Este trabalho analisa a possibilidade de plantio sustentável de dendê (Elaeis guineensis) e o uso de sua biomassa residual como combustível em uma usina termelétrica para o provimento de energia elétrica em parte do Sistema Isolado, ao sul do Estado de Roraima. Para isso são conjugadas: a análise financeira, os aspectos sociais e as questões ambientais. Parte-se da definição das áreas necessárias para o plantio do dendê e para a instalação da indústria de extração dos óleos de palma e palmiste, associada a uma usina termelétrica movida à biomassa residual de dendê. Em seguida, procede-se a análise financeira, na qual é considerada a venda dos óleos de palma e de palmiste para a indústria alimentícia e de cosméticos, enquanto a biomassa residual (cachos de frutas vazios, cascas e fibras) é utilizada como combustível um uma usina termelétrica de 10MW de potência. A análise conjunta destas atividades indica que é possível obter uma taxa interna de retorno próxima a 16,71% ao ano e um valor presente líquido de R$ 46,9 milhões quando utilizada uma taxa de desconto de 15% ao ano, para um investimento total de R$ 491,5 milhões. Pelo fato de a região analisada estar localizada no Sistema Isolado, foi incorporado ao fluxo de caixa a sub-rogação dos benefícios da Conta Consumo de Combustível. Além de provar-se economicamente viável, no quesito ambiental, o trabalho realiza uma análise quantitativa da redução de emissões de gases de efeito estufa decorrente da substituição das termelétricas a óleo Diesel prevalentes na região pela biomassa residual do dendê. Tal plantio resulta em uma redução de aproximadamente 444 mil toneladas de CO2, assim como promove a recuperação de 28.888 mil hectares de terras degradadas. A análise social, por sua vez, indica que o plantio de dendê permite que cerca de 2.888 famílias permaneçam próximas às suas terras de origem, trabalhando em atividades apropriadas para o bioma amazônico e com uma geração de renda anual de R$ 5.800 somente com o plantio do dendê. / This study examines the viability of a sustainable project with the production of palm (Elaeis guineensis) to supply oil to food or cosmetic industries and the use of the residual biomass as a biofuel by a power plant. The biofuel side of the project aims the provision of electricity in part of the so called Isolated System, in southern Roraima. The analysis combines a financial approach, with social and environmental concerns. The starting point is the definition of the area size for planting the crop and fitting the assumptions of the industries (palm oil mill and biomass-fired power plant). In the procedures it is considered the palm oil and palm kernel oil sales for the food and cosmetics industries, while the residual biomass (empty fruit bunches, shells and fiber) is used as a fuel in a thermoelectric power plant. The analysis points to an internal rate of return close to 16,7% and a net present value of US$27.6 million, using a discount rate of 15% per year, for an investment of US$ 280 million. In environmental perspective, the quantitative analysis points to the reduction in emissions of greenhouse gases from the displacement of the Diesel powered plants, quite common in the region, by residual biomass powered one. Such displacement results in a reduction of approximately 444 thousand tons of CO2, as well as the recovery of 28,888 hectare of deforested areas. In social perspective, the project allows approximately 2,888 families to remain close to their homeland, working in appropriated activities for the local biome, obtaining US$3,400 per year only with palm plantation.

Esta tese propõe uma metodologia para avaliar o emprego de técnicas de seleção e conversão da radiação solar para aumentar a produção de energia elétrica de células fotovoltaicas. Foi feita uma revisão dos mecanismos fotovoltaicos para produção de energia elétrica e os entraves para aumentar sua eficiência, em especial os impactos da temperatura e da absorção do espectro solar. Uma metodologia foi criada para definir um filtro óptico ótimo a ser utilizado em uma região na presença ou não de conversão do espectro, através de simulações computacionais, que define a faixa do espectro solar que deve ser absorvida pela célula para se ter o melhor equilíbrio entre absorção e aquecimento. Um modelo matemático foi criado e implementado computacionalmente, para calcular a produção de energia de um módulo fotovoltaico, em uma dada região com ou sem a aplicação de técnicas de conversão e seleção da radiação solar. Através de um estudo de caso com dados da cidade de Petrolina, PE, Brasil, concluiu-se que o ganho esperado para utilização de um filtro óptico que reflete ondas de comprimento superiores a 1000 nm é cerca de 1% da energia gerada. Ensaios empíricos permitiram validar a metodologia proposta, comparando os dados reais com os dados teóricos obtidos pelas simulações do modelo matemático. Após a calibração do modelo matemático, verificou-se que os resultados de potência instantânea calculados com o modelo matemático variavam cerca de 5% tanto para o módulo com filtro quanto para o módulo sem filtro. Para contornar a restrição construtiva do filtro óptico e verificar outros ganhos possíveis são propostos experimentos com compostos de conversão de radiação solar associados com filtros ópticos para seleção da radiação solar. Com isto, espera-se aumentar significativamente a produção de energia elétrica de células fotovoltaicas de Silício cristalino. / This thesis proposes a methodology to evaluate the use of solar radiation selection and conversion techniques to increase the production of electric energy of photovoltaic solar cells. A review of the photovoltaic mechanisms for the production of electrical energy and the obstacles to increase its efficiency, especially the impacts of temperature and the absorption of the solar spectrum was done. A methodology was developed to define an optimal optical filter to be used in a region in the presence or not of solar spectrum conversion, through computational simulations, which defines the range of the solar radiation that must be absorbed by the cell in order to have the best balance between absorption and heating. A mathematical model was created and implemented computationally to calculate the energy production of a photovoltaic module in a given region with or without the application of solar radiation conversion and selection techniques. A case study with data from the city of Petrolina, PE, Brazil, concluded that the expected gain for the use of an optical filter that reflects wavelengths above 1000 nm is about 1% of the power generated. Empirical tests allowed validating the proposed methodology comparing the actual data with the theoretical data obtained by the simulations of the mathematical model. After calibration of the mathematical model, it was verified that the instantaneous power results calculated with the mathematical model vary about 5% for both the filter module and the unfiltered module. To avoid the constructive constraint of the optical filter and to verify other possible gains are proposed experiments with solar radiation conversion compounds associated with optical filters to select the solar radiation. With this, it is expected to significantly increase the electricity production of crystalline silicon photovoltaic cells.

The world is currently experiencing major issues in the energy sector. The ever-growing human population, limited energy resources and the effect of greenhouse gas emissions have become major global concerns for the energy sector, including the electricity generation sector. This dilemma caused electricity providers to revise their generation methods and created a major need for consumers to utilise electricity more efficiently. Demand side management (DSM) is one initiative developed for consumers to efficiently utilise electricity. Due to their high electricity consumption and technical skills, mines are ideal targets for the implementation of DSM strategies. Therefore, the focus of this study was to investigate South African mines for possible implementation of DSM strategies on their compressed air networks. Compressed air networks at South African mines are relatively old and inadequately maintained. This causes inefficient distribution and use of compressed air. The study will therefore focus on reconfiguring mining compressed air networks for cost savings. Cost savings include financial savings on electricity bills, implementation costs and decreased maintenance. Through several investigations, the possibility of implementing energy savings strategies to reconfigure the compressed air networks of two South African mines was identified. Reconfiguring the networks would respectively entail interconnecting two shafts and relocating a compressor from an abandoned shaft to a fully productive shaft. Theoretical simulations were developed to determine the networks’ responses to the reconfiguration strategies. The simulations assisted in exposing the viability of implementing the reconfiguration strategies on the respective compressed air networks. Positive responses were obtained from the simulations and proposals were made to the respective mines for possible implementation. The proposed initiatives were implemented on the respective mines’ compressed air networks. After implementation of the interconnection strategy, a consecutive three-month performance assessment period commenced to prove the viability of the proposed savings. An average power saving of 1 700 kW was achieved during the performance assessment period. The proposed initiative to relocate the compressor is currently being implemented. A financial saving of approximately R8.9 million per annum was achieved by implementing the interconnection strategy. The large financial saving was due to the utilisation of the mine’s salvaged equipment. Further savings were achieved by the decreased maintenance on the mine’s compressors. Due to the successful implementation of the interconnection strategy, it is safe to state that cost savings can be achieved by reconfiguring mining compressed air networks. / MIng (Mechanical Engineering), North-West University, Potchefstroom Campus, 2014

Electricity availability and the costs thereof in South Africa were traditionally considered an abundant and low cost commodity, but in recent years this situation has changed altogether. Industries are challenged by a strained national electricity grid and tariff increases more than four times the national inflation rate over the past two years, with further tariff increases expected in subsequent years; thus, exposing industries to significant business risks that may jeopardise the sustainability of industries. With the majority of the national electricity supply derived from coal, South Africa's push to reduce carbon emissions exerts even more pressure on industries as electricity usage is inextricably linked to its carbon footprint. In addition, South Africa's reliance on cogeneration from industries for its 2010 - 2030 electricity capacity plan further promotes industries to become more self–sufficient concerning electricity generation. In view of the above, there is a need in the South African integrated iron and steel industry for a framework that collectively addresses the governing factors pertaining to electricity generation in this industry, technical and economical quantification of available technologies and implementation of these technologies. This dissertation researches the current driving/governing and the remediating factors to become more self–sufficient in terms of electricity generation. A framework for electricity generation opportunities in the integrated iron and steel industry is developed from the literature study and the researcher's own experience. The framework embodies four building blocks into a single and all–encompassing framework, which provides the necessary governing factors that quantify the potential need to pursue electricity generation/cogeneration, the technical and economical implications and, inevitably, the implementation requirements and guidelines. Validating the framework against case studies pertaining to ArcelorMittal Newcastle realised a correlation of between 84.6% to 97.6% concerning the technical parameters. In addition, the validation process also indicated that the framework is aligned with current practices applied by ArcelorMittal South Africa. The framework will enable South African integrated iron and steel industries to expand and adapt their own procedures to be specific to their operational requirements. The implementation of the framework should be tailored to address the specific needs concerning cogeneration in industry. / Thesis (M.Ing. (Development and Management Engineering))--North-West University, Potchefstroom Campus, 2012.

Electricity availability and the costs thereof in South Africa were traditionally considered an abundant and low cost commodity, but in recent years this situation has changed altogether. Industries are challenged by a strained national electricity grid and tariff increases more than four times the national inflation rate over the past two years, with further tariff increases expected in subsequent years; thus, exposing industries to significant business risks that may jeopardise the sustainability of industries. With the majority of the national electricity supply derived from coal, South Africa's push to reduce carbon emissions exerts even more pressure on industries as electricity usage is inextricably linked to its carbon footprint. In addition, South Africa's reliance on cogeneration from industries for its 2010 - 2030 electricity capacity plan further promotes industries to become more self–sufficient concerning electricity generation. In view of the above, there is a need in the South African integrated iron and steel industry for a framework that collectively addresses the governing factors pertaining to electricity generation in this industry, technical and economical quantification of available technologies and implementation of these technologies. This dissertation researches the current driving/governing and the remediating factors to become more self–sufficient in terms of electricity generation. A framework for electricity generation opportunities in the integrated iron and steel industry is developed from the literature study and the researcher's own experience. The framework embodies four building blocks into a single and all–encompassing framework, which provides the necessary governing factors that quantify the potential need to pursue electricity generation/cogeneration, the technical and economical implications and, inevitably, the implementation requirements and guidelines. Validating the framework against case studies pertaining to ArcelorMittal Newcastle realised a correlation of between 84.6% to 97.6% concerning the technical parameters. In addition, the validation process also indicated that the framework is aligned with current practices applied by ArcelorMittal South Africa. The framework will enable South African integrated iron and steel industries to expand and adapt their own procedures to be specific to their operational requirements. The implementation of the framework should be tailored to address the specific needs concerning cogeneration in industry. / Thesis (M.Ing. (Development and Management Engineering))--North-West University, Potchefstroom Campus, 2012.

This dissertation assesses the evolving structure and performance of the electricity supply industry (ESI) in Queensland following the restructuring and deregulation process undertaken in 1997 and 1998 respectively. This microeconomic reform process essentially replaced a vertically integrated electricity monopoly with an oligopolistic electricity market. In theory at least, restructuring a monopoly generator, and deregulating the product and capacity markets, should lead to lower electricity production costs, more cost-reflective wholesale electricity prices, and a generation plant expansion path that reflects the least-cost, optimal mix of baseload, intermediate and peaking technologies. In economic terms, the deregulated electricity market should deliver improvements in productive, allocative and dynamic efficiency. However, a likely side effect is a deterioration of ESI environmental performance, since the minimization of production costs are of paramount importance in a competitive market. This research has utilized historic data, direct comparisons to southern market outcomes, economic theory and the development and adaptation of a suite of economic cost and generation system simulation models to test the stated hypotheses of expected improvements in productive, allocative and dynamic efficiency, and a deterioration in environmental performance. This research has not had the availability of extensive historical market data upon which to draw. When research first commenced, less than six months of historical market data were available. At the time of completion of this dissertation, only three full financial years of data existed. Consequently, this research necessarily relied upon complex simulation models of economic cost and electricity generation systems, coupled with economic theory, to forecast market outcomes. The short history of market data is examined and tentative conclusions are drawn from this, which are integrated with the outputs of the simulation models. Simulation experiments have been conducted to identify the theoretically optimal market outcome, that is, the least-cost generation plant mix that would best meet the Queensland load curve, subject to a reliability constraint. This forms the 'base case', and represents that which would reasonably be expected to emerge under a centrally planned monopoly regime with a welfare maximization objective, characterised by perfect information and zero political intervention. Such a scenario establishes efficient generation system costs, prices and plant capacity mix. The 'base case' or centrally planned scenario is contrasted with forecast 'market scenarios'. Performance of the generation system is explored under specified scenarios using the economic cost and generation system simulation models, publicly available information about committed and expected future investment in plant capacity, incumbent generator trends and behavioural assumptions consistent with oligopolistic market theories. The analysis indicates that productive efficiency, or cost efficiency, is enhanced as a result of restructuring the monopoly generator into competing entities since competitive pressures force the generators to reduce costs in order to survive. Allocative efficiency, or price efficiency, declined during the first three years of the market, with all generators earning positive economic rents. The presence of these economic rents, coupled with conventional oligopolistic strategies associated with the theory of barriers to entry, resulted in a rush to commission new baseload capacity. Not surprisingly, dynamic efficiency appears to be deteriorating, with the market-induced capacity augmentation proving to be far greater than that considered optimal. Modelling results indicate that the oversupply of baseload capacity is expected to place considerable downward pressure on electricity prices, and thus allocative efficiency is forecast to improve in the intermediate run, much to the benefit of electricity consumers. In the long run, the oversupply of baseload capacity and subsequent low market price can be expected to frustrate the timely entry of new peaking or intermediate plant capacity, which will ultimately be required by the Queensland ESI given the strong electricity demand growth. What does appear to be emerging is a five or seven year electricity generation business cycle. Modelling results from this research also point to alarming environmental implications, with the general levels of greenhouse gas emissions of the electricity system increasing. While system thermal efficiency is declining, the rush of new, low-cost coal-fired capacity represents an inferior outcome to the alternative (i.e. efficient combined cycle gas plant) because the volume of greenhouse emissions is markedly higher. The outlook for Queensland's greenhouse gas emissions from electricity generation, in the absence of coincident environmental policies, is that they will more than double between the 1990 emission baseline, and the commencement of the Kyoto commitment period in 2008. Some clear warnings emerge from this research. The structure and performance of an ESI prior to deregulation is important if microeconomic reforms are to be successful. Too little generation capacity or transmission capacity is unlikely to provide a robust foundation for wholesale market implementation. To ensure that adequate competition will prevail, it will be necessary to restructure monopoly generators. The existing ESI needs to be characterised by ‘inefficiency’ if gains from trade are to be capitalized. An efficient centrally planned ESI is unlikely to benefit greatly from deregulation, particularly given that implementing a product market is likely to be a costly process. And finally, competitive markets deliver lowest cost, which is usually inconsistent with the most environmentally responsible outcome. As a result, if the environment is considered a policy imperative, it will be critical that ESI deregulation be complemented by coincident environmental regulations.

Over that past three decades, power sector reform has been a key pillar of policy agendas in more than half of the countries across the world. This thesis specifically concerns the empirical investigation of the economic performance of the international electricity generation industry. Drawing on the stochastic frontier analysis techniques, the thesis considers the influence of reform as exogenous factors in shifting frontier technology as well as shaping inefficiency function directly -determinants and heteroscedasticity variables. The first essay uses an extensive panel dataset of 91 countries over the period 1980 to 2010 to measure the impact of deregulation on efficiency and total productivity growth using stochastic input distance frontier (SIDF). Three specific issues are addressed in the first essay: (1) the relationship between deregulation and technical efficiency, (2) the extent of the rank correlation of the country intercepts with deregulation via their position on the frontier, (3) the trend of total factor productivity and its components. We establish a positive impact of deregulation on efficiency and some compelling evidence suggesting that the country intercepts equally account for the influence of deregulation aside efficiency. In particular, the technical efficiency index from the first paper reveals that most OECD European countries are consistently efficient. Building on this finding, the second essay investigates the performance in term of cost efficiency for electricity generation in OECD power sector while accounting for the impact of electricity market product regulatory indicators. Empirical models are developed for the cost function as a translog form and analysed using panel data of 25 countries during the period 1980 to 2009. We show that it is necessary to model latent country-specific heterogeneity in addition to time-varying inefficiency. The estimated economies of scale are adjusted to take account of the importance of the quasi-fixed capital input in determining cost behaviour, and adjusted economies of scale are verified for the OECD generation sector. The findings suggest there is a significant impact of electricity market regulatory indicators on cost. Cost complementarity between generation and emissions found to be significant, indicating the possibility of reducing emissions without necessarily reducing electricity generation. Finally, the third essay examines the performance of electric power industry s using consistent state-level electricity generation dataset for the US contiguous states from 1998-2014. We estimate stochastic production frontier for five competing models in order to identify the determinants of technical inefficiency and marginal effects. We find evidence of positive impacts of deregulation on technical efficiency across the models estimated. Our preferred model shows that deregulated states are more efficient in electricity generation than non-deregulated states. The result of the marginal effects shows that deregulation has a positive and monotonic effect on the technical efficiency.

This article discusses the structure of the electricity supply. This system mainly consists of three subsystems: the generation, transmission and distribution of electricity. Each system is comprised of different features like its regulation. Given the above, the author tells us the Peruvian case, on the body called the Committee of Economic Operation of the System (COES). / El presente artículo trata sobre la estructura de la provisión de electricidad. Este sistema consta principalmente de tres subsistemas: la generación, la transmisión, y la distribución de electricidad. Cada sistema está conformado por diferentes características al igual que su regulación. Ante lo mencionado, el autor nos comenta el caso peruano, sobre el organismo llamado Comité de Operación Económica del Sistema (COES).

A matriz energética mundial é composta por várias fontes primárias, dentre as quais os combustíveis fósseis, como o petróleo, prevalecem sobre as demais. No entanto, devido ao crescimento populacional e ao desenvolvimento tecnológico e industrial, haverá um conseqüente aumento na demanda de energia e devido à preocupação ambiental, será necessária a busca por outras fontes energéticas. Dentre essas, destaca-se a energia solar fotovoltaica, por possibilitar a geração de forma limpa e descentralizada. O Brasil tem a vantagem de estar localizado na zona inter-tropical, registrando altos índices de irradiação solar durante todo o ano, em comparação com outros países do mundo que já fazem uso desta tecnologia. Neste trabalho, foi estudada a inserção de sistemas fotovoltaicos conectados à rede elétrica pública e integrados em edificações residenciais urbanas. Para tanto, foram dimensionados sistemas para três residências situadas em diferentes regiões brasileiras, e que possuem as mesmas características construtivas e o mesmo consumo médio mensal de energia elétrica. Uma das premissas consideradas foi a autossuficiência energética das edificações apenas utilizando o recurso solar como fonte de geração. As cidades escolhidas para a análise foram Porto União/SC, São Carlos/SP e Petrolina/PE por possuírem diferenças significativas nos níveis de irradiação solar, representando desta forma os extremos encontrados no território brasileiro. A partir do dimensionamento foram estimadas a geração de energia elétrica anual para cada localidade e as curvas de geração foram confrontadas com as curvas de demanda diária média das regiões Sul, Sudeste e Nordeste, representando respectivamente, as três cidades escolhidas. Foram estimados os custos de instalação dos três sistemas, sendo feita ainda uma análise econômica simplificada para a verificação do impacto gerado pela inserção da tecnologia solar fotovoltaica como fonte alternativa na geração de energia elétrica em edificações residenciais urbanas. Para a avaliação econômica foi considerada a adoção do Sistema de Compensação Energética e um Período de Retorno Simples, que é a relação obtida entre o investimento feito inicialmente para a instalação de um sistema fotovoltaico e a economia anual proporcionada por essa instalação. Considerando um período de vida útil de um sistema fotovoltaico como sendo estimado em 25 anos, os resultados demonstraram que todos os sistemas seriam pagos antes desse período. A partir dos dimensionamentos, foi possível concluir ainda que a área requerida para a instalação de sistemas fotovoltaicos em residências é muito pequena e possui elevado potencial de aproveitamento, viabilizando desse modo a sua inserção no ambiente urbano. / The world\'s energy matrix is made up of several primary sources among which fossil fuels, mainly oil, prevail. Nevertheless, given population growth coupled with technological and industrial development, there will consequently be an increase in energy demands and, due to environmental concerns, looking for other energy sources is necessary. Among those, photovoltaic solar energy stands out for providing clean, decentralized energy generation. Brazil has the advantage of being located within the intertropical zone, registering higher levels of solar irradiation throughout the year compared to other countries that already use such technology. In this thesis, we studied the insertion of photovoltaic systems into the public grid and integrated to urban residential buildings. For such, we sized systems for three home environments situated in different Brazilian regions with similar building characteristics and same average monthly consumption. One of the premises considered was the buildings energy self-sufficiency based on solar resources alone. The cities chosen for the experiment were Porto União/SC, São Carlos/SP and Petrolina/PE given their significantly different exposure to solar irradiation, thus representing the extremes found in the Brazilian territory. From the initial sizing up the annual electricity demand for each location was estimated and generation curves were confronted with the daily demand curves from the South, Southeast and Northeast regions representing, respectively, the three chosen cities. Implementation costs were estimated for the three systems along with a simplified economic analysis in order to verify the impact caused by the insertion of photovoltaic solar energy as an alternative source of power generation in urban residential buildings. For the economic evaluation was considered the use of the Compensation System Energy and a Simple Payback Period, which is the ratio between the initial investment for the installation of a photovoltaic system and the annual savings provided by this facility. Considering a life cycle of a photovoltaic system as estimated at 25 years, the results showed that all systems would be paid before that period. From the sizing was still possible to conclude that the area required for the installation of photovoltaic systems in residences is very small and has a high potential for use, thereby enabling their integration into the urban environment

Continued emission of green house gases has energized research activity worldwide to develop efficient ways to harness renewal energy. The availability of large scale energy storage technologies is essential to make renewal energy a reliable source of energy. Redox flow batteries show potential in this direction. These batteries typically need expensive membranes which need replacement be-cause of fouling. The recently proposed soluble lead redox flow battery (SLRFB), in which lead ions deposit on electrodes in charge cycle and dissolve back in discharge cycle, can potentially cut down the cost of energy storage by eliminating membrane. A number of challenges need to be overcome though. Low cycleability, residue formation, and low efficiencies are foremost among these, all of which require an understanding of the underlying mechanisms. A model of laminar flow-through SLRFB is first developed to understand buildup of residue on electrodes with continued cycling. The model accounts for spatially and temporally growing concentration boundary layers on electrodes in a self consistent manner by permitting local deposition/dissolution rates to be controlled by local ion transport and reaction conditions. The model suggests controlling role for charge transfer reaction on electrodes (anode in particular) and movement of ions in the bulk and concentration boundary layers. The non-uniform current density on electrodes emerges as key to formation of bare patches, steep decrease in voltage marking the end of discharge cycle, and residue buildup with continuing cycles. The model captures the experimental observations very well, and points to improved operational efficiency and decreased residue build up with cylindrical electrodes and alternating flow direction of recirculation. The underlying mechanism for more than an order of magnitude increase in cycle life of a beaker cell battery with increase in stirrer speed is unraveled next. Our experiments show that charging with and without stirring occurs identically, which brings up the hitherto unknown but quite strong role of natural convection in SLRFB. The role of stirring is determined to be dislodgement/disintegration of residue building up on electrodes. The depletion of active material from electrolyte due to residue formation is offset by “internal regeneration mechanism”, unraveled in the present work. When the rate of residue formation, rate of dislodging/disintegration from electrode, and rate of regeneration of active material in bulk of the electrolyte becomes equal, perpetual operation of SLRFB is expected. The identification of strong role of free convection in battery is put to use to demonstrate a battery that requires stirring/mixing only intermittently, during open circuit stages between charge and discharge cycles when no current is drawn. Inspired by our experimental finding that the measured currents for apparently diffusion limited situations (no external flow) are far larger than the maxi-mum possible theoretical value, the earlier model is modified to account for natural convection driven by concentration gradient of lead ions in electrolyte. The model reveals the presence of strong natural convection in battery. The induced flow in the vicinity of the electrodes enhances mass transport rates substantially, to the extent that even in the absence of external flow, normal charge/discharge of battery is predicted. The model predicted electrochemical characteristics are verified quantitatively through voltage-time measurements. The formation of flow circulation loops driven by electrode processes is validated qualitatively through PIV measurements. Natural convection is predicted to play a significant role in the presence of external flow as well. The hitherto unexplained finding in the literature on insensitivity of charge-discharge characteristics to electrolyte flow rate is captured by the model when mixed mode of convection is invoked. Flow reversal and wavy flow are predicted when natural convection and forced convection act in opposite directions in the battery. The effect of the presence of non-conducting material (PbO on anode) on the performance of SLRFB is studied using a simplified approach in the model. The study reveals the presence of charge coup de fouet phenomenon in charge cycle. The phenomenon as well as the predicted effect of depth of discharge on the magnitude of charge coup de fouet are confirmed experimentally.