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Sugarcane ethanol production generates about 360 billion liters of vinasse, a liquid effluent with an average chemical oxygen demand of 46,000 mg/L. Vinasse still contains about 11% of the original energy from sugarcane juice, but this chemical energy is diluted. This residue, usually discarded or applied in fertigation, is a suitable substrate for anaerobic digestion (AD). Although the technology is not yet widespread—only 3% of bioethanol plants used it in Brazil in the past, most discontinuing the process—the research continues. With a biomethane potential ranging from 215 to 324 L of methane produced by kilogram of organic matter in vinasse, AD could improve the energy output of sugarcane biorefineries. At the same time, the residual digestate could still be used as an agricultural amendment or for microalgal production for further stream valorization. This review presents the current technology for ethanol production from sugarcane and describes the state of the art in vinasse AD, including technological trends, through a recent patent evaluation. It also appraises the integration of vinasse AD in an ideal sugarcane biorefinery approach. It finally discusses bottlenecks and presents possible directions for technology development and widespread adoption of this simple yet powerful approach for bioresource recovery. [ABSTRACT FROM AUTHOR]

The high production of sugarcane in Brazil and its application of ethanol and sugar production results in a higher generation of vinasse and bagasse. The treatment of these residues can be carried out using anaerobic co-digestion procedures. Besides promoting waste treatment, it enables energy exploration through biogas and hydrogen generation. Bioenergy use can also generate steam in sugar and alcohol plants by burning, sugarcane milling, fueling vehicles for the transport of products, among others. These energy applications allow total and efficient, energetic exploring of sugarcane. Hence, this study estimated the production of methane, hydrogen, thermal and electrical energy generated from vinasse and bagasse in the autonomous and annexed Brazilian ethanol and sugar plants. Three scenarios present the use of biogas generated: Scenario 1: energy use of all methane from biogas; Scenario 2: hydrogen production from the remaining methane, after considering the energy autonomy of the ethanol plants; Scenario 3: hydrogen production from all the methane generated. All the scenarios which considered the use of methane led to energy self-sufficiency in the sector. However, only annexed plants present economic feasibility for implementing the project. Scenario 2 is highlighted in this study, once beyond the sector's energetic self-sufficiency, the operational conditions enabled the storage of 9.26E+07 Nm3.d−1 of hydrogen, equal 3.04E+08 ton per year. CH 4 and H 2 production seen in a global scenario of circular economy and energy security have high benefits, contributing to the gradual transformation of an economy dependent on non-renewable resources into a circular and renewable economy. [Display omitted] • Sugarcane bagasse and vinasse use to generate H 2 and CH 4. • 9.26E+07 Nm3.d−1 of hydrogen produced. • Transformation into a circular and renewable economy. [ABSTRACT FROM AUTHOR]

The thematic area studied in this paper considers environmental issues such as atmospheric pollution from the combustion of fossil fuels, and the environmental impacts from the generation of urban agricultural solid wastes. This study has estimated the potential for hydrogen and biogas production from solid urban waste (SUW) and wine waste from Bento Gonçalves, which is a region in Brazil with the largest wine throughput and subsequent waste generation, thus providing a potential high-energy feedstock. The resulting hydrogen and biogas are assumed to displace the existing fuels in the local bus fleet. The analytical work consisted of three scenarios - scenario 1: production of biogas using SUW, sourced exclusively from the municipality of Bento Gonçalves; Scenario 2: the possibility to supply SUW from Bento Gonçalves and surrounding cities, to produce biogas; Scenario 3: the possibility to use wine waste and SUW for biogas production. Scenario 3 showed the greatest energy yield with 37.9 Gg of biomethane produced per year, which can supply the entire public bus fleet of Bento Gonçalves. The resulting hydrogen production potential using steam reforming of biomethane is 1.09 E+08 Nm3H 2.d−1 which can generate 2.62 TW h.year−1 of electrical energy, avoiding approximate emissions of 355 ktonCO 2.year−1. These findings indicate value in the production of biogas from urban and agricultural wastes, especially for the generation of methane, hydrogen and useful energy outputs. Its production from renewable and clean sources contributes to the gradual transformation of an economy currently dependent on non-renewable resources into a circular and renewable economy. [Display omitted] • Biomethane and hydrogen production from the wine industry. • 7.76 E+06 and 1.09 E+08 Nm3.d−1 of H 2 production. • 2.53 E + 04 to 3.55 E+05 tonCO 2.year−1 of avoided emissions. [ABSTRACT FROM AUTHOR]

This study analyzed biogas production from the anaerobic digestion of Coffee Wastewater (CWW), in Brazil. Physicochemical analyzes of CWW were performed before and after biodigestion. Four biodigesters B1, B2, B3, B4 maintained at 37 °C ± 2 °C were connected to a gasometer. 1.35 L of CWW and 0.15 L of inoculum (sludge from an Upflow Anaerobic Sludge Blanket) were fed into biodigesters B3 and B4, resulting in a total substrate level of 1.5 L for each one. Biodigesters B1 and B2 were fed 1.5 L of CWW that was pH adjusted to 6–8 in all four biodigesters at the start of the biodigestion. Theoretical estimations were given for the biomethane potential (BMP) arising from the chemical oxygen demand (COD). Given the BMP values, economic feasibility analysis was performed for a biogas system implemented in a coffee roasting production system under three scenarios: I - BMP for CWW COD without inoculum; II - BMP for CWW COD with inoculum; and III - BMP for the minimum required level of CWW COD needed for the system to be economically viable. The highest methane content observed was 11.4% in B4, which had the highest relative methane production to removed volatile solids (17.31 LkgVS−1 rem). • Physicochemical analysis of CWW were carried out before and after biodigestion • The biogas production from CWW were evaluated in four anaerobic batch reactor • Three economic feasibility scenarios was simulated using a theoretical BMP • The CWW biodigestion with inoculum presented better biogas yield • The BMP recovery energy for coffee roasting was not economic feasible [ABSTRACT FROM AUTHOR]

• Methane-based fuels prospects in the Brazilian market. • Engine bench testing across varied load conditions and compression ratios. • Performance evaluation across conventional fuels like ethanol and gasoline. • Assessing combustion characteristics and emissions among tested fuels. • Economic viability analysis based on cost per kWh for each fuel. Brazil has a long history of using biofuels in the transport sector, especially due to the 40 years widespread use of ethanol and almost 20 years of biodiesel. Nevertheless, more efforts are needed to reduce even further the carbon emissions of the transport sector. In addition to ethanol, gaseous fuels such as biogas and biomethane are gaining ground due to their great potential to be obtained through biomass processing. To prospect the potential use of biomethane as a vehicle fuel in Brazil, compressed natural gas (CNG), another methane-based fuel with similar composition to biomethane, was tested and had its performance and emissions compared to hydrous ethanol and Brazilian gasoline at three different operating conditions in two different compression ratios: 3.0 bar, 6.0 bar and 9.0 bar IMEP at 1800 rpm, exploring compression ratios of 11.6:1 and 14.3:1. With CNG, engine operation at MBT was possible with both compression ratios. Ethanol presented border knock near MBT for the highest compression ratio and load, while the gasoline spark timing was knock-limited for both compression ratios at the highest load. Indicated efficiency of CNG was higher than that of gasoline and lower than that of hydrous ethanol. ISCO emissions were lower for CNG, while ISTHC and ISNO X were similar to gasoline. Due to the lower LHV of biomethane, a reduction in the ISNOX value could be expected with possible increase in methane slip. Regarding cost, biomethane is the fuel with the cheapest operating cost per kWh when considering the final price for industrial consumers in Brazil. It is still difficult to estimate large-scale production cost of biomethane, but its use in partial replacement of CNG would still be able to keep fuel market competitiveness, while reducing the carbon footprint. [ABSTRACT FROM AUTHOR]

Partial load operation of SI engines is conventionally achieved by the use of a throttle to control the airflow or air-fuel mixture into the engine. When the engine operates at partial load the throttle causes high pumping losses which has an effect on decrease of the engine efficiency. One of the possible ways to decrease the pumping losses during partial loads is to operate the engine under lean mixture condition. The limitation in this case can be misfiring of used fuel. The combustion limits can be extended by addition of hydrogen to the regular fuel. This work presents an analysis of use of hydrogen-methane taking into account aspects related to the efficiency and emission of pollutants. To carry out this study an experimental system composed of a SI engine was used. Two important differentials were used. First, the engine was supplied with simulated biofuels according to the typical biogas composition of the Brazilian landfills (Bio60); second, the system was operated in partial load, with the addition of H 2 , forming the HBio60 blend, in an attempt to increase efficiency and reduce pumping losses by increasing lambda value and variation in trottle position. The same aspects were evaluated with the engine operating with biogas composed of 95% of methane (Bio95) and in mixture with hydrogen (HBio95). The tests were performed at different ignition angles and air/fuel ratio. The results showed that adding H 2 allows the combustion limits to be extended, with an effective increase of indicated efficiency. On the other hand, the reduction of NO x emissions was greater than 95% in the lean mixture provided by the presence of H 2 . The idea is to encourage change in the control algorithm of SI engines typically fueled with natural gas and use the H 2 -methane blends as fuel. Furthermore, diesel-powered buses in Brazil could be converted to SI gas engines without the loss of efficiency. [ABSTRACT FROM AUTHOR]

Brazil is the largest producer of paddy rice in the American Continent, straw discarded in the field after the rice harvest can be used for methanol production and help mitigate the impact of global warming. This paper presents the first environmental impact study of the life cycle of rice straw methanol in Brazil, whose objective was to produce an inventory and determine impacts on global warming based on collected data from actual logistic process of rice straw grown in a region in southern Brazil, since there is no such information in the Brazilian literature. Methanol production from rice straw involves different activities associated with rice cultivation, straw collection, straw transportation, and methanol production. The study focuses on the detailed evaluation of the processes responsible for direct and indirect emissions, including emissions from decomposition processes in the flooded rice fields and carbon neutral emissions from the methane production stage. The results show that the removal of rice straw from the field after harvest promoted the reduction of biogenic emissions of methane, on the other hand increased nitrous oxide and carbon dioxide emissions due to the higher use of fertilizers to maintain the yield of harvested rice. The rice straw required for the methanol plant with an annual production of 148.70 thousand tons level is 4.52 kg per of kg methanol and the life cycle carbon footprint is 8.09 × 10−01 kg CO 2eq per kg methanol, of which straw collection stage is the largest contributor with a share of 43.15%, followed by transport of straw bales with 15.32%. Comparing to fossil methanol, biomethanol has the potential to reduce GHG emissions by 67–74%. This advantage is a consequence of the carbon dioxide emissions from the gasification, gas conditioning, and rice straw burning processes being considered as neutral carbon. [Display omitted] [ABSTRACT FROM AUTHOR]

Brazil's sugarcane sector is a significant source of employment, and operates at the intersection of energy, agriculture and land use. Its future development will be affected by the values, decisions and actions of key actors. Accordingly, we report on the results of qualitative semi-structured interviews with 19 participants with expertise in relation to Brazil's sugarcane sector. We used visual aids, and reflections on past events, to structure and contextualise discussions about the future prospects for the sector as a whole, and for four of its potential products – sugar, ethanol, electricity and biogas. Interviews revealed general expectations of continued growth in the sector, particularly for its energy-related products. However, the possibility of future challenges and tensions is still evident. We suggest three inter-related areas for ongoing reflection. First, there may be value in balancing the desire for minimal intervention, technology neutral styles of policy, with the need for policy that is clear, long-term and impactful. In some cases, more targeted policies for particular actors or emergent technologies, may also be justified. Second, increased clarity on the broader objectives for the sector, including the relative prioritisation of economic, social and environmental objectives, may help industry to make the long term investments consistent with the kind of deep innovation for which there is potential. Third, it is worth reflecting on how the above issues in combination can be leveraged into a global leadership strategy, with consideration of the relative robustness of different leadership strategies within broader emerging global dynamics. • Perceptions of key actors are pertinent to future prospects for energy sectors. • Experts interviewed on perceptions of past and future of Brazil's sugarcane sector. • Long term clarity of policy and targeted measures may support diverse investors. • Clarity on environmental objectives will support long term innovation. • Opportunities for global leadership, in the context of broader global dynamics. [ABSTRACT FROM AUTHOR]

The sugarcane is the most explored raw material in Brazil to produce ethanol and for each liter of ethanol around 12 L vinasse are produced, thus, the country has high production of vinasse. The vinasse has a very high polluting potential, being considered a solid residue. In general, the vinasse is applied in sugarcane plantations, in some cases with wastewater from plants, promoting the fertirrigation. Therefore, the objective of this work was to evaluate the potential of methane generation from the vinasse generated in Brazilian ethanol plants, as well as its potential for thermal and electrical energy generation and economic viability. In all, 377 ethanol plants are registered in Brazil, where 334 are of the annexed type and only 43 autonomous. The results indicate that Brazil has the potential to generate at least 3.53E + 07 m³.d−1 of methane, 1.88E + 06 m³.d−1 in autonomous plants and 3.34E + 07 m³.d−1 in annexed plants. While all the autonomous plants have a minimum production potential of 1.21E + 07 kWh.d−1 of electrical energy and 2.28E + 07 kWh.d-1 of thermal energy, that of annexed plants reach a potential of 2.15E + 08 kWh.d−1 of electrical energy and 4.07E + 08 kWh.d−1 of thermal energy. The costs of producing electricity from methane were about 0.09 R$.kWh-1 for autonomous plants and about 0.06 R$.kWh-1 for annexed plants. NPV has a positive value in all cases indicates that this study, Autonomous plants presented IRR of 51% with a payback of one year and 11,51 months, while the annexed obtained 161% of IRR and payback of 7,56 months. [ABSTRACT FROM AUTHOR]

Indicators, such as the energy balance (EB) and greenhouse gases emissions avoided (GHGEA), are frequently used to evaluate the benefits and sustainability of biofuels. Many important papers and reports have been published in recent years to demonstrate the environmental and energetic benefits of biofuels, such as ethanol from sugar cane. EB and GHGEA often include other sugar cane products, such as electricity and bagasse. The anaerobic digestion of vinasse can generate considerable amounts of biogas but is not a common practice in Brazil. This study evaluates the potential benefits to the EB and GHGEA of ethanol by the production of biogas from vinasse and its use to produce electricity or biomethane. Biomethane can be injected on the Natural Gas Grid or used as a fossil diesel oil replacement in the mill operations of harvesting and transportation of sugar cane. The results show that biogas from vinasse can represent improvement in both indicators, which ranges from 3.5% improvement in EB by electricity generation with biogas to 27.5% improvement in GHGEA by replacing diesel in the mill operations. © 2019 American Institute of Chemical Engineers Environ Prog,39:e13226, 2020 [ABSTRACT FROM AUTHOR]

The anaerobic processing of sugarcane vinasse has been recently highlighted as an effective approach to both mitigate negative impacts of its inadequate management and recover renewable energy through biogas production. However, basic aspects of the process still require further investigations, such as understanding the impacts of the compositional variability of vinasse on the overall performance of anaerobic systems. In this context, the impacts of different types of sugarcane vinasse, i.e., from annexed (VinAn) and autonomous (VinAu) ethanol plants and spirit production (VinAl), on methane production and organic matter removal were assessed under mesophilic conditions (37 °C) from a kinetic perspective. The energetic potential of the biogas was also investigated regarding micro (methane yield) and macro (contributions to the Brazilian energy matrix) scales. The availability of biodegradable organic matter and sulfate had a direct impact on the kinetics of methane production, associating a 2-fold higher initial methane production rate with VinAl (10.12 NmL h−1) compared to VinAn (5.95 NmL h−1) and VinAu (4.25 NmL h−1). However, the methane yield was not affected by the compositional variations (328–339 NmL-CH 4 g−1COD), which indicates that vinasse may be efficiently used as substrate for bioenergy generation, regardless of its origin. The global energy production estimated for VinAn (24,816 GWh) was over 6- and 7-fold higher compared to VinAu (3984 GWh) and VinAl (3035 GWh) due to discrepancies in vinasse generation flow rates, potentially increasing the available renewable power supply in Brazil by 2.2% or over 1400% of the current bioenergy produced from biogas. Overall the electric energetic potential of sugarcane vinasses (14,486 GWh) could replace over 20% of natural gas or 90% of coal use in Brazil, satisfactorily decreasing the dependence on non-renewable energy sources. Image 1 • Bioenergy recovery from different types of sugarcane vinasse was investigated. • The availability of organic matter and sulfate directly impacts process kinetics. • Compositional variations do not impact the methane yield. • Vinasse from annexed ethanol plants presented the highest global energy potential. • Energy from biogas could replace 90% of the coal-derived energy in Brazil. [ABSTRACT FROM AUTHOR]