Techno-economic assessment of biomass-to-ethanol by indirect fluidized bed gasification: Impact of reforming technologies and comparison with entrained flow gasification

The production of ethanol from biomass via steam–air indirect circulating fluidized bed gasification (iCFBG) and subsequent catalytic synthesis has been economically assessed. Current and future states of technology have been considered. In the current scenarios, several configurations are proposed based on the reforming technology selected (steam reforming, autothermal reforming, partial oxidation, catalytic tar reforming), and a patented MoS2 catalyst is selected as a state-of-the-art mixed alcohol catalyst. In the future scenario, the expected improvement of the MoS2 catalyst is examined. A plant size of 2140dry tonne/day of wood chips (500MWth) was considered with the criterion of being energy self-sufficient. The results are compared with a previous study based on entrained-flow gasification (EFG) and also with production of biochemical ethanol from agricultural residue, showing that iCFBG with partial oxidation is the most cost-competitive option for the current state of technology, with a minimum selling price of ethanol (including 10% rate of return) of 0.75$/L.