Technoeconomic assessment of ethanol production via thermochemical conversion of biomass by entrained flow gasification

The production of ethanol via entrained flow gasification of biomass and subsequent catalytic synthesis is economically assessed by considering current and future scenarios. In the current scenarios, the process plants proposed only make use of available technologies and state-of-the-art mixed alcohol catalysts (Rh–Mn/SiO2 and KCoMoS2 catalysts). In the future scenarios, the effects of improvements in MoS2 catalyst performance and the availability of pressurized solid biomass feeding systems are assessed. A plant size of 2140 dry tonnes/day of wood chip (500 MWth) is considered with the criteria of being energy self-sufficient. The economic results are discussed and also compared with state-of-the-art production of biochemical lignocellulosic ethanol.The results reveal that although the Rhodium catalyst presents better performance than MoS2 catalysts in terms of selectivity to ethanol, the high price of the Rhodium catalyst leads to higher production costs. For current catalysts, the minimum ethanol selling price (including 10% rate of return) is in the range of 0.90–1.25 $/L. In a future scenario, expected improvements in MoS2 catalyst performance would lead to a decrease in price to 0.71 $/L. Besides, if biomass piston feeders were commercially available, as an alternative for flash pyrolysis pre-treatment, the minimum ethanol selling price would decrease to 0.55 $/L.

► Comparison of thermochemical ethanol production cost for state-of-the-art mixed alcohol catalysts via entrained flow gasification of biomass.
► High cost of mixed alcohol catalysts with precious metals overweighs their higher ethanol selectivity in terms of ethanol production cost.
► At current state of technology, lignocellulosic ethanol production cost via assessed thermochemical pathway is 5% larger than via biochemical pathway.
► Development of pressurized solid biomass feeding systems would lead to significant reduction of ethanol production costs.