Marina O.S. Dias

Integrated versus stand-alone second generation ethanol production from sugarcane bagasse and trash.

Ethanol production from lignocellulosic materials is often conceived considering independent, stand-alone production plants; in the Brazilian scenario, where part of the potential feedstock (sugarcane bagasse) for second generation ethanol production is already available at conventional first generation production plants, an integrated first and second generation production process seems to be the most obvious option. In this study stand-alone second generation ethanol production from surplus sugarcane bagasse and trash is compared with conventional first generation ethanol production from sugarcane and with integrated first and second generation; simulations were developed to represent the different technological scenarios, which provided data for economic and environmental analysis. Results show that the integrated first and second generation ethanol production process from sugarcane leads to better economic results when compared with the stand-alone plant, especially when advanced hydrolysis technologies and pentoses fermentation are included.

Second generation ethanol in Brazil: can it compete with electricity production?

Much of the controversy surrounding second generation ethanol production arises from the assumed competition with first generation ethanol production; however, in Brazil, where bioethanol is produced from sugarcane, sugarcane bagasse and trash will be used as feedstock for second generation ethanol production. Thus, second generation ethanol production may be primarily in competition with electricity production from the lignocellulosic fraction of sugarcane. A preliminary technical and economic analysis of the integrated production of first and second generation ethanol from sugarcane in Brazil is presented and different technological scenarios are evaluated. The analysis showed the importance of the integrated use of sugarcane including the biomass represented by surplus bagasse and trash that can be taken from the field. Second generation ethanol may favorably compete with bioelectricity production when sugarcane trash is used and when low cost enzyme and improved technologies become commercially available.

Butanol production in a first-generation Brazilian sugarcane biorefinery: Technical aspects and economics of greenfield projects

The techno-economics of greenfield projects of a first-generation sugarcane biorefinery aimed to produce ethanol, sugar, power, and n-butanol was conducted taking into account different butanol fermentation technologies (regular microorganism and mutant strain with improved butanol yield) and market scenarios (chemicals and automotive fuel). The complete sugarcane biorefinery with the batch acetone-butanol-ethanol (ABE) fermentation process was simulated using Aspen Plus®. The biorefinery was designed to process 2 million tonne sugarcane per year and utilize 25%, 50%, and 25% of the available sugarcane juice to produce sugar, ethanol, and butanol, respectively. The investment on a biorefinery with butanol production showed to be more attractive [14.8% IRR, P(IRR>12%)=0.99] than the conventional 50:50 (ethanol:sugar) annexed plant [13.3% IRR, P(IRR>12%)=0.80] only in the case butanol is produced by an improved microorganism and traded as a chemical.

Utilization of pentoses from sugarcane biomass: Techno-economics of biogas vs. butanol production

This paper presents the techno-economics of greenfield projects of an integrated first and second-generation sugarcane biorefinery in which pentose sugars obtained from sugarcane biomass are used either for biogas (consumed internally in the power boiler) or n-butanol production via the ABE batch fermentation process. The complete sugarcane biorefinery was simulated using Aspen Plus®. Although the pentoses stream available in the sugarcane biorefinery gives room for a relatively small biobutanol plant (7.1-12 thousand tonnes per year), the introduction of butanol and acetone to the product portfolio of the biorefinery increased and diversified its revenues. Whereas the IRR of the investment on a biorefinery with biogas production is 11.3%, IRR varied between 13.1% and 15.2% in the butanol production option, depending on technology (regular or engineered microorganism with improved butanol yield and pentoses conversion) and target market (chemicals or automotive fuels). Additional discussions include the effects of energy-efficient technologies for butanol processing on the profitability of the biorefinery.

Simulation of ethanol production from sugarcane in Brazil: economic study of an autonomous distillery

Abstract Simulation of the production of ethanol from sugarcane in an autonomous distillery was carried out using software SuperPro Designer and electronic spreadsheet. Analysis of the ethanol production costs was performed for different production scenarios, considering improvements on the energy production from sugarcane bagasse and the selling of surplus electricity. It was verified that selling of surplus electricity positively influences the ethanol production costs.

Anhydrous bioethanol production using bioglycerol – simulation of extractive distillation processes

Bioethanol has been increasingly used as fuel in the anhydrous form, mixed with gasoline. In this work, two configurations of the extractive distillation process using bioglycerol as a solvent for anhydrous bioethanol production were investigated. Simulations results show that bioglycerol is a suitable agent for the separation of ethanol-water mixtures, with low energy consumption on the column reboilers and the production of high quality anhydrous bioethanol.

Simulation of the Azeotropic Distillation for Anhydrous Bioethanol Production: Study on the Formation of a Second Liquid Phase

Abstract Bioethanol is produced from fermentation of sugars, what produces a dilute solution (around 10 wt% ethanol). Because water and ethanol form an azeotrope with concentration of 95.6 wt% ethanol at 1 atm, an alternative separation process such as azeotropic distillation must be employed to produce anhydrous bioethanol, which can be used in a mixture with gasoline. In this work, simulations of three different configurations of the azeotropic distillation process with cyclohexane for anhydrous bioethanol production were carried out using software Aspen Plus. Process parameters were optimized in order to decrease the formation of a second liquid phase inside the column. Ethanol and entrainer losses as well as energy demand were evaluated.

Economic and environmental assessment of integrated 1st and 2nd generation sugarcane bioethanol production evaluating different 2nd generation process alternatives

Abstract Integration of second generation ethanol production from lignocellulosic material with first generation ethanol production from sugarcane juice may foster its environmental and economic feasibility. Since sugarcane bagasse and trash may be used as energy feedstock in bioethanol production process, the amount of surplus lignocellulosic material that could be used for second generation bioethanol production is related to the processes energy consumption. In this work different process configurations for second generation were evaluated through simulation with Aspen Plus. Bearing this in mind, economic and environmental analyses are based on simulation results. Evaluated process alternatives presented different impact trends on sustainability indicators, indicating also that they may lead to higher ethanol output, higher economic returns and lower environmental impacts, pointing out that improvements are required in the ethanol production process for a sustainable energy future.

Simulation and optimization of the continuous vacuum extractive fermentation for bioethanol production and evaluation of the influence on distillation process

Abstract In this work, the use of a vacuum extractive fermentation reactor, which allows the production of wine with higher ethanol concentration, as well as its effects on the distillation stage, were studied for bioethanol production. Energy consumption was evaluated and compared to the conventional process, showing that the proposed configuration provides a significant reduction in energy consumption, so it seems an interesting option for process intensification.

Optimization of Bioethanol Distillation Process – Evaluation of Different Configurations of the Fermentation Process

Abstract Process simulation was used to analyze bioethanol distillation process, which requires a large amount of thermal energy. As it is shown in this study, in the ethanol production process the fermentation stage has a significant impact on energy consumption in the purification step. Thus, alternative configurations in the fermentation and distillation processes were proposed and evaluated. The results showed that vacuum extractive fermentation coupled with triple effect distillation presented the lowest energy demand among the studied configurations.