Why Hasn't Biomass-to-Bioethanol Conversion Been Commercialized Yet?

Global demand for renewable and sustainable biofuels promoted the considerable development of biomass-to-bioethanol valorization strategies. However, the efforts have not led to its large commercial realization in the United States yet. Herein, we aim to reveal the challenges such as abundant wastewater production that is discarded after biomass pretreatment, low solid loading used for biomass pretreatment, enzymatic hydrolysis and fermentation, as well as overestimation and inconsistency in techno-economic analysis. Regarding the reduction in water consumption and enhancement of sugar and ethanol concentrations, physicochemical and biological detoxification, black liquor recycling, fed-batch model, strain genetic engineering, and ethanol (1G and 2G) integration approaches are critically discussed in terms of strengths and weaknesses. Collectively, biomass-to-bioethanol commercialization necessitates comprehensive understanding of economic, environmental, and policy perspectives. Techno-economic analysis as an essential valuation for potential commercialization from laboratory scale is recommended, and it should be relaying on accurate experimental data rather than an overrated empirical assessment