This study focuses on the process integration of gasification in the thermo-chemical conversion of lignocellulosic biomass into liquid fuels thorough gasification and Fischer-Tropsch (F-T) synthesis (biomass to liquids, BtL). Two main gasification technologies are compared: the Entrained Flow (EF) gasifier and the Fast Internally Circulating Fluidized bed (FICFB) gasifier. The comparison is carried out through the detailed energy and mass balances as well as the pinch analysis of the explored process options, the characteristic results of the process integration of each configuration are presented. The role of torrefaction for the FICFB gasifier is evaluated and the trade off between the mass loss engendered and the improved process integration is highlighted.