scholarly journals FULL-SCALE PROTOTYPE OF AN OVERTOPPING BREAKWATER FOR WAVE ENERGY CONVERSION

2017 ◽  
pp. 12 ◽  
Author(s):  
Pasquale Contestabile ◽  
Ferrante Vincenzo ◽  
Enrico Di Lauro ◽  
Diego Vicinanza
Keyword(s):  
Energy Conversion ◽  
Wave Energy ◽  
Energy Production ◽  
Wave Interaction ◽  
Full Scale ◽  
Small Scale ◽  
Scaling Effects ◽  
Comprehensive Overview ◽  
Rubble Mound ◽  
Traditional Structures

The Overtopping BReakwater for Energy Conversion (OBREC) is a new typology of overtopping wave energy converter (OTD) integrated into a traditional rubble mound breakwater. The device can be considered as an innovative non-conventional breakwater that has the same functions as the traditional structures with the added-valued of the energy production. The paper presents a comprehensive overview of the OBREC, offering a synthesis of the complete design process, from the results of the two complementary test campaigns in small scale carried out in 2012 and 2014 at Aalborg University, to the description of the full-scale device installed in Naples in 2016. The device represents the first OTD device in full-scale integrated into an existing rubble mound breakwater and it has been equipped by an instrumental apparatus to measure its response to the wave interaction. The monitoring of the full-scale device in the port of Naples, particularly during storm conditions, is aimed to study the scaling effects in wave loading and the overall performance of this breakwater-integrated OTD, included performance in terms of the energy production.

Development and Testing of a Point Absorber Wave Energy Conversion

2011 ◽  
Author(s):  
Jacob Foster ◽  
Reza Ghorbani ◽  
Pierre Garambois
Keyword(s):  
Energy Conversion ◽  
Wave Energy ◽  
Energy Production ◽  
Small Scale ◽  
Wave Energy Conversion ◽  
Sea State ◽  
Point Absorber ◽  
The Third ◽  
Commercial Viability ◽  
The University

Wave energy conversion as a means for small scale energy production is approaching commercial viability. This paper presents the undergoing development of a wave energy conversion device at the University of Hawaii at Manoa. The device is a three part point absorber with two buoys, one floating and absorbing incoming waves; the other maintaining tension on the third mechanism, the submerged power-take-off unit. This design is discussed as three concept configurations for WEC construction. The analytical solution is developed, and the buoys response is computed due to a selected and analyzed sea-state.

Drilling Riser VIV Tests With Prototype Reynolds Numbers

2013 ◽  
Author(s):  
Halvor Lie ◽  
Henning Braaten ◽  
Jamison Szwalek ◽  
Massimiliano Russo ◽  
Rolf Baarholm
Keyword(s):  
Cross Flow ◽  
Effect Study ◽  
Full Scale ◽  
Scale Model ◽  
Small Scale ◽  
Scaling Effects ◽  
Research Activity ◽  
Forced Motion ◽  
Auxiliary Lines ◽  
Viv Suppression

For deep-water riser systems, Vortex Induced Vibrations (VIV) may cause significant fatigue damage. It appears that the knowledge gap of this phenomenon is considerable and this has caused a high level of research activity over the last decades. Small scale model tests are often used to investigate VIV behaviour. However, one substantial uncertainty in applying such results is scaling effects, i.e. differences in VIV response in full scale flow and small scale flow. To (partly) overcome this obstacle, a new innovative VIV test rig was designed and built at MARINTEK to test a rigid full scale riser model. The rigid riser model is mounted vertically and can either be elastically mounted or be given a forced motion. In the present version, the cylinder can only move in the cross-flow (CF) direction and is restricted in the in-line (IL) direction. The paper reports results from a drilling riser VIV experiment where the new rest rig has been used. The overall objective of the work is to study possible VIV suppression to improve operability of retrievable riser systems with auxiliary lines by adding riser fins. These fins are normally used as devices for protection of the auxiliary lines. The test program has recently been completed and analysis is an on-going activity. However, some results can be reported at this stage and more results are planned to be published. A bare riser model was used in a Reynolds number (Rn) scaling effect study. The riser model was elastically mounted and towed over a reduced velocity range around 4 – 10 in two different Rn ranges, 75 000 – 192 000 (subcritical regime) and 347 000 – 553 000 (critical regime). The difference in the displacement amplitude to diameter ratio, A/D, is found to be significant. The elastically mounted riser was also towed with various drilling riser configurations in order to study VIV/galloping responses. One configuration included a slick joint riser model with 6 kill & choke lines; another has added riser fins too. The riser model is based on a specific drilling riser and the kill and choke lines have various diameters and have a non-symmetrical layout. The various riser configurations have also been used in forced motion tests where the towed model has been given a sinusoidal CF motion. Forces have been measured. Determination of the force coefficients is still in progress and is planned to be reported later. Scaling effects appear to be a significant uncertainty and further research on the subject is recommended. The slick joint drilling riser configuration generally increased the displacements compared to displacements of the bare riser model. The drilling riser configuration with protection fins, kill and choke lines generally reduced the displacements compared to displacements of the bare riser model. For both riser systems, tests showed that the response is sensitive to the heading of the current.

Design and Potential Application of Small Scale Wave Energy Converter

2017 ◽  
Author(s):  
Tunde O. Aderinto ◽  
Francisco Haces-Fernandez ◽  
Hua Li
Keyword(s):  
Wave Energy ◽  
Energy Production ◽  
Energy Resource ◽  
Appropriate Technology ◽  
Wave Energy Converter ◽  
Small Scale ◽  
Ocean Energy ◽  
Energy Converter ◽  
Wave Energy Converters ◽  
Wave Properties

Although theoretical available wave energy is higher than most of ocean energy sources, the commercial utilization of wave energy is much slower than other ocean energy sources. The difficulty of integration with the electrical grid system and the challenges of the installation, operation and maintenance of large energy generation and transmission systems are the major reasons. Even though there are successfully tested models of wave energy converters, the fact that wave energy is directly affected by wave height and wave period makes the actual wave energy output with high variation and difficult to be predicted. And most of the previous studies on wave energy and its utilization have focused on the large scale energy production that can be integrated into a power grid system. In this paper, the authors identify and discuss stand-alone wave energy converter systems and facilities that are not connected to the electricity grid with focus on small scale wave energy systems as potential source of energy. For the proper identification, qualification and quantification of wave energy resource potential, wave properties such as wave height and period need to be characterized. This is used to properly determine and predict the probability of the occurrence of these wave properties at particular locations, which enables the choice of product design, installation, operation and maintenance to effectively capture wave energy. Meanwhile, the present technologies available for wave energy converters can be limited by location (offshore, nearshore or shoreline). Therefore, the potential applications of small scale stand-alone wave energy converter are influenced by the demand, location of the need and the appropriate technology to meet the identified needs. The paper discusses the identification of wave energy resource potentials, the location and appropriate technology suitable for small scale wave energy converter. Two simplified wave energy converter designs are created and simulated under real wave condition in order to estimate the energy production of each design.

Resource Scalability at Wave Energy Test Sites

2014 ◽  
Author(s):  
Brendan Cahill
Keyword(s):  
Wave Energy ◽  
Energy Resource ◽  
Ocean Waves ◽  
Primary Objective ◽  
Full Scale ◽  
Physical Models ◽  
Small Scale ◽  
Marine Energy ◽  
Lake Washington ◽  
Guide Device

Harnessing the power of ocean waves offers enormous potential as a source of renewable energy. To date the technologies for capturing this resource, collectively known as wave energy converters (WECs), have yet to reach commercial viability and continued research and development efforts are required to move wave energy to the industrial scale. Integral to this process is ensuring that technologies progress along a staged development pathway; proving WEC concepts using small scale physical models in controlled settings such as laboratory wave tanks before eventually advancing to testing sub-prototype and full scale devices in real sea conditions. The primary objective of this research is to improve the understanding of how best to address the scaling of wave resource measurements and wave energy device power production when analyzing the results of sea-trials. This paper draws on measured data from three test sites; Galway Bay in Ireland, the Pacific Marine Energy Test Centre off the coast of Oregon, and Lake Washington, and assesses how accurately they recreate, at reduced scale, the conditions that commercial WEC installations are likely to encounter at exposed deployment locations. Appropriate techniques for extrapolating these results to predict the performance of commercial WECs at energy-rich locations on the west coasts of Ireland and the US are also demonstrated and discussed. The output from this research will be a set of protocols for addressing wave energy resource scalability to help guide device developers through this important stage of technology progression. Improved knowledge regarding resource scalability will allow for more streamlined progression of WEC concepts from wave tanks to sea-trials, and eventually to full-scale ocean deployment. It will also result in a reduced uncertainty about device power output and survivability, which are key drivers in determining the economic viability of projects.

Wave loadings acting on innovative rubble mound breakwater for overtopping wave energy conversion

2017 ◽  
Vol 122 ◽  
pp. 60-74 ◽  
Author(s):  
Pasquale Contestabile ◽  
Claudio Iuppa ◽  
Enrico Di Lauro ◽  
Luca Cavallaro ◽  
Thomas Lykke Andersen ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Wave Energy ◽  
Wave Energy Conversion ◽  
Rubble Mound

Wave Energy Conversion for Shoreline Protection

2013 ◽  
Vol 47 (4) ◽  
pp. 187-192 ◽  
Author(s):  
Michael E. McCormick ◽  
Robert C. Murtha ◽  
Jeffrey Steinmetz
Keyword(s):  
Energy Conversion ◽  
Wave Energy ◽  
Water Wave ◽  
Ocean Waves ◽  
Wave Climate ◽  
Full Scale ◽  
Scale Model ◽  
Wave Energy Conversion ◽  
Shoreline Protection ◽  
Scale Test

AbstractThis paper is based on the premise that “wave energy conversion” is the conversion of the energy of ocean waves into other energy forms for the benefit of the environment. By taking advantage of the diffraction focusing phenomenon, commonly associated with water wave energy conversion, a bimodal buoy called the Antenna Buoy has been developed to both attract and dissipate incident water wave energy. As a result, arrays of the buoy can be deployed to form an effective floating breakwater system. Results from a full-scale experimental study show that an array of buoys, with each buoy pair separated by about 10 body widths, can dissipate up to 65% of the incident wave energy, where the value of the energy dissipation depends on the wave frequency. To arrive at this value, the full-scale test was conducted in a vertical-walled tank, where wall reflections were from “virtual” units in an array. The full-scale model used in the study is based on the averaged wave climate in the central-to-northern waters of the Chesapeake Bay. In addition to being effective in its design operation, the bimodal buoy can be repositioned or removed, as the site situation might require.

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