Fischer-Tropsch (FT) diesel derived from biomass via gasification is an attractive clean and carbon neutral transportation fuel, directly usable in the present transport sector. System components necessary for FT diesel production from biomass are analysed and combined to a limited set of promising conversion concepts. The main variations are in gasification pressure, the oxygen or air medium, and in optimisation towards liquid fuels only, or towards the product mix of liquid fuels and electricity. The technical and economic performance is analysed. For this purpose, a dynamic model was built in Aspen Plus(R), allowing for direct evaluation of the influence of each parameter or device, on investment costs, FT and electricity efficiency and resulting FT diesel costs. FT diesel produced by conventional systems on the short term and at moderate scale would probably cost 16 is an element of/GJ. In the longer term (large scale, technological learning, and selective catalyst), this could decrease to 9 is an element of/GJ. Biomass integrated gasification FT plants can only become economically viable when crude oil price levels rise substantially, or when the environmental benefits of green FT diesel are valued. Green FT diesel also seems 40-50% more expensive than biomass derived methanol or hydrogen, but has clear advantages with respect to applicability to the existing infrastructure and car technology. (C) 2004 Elsevier Ltd. All rights reserved.