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Abstract This study sought to quantify and characterize cassava waste as fuel. The wastes from three cultivars were collected to study and were divided into three distinct parts of the cassava plant: seed stem, thick stalks, and thin stalks. Physical and chemical analyzes were carried out to determine the elemental composition of the waste: volatile matter; fixed carbon; ash; moisture; lignin; cellulose; hemicellulose; ash composition and higher heating value were determined. We conducted a thermogravimetric analysis in oxidizing and inert atmospheres to study the behavior of the waste as fuel. The root productivity obtained ranged from 7.7 to 13.0 t ha−1 yr−1 on a dry basis (db), and the ratio between waste and roots varied from 0.36 to 0.91. The physical and chemical properties of cassava waste are analogous to those of woody biomass regarding the elemental composition, the higher heating value, and thermogravimetric analysis. Ash content varied from 2.5% to 3.5%, reaching around 6.0% in samples unwashed. Approximately 60% of the ashes are alkali oxides, especially P2O5, K2O, and CaO, which have low melting points. The alkali index calculated suggests that there is a strong tendency that the combustion process leads to ash fouling and the formation of ash deposits.

Os sistemas fotovoltaicos conectados à rede vêm cada vez mais ganhando espaço no Brasil. Isto é fruto de uma política energética regulatória iniciada em 2012, expansão mundial dessa tecnologia e o alto potencial de irradiação solar disponível no país. Este trabalho tem por objetivo comparar grandezas elétricas medidas no ponto comum de conexão (PCC) de uma unidade consumidora (UC) com perfil de carga comercial e sua microusina fotovoltaica (FV) de 45kWp conectada à rede elétrica em relação ao atendimento dos parâmetros da qualidade da energia elétrica (QEE) em regime permanente estabelecidos no Módulo 8 do Procedimento de Distribuição (PRODIST) da Agência Nacional de Energia Elétrica (ANEEL). Os parâmetros analisados no PCC da instalação foram: perfil de tensão, fator de potência, distorção harmônica total de tensão, fator de desequilíbrio e frequência. Também é apresentado o consumo e geração da unidade consumidora com a usina fotovoltaica para um dia útil e um dia do final de semana. Os resultados obtidos mostram que a UC com a usina FV conectada à rede elétrica em operação não impacta na QEE da rede de distribuição e os parâmetros analisados estão dentro dos limites estabelecidos pelo Módulo 8 do PRODIST da ANEEL, com exceção da tensão que requer ajustes no comutador de carga do transformador da distribuidora que alimenta a instalação.

This work has as object of study some of the expressions of the water privatization process in contemporary Brazil. The objective was to analyze different expressions of the water privatization process in Brazil. To achieve this general objective, we seek to: Discuss the fundamentals of the environmental issue and its relationship with the finitude of natural resources in contemporary capitalism; To situate water as one of the main resources inherent to the production and valorization processes in the capitalist mode of production; To bibliographically map some expressions of water privatization in the Brazilian State. Methodologically, the research is characterized as exploratory, with data of a bibliographic and qualitative nature. In the case of data collection, we use printed and electronic references of different natures, such as: monographs, theses and dissertations, scientific journals, annals of scientific meetings, among others. Regarding the data source, we define two types of water privatization: 1) Electricity generation (dams / hydroelectric plants); 2) Water distribution by companies / environmental sanitation. A research script was used as a data collection instrument, which guided the selection of the sample of texts based on three aspects of categorization prioritized in the script, namely: characteristics, favorable and contrary arguments; developments and social consequences identified. We analyzed the data in the light of the historical-dialectical materialist method, understanding that it establishes an analysis of reality from the category of totality, representing it in a historical-critical way. The results obtained through this research demonstrate that water privatization is an essential mechanism for the accumulation and valorization of capital to the detriment of the social use of this natural resource to satisfy the needs of living beings. Thus, it highlights the relevance of this study for conducting a contemporary and necessary debate, with theoretical and practical content ; Este ...

Based in the importance of the Economic Dispatch for operation and planning of power systems, this paper presents the Trelea Particle Swarm Optimization method (Trelea-PSO) applied to this issue. In this paper the ED problem is modeled considering the valve-point effects and multiple fuels, though a non-convex function. Study cases composed of two 10 thermal generators systems are presented to validate the proposed methodology. The results obtained was compared to others presented in literature.

Most of the energy consumed in the world is derived from fossil fuels such as coal and oil, making it limited. Energy is the fundamental basis of human activities. Be they domestic, commercial, industrial, food production or agriculture. And, according to the environmental view point it is necessary to reduce consumption of fossil fuels and increased use of alternative fuels. Soon, biodiesel appears as promising substitute for fossil fuels, being a biofuel derived from oil or animal fats composed of alkyl esters that can replace all or part diesel engines in ciclodiesel. However, when oil derivative is susceptible to oxidative degradation by heat mediated reactions, and traces of metals, especially in the presence of oxygen. Today, most of all biodiesel is derived from soybean in Brazil, which has on average 55% linoleic acid (18:2) and 7.5% linolenic acid (18:3) in its composition, degrading the biofuel. This work is a study of antioxidants derived from cashew nut liquid - technical CNSL, aiming to use them directly as antioxidants in biodiesel in order to improve their stability to oxidation. We carried out the extraction of the components of technical CNSL and electrochemical synthesis of the antioxidant pathway, which were later confirmed using techniques FT-IR, NMR 1H, GC-MS, electrochemical and TG. The results show that antioxidants are low production costs, biodiesel-soluble, have high thermal stability at around 220°C as well as high thermo-oxidative stability, the Rancimat performed with higher potential induction 7h, making promising and effective options to be used as additives for biofuels. Through the electrochemical techniques, it was found that the material exhibits an irreversible adsorption on the platinum electrode used. In addition to an anodic peak in the first scan and even an irreversible oxidation with a characteristic potential of antioxidant activity in about +0,6V and +1,0V. ; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) ; A maior parte da energia consumida no ...

In this work, the Monte Carlo method (MC) was extended to simulate the packing and segregation of particles subjected to a gravitational field and confined inside rigid walls. The method was used in systems containing spheres inside cylinders. The calculation of void fraction profiles in both the axial and radial directions was formulated, and some results are presented. In agreement with experimental data, the simulations show that the packed beds present structural ordering near the cylindrical walls up to a distance of about 4 particle diameters. The simulations also indicate that the presence of the cylindrical wall does not seem to have a strong effect on the gravitational segregation phenomenon.

This paper estimates the profit of the joint operation of a wind farm and a li-ion battery energy storage system (BESS) in the Iberian electricity market (MIBEL). The day-ahead and first intraday energy markets, and the tertiary regulation market are considered to optimize the joint operation of both assets. A rolling window combined with a non-linear optimization model are used to design the operation strategy. The BESS lifetime (as a function of the depth of discharge) is considered in the optimization problem, and different BESS capacities and initial state of charge values are tested to determine their approximate optimum values. The model and strategy designed were tested using real data from the MIBEL market and predicted data from Sotavento wind farm. The resulting incomes were compared to the BESS investments costs to determine, for a given capacity, when the project becomes viable.

This study evaluated the environmental conditions of two watersheds selected on the basis of similarities in land use. The environmental conditions of the watersheds were analyzed using two geoprocessing methods and in situ evaluations by applying the rapid assessment protocol (RAP). Geospatial image processing was used to analyze land use, slope, soil classification, and rainfall, while RAP was used to evaluate the connectivity and size of riparian corridors. The results revealed varied uses of land with the landscape matrix in both watersheds, composed of agriculture, pasture, and urban centers. Urban centers were defined as spots and riparian zones as corridors. The analysis of environmental fragility considering all the geospatial variables, classified both watersheds as having medium fragility. The most fragile sites were the urban centers, which had a high slope and degraded riparian zone. Onsite assessments have shown that corridors do not have the size required by legislation; they are fragmented and unstructured, and they contain exotic species. We also propose that a multi-factorial approach be used to evaluate watersheds, associating geospatial assessments and onsite analyses that consider the limitations pointed out in each protocol. This reduces sampling errors and shows the actual state of conservation in riparian zones.

In this study, pyrolysis of residual biomass from the agro-alimentary industry of Argentina was investigated. The studied biomasses were rice husk, peanut shell and wheat straw. The effect of pyrolysis temperature over solid (bio-char), liquid (bio-oil) and gas (bio-gas) fractions weight yields were evaluated for each biomass, in the range of 350-650 °C. The maximum yield of bio-oil was obtained at 550 °C for rice husk (45 wt%) and wheat straw (58 wt%), and at 500 °C for peanut shells (51 wt%). At those temperatures, the data recorded the smallest spread around the mean. Different characterization techniques of raw biomass were reported, namely, thermal behavior; proximate and ultimate analysis; content of Ca, Al, K, Si and Fe; and hemicellulose, cellulose and lignin composition. Bio-oils characterization included water content and chemical compounds identification. Furthermore, bio-char HHV and BET surface area were measured. Rice husk bio-oil showed 21% selectivity towards furans of which 75% corresponded to furfural and 5-HMF. Peanut shell bio-char presented the highest Higher Heating Value (7250 kcal/kg) and BET surface area (215 m2/g). In addition, co-pyrolysis reactions and the synergistic effects over obtained products completed this study. Co-pyrolysis bio-oils yields varied between 41 and 46 wt%, for all the mixtures. Bio-oil water content decreased up to 15% for rice husk mixed with peanut shell or wheat straw. Moreover, 5-HMF was detected in all bio-oils, and furfural selectivity was higher than 5% in the three mixtures investigated.