Sugarcane Biorefinery Research Articles

Pre-treatment of filter cake for anaerobic digestion in sugarcane biorefineries: Assessment of batch versus semi-continuous experiments

Anaerobic digestion (AD) of sugarcane filter cake (SFC) was investigated by comparing the performance of pre-treatment methods in biochemical methane potential (BMP) tests and semi-continuous experiments. For that, SFC was pre-treated by autoclaving the substrate alone or with sodium hydroxide (NaOH). Experimental data from BMP tests were fitted to a kinetics model and further used for simulating the AD process in a continuous stirred-tank reactor (CSTR). BMP tests showed differences (p < 0.05) in total methane potential (SBMP), which have affected methane yields during simulation in a CSTR. Untreated produced 185 mL CH4 gVS−1, autoclaved pre-treatment 174 mL CH4 gVS−1 and autoclaved with NaOH pre-treatment 222 mL CH4 gVS−1. Interestingly, such higher performance of autoclaved with NaOH pre-treatment was only observed at earlier stages during semi-continuous feeding experiment. At steady-state no significant differences (p > 0.05) in terms of methane yield were observed among the reactors (average of 224 mL CH4 gVS−1). These results demonstrate that the benefits of pre-treatment could only be observed in BMP tests, which is likely explained by a better adaptation of the microbial community to the substrate during long term semi-continuous experiment, making SFC pre-treatment ineffective in a single-stage CSTR and under this feeding regime.

Use of anaerobic co-digestion as an alternative to add value to sugarcane biorefinery wastes

In this study the anaerobic co-digestion (AcD) of sugarcane biorefinery by-products, i.e. hemicelluloses hydrolysate (HH) (obtained by hydrothermal pretreatment of sugarcane bagasse), vinasse, yeast extract (YE) and sugarcane bagasse fly ashes (SBFA), was optimized by means of biochemical methane potential experiments. The best experimental conditions of AcD (25–75% HH-to-vinasse mixture ratio; 1.0 g L−1 YE; 15 g L−1 SBFA and 100–0% HH-to-Vinasse; 1.5 g L−1 YE; 45 g L−1 SBFA) led to the production of 0.279 and 0.267 Nm3 of CH4 per kg of chemical oxygen demand (COD) with an energy surplus of 0.43 and 0.34 MJ kg SB−1, respectively. Adsorption experiments using SBFA were carried out and showed this residue could adsorb up to 61.71 and 17.32 mg g−1 of 5-hydroxymethyl-2-furfuraldehyde and 2-furfuraldehyde, thereby reducing toxicity and improving biogas production.

Beyond ethanol, sugar, and electricity: a critical review of product diversification in Brazilian sugarcane mills

AbstractProcess integration is an interesting option to reduce costs and improve the economic viability of new processes in sugarcane mills. Brazil has a prolific sugar‐energy sector, with hundreds of sugarcane mills that could possibly act as sources of carbon, energy, and water for annexed plants. While many studies analyze the integration of new technologies into sugarcane biorefineries as greenfield plants, the assessment and establishment of integrated processes into existing plants will help detecting process bottlenecks and enabling the required levels of integration to be better understood prior to designing a full‐scale, greenfield biorefinery. The present review provides an overview of the possibilities for sugarcane mills to diversify the portfolio of products from sugarcane biomass – beyond ethanol, sugar, and electric energy. The work initially considers the integrated production of market‐ready sugarcane‐derived products, such as animal feed, industrial salts, and hydrocarbons in existing Brazilian plants. Finally, the study outlines the prospects for future integration of non‐traditional process alternatives in sugarcane mills, namely bioplastics, organic acids, molecular hydrogen, and advanced lignocellulosic compounds. © 2019 Society of Chemical Industry and John Wiley &amp; Sons, Ltd.

Biomass Energy for Economic and Environmental Sustainability in India

India has emerged as the biggest sugar producer after Brazil producing 32.2 million MT sugar which is nearly 20% of global sugar output and is the top most consumer of the sugar in the world. The Indian sugar industry which encompasses about 524 operating sugar mills, 180 integrated distilleries and 260 co-generation plants lacks sustainability and has now realized that sugar, molasses and bagasse can no longer be regarded as final product or by-products from sugar industry. Thus, value additions, diversifications and transformations are to be vigorously investigated as possible routes to new market and making sugar industry less dependent on single commodity, i.e., sugar. The future of the sugar industry, as a whole, lies in development of sugarcane bio-refineries, i.e., bio-electricity, bio-ethanol, bio-manure and chemicals, etc. Sugar industry can be potential source of providing renewable, clean and green bioenergy in the interest of the industry itself by creating value addition, energy security for the nation and also to address the environmental issues.

Sugarcane ethanol and beef cattle integration in Brazil

New models for renewable energy production are needed to simultaneously decrease greenhouse gases (GHG) emissions, use land more efficiently and replace large amounts of fossil fuel. Ethanol production and livestock feed integration as practiced in the United States (USA) is one model for ethanol production combined with animal feed production. Brazil, the second largest ethanol and beef cattle producer in the world, can adapt the USA model of corn ethanol and cattle integration considering its local characteristics. This paper evaluates the techno-economic and environmental feasibility of sugarcane ethanol and cattle integration, thereby avoiding pasture displacement into forests or other sensitive lands. Cattle can be fattened in feedlots using some sugarcane ethanol byproducts. Intensification of cattle production by integration with sugarcane production releases pasture area to produce more biofuels, without needing more land for cattle production. The release of pasture land to produce more sugarcane results in what we call “avoided ILUC”, the resultant reduced GHG emissions compared to conventional sugarcane ethanol, because no additional land is needed to accommodate an additional sugarcane ethanol production. Simulations were performed using the Virtual Sugarcane Biorefinery (VSB) model developed by the Brazilian Bioethanol Science and Technology Laboratory (CTBE). We calculated as economic parameters the internal rate of return (IRR), net present value (NPV) and payback time. Climate impacts were assessed via Life Cycle Assessment. Sugarcane and cattle integration decreases overall climate impacts compared to non-integrated systems. Techno-economic feasibility is achieved by additional land rental revenues for released pasture area and by carbon credits.

Energy Integration of Biogas Production in an Integrated 1G2G Sugarcane Biorefinery: Modeling and Simulation

The integration of the first and second generation (1G2G) ethanol production promotes the increase of biofuel productivity per hectare of planted sugarcane, as well as the main liquid waste stream: vinasse, derived from ethanol distillation. As a sustainable way for it disposal, biogas production from anaerobic digestion (AD) promotes environmental suitability while enabling bioenergy generation. This work evaluated the potential energy generated from AD applied to vinasse within the context of an integrated 1G2G sugarcane biorefinery. Data from a literature survey based the scenario modeling and assessment, including economic and environmental indicators to compare the studied alternatives. AD allowed at least 68% increase of released bagasse for 2G ethanol production compared to 2G base scenario, being able to even double 2G ethanol productivity to 30 L t−1 cane. Organic matter removal efficiency of vinasse AD played an important role in 2G ethanol production so that higher the efficiency, larger the fraction of bagasse released for ethanol production. Economic indicators showed the unviability of 1G2G sugarcane mill including AD unit when considering the current technologies for 2G ethanol production in view of their high operational costs; however, with the envisaged technologies for 2025, the internal rate of return (IRR) of 14.3 and 17% was achieved, when considering conservative and optimistic data for vinasse AD efficiency, respectively. The results evidenced the importance of investment in R&D especially in 2G ethanol production but also in the AD of vinasse to reach the viability of this business.

Enriched microbial consortia for dark fermentation of sugarcane vinasse towards value-added short-chain organic acids and alcohol production

The role of sugarcane vinasse as a nutrient source and the impacts of different inoculum pretreatment methods (acid-thermal and thermal treatment) were assessed in acidogenic systems aiming to produce value-added short-chain organic acids (SCOA) and alcohols. In-depth microbiome characterization was also conducted by high-throughput sequencing of the 16S rRNA gene using the Miseq Illumina platform. SCOA production was 47.3 % higher in vinasse-fed reactors, with isobutyric (up to 10.3gL-1) and butyric (up to 10.6gL-1) acids as the primary metabolites most likely resulting from lactate conversion. Ethanol comprised the main product from solventogenic pathways in all conditions, with values ranging between 2.7 and 5.2gL-1, whereas no butanol was detected. Microbial analyses revealed high relative abundance values for the Clostridium, Lactobacillus, Bacillus and Ruminococcus genera, with the predominance of the Clostridium genus (17%) in acid-thermal treatment reactors and the Lactobacillus genus (37%) in thermal treatment reactors. Overall, vinasse proved to be a suitable substrate for value-added SCOA production, which characterizes a potential management approach to this wastewater stream. In this sense, the biochemical production of butyrate from vinasse could diversify the product portfolio of sugarcane biorefineries, also minimizing bioenergy losses by converting residual carbon fractions.

Comparative life cycle assessment of byproducts from sugarcane industry in Pakistan based on biorefinery concept

A comparative life cycle assessment of the sugarcane biorefinery in different conceptual arrangements was conducted considering four different alternatives with increasing utilization of byproducts. The first alternative with the least use of byproducts was taken as the base case and the fourth alternative was a completely integrated plant with gradually enhanced and efficient use of byproducts. The functional unit was defined as the production of 1 t of sugar in the biorefinery complex. The calculations were performed for the eight most relevant impact categories including global warming, freshwater eutrophication, terrestrial acidification, terrestrial ecotoxicity, freshwater ecotoxicity, human carcinogenic toxicity, mineral resource scarcity, and fossil resource scarcity. Overall, it was observed that for most of the impact categories, the values were progressively reduced with an increased use of byproducts (i.e., prevention of cane burning and its recovery; filter cake, ash, wastewater, and sludge as fertilizer; bagasse and cane trash for high-pressure cogeneration; ethanol as biofuel and recovery of CO2; biogas for waste to energy production). In general, it could be concluded that an enhanced and efficient use of byproducts would significantly improve the environmental performance of the biorefinery complex.

Thermo-economic evaluation of a new approach to extract sugarcane wax integrated to a first and second generation biorefinery

This study evaluates the integration of supercritical fluid extraction process to obtain sugarcane wax extract from the sugarcane filter cake residue. This cake is eliminated from the decantation process of sugarcane juice in the sugarcane biorefinery and it is generally used as a fertilizer. From this cake a lipophilic material, containing long-chain fatty alcohols and phytosterols, can be selectively recovered by means of the use of supercritical CO2 as extracting solvent. Aspen Plus® software was used to simulate the sugarcane biorefinery producing electricity, conventional and cellulosic ethanol and wax extract. A thermal-economic model was developed in Matlab software to perform energy integration and the economic analysis of this novel biorefinery concept. The results showed that by increasing temperature and pressure of the extraction process it is possible to produce more wax extract at an overall lower investment as lower extraction time is necessary, decreasing the number of extractors working in parallel. The integration of the extraction process to the sugarcane biorefinery had no impact on the overall ethanol production and had small impact on the electricity available for sale to the grid, decreasing only around 3% the net electricity. Payback time is strongly reduced by this integration strategy, decreasing 74% when the best configuration for SFE is adopted. The selling price for the wax extract strongly influences on the economic viability of this process, indicating that the integration of this extraction process to the sugarcane biorefinery is only economic attractive if the wax extract selling price is higher than 26.5 USD/kg.

Comparison of extraction techniques for product diversification in a supercritical water gasification-based sugarcane-wet microalgae biorefinery: Thermoeconomic and environmental analysis

This study presents a thermoeconomic and environmental assessment of the extraction of lipids and proteins from wet microalgal biomass in a 3G biorefinery by two different technologies: supercritical fluid extraction (SFE) and low-pressure solvent extraction (LPSE). Simulation tools were used to study a sugarcane biorefinery producing ethanol from sugarcane juice (1G) and bagasse (2G); the microalgal growth in an open pond; and the processing of microalgal biomass into lipids, proteins and synthetic natural gas (SNG). Supercritical water gasification (SCWG) of microalgal biomass enables an increase in biofuel production of 10.2% MJ when no extraction process is considered and of 1.9% MJ when LPSE is considered. The heat demand of the proposed biorefinery with LPSE was increased by 87.8% compared with the demand of the sugarcane biorefinery without microalgal growth and processing. When the SFE process is considered, the heat demand of the overall process increased 3.2 times. SFE for wet microalgae processing is not economically attractive, as it increases the total investment by 71%. The CO2 flow used in the SFE process demonstrated to be a key factor in the thermoeconomic viability of the process. Regarding the wet processing of microalgae prior to SCWG, the best alternative studied was the use of LPSE technology.

Expansion assessment of the sugarcane and ethanol production in the Llanos Orientales region in Colombia

AbstractThe Cauca River Valley region has traditionally been the main sugarcane production area for the sugar and ethanol industries in Colombia. This area is not expected to expand its agricultural frontiers, mainly due to social, geographic, and water limitations.This study is part of the Bioenergy Contribution of Latin America, the Caribbean and Africa to the Global Sustainable Bioenergy Initiative (LACAf) project, which assessed potential regions for the expansion of ethanol production in Colombia and Mozambique. Studies linked to the LACAf project have identified the Llanos Orientales (eastern savannas) region as the most appropriate option for sugarcane expansion in Colombia, due to its favorable climate and a significant amount of arable land available for agriculture. The main goal of this study was to assess the economic benefits and environmental impacts of several simulated ethanol biorefineries in the Llanos Orientales region. The study was performed using the Virtual Sugarcane Biorefinery, which allows the evaluation of integrated new alternatives for sugarcane and ethanol production. The results of this research showed that all the first‐ and second‐generation biorefineries assessed were profitable and attractive. Furthermore, the results of the simulations for the Lanos Orientales region have shown great potential for reducing environmental impacts compared to the current production in the Cauca River Valley. Consequently, the ethanol produced could qualify as ‘advanced’ in terms of the US Environmental Protection Agency criteria, and it meets the requirements of the European Parliament, representing a business opportunity to enter into the largest ethanol markets, and increasing biofuel production in Colombia. © 2018 Society of Chemical Industry and John Wiley &amp; Sons, Ltd

Comparative Performance Indexes for Ethanol Production Based on Autonomous and Annexed Sugarcane Plants

Future biomass conversion systems have to be developed using advanced technological routes in order to compete with fossil fuels, as well as to fulfill sustainability criteria. An attractive biomass feedstock for ethanol production is sugarcane, which is available in large amounts in several regions around the world. Although first-generation ethanol is a consolidated process, due to their large-scale production and tradition, there is still room for improved economic and environmental outcomes in the bioethanol industry.Bearing this in mind, this work presents a detailed process design strategy for biomass to ethanol production (1st-generation ethanol technology) from sugarcane. The simulation processes were performed using Aspen Plus® software focus on the annexed plant (production of bioethanol and sugar) and autonomous distillery(only bioethanol is produced) systems. Furthermore, a performance comparison in terms of the exergy efficiency and the destroyed exergy rate as a metric conversion of the processes are determined. Hence, the techno-economic bottlenecks in bioethanol production are attained using the exergy as an index. In addition, the sustainability aspects involved in the process design of the sugarcane biorefineries was discussed through the renewability exergy index. The results showed that the annexed plant has a reduction in the process irreversibilities rate of 6 % approximately, and in the average unitary exergy cost rate of 10 % approximately, in comparison to the autonomous distillery. Even though the proposed methodology is applied to 1G ethanol, it may well suited for several bioprocesses as a tool to help in taking decisions regarding design as well as operational policy definitions.

Sustainable Production of Food and Bioenergy: Techno- economic and Environmental Assessment of Sugarcane Ethanol and Livestock Integration

Despite their advantages when replacing fossil fuels, biofuels have faced some concerns related to their expansion within the so-called “food vs. bioenergy” debate. This debate relies on the premise that the use of food crops and/or the increase of land use for bioenergy production would affect food availability and price. Nevertheless, it is worth to mention that livestock production is the largest anthropic use of land resources worldwide. In Brazil, livestock production mainly consists of extensive management with low technology level, which results in a low average productivity. The intensification of this system would release pasture areas to expand cropland for biofuels production. In this way, the integration of sugarcane ethanol and livestock production would allow taking advantage of the synergies between both systems; for instance, using sugarcane agroindustrial residues as animal feed ingredients in feedlot systems. In addition, ethanol production from lignocellulosic feedstock (second-generation process) is also a possible solution towards a productive land use, since a larger amount of biofuels can be produced per crop area. This work focuses on the sustainability assessment of a first- and second-generation (1G2G) ethanol facility that produces animal feed using sugarcane by-products integrated to livestock production in feedlots. The Virtual Sugarcane Biorefinery (VSB) – a computer framework that simulates the entire production chain and assesses the sustainability impacts of different biorefinery alternatives/routes – was used in this work. This paper indicates that the integration of a future 1G2G sugarcane mill with intensive livestock system may be a feasible alternative. Regarding the economic performance, verticalization of a mill with intensive livestock is preferable when compared to extensive cattle production. Integrated scenarios also have environmental advantages, such as the production of more outputs using the same area, as well as more efficient technologies that may represent lower emissions. In addition, this paper revealed that it is possible to sustainably produce biofuels without displacing food crops or livestock production, which otherwise could advance, for example, in forest areas.

Year-round biogas production in sugarcane biorefineries: Process stability, optimization and performance of a two-stage reactor system

The concept of year-round biogas production to increase the capacity factor of anaerobic digestion (AD) plants in sugarcane biorefineries was investigated for the first time in semi-continuous feeding mode. To simulate the use of sugarcane vinasse during the sugarcane season and sugarcane filter cake (SFC) during the off-season period, a two-stage reactor system based on an acidogenic continuous stirred-tank reactor (1st stage) followed by solid–liquid separation and an upflow anaerobic sludge blanket (UASB) reactor (2nd stage) to convert the COD-rich liquid fraction into biogas was operated. Additionally, to optimize the biogas production from SFC, the effects of its thermo-chemical pre-treatment on AD were investigated in a parallel reactor set-up. The saponification effect provided by autoclaving the substrate with sodium hydroxide improved the hydrolysis/fermentation of SFC in the acidogenic reactor, which in turn resulted in a 28% higher volumetric methane production in the methanogenic reactor (p < 0.05). However, the methane yields observed during operation of the two-stage reactor system were markedly lower than previously found in biochemical methane potential tests using SFC. In this case, the feed-in with low suspended solids required by UASB reactors prevented the utilization of the non-hydrolyzed/fermented solid fraction of SFC (> 60% of the substrate’s methane potential). Nevertheless, the capacity factor of the AD plants in sugarcane biorefineries could be increased from 0.55 up to 0.69 when considering a 200 d a−1 sugarcane season (0.66–0.83 for a longer season of 240 d a−1), representing an increase of 25.7%. The average capacity factor for biogas combined heat and power and upgrading units of around 0.91 (8000 h a−1) would be reached if further developments could improve the solubilization of non-hydrolyzed/fermented solids or alternatively allow their direct use in the methanogenic reactor.

Ethanol production potential from AFEX\u2122 and steam-exploded sugarcane residues for sugarcane biorefineries

BackgroundExpanding biofuel markets are challenged by the need to meet future biofuel demands and mitigate greenhouse gas emissions, while using domestically available feedstock sustainably. In the context of the sugar industry, exploiting under-utilized cane leaf matter (CLM) in addition to surplus sugarcane bagasse as supplementary feedstock for second-generation ethanol production has the potential to improve bioenergy yields per unit land. In this study, the ethanol yields and processing bottlenecks of ammonia fibre expansion (AFEX™) and steam explosion (StEx) as adopted technologies for pretreating sugarcane bagasse and CLM were experimentally measured and compared for the first time.ResultsEthanol yields between 249 and 256 kg Mg−1 raw dry biomass (RDM) were obtained with AFEX™-pretreated sugarcane bagasse and CLM after high solids loading enzymatic hydrolysis and fermentation. In contrast, StEx-pretreated sugarcane bagasse and CLM resulted in substantially lower ethanol yields that ranged between 162 and 203 kg Mg−1 RDM. The ethanol yields from StEx-treated sugarcane residues were limited by the aggregated effect of sugar degradation during pretreatment, enzyme inhibition during enzymatic hydrolysis and microbial inhibition of S. cerevisiae 424A (LNH-ST) during fermentation. However, relatively high enzyme dosages (> 20 mg g−1 glucan) were required irrespective of pretreatment method to reach 75% carbohydrate conversion, even when optimal combinations of Cellic® CTec3, Cellic® HTec3 and Pectinex Ultra-SP were used. Ethanol yields per hectare sugarcane cultivation area were estimated at 4496 and 3416 L ha−1 for biorefineries using AFEX™- or StEx-treated sugarcane residues, respectively.ConclusionsAFEX™ proved to be a more effective pretreatment method for sugarcane residues relative to StEx due to the higher fermentable sugar recovery and enzymatic hydrolysate fermentability after high solids loading enzymatic hydrolysis and fermentation by S. cerevisiae 424A (LNH-ST). The identification of auxiliary enzyme activities, adequate process integration and the use of robust xylose-fermenting ethanologens were identified as opportunities to further improve ethanol yields from AFEX™- and StEx-treated sugarcane residues.

Defining research & development process targets through retro-techno-economic analysis: The sugarcane biorefinery case

A new approach is reported for techno-economic analysis of lignocellulosic ethanol production. With this methodology, general targets for key process variables can be draw, a valuable feedback for Research & Development teams. An integrated first- and second-generation ethanol from sugarcane biorefinery is presented as a case study for the methodology, with the biomass pretreated by liquid hot water, followed by enzymatic hydrolysis of the cellulose fraction. The hemicellulose fraction may be either fermented or biodigested. The methodology was able to identify the main variables that affect the process global economic performance: enzyme load in the cellulose hydrolysis reactor, cellulose-to-glucose, and xylose-to-ethanol yields. Windows of feasible operation are the graphical output of the methodology, outlining regions to be further explored experimentally. One example of quantitative result is that the maximum feasible enzyme load was 11.3 FPU/gcellulose when xylose is fermented to ethanol and 7.7 FPU/gcellulose when xylose is biodigested.

A new insight into sugarcane biorefineries with fossil fuel co-combustion: Techno-economic analysis and life cycle assessment

In this study, alternative lignocellulosic biorefineries annexed to a typical sugarcane mill were investigated, to produce ethanol, lactic acid or methanol, or co-production of ethanol and lactic acid, all with surplus electricity for sale by conversion of sugarcane bagasse and harvesting residues (brown leaves) as accessible feedstock. In order to meet the energy demand of the sugar mill and biorefinery, burning a portion of feedstock or fossil source (coal) along with residues in the centralized combined heat and power unit were assumed as energy supplement strategies. A thorough Aspen Plus simulation was developed for each biorefinery scenario considering all required process units and supplementary units (i.e. combined heat and power, waste water treatment and evaporation). Furthermore, mass and energy balances along with costing data were applied to carry out techno-economic analysis, Monte Carlo finical risk study and life cycle assessment, in a multi-criteria desirability matrix. The lactic acid production biorefinery was found to be the most energy intensive process with highest chemical consumption and the highest conversion of biomass carbon input to products. Consumption of coal as an alternative source of energy enhanced the available biomass for valorization. Biorefineries with coal combustion producing ethanol or ethanol-lactic acid showed better environmental performance than methanol producing biorefineries, based on 1 ton of product. Although, the co-production of ethanol and lactic acid showed the largest likelihood of economic success, Methanol producing scenarios had a zero likelihood of an economic viability without substantial financial incentives or enhanced market prices.

Diversifying the technological strategies for recovering bioenergy from the two-phase anaerobic digestion of sugarcane vinasse: An integrated techno-economic and environmental approach

Abstract Technical, economic and environmental aspects of implementing two-phase anaerobic digestion (AD), i.e., acidogenic + methanogenic systems, in sugarcane biorefineries for the treatment of vinasse were assessed based on different strategies to using the hydrogen-rich biogas (biogas-H2) generated via acidogenesis. Phase separation greatly enhanced the bioenergy recovered from vinasse AD compared with single-phase systems (methanogenic phase exclusively). The best results for generating electric energy were observed in combined cycle-based power plants that utilized biohythane (10.8 MW + 5.5 MW for the harvest and inter-harvest, respectively), which is the gaseous biofuel from blending biogas-H2 with the methane-rich stream from the methanogenic phase (biogas-CH4). Moreover, the results of this study indicated that scaling up two-phase AD systems is economically feasible for the treatment of sugarcane vinasse (net present value = USD 208.58–219.86 million) because a better or equivalent economic performance was attained compared with single-phase processes. Optimizing the alkalinization of methanogenic reactors strongly affected both the economic and environmental performance of the process, with better results observed with the use of low sodium hydroxide dosages (4 g NaOH kg−1COD). In summary, our results highlighted that two-phase biodigestion may enhance energy production from vinasse by 20–30% without impairing the profitability of the biorefinery and could lead to slight improvements in the environmental performance of the ethanol production chain via the use of an optimized alkalinization strategy.

Pulp and Paper from Sugarcane: Properties of Rind and Core Fractions

Two distinct lignocellulosic fractions (rind and core) can be obtained through a physical separation of sugarcane stalks. Although presenting differences in morphology, both fractions can be employed to produce pulps and papers. The pulps and paper sheets produced from the core and rind fractions were characterized by their chemical composition, physical properties and mechanical properties. The pulps obtained from the core presented a higher amount of fines, lower drainage ability and rendered denser and stiffer sheets. The pulps from the rind, which have a higher content of fibers and higher degree of polymerization, produced sheets with higher air permeability and water absorption. Both paper sheets presented mechanical and physical properties comparable to commercial papers and papers from different cellulosic sources. The different properties exhibited by the papers produced from each fraction allow their use for distinct purposes, and expands the opportunities in the context of sugarcane biorefinery.

Process integration of a multiperiod sugarcane biorefinery

Process integration in sugarcane biorefineries allows reducing steam consumption. As a consequence, the bagasse surplus can be diverted to second generation ethanol production. Furthermore, sugarcane plants can vary the production of ethanol and electricity, depending on the demand. For those reasons, equipment present in the plant might be required to operate under different conditions. This study presents the energy integration of a sugarcane biorefinery. A Mixed Integer Nonlinear Programming (MINLP) optimization model is proposed to solve the problem of synthesizing a Heat Exchanger Network (HEN) able to periodically operate under the distinct conditions required in the biorefinery, i.e., a multiperiod HEN. For solving the MINLP problem, a hybrid metaheuristic approach was used, which combines Simulated Annealing and Rocket Fireworks Optimization. The proposed strategy achieved lower HEN total annualized cost (TAC) when compared with the project energy integration that is commonly found in Brazilian plants. This reduction in TAC, in particular in utilities demand, allows the surplus bagasse to be available for the most suitable application: produce 2G ethanol or more electricity.