Exergetic, energetic, economic and environmental evaluation of concentrated solar power plants in Libya

The PhD project addresses the potential of using concentrating solar power (CSP) plants as a viable alternative energy producing system in Libya. Exergetic, energetic, economic and environmental analyses are carried out for a particular type of CSP plants. The study, although it aims a particular type of CSP plant – 50 MW parabolic trough-CSP plant, it is sufficiently general to be applied to other configurations. The novelty of the study, in addition to modeling and analyzing the selected configuration, lies in the use of a state-of-the-art exergetic analysis combined with the Life Cycle Assessment (LCA). The modeling and simulation of the plant is carried out in chapter three and they are conducted into two parts, namely: power cycle and solar field. The computer model developed for the analysis of the plant is based on algebraic equations describing the power cycle and the solar field. The model was solved using the Engineering Equation Solver (EES) software; and is designed to define the properties at each state point of the plant and then, sequentially, to determine energy, efficiency and irreversibility for each component. The developed model has the potential of using in the preliminary design of CSPs and, in particular, for the configuration of the solar field based on existing commercial plants. Moreover, it has the ability of analyzing the energetic, economic and environmental feasibility of using CSPs in different regions of the world, which is illustrated for the Libyan region in this study. The overall feasibility scenario is completed through an hourly analysis on an annual basis in chapter Four. This analysis allows the comparison of different systems and, eventually, a particular selection, and it includes both the economic and energetic components using the “greenius” software. The analysis also examined the impact of project financing and incentives on the cost of energy. The main technological finding of this analysis is higher performance and lower levelized cost of electricity (LCE) for Libya as compared to Southern Europe (Spain). Therefore, Libya has the potential of becoming attractive for the establishment of CSPs in its territory and, in this way, to facilitate the target of several European initiatives that aim to import electricity generated by renewable sources from North African and Middle East countries. The analysis is presented a brief review of the current cost of energy and the potential of reducing the cost from parabolic trough- CSP plant. Exergetic and environmental life cycle assessment analyses are conducted for the selected plant in chapter Five; the objectives are 1) to assess the environmental impact and cost, in terms of exergy of the life cycle of the plant; 2) to find out the points of weakness in terms of irreversibility of the process; and 3) to verify whether solar power plants can reduce environmental impact and the cost of electricity generation by comparing them with fossil fuel plants, in particular, Natural Gas Combined Cycle (NGCC) plant and oil thermal power plant. The analysis also targets a thermoeconomic analysis using the specific exergy costing (SPECO) method to evaluate the level of the cost caused by exergy destruction. The main technological findings are that the most important contribution impact lies with the solar field, which reports a value of 79%; and the materials with the vi highest impact are: steel (47%), molten salt (25%) and synthetic oil (21%). The “Human Health” damage category presents the highest impact (69%) followed by the “Resource” damage category (24%). In addition, the highest exergy demand is linked to the steel (47%); and there is a considerable exergetic demand related to the molten salt and synthetic oil with values of 25% and 19%, respectively. Finally, in the comparison with fossil fuel power plants (NGCC and Oil), the CSP plant presents the lowest environmental impact, while the worst environmental performance is reported to the oil power plant followed by NGCC plant. The solar field presents the largest value of cost rate, where the boiler is a component with the highest cost rate among the power cycle components. The thermal storage allows the CSP plants to overcome solar irradiation transients, to respond to electricity demand independent of weather conditions, and to extend electricity production beyond the availability of daylight. Numerical analysis of the thermal transient response of a thermocline storage tank is carried out for the charging phase. The system of equations describing the numerical model is solved by using time-implicit and space-backward finite differences and which encoded within the Matlab environment. The analysis presented the following findings: the predictions agree well with the experiments for the time evolution of the thermocline region, particularly for the regions away from the top-inlet. The deviations observed in the near-region of the inlet are most likely due to the high-level of turbulence in this region due to the localized level of mixing resulting; a simple analytical model to take into consideration this increased turbulence level was developed and it leads to some improvement of the predictions; this approach requires practically no additional computational effort and it relates the effective thermal diffusivity to the mean effective velocity of the fluid at each particular height of the system. Altogether the study indicates that the selected parabolic trough-CSP plant has the edge over alternative competing technologies for locations where DNI is high and where land usage is not an issue, such as the shoreline of Libya.

Optimization of lipase production from yeasts strains isolated from olive mil wastewater

Dissertação submetida à Universidade de Lisboa, Faculdade de Ciências para a obtenção do Grau de Mestre em Microbiologia Aplicada.

Aplicação de peroxidase para degradação de deoxinivalenol

Deoxinivalenol (DON), uma das principais micotoxinas encontradas em matrizes alimentares, é um composto químico que possui em sua estrutura um anel epóxido que lhe confere alto grau de toxicidade. A aplicação de enzimas em processos de degradação de DON vem se destacando, pela estabilidade durante o processo reacional e baixo custo de produção. O objetivo desse trabalho foi estudar o potencial de peroxidase proveniente de farelo de arroz (FA) e farelo de soja (FS) para degradar DON. As condições de obtenção da PO a partir de FA foram definidas por planejamento experimental DCCR 23 , sendo extraída de 5 g de farelo com 50 mL de tampão fosfato 0,04 mol L-1 pH 5, agitados orbitalmente durante 60 min a 100 rpm, e para a PO obtida de FS as condições diferenciaram somente quanto a solução extratora, tampão fosfato 0,01 mol L-1 pH 4,7. A técnica que apresentou melhores índices de purificação para a enzima foi a partição trifásica apresentando fator de purificação e recuperação de 5,6 e 50 % para a obtida de FA e 13,61 e 50 % para FS. A PO de FA apresentou maior atividade em tampão fosfato 5 mmol L-1 pH 5,5 para as formas bruta e pura, diferindo na temperatura de reação de 25 °C e 10 °C, KM de 0,15 e 0,06 mmol L-1 e Vmáx de 769 e 667 U mg-1 , respectivamente. A PO de FS as condições foram: tampão fosfato 5 mmol L-1 pH 5, reação a 35 e 30 °C durante 10 e 5 min, KM de 0,17 e 0,05 mmol L-1 e Vmáx de 196 e 182 U mg-1 , respectivamente. A PO de FA demonstrou maior estabilidade em pH 5 enquanto que a de FS em pH 6, ambas enzimas apresentaram maior estabilidade térmica a 0 °C, as massas moleculares encontradas por eletroforese foram 41 e 34 kDa, respectivamente. Ao final das etapas de obtenção, purificação e caracterização obteve-se uma atividade específica de 116 e 794 U.mg-1 , e 4363 e 17453 U g-1 , respectivamente para PO de FA e FS. A determinação de DON e De-DON foi realizada por HPLC-DAD e LC-ESI-MS/MS para avaliação dos ensaios de degradação. A enzima comercial HRP, mostrou maior potencial de redução sobre DON (55% após 1 h de reação), no entanto em 3 h de reação, a concentração inicial da micotoxina DON foi verificada, o que evidencia que a redução pode ocorrer por adsorção ou por formação de um composto de degradação que apresente a mesma massa molecular. O emprego da enzima PO obtida de FA e FS na degradação necessita de uma avaliação cinética micotoxicologica para definição das condições de redução significativa dos níveis de DON.

Estudo do comportamento plástico, mecânico, microestrutural e térmico do concreto produzido com resíduo de porcelanato

Population growth experienced in major cities, allied to society s need of infra-structure, especially ones related to habitational demands, increases the consumption of construction materials. As a consequence, consumption of natural resources itself. Thus, due to this process, concrete is one of the most produced materials in civil construction. This is also due to the great diversity of its application, easiness in its execution and adequate mechanical performance, as well as low production costs. Following the same tendencies in construction development, the ceramic industry has intensified the production of porcelain ceramic tiles and floors. These are achieved by a fine finishing and receive polishing at the end of the fabrication process. This work researched the use of porcelain residues in polishing for the production of concrete. All of which; due to economical and environmental issues. This process aims to prove adequate destiny for this type of residue, due to environmental issues, incorporating it to the concrete itself; all of which provides economy in consumption of the materials that constitute concrete. Thus, the main characteristics of concrete were investigated through the inclusion of different concentration of the porcelain residue as additional trait element. The residue rates incorporated to the trait varied from 10% to 50% in relation to the cement mass, in the traits with plastic additives and without plastic additives. It is observed that the inclusion of porcelain residue produced a meaningful alteration in the consistency of fresh concrete. This residue has a fine granulometry and it considerably absorbed the water used in the concrete spreading, influencing the way this material is dealt with. Thus, the value of cement striking decreases with the increase of residues present in trait. The maximal incorporation of the residue was of 50%, massively, for the same factor water/initial cement. The use of residues in concrete results in an 40% increase in the compression resistance. It is also proportional to residue concentration of porcelain in the trait. The microstructure was also favored once porosity and concrete absorption decreases with the use of this residue. The parameters demonstrate the quality and durability of the concrete produced with this residue. The use of porcelain residue in concrete composition has not produced meaningful thermal behavior changes. Thermal conductivity, heat capacity and thermal diffusivity have been maintained basically constant

Modificação superficial de filmes de poliéster usando plasma a baixa temperatura

A polyester film has a vast application field, due some properties that are inherent of this kind of material such as, good mechanical resistance, chemical resistance to acids and bases and low production cost. However, this material has some limitations as low superficial tension, flat surface, low affinity to dyers, and poor adhesion which impede the use of the same ones for some finality as good wettability. Among the existent techniques to increase the superficial tension, plasma as energy source is the more promising technique, because of their versatility and for not polluting the environment. The plasma surface polymeric modification has been used for many researchers, because it does not affect the environment with toxic agents, the alterations remains only at nanometric layers and this technique shows expressive results. Then, due to its good acceptance, polyester films were treated with oxygen plasma varying the treatment time from 10 to 60 min with an increase of 10 min to each subsequent treatment. Also, the samples were treated with a gas mixture (nitrogen + oxygen) varying the percentage of each gas the mixture from 0 to 100%, the treatment time remaining constant to all treatments (10 min). After plasma treatment the samples were characterized by contact angle, surface tension, Raman spectroscopy, Infrared attenuated total reflection (IR-ATR) and atomic force microscopy, with the aim to study the wettability increase of treated polyester films as its variables. In the (O2/N2) plasma treatment of polyester films can be observed an increase of superficial roughness superior to those treated by O2 plasma. By the other hand, the chemical modification through the implantation of polar groups at the surface is obtained more easily using O2 plasma treatment

Efeito da velocidade de aquecimento nas propriedades de produtos da cerâmica estrutural

Heating rate is one of the main variables that determine a fire cycle. In industrial processes that use high temperatures, greater fire great can reduce the cost of production and increase productivity. The use of faster and more efficient fire cycles has been little investigated by the structural ceramic industry in Brazil. However, one of the possibilities that aims at modernizing the sector is the use of roller kilns and the inclusion of natural gas as fuel. Thus, the purpose of this study is to investigate the effect of heating rate on the technological properties of structural ceramic products. Clay raw materials from the main ceramic industries in the state of Rio Grande do Norte were characterized. Some of the raw materials characterized were formulated to obtain the best physical and mechanical properties. Next, raw materials and formulations were selected to study the influence of heating rate on the final properties of the ceramic materials. The samples were shaped by pressing and extrusion and submitted to rates of 1 °C/min, 10 °C/min and 20 °C/min, with final temperatures of 850 °C, 950 °C and 1050 °C. Discontinuous cycles with rates of 10 °C/min or 15 °C/min up to 600 °C and a rate of 20 °C/min up to final temperature were also investigated. Technological properties were determined for all the samples and microstructural analysis was carried out under a number of fire conditions. Results indicate that faster and more efficient fire cycles than those currently in practice could be used, limiting only some clay doughs to certain fire conditions. The best results were obtained for the samples submitted to slow cycles up to 600 °C and fast fire sinterization up to 950 °C. This paper presents for the first time the use of a fast fire rate for raw materials and clay formulations and seeks to determine ideal dough and processing conditions for using shorter fire times, thus enabling the use of roller kilns and natural gas in structural ceramic industries

Avaliação econômica da co-inoculação de Rhizobium tropici e Azospirillum brasilense no feijoeiro-comum.

O objetivo deste trabalho consistiu em determinar o efeito da co-inoculação de Rhizobium tropici e Azospirillum brasilense nos parâmetros econômicos da cultura do feijoeiro-comum.

Avaliação do desempenho econômico e do potencial de geração de renda da estrutura produtiva de pequena escala de dendezeiro híbrido interespecífico na mesorregião metropolitana de Belém, Pará.

2016

Large scale laboratory cultures of Ankistrodesmus gracilis (Reisch) Korsikov (Chlorophyta) and Diaphanosoma biergei Korinek, 1981 (Cladocera)

O objetivo deste trabalho foi avaliar o cultivo em larga escala de Ankistrodesmus gracilis e Diaphanososma birgei em laboratório através do estudo da biologia das espécies, composição bioquímica e custo operacional de produção. A. gracilis apresentou um crescimento exponencial até o sexto dia, ao redor de 144 x 10(4) células mL-1. Logo em seguida, sofreu um brusco decréscimo apresentando 90 x 10(4) células mL-1 (oitavo dia). A partir do décimo primeiro dia, as células algais tenderam a crescer novamente, apresentando um máximo de 135 x 10(4) células mL-1 no 17º dia. No cultivo de D. birgei, foi observado o primeiro pico de crescimento no nono dia com 140 x 10² indivíduos L-1, aumentando novamente a partir do décimo segundo dia. A alga clorofícea A. gracilis e o zooplâncton D. birgei possuem aproximadamente 50 e 70% de proteína (PS), respectivamente, com teor de carboidrato acima de 5%. A eletricidade e mão de obra foram os itens mais dispendiosos e, de acordo com os dados obtidos, a temperatura, nutrientes, disponibilidade de luz e manejo do cultivo, foram fatores determinantes sobre a produtividade. Os resultados indicam que o meio NPK (20-5-20) pode ser utilizado diretamente como uma alternativa de cultivo em larga escala, considerando o baixo custo de produção, promovendo adequado crescimento e valor nutricional para A. gracilis e D. birgei.

Probiotic in feeding of juvenile matrinxã (Brycon amazonicus): economic viability

Objetivou-se analisar a viabilidade econômica do uso do probiótico Bacillus subtilis na alimentação de matrinxã Brycon amazonicus, em tanques-rede. O experimento foi conduzido no Polo Regional do Vale do Ribeira, no município de Pariquera-Açu, São Paulo, Brasil, entre fevereiro e julho de 2009. Foram avaliados 960 peixes juvenis, divididos em 12 tanques-rede de 2,7 m³ (1,5 x 1,5 x 1,2 m) em uma área total de 600 m², com profundidade média de 1,50 m. Os testes foram conduzidos com um tratamento testemunha (T1), duas doses de probiótico (T2 = 5 g e T3 = 10 g kg-1 de ração) e quatro repetições. Os resultados mostraram que o T2 proporcionou melhor desempenho zootécnico e econômico da matrinxã na fase de engorda no sistema intensivo de criação.

Desenvolvimento de uma unidade pirolítica com reator de cilindro rotativo: obtenção de bio-óleo

The demand for alternative sources of energy drives the technological development so that many fuels and energy conversion processes before judged as inadequate or even non-viable, are now competing fuels and so-called traditional processes. Thus, biomass plays an important role and is considered one of the sources of renewable energy most important of our planet. Biomass accounts for 29.2% of all renewable energy sources. The share of biomass energy from Brazil in the OIE is 13.6%, well above the world average of participation. Various types of pyrolysis processes have been studied in recent years, highlighting the process of fast pyrolysis of biomass to obtain bio-oil. The continuous fast pyrolysis, the most investigated and improved are the fluidized bed and ablative, but is being studied and developed other types in order to obtain Bio-oil a better quality, higher productivity, lower energy consumption, increased stability and process reliability and lower production cost. The stability of the product bio-oil is fundamental to designing consumer devices such as burners, engines and turbines. This study was motivated to produce Bio-oil, through the conversion of plant biomass or the use of its industrial and agricultural waste, presenting an alternative proposal for thermochemical pyrolysis process, taking advantage of particle dynamics in the rotating bed that favors the right gas-solid contact and heat transfer and mass. The pyrolyser designed to operate in a continuous process, a feeder containing two stages, a divisive system of biomass integrated with a tab of coal fines and a system of condensing steam pyrolytic. The prototype has been tested with sawdust, using a complete experimental design on two levels to investigate the sensitivity of factors: the process temperature, gas flow drag and spin speed compared to the mass yield of bio-oil. The best result was obtained in the condition of 570 oC, 25 Hz and 200 cm3/min, temperature being the parameter of greatest significance. The mass balance of the elementary stages presented in the order of 20% and 37% liquid pyrolytic carbon. We determined the properties of liquid and solid products of pyrolysis as density, viscosity, pH, PCI, and the composition characterized by chemical analysis, revealing the composition and properties of a Bio-oil.

Custos, receitas e indicadores financeiros da coleta e beneficiamento da castanha-do-brasil.

2006

Perspetivas de utilização do potencial eólico em Timor-Leste

A exigência energética global está mais orientada para a utilização das fontes de Energias Renováveis (FERs), comprometendo e garantindo um desenvolvimento sustentável. Este trabalho tem como objetivo contribuir para o atingir das metas do PED 2011-2030, no que refere à utilização das FER, em particular do potencial eólico em Timor-Leste. Timor-Leste tem apresentado um grande interesse na política de aproveitamento de FER para alcançar a meta de longo prazo de PED 2030, comprometendo-se com o desenvolvimento sustentável através de ERs. Este trabalho pretende contribuir em particular com o estudo do aproveitamento de energia eólica. Com base no clima do vento de longo termo entre 2004 – 2012, da estação meteorológica (EM) de Díli e conjugando estes com os dados da campanha experimental de Martifer cedidos, de Dezembro 2008 - Novembro 2009, obteve-se o coeficiente de variabilidade (Cvariab.) inter-anual. Foi assim possível construir o mapa médio do vento de longo termo, com modelo atmosférico de mesoscala, numa resolução refinada de 3×3 km. Para a identificação dos locais mais favoráveis do vento, foi utilizado o modelo ArcGIS para georreferenciação do recurso. A filtragem das restrições e os constrangimentos do terreno permitiu construir o mapa do vento sustentável de Timor-Leste, por distritos, subdistritos, sucos, do enclave de Oecússi e a ilha de Atauro, o que conduziu à hierarquização de cinco zonas favoráveis (zona 1 - 5). A contribuição para o plano energético de Timor-Leste consiste em duas fases: - a 1ª fase o aproveitamento eólico em três PEs nas zonas monitorizadas (3 e 5) oriundo de dados cedidos pela Martifer, contabilizou-se um total de 424.694 MWh de produção de energia anual, tendo-se verificado o custo normalizado de energia (LCOE) no valor médio calculado de 0,046 €/kWh; - na 2ª fase a construção de acesso e o desenvolvimento de PEs nas zonas 1, 2 e 4 para o Cenário de Max-Renovável. Assim sendo, viabilizam a "Perspetiva de Utilização da Energia Eólica" no quadro do PED 2011 - 2030 de Timor-Leste, que viria reduzir o custo de produção de energia atual, e a emissão de CO2; Abstract: Prospects of Using Wind Energy in Timor-Leste The demand for global energy is more focused on the use of Reneweable Energy sources (REs), ensuring and committing itself to sustainable development. This study was prompted by the wish to contribute to the achievement the goals of the Strategic Development Plan (PED 2011-2030) regarding the use of REs, particularly the wind energy in Timor-Leste. Timor-Leste has presented a great interest in the use of renewable energy sources policy to achieve the long term goal of the PED 2030, committing to a sustainable development through renewable energy. This thesis intends to contribute in particular with the study of the use of wind energy. Based on the long term wind climate between 2004 and 2012 of the Díli weather station and combining these data with the Martifer campaign experimental data of December 2008 - November 2009, the interannual variation coefficient (Cv) was obtained. Thus, it was possible to build the map of long term average wind with atmospheric mesoscale model in a refined resolution of 3×3 km. The ArcGIS model was used for the identification of the most favorable locations of the wind for its georeferencing. The constraining of filtering and the constraints of the terrain allowed to construe the sustainable wind map of Timor-Leste in distritos, subdistritos, sucos, and also of the enclave of Oecussi and Atauro island, which led to the ranking of five favorable areas (zone 1-5) for an immediate experimental campaign of wind characterization and utilization of this resource in wind parks. The contribution to Timor-Leste's energy plan consists of two phases: - the first phase of three wind farms in zone (3 and 5) from data provided by Martifer, a total of 424,694 MWh, and levelyzed cost of electricity (LCOE) in the calculated average value of 0.046 €/kWh; - in the second phase the construction of access and development of wind farms in zones 1, 2 and 4 for the Max-Renewable Scenario. As such, they make possible the "Perspective of Wind Energy Use" in Timor Leste’s PED 2011 - 2030, which would reduce current energy production costs and CO2 emissions.

Viabilidade econômico-financeira para a implantação do cultivo de maçã no Vale do São Francisco.

O objetivo deste trabalho é analisar a viabilidade econômica do cultivo de maçã, realizado no Vale do São Francisco, utilizando-se indicadores de exequibilidade de projetos, o valor presente líquido (VPL) e a taxa interna de retorno (TIR), referente à produção do ano 2015. Os resultados confirmam a factibilidade da produção de maçã,onde a TIR (52,24%) supera a taxa mínima de atratividade (TMA) (35%), condição necessária para o projeto tornar-se viável.

Comportamento físico-hídrico de solos arenosos no Projeto Apolônio Salles - Petrolândia - PE.

Muitas áreas com solos arenosos vêm sendo irrigadas de modo inadequado devido a falta de conhecimentos, particularmente físico-hídricos, causando desperdícios da água e insumos, concorrendo para o aumento do custo de produção agrícola e degradação ambiental. Com o objetivo de gerar conhecimentos sobre aspectos relacionados com parâmetros físicos e hídricos dos solos arenosos irrigados no Projeto de irrigação Apolônio Sales em Petrolândia - PE foram realizados estudos hidropedológicos centrados principalmente nas determinações do movimento e armazenamento da água no solo. Foram selecionados 05 lotes irrigados onde foram descritos e amostrados perfis de Neossolos Quartzarênicos e avaliada a velocidade de infiltração básica, a capacidade de infiltração capacidade de campo dos solos. Os perfis analisados apresentam pequenas diferenças quanto à textura em profundidade, diretamente relacionadas às variações dos parâmetros hidrodinâmicos estudados. Nos solos com textura areia em superfície e tendendo a areia franca em subsuperfície, os valores médios das taxas de infiltração básica variaram entre 286 e 904 mm/h. Já nas repetições dos testes, iniciados com o solo no estado úmido (em torno da capacidade de campo), a faixa de variação dos valores médios de 228 e 413 mm/h. Solos com textura somente na classe areia, os valores médios dos testes situaram-se na faixa de 604 e 668 mm/h. Nas repetições dos testes, a variação média das taxas de infiltração foi de 190 e 292 mm/h. Tais valores caracterizam taxas de infiltração rápida a muito rápida. Com relação ao armazenamento hídrico, as diferenças mais notáveis entre os solos, indicam que estão relacionadas ao conteúdo e a distribuição das frações mais finas nos perfis dos solos.