothermal liquefaction, evaporation, gasification and Fischer-Tropsch synthesis, using lignocellulosic forest residues as feedstock, to produce hydrocarbons suitable for upgrading to drop-in biofuels. The energy, mass and carbon efficiencies obtained were 40%, 20% and 32%, respectively. The Fischer-Tropsch crude carbon chain length distribution peaked at carbon chain length 10 with a heavy right tail , which is beneficial for upgrading the Fischer-Tropsch crude to jet fuel. Life cycle assessment was performed for two potential production plants at different sites in Sweden (one in northern Sweden and the other in southern Sweden). Compared with the fossil fuel comparator in the European Union's Renewable Energy Directive (II), the reduction in life cycle greenhouse gas emissions was 85-95% for the Fischer-Tropsch crude produced in northern Sweden and 92-97% for that produced in southern Sweden, depending on differences in the transportation distance and feedstock used.

Keywords: Chemical process model; Fischer-Tropsch; Gasification; Hydrothermal liquefaction; Life cycle assessment.