Resumo em Inglês:

ABSTRACT To provide an efficient and reliable calibration method with reduced time cost and increased accuracy, the angle of repose (AoR) in the simulation is batch-processed based on Python and the GA-BP neural network is used to improve the prediction accuracy of the DEM parameters of coated fertilizer particles. The single-factor test data were firstly interpolated to obtain sufficient training samples, thus avoiding the drawback that the BP network tends to fall into the local minimum during the training process. Then the GA-BP neural network was trained in combination with the orthogonal combination test, and the fitted correlation coefficients were all greater than 0.975, indicating that the algorithm has strong generalization performance and good stability. The predicted values matched the expected output values, indicating that the GA-BP neural network can accurately predict the nonlinear function output, and the network predicted output can be approximated as the actual output of the function. With the actual AoR as the output value, the simulation value of the AoR was obtained as 24.457° when the coefficient of restitution (CoR), coefficient of static friction (CoSF), and coefficient of rolling friction (CoRF) were 0.509, 0.176, and 0.0332, respectively, and the relative error with the actual value was 0.068%, indicating that the well-fitted GA-BP neural network could accurately predict the DEM parameters of fertilizer particles.

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ABSTRACT Macaw palm (Acrocomia aculeata) is a potential raw material for biodiesel production owing to its high oil content. In this study, a model is created that can estimate the oil percentage in Macaw fruit using spectral indices obtained via computer vision. Ninety Macaw fruits are used to perform an experiment. They are categorized into three stages of maturation and counted in terms of weeks after flowering. Images of the fruits are captured using a multispectral camera in the visible spectral region (RGB) and infra-red regions (NIR), which allows spectral indices to be obtained. A model is established using the principal component regression method and used to estimate the oil content based on the colorimetric characteristics of Macaw palm fruits. The selected model is composed of the first two principal components, which indicate an explanatory potency of 91.57% of the variance. Applying this information to the validation data, the model exhibits a determination coefficient of 0.91, mean square error of 10.61%, and standard error of 5.46% in terms of the oil content, which indicates that computer vision is a promising alternative method for estimating oil content.

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ABSTRACT A common scenario in the developing countries is the low income and less education of producers. Thus, the tools used for irrigation management must be cheap and easy to handle. In this work, an autonomous and low-cost network of micro-weather stations has been developed for irrigation management. Simulations were performed to evaluate the ability of intelligent systems to compute evapotranspiration with noisy and insufficient data. The network of micro-weather stations was then applied to autonomous irrigation management of a crop of bell peppers. Statistical analysis was performed on data from the developed system and a standard weather station. The results show no statistical difference between the values of evapotranspiration calculated with data from these two sources. The developed system performed with a coefficient of determination of 0.968, mean absolute error of 0.055 mm day−1, and root mean square error of 0.063 mm day−1. The study shows that low-cost intelligent systems can be used as viable tools for efficient irrigation management.

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ABSTRACT This paper proposes geothermal energy as an alternative solution to the water–energy dilemma in the northeastern region of Brazil (NEB). The main application of this study was to provide a theoretical basis to support a different approach to policies minimizing water scarcity and ensuring sustainability. The analysis developed in this study compares the levelized cost of electricity (LCOE) for many different energy sources. The novelty of this study is the use of geothermal energy in the context of the Brazilian Northeast, focusing on water desalination processes, which are expensive in terms of energy. Therefore, this study is highly important because it offers the potential of addressing the energy/economic barrier related to water desalination in environments with economically viable geothermal energy. This is the case in Northeast Brazil with potential for reuse of abandoned oil wells. In the form of enhanced geothermal systems (EGS), geothermal energy is a competitive energy source compared to other sources in the Brazilian Energy Matrix, especially when considering factors in addition to the economic benefits. In the form of EGS, geothermal energy is a suitable option for addressing water scarcity in the northeast region in a sustainable and low-emission manner. This is a strategic opportunity for NEB in the context of energy production and freshwater production through desalination.

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ABSTRACT Coffee stands out worldwide for being widely traded and consumed. However, this consumption generates a large amount of spent coffee grounds (SCGs) that are typically arbitrarily discarded. This biomass has a high heating value and molecular composition that allows for it to be a raw material for generating heat and energy. The search for renewable energy sources should consider the potential of SCGs. Thus, the objective of this study was to estimate the energy potential of SCGs in Brazil. The methodology consisted of searching for data to represent the generation of SCGs in the country and estimate its energy potential. It was found that the amount of SCGs available for power generation through direct combustion was approximately one thousand tons, and the power generation potential was 6.83 TWh/year in Brazil. This energy is sufficient to meet, for example, the total annual demand for public lighting in the country's Southeast. These results are the first steps towards evaluating the potential use of SCGs as an energy source and its environmental benefits. Additionally, this study explored limitations and barriers, providing valuable information for developing routes for using this energy residue and incentives for public policies.

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ABSTRACT The growing interest in alternative fuels based on plant oils has led to the search for new plant species. Given this, during 2015–2020, oil from 12 varieties of oilseed radish was studied using standard research protocols. The average content of the dominant fatty acids in the oils studied was: [cis-9] oleic (C 18:1) 33.95% (Cv = 14.2%), [cis-9,12] linoleic (C 18:2) 16.20% (Cv = 20.8%), [cis-13] erucic (C 22:1) 15.18% (Cv = 17.9%), [cis-9, 12, 15] α-linolenic (C 18:3) 13.33% (Cv = 18.5%) and palmitic (C 16:0) 5.42% (Cv = 18.5%), with a monounsaturated fatty acid content of 59.69% and a ratio of polyunsaturated/monounsaturated fatty acids of 0.508. The studied varieties were ranked in the order of increasing suitability as a component of biofuels: ‘Zhuravka’ < ‘Raiduha’ < ‘Lybid’ < ‘Olga’ < ‘Iveya’ < ‘Ramonta’ < ‘Alpha’ < ‘Tambovchanka’ < ‘Fakel’ < ‘Snizhana’ < ‘Sabina’ < ‘Nika’. The technological suitability of oil from the ‘Zhuravka’ variety was confirmed based on analysis of its physicochemical parameters when subjected to polymerization (at 280 °C) and oxypolymerization (at 120 and 150 °C). Under these conditions the basic parameters of the oil varied within the technological limits that determine its suitability for thermodynamic combustion processes in systems with controlled pressure and temperature.

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ABSTRACT Covered lagoon biodigesters are widely used in Brazil for treatment of agro-industrial effluents; however, under natural conditions, they operate at temperatures below the ideal. Thus, external sources for heating the effluent can enhance reactor performance and optimize thermal exchanges between the biodigester and the environment. This study aimed to evaluate the thermal exchanges in the internal and external environments of a covered lagoon biodigester from the influence of effluent heating through solar energy. Mathematical modeling (EnergyPlus software) was used as a tool to simulate thermal exchanges and obtain heat transfer rates. To do so, two scenarios were considered: with and without heated effluent. The results showed that solar radiation is the primary source of heating for anaerobic reactors and that the high thermal inertia of the soil contributes to a small variation in temperature of the resident biomass over the course of the day, even in the scenario with heated effluent. The temperature of the resident biomass reached and stabilized at 30°C, even after thermal exchanges with biogas and soil, in both hot and cold periods when heating was applied.

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ABSTRACT The combination of crambe (Crambe abyssinica L.) biodiesel and biogas could be a renewable energy alternative for internal combustion engines. Therefore, the emissions and engine performance of crambe biodiesel blends (B0, B10, B30, B50, B75, and B100) were evaluated in both the dual mode (biogas) and normal mode (biodiesel). The tests were performed on a 5-kVA generator engine at loads ranging from 1 to 4 kW. The power generated in the normal mode was 17% lower than that generated in the dual mode. The dual mode showed a lower specific fuel consumption than the normal mode. In the normal mode, loss of power occurred as the proportion of biodiesel increased. Furthermore, nitrogen oxide emissions decreased with the addition of biogas. In the dual mode, the emissions increased as the biodiesel content increased. Carbon monoxide emissions decreased in both the normal and dual modes with an increase in biodiesel. The addition of biogas in the dual fuel mode with crambe biodiesel is an efficient alternative for partial substitution of diesel.

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ABSTRACT Brazil has been facing a huge rise in fuel and diesel prices due to the rise in the international market and the war between Ukraine and Russia. The rise in electricity prices is also a problem that affects everyone in Brazil. This study aimed to evaluate the performance and emissions of a diesel engine for power generation that operates with crambe-based fuels with blends of 0% (control), B5, B10, B15, B20, B50, B70, and B90. The fuels were tested in an 8 kVA generator engine at a load of up to 6000 W. The biofuels were obtained from a mixture of diesel with crambe biodiesel at incremental levels from B0 to B90 in the fuel mixture. The increased proportion of crambe biodiesel resulted in lower specific consumption. Crambe biodiesel resulted in a reduction of CO, CO2, and NO2 emissions due to an increase in crambe biodiesel at the proportion. The results indicate that crambe biodiesel blends are viable technical solutions for the partial replacement of conventional diesel.

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ABSTRACT Anaerobic digestion (AD) stands out as a degradation pathway for the treatment of agro-industrial waste. This study aimed to evaluate the biogas production (Pb) from the co-digestion of swine (SW) and laying hen waste (LHW) under different temperature conditions (psychrophilic x mesophilic). The studies were carried out on a laboratory scale in anaerobic reactors (1.25 L) in a batch system for 60 days. Three mixtures in volumetric proportions (%) of 25/75 (P1), 50/50 (P2), and 75/25 (P3) (SW/LHW) were studied. The mixtures were characterized before and after AD in terms of TS, VS, and COD under temperatures of 18 and 36 °C, with Pb measured daily. Pb was higher at 36 °C for all mixtures compared to the psychrophilic condition (18 °C). Among the mixtures, the highest Pb value was observed for P3, reaching 0.34 and 0.60 m3 biogas kg−1 CODremoved for 18 and 36 °C, respectively. The digestate showed an increase in the contents of micro-and macronutrients for P1, P2, and P3 after AD, which indicates its use for agricultural purposes. The co-digestion of swine and laying hen waste is a promising proposal in terms of management and energy recovery of biogas, especially for mesophilic conditions in mixtures with a predominance of laying hen waste.

Resumo em Inglês:

ABSTRACT The use of agricultural residues in anaerobic digestion (AD) for biogas production promotes environmental and socioeconomic benefits. This study aimed to evaluate the biogas production from dry coffee husks (DCH), wet coffee husks (WCH), and cattle manure (CM) in AD. Prototypes of Indian anaerobic benchtop digesters with a batch feeding system supplied with 100 CM, 100 DCH, and 100 WCH for anaerobic mono-digestion (AMoD) and 25:75 DCH:CM and WCH:CM for anaerobic co-digestion (ACoD) were used in the experiment. The dry husk was mechanically pre-treated with grinding in a manual mill. Moisture and total solid presented no statistically significant difference between the studied relationships but the coffee husk as a co-digestant acidified the medium to be digested. The 25:75 DCH:CM ratio anticipated biogas production (7th week) and showed higher potential for weekly and accumulated biogas production. The Gompertz model showed the best fit considering the coefficient of determination, mean relative error, standard deviation of the estimate, and mean squared deviation. Therefore, the coffee husk as a co-digestant of cattle manure is a potential lignocellulosic biomass for biogas production provided that the process is conducted under pre-treatment.

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ABSTRACT Agribusiness and commerce are two major sectors that consume electricity. Agribusiness can generate energy but not enough to meet its needs. Thus, energy efficiency is fundamental for the sector’s sustainability. This study aimed to apply PROCEL energy evaluation methods in a Brazilian agribusiness company, specifically in the meat retail sector, located in the Alta Paulista region. This research has a quantitative approach, and PROCEL’s RTQ-C manual, bibliographical research on the energy issue, and the functioning of the company’s environment were used. The commercial establishment received the B classification index, which can be considered good but has several points of improvement, mainly on air conditioning, which provides better energy efficiency to the company. Therefore, the company can obtain economic and environmental returns by improving such areas, and the present research serves as a basis for evaluating energy efficiency in other companies in the same sector.

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ABSTRACT The objective of this study was to analyze the influence of climate change on the flow duration curves of five small rural catchments in the Amazon, as well as the hydroelectric power duration curves of micro hydroelectric power plants (MHPs) which can be implemented in the respective hydroelectric sites. The scenarios used were RCP 4.5 and RCP 8.5, defined during the 5th IPCC Report; these are the main optimistic and realistic greenhouse gas emission scenarios in the future. They projected on the flow duration curves of the small catchments under study and, consequently, on the hydroelectric power duration curves. Future precipitation was obtained via the PROJETA platform. For the simulation of flow duration curves, a rainfall-runoff model was used. The determination of the power duration curves was considered with the observed and simulated flow duration curves and with design parameters available in the literature. Based on the simulations, the reduction of high duration flows (minimum flows) was verified for the future scenarios studied, mainly for RCP 8.5, reflecting directly in the reduction of the hydro energetic potential of the analyzed rural catchments.

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ABSTRACT Bioenergy production relies on resources such as agricultural waste, which has prompted extensive research on biofuels. The heating value is a crucial parameter for evaluating energy sources. This study aims to analyze and propose formulations for estimating the higher heating value (HHV) based on proximate and ultimate chemical analysis of biomass. A database consisting of 142 samples was created, and 14 formulas available in the literature were initially tested. The datasets for each composition type were classified using the k-means algorithm, and the new sample spaces were validated. For proximate analysis data, specific multiple linear regression models were developed for two classes, one with an average SE of 1.05 MJ kg -1 , and the other with an average SE of 1.27 MJ kg -1 . For samples with ultimate analysis, a general model was formulated with an average SE of 1.11 MJ kg -1 . Sample classification for proximate analysis did not significantly affect the fit of models. Considering that proximate analysis is less expensive than ultimate analysis, the proposed method shows promise in optimizing and reducing costs for determining the HHV of biomass for energy production. of 0.697 and of 0.678 and of 0.701 and

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ABSTRACT The increasing electricity consumption, inflated costs, and environmental restrictions drive the need for more efficient energy usage and the development of energy conservation programs. Many farms in Brazil produce their animal feed by crushing grains and cereals using electric motor-equipped devices. However, these motors are often oversized and operate during peak times, leading to increased production costs. This study aimed to mathematically model electricity billing under the green tariff (group A) for an egg production farm. The model incorporated mathematical equations based on selected electrical parameters such as load, power factors, energy demand, and active consumption. The Mathematica software was used to implement the proposed model. The farm provided the past twelve electricity bills, which were inputted into the software, generating three-dimensional surface graphics and contour maps. These visualizations revealed an inversely proportional relationship between bill prices and power/load factor indicators. This study concludes that the presented methodology can be employed by agribusiness companies to assess performance, explore alternatives, avoid potential fines, and optimize energy consumption.

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ABSTRACT In this work, we sought to minimize electricity costs in the coffee bean drying process by carrying out the theoretical sizing of the economic viability of the Photovoltaic Power plant (PVP) ongrid used to supply a Dryer Unit (DU). The methodology consisted of adequate sizing of a PVP generation plant to promote the electric energy balance. It used economic indicators such as internal rate of return, discounted payback, and net present value. Two scenarios were considered: a pessimistic with DU use on-peak period; and an optimistic with full use of the DU during the off-peak period. It was considered local electricity tariff values, and the results indicated the economic feasibility for the PVP installation also the feasibility of the dryer use in both scenarios, there are no restrictions on operating hours. It can be concluded that it is essential to understand the Brazilian electricity bill legislation because only in this way is it possible to properly develop the on-grid photovoltaic power plant projects. The technical and economic parameters are inseparable and indicated that the electricity tariff should not exceed US$ 0.22 (kWh) -1 to ensure the photovoltaic power plants installation viability to supply DUs that remain in operation during on-peak periods.

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ABSTRACT Turning residual biomass into bioenergy promotes rational environmental waste disposal and turn it into a source of energy. In the last decade, the idea of using lignocellulosic biomass to make second-generation (2G) biofuels has become more popular in the energy industry. Thus, this study aimed to show the potential of residual lignocellulosic biomass as raw material for clean and sustainable energy and the technological advances focused on making it economically viable. A narrative review was adopted, in which the material used in the bibliographic survey was organized from scientific sources collected in high-relevance databases. The various factors presented in the review guarantee that the use of lignocellulosic biomass is considered a promising substrate. Furthermore, it indicates a solution to the competition between food supply and fuel production, which occurs with first-generation biofuels, which in the long term seem to be unsustainable. However, despite technological advances for its production and commercialization on a large scale, investment in scientific research is necessary to make the adopted technologies viable.

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ABSTRACT Regional development in the state of Pará (Brazil) continues to be limited by lack of access to energy. This is a problem that is widespread in several rural communities and agricultural regions. Therefore, this study aimed to analyze the potential use of palm oil and cocoa processing waste biomass, which are abundant in the state and whose energy capacities can be used to generate electricity in biomass gasification plants. To do so, a literature review on elementary and calorific value analysis of palm oil (empty fruit bunches, fibers, kernel shell and cake, trunks, and others) and cocoa (pod husks) were conducted. The findings have shown that both waste biomass materials have satisfactory energetic characteristics for use in gasification plants. Thus, palm oil and cocoa processing waste biomasses are alternative energy sources for producers of these fruits in upstate Pará, enabling the development of the region.

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ABSTRACT The increase in distributed generation (DG) interferes with the energy distribution system, which may present low voltages due to voltage drops and high voltages due to the insertion of distributed generation, resulting from renewable energy sources in rural areas. These voltage levels must be controlled to comply with the limits imposed by the distribution rules and procedures (PRODIST). This study aims to evaluate the voltage rise caused by DG, simulating three DG insertion scenarios, as well as simulate strategies to correct these voltage levels, such as the limitation of the active power supply, the reactive supply by the consumer and the utility, and the installation of on-load tap changers. The simulations were performed using the MATLAB® program, more specifically the PSAT toolbox. Correction techniques were simulated using the active power supply limitation method, the reactive power supply method by consumers, and the voltage regulator process once the voltage rise effect was identified. The first two proved to be ineffective in this case, while the last one meets the voltage levels required by the National Electric Energy Agency.

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ABSTRACT In Brazil, sugarcane is the crop whose agro-industrial development has taken the longest path and has the greatest prominence in the national agro-industry, without precedent. With 500 years of history, Brazil is today the largest producer of sugarcane raw material and sugarcane ethanol in the world. In addition, has the world's largest program for the replacement of fossil fuel by ethanol in vehicles and shares with India the position of largest sugar producer; in addition, it has developed the largest active sugarcane genetic improvement program in the world. However, in contrast to these achievements throughout its history, it has also received criticism even from businesspersons of the sector itself, mainly regarding State intervention and its inefficiency. This is a paradox: “success and inefficiency?” The general objective of this work was to analyze exactly this contradiction since the great agro-industrial development occurred especially during the 60 years of State intervention (1930‒1990). We concluded that this intervention was a key element in the success of the agroindustry both during and after the intervention. Many personalities deserve mention in this process, in both the field of ideas and decisions and practical actions: politicians, public agents, businesspersons, sugar mill owners, agroindustry technicians, and independent producers. We selected a researcher, Dr. Gilberto Miller Azzi, as an example, due to the fact that, from 1955 onwards, as a researcher at the IAA, he represented the scientific and technological area of the Brazilian State, acting decisively for the achievements of the sector. In this regard, an analysis was made of the main factors that have leveraged the national sugar and alcohol sector from the 1930s to the present day.

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ABSTRACT Currently, concern about the burning of fossil fuels and the consequences for the planet has increased and become the agenda of discussions at global levels. In this sense, biofuels are an important alternative, and this article seeks to review the literature on the use of microalgae as raw material for the manufacture of biodiesel, the transesterification process as a conversion method, the technologies used to optimize this process, the characteristics of biodiesel that are required by Brazilian legislation, and the challenges for production. Brazil has a very large potential for the production of these biofuels but their production on a large scale still requires further studies so that it can be part of the country’s energy matrix, including in the agro-industrial sector.