Samuel Nelson Melegari de Souza

Access to water for irrigation and agricultural activities in remote rural areas often depends on alternative energy solutions, especially in locations without connection to the electric power grid. This study proposes to construct and experimentally evaluate a pumping system driven by a floating water wheel, designed to operate continuously in rivers with moderate flow, presenting itself as a sustainable, low-cost alternative suited to the needs of family farmers and rural communities. The system was constructed, installed, and tested along a stretch of the Tormenta River, in the municipality of Catanduvas, in the state of Paraná, Brazil, where measurements of pumped flow rate, manometric head, torque, rotational speed, and current velocity were performed. Based on experimental data, hydraulic power, mechanical power, and pumping power were determined, as well as the hydraulic, mechanical, and overall efficiencies of the system. The prototype operated continuously, despite the intermittent behavior characteristic of the Wirtz pump, and achieved a maximum hydraulic efficiency of 72%. The pumped flow rates proved to be compatible with the water demands of small family-owned agricultural properties. The economic analysis indicated that the system is viable when compared to the avoided cost of conventional water supply, presenting a discounted payback period shorter than the estimated service life of the equipment and a levelized cost of energy close to one Brazilian real per cubic meter of pumped water. The results demonstrate that floating water wheels constitute a sustainable, low-cost, and technically feasible solution for isolated rural communities.

This study aimed to evaluate the use of three-dimensional (3D) modeling and virtual reality (VR) as tools for spatial optimization and emission reduction in an agro-industrial requalification project in Ibema-PR, Brazil. The methodology comprised digital modeling in SketchUp, immersive validation in a Meta Quest 2 headset, and quantification of the carbon footprint associated with the main construction inputs (concrete, steel, masonry, and zinc), which included transportation, on-site diesel consumption, and end-of-life (EoL) emissions. The inventory indicated a baseline carbon footprint of 1,052.5 tCO₂, and the application of 3D and VR modeling demonstrated mitigation potential of 105.3 tCO₂ (10% – conservative scenario), 210.5 tCO₂ (20% – moderate scenario), and 315.7 tCO₂ (30% – optimistic scenario). These reductions correspond to up to 1.26 million km traveled by car, 31.6 thousand trees in annual sequestration, or 16.3 thousand months of residential electricity, respectively. In financial terms, the carbon credits avoided represent values ranging from R$ 5.26 thousand to R$ 94, 700, depending on the reference market. The results demonstrate the relevance of digital modeling as a sustainability strategy, while reconciling constructive efficiency, resource savings, and academic awareness for environmentally responsible practices.

The analysis of energy generation variation throughout the year reveals a geometric structure intrinsically linked to the solar analemma, whose patterns resemble the Möbius strip and Klein bottle. This behavior suggests that the global effective incident energy and the energy converted by solar panels do not follow a trivial linear relationship, but a distribution influenced by unconventional topological properties. Modeling this system in a Riemannian space—using the analemma’s metric and scalar curvature—allowed the formulation of a differential equation governing the generated energy, incorporating seasonal variations and dependencies on panel inclination and orientation. From an exergy perspective, a correspondence between exergy destruction, owing to system irreversibilities, and geometric effects, described by scalar curvature, was identified. The resulting equation, expressed through the Laplace–Beltrami operator, indicated that energy variation can be described in a space with non-orientable properties, supporting the hypothesis that the energy distribution behaves analogously to complex topological surfaces. This approach enhances the understanding of the relationship between solar energy generation and spatiotemporal geometry while providing a mathematical framework to optimize energy harvesting throughout the year. By linking the curvature of the analemma with exergy principles, this study proposes a new paradigm for modeling energy efficiency based on geometric and topological analysis.

Beef tallow is the second major feedstock used for biodiesel production in Brazil; however, studies on its performance and emissions in diesel engines remain limited. This study evaluates the performance and emissions of a single-cylinder diesel engine operating on beef tallow biodiesel blends (B10, B20, B30, and B100) under varying load conditions. Engine tests were conducted using a hydraulic dynamometer at loads ranging from 1 to 5 Nm. The specific fuel consumption (SFC), exhaust gas temperature (EGT), nitrogen oxides (NOx), hydrocarbons (HC), carbon monoxide (CO), and carbon dioxide (CO2) were measured. The biodiesel blends exhibited higher SFC than diesel due to their lower energy content, although SFC decreased at higher engine loads. Beef tallow biodiesel consistently produced lower NOx emissions than diesel fuel across all operating conditions, indicating a potential environmental benefit associated with its higher degree of saturation. In general, the B10 and B20 blends exhibited the most balanced overall performances, combining moderate fuel consumption and controlled emissions. These results demonstrate that beef tallow biodiesel is a technically viable alternative for small diesel engines, supporting its use as a renewable substitute for fossil fuels in practical applications.

In this study, we investigate the dual-fuel operation of compression ignition engines using biodiesel at varying concentrations in combination with biogas, with and without hydrogen enrichment. A response surface methodology, based on a central composite experimental design was employed to optimize energy efficiency and minimize pollutant emissions. The partial substitution of diesel with gaseous fuel substantially reduces the specific fuel consumption, achieving a maximum decrease of 21% compared with conventional diesel operation. Enriching biogas with hydrogen, accounting for 13.3% of the total flow rate, increases the thermal efficiency by 0.8%, compensating for the low calorific value and reduced volumetric efficiency of biogas. Variations in biodiesel concentration exhibits a nonlinear effect, yielding an additional average efficiency gain of 0.4%. Regarding emissions, the addition of hydrogen to biogas contributes to an average reduction of 5% in carbon monoxide emissions compared to the standard dual-fuel operation. However, dual-fuel operation leads to higher unburned hydrocarbon emissions relative to neat diesel; hydrogen enrichment mitigates this drawback by reducing hydrocarbon emissions by 4.1%. Although NO_x emissions increase by an average of 26.6% with hydrogen addition, dual-fuel strategies achieve NO_x reductions of 11.5% (hydrogen-enriched mode) and 33.3% (pure biogas mode) relative to diesel-only operation. Furthermore, the application of response surface methodology is robust and reliable, with experimental validation showing errors of 0.55–8.66% and an overall uncertainty of 4.84%.

The biofertilizer segment stabilized in anaerobic digesters offers a promising solution for reducing reliance on imported products. However, the development of this sector is largely constrained by logistical challenges, as well as the cost and feasibility of processing, transporting, and distributing organic fertilizers. To address these issues, this research presents a comprehensive thermoeconomic study of four scenarios applied in a rural microgeneration power plant in Toledo, Paraná state, Brazil. The main objectives were to determine the cost of the primary products, evaluate the system’s potential for energy self-sufficiency, and assess its economic viability. These findings would help amortize the costs associated with installing and operating the technology while adding greater value to its by-products. In the thermodynamic analysis, the potential for electricity generation from swine residues was evaluated. The economic analysis used the net present value, internal rate of return, payback period, and levelized costs of both energy and biofertilizer. By comparing the energy consumption required to fertigate 1 m³ of swine manure with its electricity generation potential, the system could achieve energy self-sufficiency. Moreover, the economic indicators of the scenarios demonstrate their viability, driven by the sale of electricity, transportation services, and biofertilizers.

The operating costs and investment in microgeneration plants are high, and the maximum efficiency of the process should be targeted such that farmers can obtain the best financial returns. In this study, the efficiency of a microbiogas plant was estimated using a methodological analysis that involved a biodigester mass balance and plant energy balance. The plant had two biodigesters and an engine generator. The biodigesters under study were considered low tech. The results showed 65% utilization of the volatile solids present in the substrate by the biodigesters, producing biogas with an average methane concentration of 57%. The equipment necessary for the operation of the system consumed 19.45% of the energy produced, and most of this energy was used for the transportation of substrates. The energy balance of the plant indicated an energy efficiency of 27.24% during the production process. The hydraulic retention time, pH, intermediate/partial alkalinity ratio, and organic loading rate indicate that reactor A is underutilized, has a low nutrient supply, and may result in low methane production. These indicators suggest that biogas production and quality can be improved by better distribution of substrates among the digesters.

A exploração do solo, especialmente para fins agrícolas, desempenha um papel crucial no desenvolvimento humano, mas práticas inadequadas têm levado à degradação da qualidade do solo e do meio ambiente. Estudos sobre Latossolos, amplamente encontrados no Brasil, indicam que diferentes formas de manejo influenciam significativamente seus atributos físicos e químicos. Solos sob mata nativa geralmente apresentam maior condutividade hidráulica, estabilidade de agregados e equilíbrio químico, em comparação com sistemas agrícolas intensivos. O objetivo desse estudo foi realizar uma revisão detalhada dos sistemas de manejo adotados no oeste do Paraná e comparar com a mata nativa. Práticas como o sistema de plantio direto com rotação de culturas têm demonstrado resultados positivos, aproximando-se das condições de solos naturais, enquanto o plantio direto sem rotação e as pastagens frequentemente mostram limitações, como redução na infiltração de água e estabilidade estrutural. Indicadores como densidade do solo, porosidade, condutividade hidráulica, pH, nutrientes e matéria orgânica têm sido utilizados para avaliar os impactos desses sistemas. A literatura reforça a necessidade de práticas conservacionistas, como rotação de culturas e cobertura vegetal, para mitigar os impactos da exploração agrícola e promover a sustentabilidade dos solos. Esses achados destacam a importância de integrar estratégias de manejo que favoreçam tanto a produtividade quanto a preservação ambiental.

O presente artigo aborda a temática das energias renováveis, com foco no biodiesel aditivado, enfatizando sua definição, produção e os desafios associados ao seu uso. A introdução discute a crescente demanda por fontes de energia sustentáveis e a importância do biodiesel como alternativa aos combustíveis fósseis. Também são apresentadas as propriedades benéficas dos aditivos para o biodiesel, que podem melhorar sua eficiência e desempenho, além de mitigar problemas relacionados à corrosão e degradação. A metodologia é baseada em uma revisão bibliográfica abrangente, que analisa diferentes estudos e investigações sobre a produção de biodiesel e o uso de aditivos, sem a realização de experimentos diretos. A pesquisa contempla os principais desafios enfrentados pela indústria do biodiesel, como a variabilidade das matérias-primas e a necessidade de adequações tecnológicas para garantir a qualidade do produto final. Os resultados discutem o impacto positivo do uso de biodiesel aditivado, incluindo melhorias na performance dos motores, redução das emissões de poluentes e o potencial de sustentabilidade econômica e ambiental. A análise também revela que a adoção de políticas públicas eficazes e o aumento da conscientização pública são fundamentais para promover a aceitação e expansão do biodiesel no mercado. Por fim, as considerações finais ressaltam a importância da colaboração entre academia, indústria e governo para o desenvolvimento de estratégias que integrem o biodiesel aditivado à matriz energética, contribuindo para um futuro mais sustentável e resiliente.

Este trabalho foi desenvolvido em uma granja de ciclo completo localizada no extremo oeste do estado de Santa Catarina - Brasil, que possui o manejo diferenciado no tempo de retenção das cargas orgânicas com volume de efluentes diários de 165 m³, tendo capacidade de alojamento de 3.500 fêmeas em sistema de UPL e 10.000 animais em ciclo de terminação. A granja teve o plantel ampliado e para atender a demanda de tratamento de efluentes, a unidade de biodigestão precisou ser reestruturada com outras tecnologias. Portanto, em 2023 realizou-se a implantação de um novo biodigestor, um reator CSTR de alta taxa com mistura completa, aquecimento e isolamento térmico. Desta forma, este estudo tem por objetivo avaliar o comportamento do aquecimento no reator CSTR, sendo analisada as temperaturas da água na entrada e saída do reator na faixa de melhor produção de biogás. Diante dos resultados obtidos, tem-se que mesmo o local sendo de clima temperado com oscilações na temperatura ambiente, não ocorreram perdas consideráveis do calor no sistema de aquecimento, apontando que o material utilizado no sistema é adequado para esta aplicação, auxiliando a digestão anaeróbia com a estabilidade de temperatura.