Analysis of the efficiency of wind turbine gearboxes using the temperature variable

The aim of this paper is to evaluate how lubricant selection affects gearbox efficiency and overall energy production by analysing real data from wind farms, monitored and controlled by a Supervisory Control and Data Acquisition (SCADA system). The turbines analysed worked with two or more oil types for the same amount of hours, which allowed to establish relations between the active power curves and wind velocity; oil temperature inside gearboxes and wind velocity; and oil temperature inside gearboxes and active power production. The results of this study evidenced a direct relation between oil characteristics and energy efficiency i.e. gearboxes working with mineral oil perform better then gearboxes working with synthetic oils. Those differences can be significant in terms of active power production. Also, it was observed oil degradation as function of temperature increase, with changes on viscosity, which reveals that temperature behaviour along the active power curve is strongly related to oil' characteristics. (C) 2018 Elsevier Ltd. All rights reserved.Agência financiadora Portuguese Foundation for Science and Technology (FCT) PTDC/AAG-TEC/1710/2014 MONITOR project - Atlantic Area EAPA_333/2016 Portuguese Foundation for Science and Technology under the Portuguese Researchers' Programme 2014 IF/00286/2014/CP1234 Marie Sklodowska-Curie Actions of the European Union's H2020-MSCA-IF-EF-RI-2016/under REA - 748747info:eu-repo/semantics/publishedVersionhttp://creativecommons.org/licenses/by/4.0

Marine energy prototype testing at Ria Formosa

Economic growth and increasing human demands are among the most important factors for growing world energy consumption. Energy is present in everything around us: it is a property of all objects and is essential to life. We find various forms of energy in the world around us. When plants grow, for example, they are converting sunlight energy into chemical energy in the form of carbohydrates and other compounds stored in your body (e.g. sugars). The form of energy that man uses most today is the chemical energy contained in fossil fuels, such as oil, coal and natural gas. About 80% of the energy we use comes from these sources. However, these sources are very polluting, since their use releases substances harmful to the environment and to public health. An example of this is the increased concentration of greenhouse gases such as carbon dioxide (CO2) in the atmosphere, which is a cause of climate change. In addition to pollutants, these sources of energy are non-renewable, which means that they are being consumed at a faster rate than is necessary for their production, so their availability is decreasing. Due to the increasing oil and natural gas prices, reduced fuel reserves and the requirement for reduced CO2 emissions to avert climate change, the use of alternative energy sources is both financially unavoidable and environmentally preferable (UN, 2015). Hence, generating renewable energy is nowadays one of the most relevant endeavours for research. Countries worldwide now recognise the need to incorporate renewable energy resources in their energy policy as an alternative to finite fossil fuel resources in order to achieve future energy security and to mitigate the effects of climate change induced by human activities. Today, renewable energy is now firmly entrenched as the world's fastest growing energy sector (IEA, 2017).info:eu-repo/semantics/publishedVersio

An evaluation of offshore wind power production by floatable systems: a case study from SW Portugal

The challenge for floating offshore wind structures is to reduce costs. The industry needs a wind turbine support solution that can be fabricated and deployed from existing shipyards and port facilities, while investors need accurate estimations and forecasts of wind resources and quantified information on the inherent variability in wind power generation. This paper merges hindcast model data with observed in situ data to characterize the wind resource potential off the SW coast of Portugal. The validation procedure adopted allows an estimation of the coefficient used for power-law extrapolation of the wind measurements and a reduction in the uncertainty of the power density calculations. Different types of turbine model are compared and site metocean characteristics are examined as a basis for choosing between existing wind floatable solutions. The calculations using four different wind turbine models indicate a preferable installed capacity of 3-4 MW for a hub height of 90-120 m (i.e., representing the best capacity factor and load hours). There is a consistent difference in power density of about 20% from a location 5 nautical miles (NM) offshore to one 10 NM offshore, which represents an increment of 20% -25% in energy production depending on the particular wind turbine capacity factor. (C) 2017 Elsevier Ltd. All rights reserved.Portuguese Foundation for Science and Technology [FCT - PTDC/AAG-TEC/1710/2014]Portuguese Foundation for Science and Technology under the Portuguese Researchers' Programme [IF/00286/2014/CP1234]Portuguese Foundation for Science and Technology Investigator Programme [IF/01142/2015

Assessing the effects of Tidal Energy Converter array size on hydrodynamics of Ria Formosa (Portugal)

info:eu-repo/semantics/publishedVersio

Optimal configuration problem identification of electrical power cable in tidal turbine farm via traveling salesman problem modeling approach

Electrical power cables in tidal turbine farms contribute a significant share to capital expenditure (CAPEX). As a result, the routing of electrical power cables connecting turbines to cable collector hubs must be designed so as to obtain the least cost configuration. This is referred to as a tidal cable routing problem. This problem possesses several variants depending on the number of cable collector hubs. In this paper, these variants are modeled by employing the approach of the single depot multiple traveling salesman problem (mTSP) and the multiple depot mTSP of operational research for the single and multiple cable collector variants, respectively. The developed optimization models are computationally implemented using MATLAB. In the triple cable collector cable hub variant, an optimal solution is obtained, while good-quality suboptimal solutions are obtained in the double and single cable collector hub variants. In practice, multiple cable collector hubs are expected to be employed as the multiple hub configurations tend to be more economic than the single hub configurations. This has been confirmed by this paper for an optimal tidal turbine layout obtained with OpenTidalFarm. Suggestions are presented for future research studies comprising a number of heuristics.info:eu-repo/semantics/publishedVersio

Estimating the optimum size of a tidal array at a multi-inlet system considering environmental and performance constraints

This paper investigates the optimum tidal energy converter array density at a tidal inlet by applying surrogate-based optimisation. The SBO procedure comprises problem formulation, design of experiments, numerical simulations, surrogate model construction and constrained optimisation. This study presents an example for the Faro-Olhão Inlet in the Ria Formosa (Portugal), a potential site for tidal in-stream energy extraction. A 35 kW Evopod™ floating tidal energy converter from Oceanflow Energy Ltd. has been used for array size calculations considering two design variables: (1) number of array rows, and (2) number of tidal energy converter per row. Arrays up to 13 rows with 6–11 tidal energy converters each are studied to assess their impacts on array performance, inlets discharges and bathymetry changes. The analysis identified the positive/negative feedbacks between the two design variables in real case complex flow fields under variable bathymetry and channel morphology. The non-uniformity of tidal currents along the array region causes the variability of the resource in each row, as well as makes it difficult to predict the resultant array configuration interactions. Four different multi-objective optimisation models are formulated subject to a set of performance and environmental constraints. Results from the optimisation models imply that the largest array size that meets the environmental constraints is made of 5 rows with 6 tidal energy converter each and an overall capacity factor of 11.6% resulting in an energy production of 1.01 GWh year−1. On the other hand, a higher energy production (1.20 GWh year−1) is achieved by an optimum array configuration, made of 3 rows with 10 tidal energy converters per row, which maximises power output satisfying environmental and performance restrictions. This optimal configuration permits a good level of energy extraction while having a reduced effect on the hydrodynamic functioning of the multi-inlet system. These results prove the suitability and the potential wide use of the surrogate-based optimisation method to define array characteristics that enhance power production and at the same time respect the environmental surrounding conditions.info:eu-repo/semantics/publishedVersio

Eduardo González-Gorbeña Eisenmann's Quick Files

The Quick Files feature was discontinued and it’s files were migrated into this Project on March 11, 2022. The file URL’s will still resolve properly, and the Quick Files logs are available in the Project’s Recent Activity

Eficacia In Vitro del Cemento Obturador Sealer 26 asociado a Amoxicilina más Ácido Clavulánico y Sealer 26 Puro sobre el Crecimiento de Actinomyces Odontolyticus y Enterococcus Faecalis. Arequipa. 2014

Tesis de segunda especialidadEl presente trabajo de Investigación tuvo como objetivo determinar la eficacia de los cementos obturadores Sealer 26 asociado a amoxicilina mas ácido clavulánico y Sealer 26 en el crecimiento de Actinomyces Odontolyticus y Enterococcus faecalis, microorganismos bien conocidos por provocar gran porcentaje de fracasos en endodoncia. Se trata de una investigación cuasi experimental, de abordaje cuantitativo, prospectivo, transversal, comparativo, de laboratorio, de nivel explicativo. Se utilizó la observación experimental microbiológica para determinar la sensibilidad de Actinomyces Odontolyticus y Enterococcus Faecalis. El procedimiento consistió en sembrar las cepas Actinomyces Odontolyticus en placas con Agar KF Streptococcus y Enterococcus Faecalis en Agar Base Sangre, luego se colocaron discos de sensibilidad de pasaje lento de 5mm de diámetro impregnados con cementos obturadores Sealer 26 asociado a amoxicilina mas ácido clavulánico y Sealer 26 como grupos experimentales y Clorhexidina al 2% como grupo control, se utilizó 16 muestras para cada microorganismo a investigar, posteriormente se procedió a incubar las placas en la cámara de anaerobiosis a una temperatura de 37°C y con una concentración de 7.0% de CO2, registrando las medidas de halo de inhibición expresado en milímetros utilizando una regla vernier a las 24 horas. Los resultados obtenidos y luego sistematizados indicaron que el cemento de Obturación Sealer 26 asociado a amoxicilina mas ácido clavulánico (51.56 mm) es mas eficaz que el cemento de Obturación Sealer 26 puro (10.19 mm) sobre el crecimiento del microorganismo Actinomyces Odontolyticus; y que el mismo cemento Sealer 26 asociado a amoxicilina mas ácido clavulánico (33.81 mm) es mas eficaz que el cemento de Obturación Sealer 26 puro (13.88 mm) sobre el crecimiento del microorganismo Enterococcus Faecalis. En conclusión el cemento de obturación Sealer 26 asociado a amoxicilina mas ácido clavulánico presenta mejor eficacia antimicrobiana que el cemento Sealer 26 puro sobre el crecimiento de Actinomyces Odontolyticus y Enterococcus Faecalis, formando halos de inhibición de mayor diámetro. Palabras Clave: Antimicrobiano, Actinomyces Odontolyticus, Enterococcus Faecalis, Sealer 26

Energias limpas na Ria Formosa, o caminho da sustentabilidade

O crescimento económico e populacional está entre os fatores mais importantes para o aumento do consumo energético mundial. Atualmente, a forma de energia que o Homem mais utiliza é a energia química (cerca de 80%), nomeadamente, combustíveis fósseis, como o petróleo, o carvão e o gás natural. No entanto, essas fontes são muito poluentes, pois a sua utilização é responsável pela emissão de substâncias nocivas para o ambiente e para a saúde pública. Um exemplo disso, é o aumento da concentração de gases com efeito estufa na atmosfera, como o dióxido de carbono (CO2), que é uma das principais causas do aquecimento global. Além da emissão de poluentes, essas fontes de energia não são renováveis, o que significa que estão sendo consumidas a uma taxa mais rápida do que a necessária para sua produção e, portanto, a sua disponibilidade é limitada e diminuirá ao longo do tempoinfo:eu-repo/semantics/publishedVersio

Baseline assessment of underwater noise in the Ria Formosa

The Ria Formosa is a sheltered large coastal lagoon located on the Atlantic South Coast of Portugal, that has been classified as a natural park since 1987. The lagoon hosts a diverse and abundant fish community and other species of commercial importance. Several economical activities are supported by shipping, and as such, vessel traffic within the Ria Formosa lagoon is very intense at some locations during particular seasons of the year, creating high levels of underwater noise. Recently, strong efforts are being made to turn the main inlet of the lagoon, the Faro-Olhão Inlet, a testing site for small scale tidal stream turbines, which will bring an additional source of underwater noise. Underwater noise can be one of a number of factors causing habitat degradation, as it can perturb fish behavior and cause physiological damage. Therefore, in order to comply with underwater noise pollution regulations, tidal energy technology developers are very interested in minimising the introduction of acoustic energy in the environment during the operation of their devices. Under the scope of project SCORE, which involved the deployment and operation of a floating tidal energy converter, this paper presents and discusses the first baseline noise monitoring performed at Ria Formosa. The acoustic data were collected in two occasions over several days, one in the winter and the other in the summer, in 2017. The obtained analysis results highlight the potential impact of the intense boat traffic in Ria Formosa, and the wide range of sound levels introduced in that ecosystem, and the high diurnal and seasonal variability.PTDC/AAG-TEC/1710/2014; IF/00286/2014/CP1234info:eu-repo/semantics/publishedVersio