This work focuses on the production of F-T diesel from wood biomass, considering three different systems: production of wood pellets, bioslurry via fast pyrolysis, and use of untreated biomass. This study aims to find the most energy efficient way in which the wood biomass can be transformed into synthetic diesel, and the importance of every step taking part in the entire system. The assessment of these routes considers the whole chain: extraction of biomass, transport of raw material to a local plant, pre-treatment if necessary, transport to the central gasification plant, gasification process and Fischer-Tropsch synthesis. The three BTL routes are compared by means of Primary Energy Factors (PEF). In order to obtain reliable results, the transport distance from the local plant to the central gasification plant and the moisture content of biomass have been modified. Primary energy factors, only taking into account the non-renewable part, have also been calculated. The results show that gasification process and Fischer-Tropsch synthesis are the decisive steps. At the moment, the use of untreated biomass seems to be the best option in spite of the high transport energy. However, when the moisture content is high (about 60%) and only the non-renewable part is considered then, the second route, which is based on bioslurry production, is the most energy efficient.