An integrated process for total bioethanol production and zero CO2 emission

Abstract

Increasing oil prices and global concern about climate change motivate the investigation of more efficient means of bioethanol production. An integrated process is proposed in this Thematic Project, aiming to maximize the productivity of bioethanol from sugarcane molasses, bagasse and straw, which give rise to, respectively, first and second generation bioethanol. The Greenhouse Gas carbon dioxide, produced in this two ethanol generations processes, is proposed to be used in the production of a third generation of ethanol, which comes both from algal/bagass biomass and catalytic transformation or biological fermentation of synthesis gas. This challenging integrated process has the major appeal of not emitting carbon dioxide and makes the best of the carbon-containing material for producing ethanol, turning it, when technically and economically feasible, a milestone for improving Brazilian bioethanol competitiveness. The specific objectives of this project look for ways of turning this integrated process into a technically and economically feasible one, investigating new technologies for each part of processes, covering first, second and third generation aiming anhydrous low bioethanol production. In this way, it will be studied alternative fermentation processes (extractive units), eco-efficient pretreatments as a part of an integrated bioethanol from sugarcane bagasse and straw, development of high-performing enzyme formulations and process techniques of both enzymatic hydrolysis and fermentation, coupled with the development of suitable yeast to ferment sugarcane biomass carbohydrates. In addition, the possibility of microalgae consuming CO2 from alcoholic fermentation, constituting energy generation cycle with environment protection and production of bioethanol through the synthesis gas, which is obtained from biomass will be investigated. Besides that, multiple effect operation of the distillation columns of the process will be studied in order to reduce steam consumption on reboilers and compared to alternative strategies, including the hybrid ones. The study of alternative entrainers (ionic liquids and hyperbranched polymers) for the extractive distillation process for anhydrous bioethanol production will be carried out. Process modeling and simulation, either of single units or for the large scale plant will be used as a tool for process evaluation and decision taking. Process optimization will be considered to extract the best yield of each routes so that quantitative discrimination will be possible. In any case, methodologies that may be necessary whenever a re-estimation of parameters is required and among other tools software sensors based on Artificial Neural Network will be developed to infer concentrations of biomass, bioethanol and substrate from secondary measurements, such as pH, turbidity and CO2 flow rate. The global processes evaluation will make use of the experimental data collected in the experiments, industrial data and information and together with process simulation trough commercial simulators and tailor made softwares. All the routes will be evaluated in the optimal conditions achieved by a set of suitable optimization algorithms including the deterministic and stochastic based ones. (AU)