Multiple Regression Analysis in the Development of NiFe Cells as Energy Storage Solutions for Intermittent Power Sources Such as Wind or Solar

Multiple regression analysis was used to investigate the effect of bismuth sulphide and iron sulphide as anode additives for NiFe cells. With this in mind, in-house made Fe/FeS/Bi2S3 based electrodes were cycled against commercially available nickel electrodes. A simplex centroid design was used to investigate the combined effects of any of the aforementioned additives on cell performance. The manuscript ends with an initial look at electrolyte systems as a means to further improve the performance of our cells. Finally, our findings support the idea that HS- ions improve the overall performance of NiFe cells

Aqueous batteries as grid scale energy storage solutions

Energy storage technologies are required to make full use of renewable energy sources, and electrochemical cells offer a great deal flexibility in the design of energy systems. For large scale electrochemical storage to be viable, the materials employed and device production methods need to be low cost, devices should be long lasting and safety during operation is of utmost importance. Energy and power densities are of lesser concern. For these reasons, battery chemistries that make use of aqueous electrolytes are favorable candidates where large quantities of energy need to be stored. Herein we describe several different aqueous based battery chemistries and identify some of the research challenges currently hindering their wider adoption. Lead acid batteries represent a mature technology that currently dominates the battery market, however there remain challenges that may prevent their future use at the large scale. Nickel–iron batteries have received a resurgence of interest of late and are known for their long cycle lives and robust nature however improvements in efficiency are needed in order to make them competitive. Other technologies that use aqueous electrolytes and have the potential to be useful in future large-scale applications are briefly introduced. Recent investigations in to the design of nickel–iron cells are reported with it being shown that electrolyte decomposition can be virtually eliminated by employing relatively large concentrations of iron sulfide in the electrode mixture, however this is at the expense of capacity and cycle life

Sheds extratores e captadores de ar: influência da geometria e da dimensão das aberturas no desempenho da ventilação natural nas edificações

Resumo A ventilação natural é uma eficiente estratégia projetual para o condicionamento térmico passivo de edificações, ocorrendo por ação dos ventos, efeito chaminé ou pela combinação de ambos. Dentre as estratégias de ventilação, destacam-se os sheds, aberturas no telhado, que funcionam como captadores ou extratores de ar, dependendo de sua localização em relação aos ventos dominantes. O objetivo desse artigo é avaliar a influência da variação na geometria dos sheds e na dimensão das aberturas de entrada e saída de ar no desempenho da ventilação natural. O sistema foi avaliado para os ângulos de incidência dos ventos externos de 0° e 45° (extração) e 135° e 180° (captação). A metodologia adotada foi a simulação por Dinâmica dos Fluídos Computacional (CFD), utilizando como ferramenta o software CFX. Foram realizadas análises quantitativas (taxas de renovação de ar/hora e coeficiente de pressão nas aberturas) e qualitativas (planos de contorno e vetores de direção e intensidade do fluxo de ar). Os resultados indicam que sheds com geometrias aerodinâmicas e o aumento das aberturas de saída de ar incrementam o fluxo de ar interno. Para os sheds captadores o aumento isolado das aberturas de entrada de ar não proporciona uma melhora significativa na captação dos ventos pela cobertura