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Dp Howe - One of the best experts on this subject based on the ideXlab platform.
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Integration of oscillating water column wave energy converters within multi-use Maritime Structures
2020Co-Authors: Dp HoweAbstract:Ocean energy presents arguably one of the most rich renewable energy solutions currently under exploration, and consists of a variety of potential resources including tidal barrages, salinity gradients and ocean thermal energy. However two sources, tidal currents and ocean waves, are considered by many as the most promising and have subsequently observed the greatest development in recent decades. Ocean waves offer a predictable, dense and virtually untapped energy resource with potential to significantly contribute towards the rising global energy demands. A number of prototype failures and subsequent lack of long term commercial deployments has consequently impacted the development of Wave Energy Converter (WEC) technologies, such that the technologies are considered immature and currently economically uncompetitive with renewable energy counterparts such as wind and solar. To combat the economic argument, a number of solutions have been devised to reduce the high costs currently associated with ocean wave energy, one of which is integration within Maritime Structures to create synergistic multi-purpose platforms. While concepts have been formulated for the integration of various WEC technologies, the Oscillating Water Column (OWC) WEC is favoured as a predominant devices for implementation due to its rigid design, capability for incorporation within solid edifices, and relative ease of maintenance due to all moving parts above water. The OWC device's operational principle, in its most elementary form, utilises incident wave interaction to oscillate a trapped column of water inside the chamber, subsequently operating in a 'piston-type' motion to force air in and out of a turbine. The economic benefits of OWC device integration encompass both the capital and operating expenditure, from costs shared during the construction, through to the reduction in maintenance and grid connection costs, ultimately making the concept more competitive within the renewable energy sector. With some full scale demonstration cases and commercial devices currently operational, the vast majority of Maritime Structure integrated WECs target bottom-mounted breakwaters, which are typically depth limited due to the economic constraints associated with deep water construction. This type of integration restricts the operational range of the concept to onshore/nearshore regions; however, with the expansion of many blue economy industries into offshore regions, opportunities arise for exploration of wave energy conversion to serve in deeper waters. In order to migrate from the nearshore integrated concepts, integration within floating offshore Structures, such as breakwaters and offshore platforms, must be explored for viability from both economic and operational perspectives. Understanding the hydrodynamic performance of OWC devices integrated within Maritime Structures, both _fixed and floating, is the focus of this research project. Initial stages of the research project considered a detailed model scale experimental investigation regarding integrated OWC device performance, which was conducted to explore two specific parameters respective impact on OWC device energy absorption; firstly, the cross-sectional geometry, and secondly, breakwater integration. An isolated OWC device of rectangular cross-section was compared to a previously researched device with a circular cross-section of equivalent area to explore the impact on energy absorption, where negligible difference in performance was observed between the geometrically varying devices. Following this realisation, both respective devices were incorporated within a model scale, gravity-based breakwater to compare the extraction efficiency of the devices between both isolated and integrated configurations. The results obtained indicated that the energy absorption capacities of the OWC devices are significantly improved through breakwater integration, with the rectangular OWC device recommended due to its orthogonal construction allowing for less complex incorporation. This research provided a foundation for the performance of OWC device integrated Maritime Structures, and enhanced the potential for OWC device integration within floating offshore Structures. Development of the project generated a second comprehensive model scale investigation designed to establish a proof-of-concept for a floating breakwater integrated with multiple OWC devices. A generic π-type, soft-moored breakwater was integrated with a modular number of OWC devices and subjected to both regular and irregular sea states to analyse how variations to device configuration, breakwater width, pneumatic damping, wave height and motion constraints impact two overarching parameters; the energy absorption of the integrated OWC devices, and the performance of the floating breakwater. The investigation yielded substantial insights regarding the beneficial impact OWC device integration can have on the motion characteristics of the floating breakwater, while minor reduction was simultaneously observed for wave transmission and reflection. The investigation also highlighted the importance of device spacing with respect to OWC device performance, where insufficient spacing was found to have a detrimental impact on energy absorption where destructive device-device interference was observed. Through specific configuration of the aforementioned design parameters, the WEC/breakwater concept was able to obtain total device conversion efficiencies of up to approximately 80% at resonance in regular waves, and observed equivalent performance in irregular waves. This project reveals that Maritime Structure integration of OWC WECs provides significant benefits to the hydrodynamic performance of the integrated devices, which in association with the previously established economic benefits, further strengthens the viability of the concept, and provides foundation for future development
Macfarlane G - One of the best experts on this subject based on the ideXlab platform.
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Performance analysis of a floating breakwater integrated with multiple oscillating water column wave energy converters in regular and irregular seas
'Elsevier BV', 2020Co-Authors: Howe D, Nader J-r, Macfarlane GAbstract:Maritime Structure integration is widely considered as a potential solution for reducing the high Levelised Cost of Electricity (LCOE) associated with Wave Energy Converter (WEC) technologies. However, the majority of published research has focused on fixed Structure integration [1,2], with far fewer investigating the potential for floating Structure integration [3]. Expanding on previous works [4,5], this article investigates the performance of a π-type floating breakwater integrated with multiple Oscillating Water Column (OWC) WECs through model scale hydrodynamic experimentation. While under varying structural arrangements including device configurations and motion constraints, the model was subjected to 13 generic irregular wave spectra. Results of the experimental investigation illustrate that OWC device integration provides distinct benefits to the non-dimensional performance parameters of the floating breakwater in irregular sea states, which correlates strongly with the results obtained from previous regular wave analyses [4,5]. With firm correlation between the regular and irregular analyses, it is hypothesized that device development could potentially forgo regular wave investigations in preference of irregular wave testing, as it yields a broader bandwidth of results with reduced temporal requirements. Similarly, it is illustrated that the irregular non-dimensional parameter spectra can be used to effectively predict the performance characteristics of the device across different sea states. This article furthers the concept validation and feasibility of OWC WEC integrated floating breakwaters, and aids in the progression of the concept through the Technology Readiness Levels
Howe D - One of the best experts on this subject based on the ideXlab platform.
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Performance analysis of a floating breakwater integrated with multiple oscillating water column wave energy converters in regular and irregular seas
'Elsevier BV', 2020Co-Authors: Howe D, Nader J-r, Macfarlane GAbstract:Maritime Structure integration is widely considered as a potential solution for reducing the high Levelised Cost of Electricity (LCOE) associated with Wave Energy Converter (WEC) technologies. However, the majority of published research has focused on fixed Structure integration [1,2], with far fewer investigating the potential for floating Structure integration [3]. Expanding on previous works [4,5], this article investigates the performance of a π-type floating breakwater integrated with multiple Oscillating Water Column (OWC) WECs through model scale hydrodynamic experimentation. While under varying structural arrangements including device configurations and motion constraints, the model was subjected to 13 generic irregular wave spectra. Results of the experimental investigation illustrate that OWC device integration provides distinct benefits to the non-dimensional performance parameters of the floating breakwater in irregular sea states, which correlates strongly with the results obtained from previous regular wave analyses [4,5]. With firm correlation between the regular and irregular analyses, it is hypothesized that device development could potentially forgo regular wave investigations in preference of irregular wave testing, as it yields a broader bandwidth of results with reduced temporal requirements. Similarly, it is illustrated that the irregular non-dimensional parameter spectra can be used to effectively predict the performance characteristics of the device across different sea states. This article furthers the concept validation and feasibility of OWC WEC integrated floating breakwaters, and aids in the progression of the concept through the Technology Readiness Levels
Nader J-r - One of the best experts on this subject based on the ideXlab platform.
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Performance analysis of a floating breakwater integrated with multiple oscillating water column wave energy converters in regular and irregular seas
'Elsevier BV', 2020Co-Authors: Howe D, Nader J-r, Macfarlane GAbstract:Maritime Structure integration is widely considered as a potential solution for reducing the high Levelised Cost of Electricity (LCOE) associated with Wave Energy Converter (WEC) technologies. However, the majority of published research has focused on fixed Structure integration [1,2], with far fewer investigating the potential for floating Structure integration [3]. Expanding on previous works [4,5], this article investigates the performance of a π-type floating breakwater integrated with multiple Oscillating Water Column (OWC) WECs through model scale hydrodynamic experimentation. While under varying structural arrangements including device configurations and motion constraints, the model was subjected to 13 generic irregular wave spectra. Results of the experimental investigation illustrate that OWC device integration provides distinct benefits to the non-dimensional performance parameters of the floating breakwater in irregular sea states, which correlates strongly with the results obtained from previous regular wave analyses [4,5]. With firm correlation between the regular and irregular analyses, it is hypothesized that device development could potentially forgo regular wave investigations in preference of irregular wave testing, as it yields a broader bandwidth of results with reduced temporal requirements. Similarly, it is illustrated that the irregular non-dimensional parameter spectra can be used to effectively predict the performance characteristics of the device across different sea states. This article furthers the concept validation and feasibility of OWC WEC integrated floating breakwaters, and aids in the progression of the concept through the Technology Readiness Levels
Laura Bricio Garberi - One of the best experts on this subject based on the ideXlab platform.
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comportamiento funcional y ambiental de los diques exentos de baja cota de coronacion y su importancia en la ingenieria de costas
2011Co-Authors: Laura Bricio GarberiAbstract:La costa constituye una estrecha franja sometida a grandes desequilibrios; en muchos puntos se encuentra en profundo estado de regresion, como consecuencia de multiples y variadas causas: oleaje, mareas y corrientes, construccion de obras maritimas que interrumpen las corrientes litorales y el transporte de sedimentos, subida del nivel medio del mar, desarrollo de areas costeras y urbanismo masivo en la zona activa de las playas, etc. Todo ello provoca la erosion de un gran numero de playas, asi como su degradacion ambiental y paisajistica. Esta situacion precaria del litoral constituye, hoy en dia, un serio y preocupante problema, al que los Ingenieros de Costas dedican su actividad, en busca de soluciones que garanticen la estabilidad de la costa. Con este fin, se han venido utilizando, a lo largo del tiempo, diferentes metodos de proteccion, basados la mayoria en la construccion de obras maritimas, de entre las que hay que destacar los diques exentos. Los diques exentos son obras artificiales inspiradas en el funcionamiento de formaciones naturales que existen en el litoral, paralelas generalmente a la orilla, que protegen de la accion del oleaje un determinado tramo, y que son capaces de crear zonas de acrecion en la costa. Es por ello que estas obras maritimas se han venido utilizando de forma generalizada desde los anos setenta en paises como Japon, EE.UU., Israel, Espana, Italia o Australia. El estudio llevado a cabo para la realizacion de esta Tesis Doctoral se centra precisamente en este tipo de obras maritimas, y se plantea como objetivo principal el desarrollo de un metodo de diseno funcional y ambiental (no estructural) que permita definir las caracteristicas fundamentales de un dique exento en funcion del efecto que se quiera inducir en la costa, satisfaciendo las demandas sociales y preservando o mejorando la calidad del medio ambiente litoral. Ademas, se busca la aplicabilidad general del metodo, mediante la consideracion de relaciones entre variables de distinta naturaleza (climaticas, geomorfologicas y geometricas) que influyen en los cambios de la costa tras la construccion del dique exento. El estudio de las relaciones entre las distintas variables se realiza sobre los datos de una base de diecinueve diques exentos reales, existentes en el litoral mediterraneo espanol, y siguiendo una metodologia basada en el planteamiento de algunos monomios adimensionales y en la busqueda de relaciones de dependencia entre ellos. Finalmente, la discusion de los resultados obtenidos conduce a la propuesta de un metodo de diseno de diques exentos, que considera algunas de las relaciones graficas encontradas entre las variables estudiadas y con el que se consigue el objetivo principal anteriormente expuesto. ABSTRACT The coast is a narrow strip subjected to large imbalances. At many points, it is in a profound state of regression as a consequence of many, varied causes: wave action, tides and currents; Maritime constructions interrupting sediment transportation; mean sea level rise; development of coastal areas and massive town planning in the active area of beaches, etc. All these reasons lead to the erosion of a large number of beaches and their environmental and landscape degradation. This precarious coastline situation today constitutes a serious problem of great concern. Coastal Engineers, aware of the generalised beach erosion problem, are focusing their work seeking solutions to guarantee coastal stability. Different methods of protection have been used throughout time mostly based on artificial beach nourishment and the building of Structures, amongst which detached breakwaters play a major role. Detached breakwaters are artificial Structures, inspired on the coastal natural formations. These Structures are generally parallel to the coastline, protecting a certain stretch from wave action and being able to create accretion areas. This is why detached breakwaters have been in general use since the 1970s, with different results, in countries such as Japan, the USA, Israel, Spain, Italy or Australia. The study undertaken for this thesis focuses precisely on this type of Maritime Structure, with the main purpose of developing a functional and environmental design method (not structural) which let us define the most fundamental characteristics of a detached breakwater, based on the effects that we want to produce on the shoreline, satisfying social requests and preserving or improving the quality of the coastal environment. Moreover, the research looks for the general application of the method, considering relationships among different kind of variables (climatic, geomorphologic and geometrical) with influence on the changes that the coast undergo after the detached breakwater construction. The study among the different variables is carried out with a database of nineteen real cases on the Mediterranean Spanish coastline, following a methodology based on the identifying of some non-dimensional monomials and the search of dependency rates among them. Finally, the discussion of the obtained results leads to the proposal of a detached breakwater design method, which takes into account graphic relationships founded out among the studied variables, and achieving the previously exposed main objective.