The problem of producing synthetic liquid fuels by alternative routes is addressed. Industrial processes known as Gas To Liquid (GTL), Coal To Liquid (CTL) and Biomass To Liquid (BTL) are considered: they use natural gas, coal and biomass as feedstocks, respectively. By means of process simulation, it is shown that the fuel produced on a weight basis per unit of feedstock (natural gas, coal and wood) are 66.7, 32.5 and 16.8%, respectively; in addition, the CO2 emitted per unit mass of liquid fuel is 0.90 kg CO2/kg for GTL, 4.79 kg CO2/kg for CTL and 6.08 kg CO2/kg for BTL process. In this last case, carbon dioxide is not an issue because it derives from a renewable source. The evaluation of production costs of synthetic fuel for a GTL process is carried out under two different scenaries: a plant localised where natural gas is readily available, and another one built far from the country where the gas is produced. A comparison between the costs of synthetic fuels from a GTL process and conventional fuel from oil refining is carried out to show the competitiveness of this alternative fuel. A financial analysis permits to conclude that, if a GTL plant is localised where the natural gas is extracted, the return of investment is after 2.4 years, whereas it changes to 6.9 years if the plant is located in western industrialised countries.
Keywords: biomass to liquid, BTL, coal to liquid, CTL, Fischer?Tropsch synthesis, FT synthesis, gas to liquid, GTL, gasification, synthetic fuels, liquid fuels, alternative fuels, alternative propulsion, natural gas, simulation, carbon dioxide emissions, greenhouse gas emissions, GHG emissions, ROI, return on investment