Loading...
9 results
Search Results
Now showing 1 - 9 of 9
- Turbine design dependency to turbulence: an experimental study of three scaled tidal turbinesPublication . Slama, Myriam; Pinon, Grégory; El Hadi, Charifa; Togneri, Michael; Gaurier, Benoît; Germain, Grégory; Facq, Jean-Valéry; Nuño, José; Mansilla, Pablo; Nicolas, Erwann; Marcille, Julie; Pacheco, AndréIn this paper the turbulence effects are studied for three rotors mounted on the same instrumented hub. Two scaled models of industrial turbines and one open-geometry turbine are considered. The turbulence characteristics are obtained from 2D Laser Doppler Velocimeter measurements and the turbine behaviour is analysed from thrust and torque measurements. Three turbulence intensities and a large range of tip speed ratios and flow velocities are considered. The results are anonymised in order to ensure confidentiality. The rotors have different blade profiles, blade numbers and solidity. The rotor design largely modifies the mean power and thrust coefficients. The turbulence intensity only slightly changes these results but has a larger influence on the fluctuating loads than the different rotor designs. The spectral analysis of the rotor torque and thrust shows that, at low frequencies the load variations are correlated to those of the flow velocity with some differences due to the turbulence intensity levels. The coherences between the loads and the velocity seem to be not affected by the rotor type. At high frequencies, the load variations are correlated to the speed control unit of the scaled model and the rotor design has an impact on the rotational speed and loads coherences.
- Cost-benefit analysis of tidal energy production in a coastal lagoon: the case of Ria Formosa – PortugalPublication . Rodrigues, Nuno; Pintassilgo, Pedro; Calhau, Francisco; G-Gorbeña, Eduardo; Pacheco, AndréThe energy that can be extracted from tidal currents is one of the most promising renewable energy sources due to its high density/predictability. Within this paper this energy source is evaluated economically respecting sustainability principles. This evaluation contrasts from previous studies due to the application of a cost-benefit analysis based on a hydro-morphodynamic model, and moving away from the classic proxy of wind energy. It further includes, via the Monte Carlo method, a probabilistic underpinning to the project. The hydro-economic model was applied to a tidal energy project using an Evopod 1:4th scale prototype, based on a real deployment of an Evopod 1:10th scale device in the Ria Formosa, Algarve. The results show that, under the current costs and benefits, the project is not economically viable. However, there are admissible parameter ranges that make the project viable such as significant reduction of investment costs, increased capacity factors and favourable energy prices. This novel methodology has potential to be applied to other tidal energy projects on estuarine systems worldwide, and consists of a comprehensive modelling approach, including the technical, environmental, and socio-economic dimensions of the project, not only in a deterministic setting but also in a probabilistic one.
- Application of simple harmonic motion theory to the prediction of floating wind turbine first order motionsPublication . Mackie, G.; Pacheco, André; Sequeira, C.An alternative solution for achieving a high stability floating foundation for supporting large horizontal axis wind turbines is compared against current floating offshore wind solutions. The testing of a 1:36th scale model of the solution, called Starfloat, in the wind/wave basin of the Cantabria Coastal and Ocean Basin, Santander and the design of this physical model, including scaling issues, is discussed. A method for calculating the added mass of entrained water in heave and surge and the added mass moment of inertia in pitch for semi-submerged cy-lindrical columns is presented and the computed natural periods of motion are compared against physical trial measurements obtained from motion decay tests. The wave forces exciting the simple harmonic motion are calculated and the resultant approximate solution for the uncoupled floating platform motions in heave, pitch and surge are compared against response amplitude operator curves obtained from the physical model trials, showing reasonable correlation. The importance of depth correction for wave particle velocities and accelera-tions is very evident and emphasises the need for physical models to be exposed to the correct orbital particle motions over the water column if measured pitch and surge motions are to be a realistic representation of full scale performance.
- Energy transition process and community engagement on geographic islands: the case of Culatra Island (Ria Formosa, Portugal)Publication . Pacheco, André; Monteiro, Jânio; Santos, Joni; Sequeira, Claudia; Nunes, J.Islands have the potential to be precursors in the transition to clean energy, by adopting new technologies and applying innovative solutions that can serve as showcases at an international level. This paper is a contribution towards understating the importance of community engagement on energy transition processes. It covers multiple aspects of a green transition process, including technical, environmental, social, and economic issues. Starting by a participatory diagnosis process, the community of a small island located in Portugal (Culatra Island, Algarve), was challenged to lead the transition process and define different pillars of energy transition. The process brought together local authorities, academia, citizens and companies. Using practical examples, it is shown how the community is succeeding in tailoring new technological solutions for a green transition, according with the specific needs of the island, as expressed by the islanders themselves, including batteries, electric vehicles, retrofitting of homes, or heat pumps, which, when combined, could lay the foundations for the creation of a Renewable Energy Community and leverage socioeconomic benefits.
- Energias limpas na Ria Formosa, o caminho da sustentabilidadePublication . Pacheco, André; González-Gorbeña Eisenmann, Eduardo; Sequeira, ClaudiaO 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 tempo
- Baseline assessment of underwater noise in the Ria FormosaPublication . Soares, C; Pacheco, André; Zabel, Friedrich; G-Gorbeña, Eduardo; Sequeira, ClaudiaThe 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.
- Flood vulnerability under sea level rise for a coastal community located in a backbarrier environment, PortugalPublication . Croteau, Raphaelle; Pacheco, André; Ferreira, ÓscarSea level rise will be a major threat to coastal communities within the next century due to the intensity and severity of the floods it can cause. A new methodology considering water infiltration, slope, and hydraulic connectivity was developed to assess the potential inundation extension associated with different total water level and sea level rise scenarios on sandy coasts. This methodology was applied for the current conditions as well as 2050 and 2100 scenarios of storm surge and high tide levels with return periods of 1 year and 100 years. The study area is Culatra village, located on the lagoon side of a barrier island in southern Portugal. The effects of shoreline evolution after the construction of a harbor and associated beach nourishment were also evaluated within the inundation scenarios. The results show that, within the study area, total water level variations caused by sea level rise have a greater influence on the inundation extension than shoreline retreat. The village appears to be safe for the current and 2050 total water level scenarios with a 1-year return period but would be highly affected by 100-year return periods, especially from 2050 onwards. This novel approach represents an improvement on more common flood mapping methods such as the bathtub approach and can be easily applied to other backbarrier environments under sea level rise or facing coastal erosion.
- Use of an environmental proxy to determine turbulence regime surrounding a full-scale tidal turbine deployed within the Fromveur Strait, Brittany, FrancePublication . Fowell, R.; Togneri, M.; Pacheco, André; Nourrisson, O.Establishing a relationship between tidal current conditions and tidal turbine performance and loads is a criti-cally important consideration for turbine reliability. Nonetheless, obtaining in-situ information is often chal-lenging, and as a result both environmental and load data may be more sparse than desired. This study presents a method to make use of limited data sets by establishing a relationship between measurements of hydrodynamic variability and turbine power or blade strain variability, even when these measurements are not taken simul-taneously. The method is tested on data from the deployment of a full-scale pilot tidal turbine: in situ velocity measurements and turbulence characteristics taken at times when the turbine was not installed were associated with power and strain measurements during the turbine's deployment via a Delft3D proxy. The data show that the variability of active power correlates well with larger turbulence kinetic energy (TICE) when comparing similar populations via the proxy. Examination of blade strain variance against TICE shows a weaker correlation, with fat-tailed distributions and extremely high strain values prominent across all flow speeds. Acceleration or deceleration of the flow influenced the power variability of the turbine, with larger standard deviations recorded across accelerating flows. No significant difference was found when comparing blade strain variance in accel-erating and decelerating flows. We conclude that the proxy method studied can establish a population-level relationship between non-simultaneous environmental and load data, but that the accuracy and precision of this relationship depends on the amount of data available: this method is therefore only suitable where there is a sufficiently rich dataset.
- Development and implementation of a smart charging system for electric vehicles based on the ISO 15118 standardPublication . Santos, Joni; Francisco, André; Cabrita, Cristiano Lourenço; Monteiro, Jânio; Pacheco, André; Cardoso, PedroThere is currently exponential growth in the electric vehicle market, which will require an increase in the electrical grid capacity to meet the associated charging demand. If, on the one hand, the introduction of energy generation from renewable energy sources can be used to meet that requirement, the intermittent nature of some of these sources will challenge the mandatory real-time equilibrium between generation and consumption. In order to use most of the energy generated via these sources, mechanisms are required to manage the charging of batteries in electric vehicles, according to the levels of generation. An effective smart charging process requires communication and/or control mechanisms between the supply equipment and the electric vehicle, enabling the adjustment of the energy transfer according to the generation levels. At this level, the ISO 15118 standard supports high-level communication mechanisms, far beyond the basic control solutions offered through the IEC 61851-1 specification. It is, thus, relevant to evaluate it in smart charging scenarios. In this context, this paper presents the development of a charge emulation system using the ISO 15118 communication protocol, and it discusses its application for demand response purposes. The system comprises several modules developed at both ends, supply equipment and electric vehicles, and allows the exchange of data during an emulated charging process. The system also includes human interfaces to facilitate interactions with users at both ends. Tests performed using the implemented system have shown that it supports a demand response when integrated with a photovoltaic renewable energy source. The dynamic adjustment to charging parameters, based on real-time energy availability, ensures efficient and sustainable charging processes, reducing the reliance on the grid and promoting the use of renewable energy.