RESUMO As usinas hidrelétricas de pequeno porte correspondem a 6 GW da potência instalada no Brasil. Contudo, recentemente, a geração de energia elétrica de cada usina se mostrou abaixo do previsto por suas respectivas garantias físicas. Assim, este artigo analisa o histórico de vazões de 24 usinas utilizando cartas de controle exponencial de média móvel na tentativa de verificar se as mudanças climáticas ou no uso e ocupação do solo poderiam ter alterado ao longo do tempo a vazão média anual disponível na bacia. Os gráficos não mostraram nenhuma tendência de queda ou aumento na vazão média, mas demonstraram um recorrente número de pontos fora de controle, o que comprova a sensibilidade da energia assegurada em relação às variações hidrológicas e a necessidade de se avaliar o uso de vazões médias diárias para o cálculo e análise da energia gerada por usinas hidrelétricas de pequeno porte.

ABSTRACT Small hydroelectric power plants make up 6 GW of installed capacity in Brazil. However, electricity generation at the plants has been below their expected Assured Energy Levels (AELs) recently. This paper analyzes the flow history of 24 plants using exponential moving average control charts in an attempt to verify whether climate change or land use and occupation could have changed the average annual flow available in the basin over time. The graphs showed neither a decreasing or increasing trend in average flows, but rather showed a recurring number of out-of-control points, which proves the sensitivity of assured energy to hydrological variations and the need to evaluate the use of daily average flow rates for calculating and analyzing the energy generated by small power plants.

AbstractDistribution becomes the main link in a supply chain when transport efficiency is concerned. Being a huge size country, transport related problems in Brazil should be treated through the application of new information technology and more efficient logistic tools. This paper evaluates ducts and railway modes by the complete cost methodology to find the best alternative for the transportation of petroleum derived products, in a Case Study. The method deals with technical, economic, environmental, social and political factors being equally important, following the concepts of sustainable development. In general, only aspects related to investment, construction, equipment acquisition and financial return have been considered, which is inadequate for the effective functioning of a project. If only construction financial costs were concerned, the best alternative for the transportation of petroleum products would be the railway. However, the Complete Cost analysis shows that ducts are more advantageous with the highest valuation factors (291, 54 points) versus the railway (257,83 points). Therefore, this study contributes to a more effective evaluation and discussion about the important aspects to be evaluated in making a choice for the most sustainable transport mode.