The Open Sea Tests of the Offshore Floating Type Wave Power Device “Mighty Whale”: Performance of the Prototype

2002 ◽  
Author(s):  
Teruhisa Ogata ◽  
Yukihisa Washio ◽  
Hiroyuki Osawa ◽  
Yasushi Tsuritani ◽  
Seiya Yamashita ◽  
...  
Keyword(s):  
Wave Height ◽  
Wave Energy ◽  
Wave Period ◽  
Power Device ◽  
Design Stage ◽  
Wave Power ◽  
Significant Wave ◽  
Type Wave ◽  
Open Sea ◽  
Floating Type

This paper presents the characteristics of wave conditions, wave energy absorption, response of hull-motion and wave height dissipation based on the results of the open sea tests. 0.5–1.0m of significant wave height and 6–7 seconds of significant wave period appear the most predominant, and average wave energy is estimated 4.88kW/m around the test site. Average power output for the test is approximately 6kWh and the maximum total energy efficiency is around 15% that is ranging from 6–7 seconds of significant wave period. Slow drift oscillation of hull was observed motion in surge, sway and yaw and the value of its amplitude almost equal to estimated values in design stage. Then the mean value of transmission coefficient is about 0.8 under 8.0 seconds of significant wave period. We are considering that the results of the tests should be useful for optimum design of an offshore floating type wave power device.

scholarly journals Physical Modelling of the Effect on the Wave Field of the WaveCat Wave Energy Converter

2021 ◽  
Vol 9 (3) ◽  
pp. 309
Author(s):  
James Allen ◽  
Gregorio Iglesias ◽  
Deborah Greaves ◽  
Jon Miles
Keyword(s):  
Wave Height ◽  
Wave Energy ◽  
Significant Wave Height ◽  
Wedge Angle ◽  
Wave Energy Converter ◽  
Wave Period ◽  
Surface Elevation ◽  
Energy Converter ◽  
Significant Wave ◽  
Model Scale

The WaveCat is a moored Wave Energy Converter design which uses wave overtopping discharge into a variable v-shaped hull, to generate electricity through low head turbines. Physical model tests of WaveCat WEC were carried out to determine the device reflection, transmission, absorption and capture coefficients based on selected wave conditions. The model scale was 1:30, with hulls of 3 m in length, 0.4 m in height and a freeboard of 0.2 m. Wave gauges monitored the surface elevation at discrete points around the experimental area, and level sensors and flowmeters recorded the amount of water captured and released by the model. Random waves of significant wave height between 0.03 m and 0.12 m and peak wave periods of 0.91 s to 2.37 s at model scale were tested. The wedge angle of the device was set to 60°. A reflection analysis was carried out using a revised three probe method and spectral analysis of the surface elevation to determine the incident, reflected and transmitted energy. The results show that the reflection coefficient is highest (0.79) at low significant wave height and low peak wave period, the transmission coefficient is highest (0.98) at low significant wave height and high peak wave period, and absorption coefficient is highest (0.78) when significant wave height is high and peak wave period is low. The model also shows the highest Capture Width Ratio (0.015) at wavelengths on the order of model length. The results have particular implications for wave energy conversion prediction potential using this design of device.

scholarly journals Wave Energy Assessment in the Bohai Sea and the Yellow Sea Based on a 40-Year Hindcast

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2087
Author(s):  
Jie Dong ◽  
Jian Shi ◽  
Jianchun Zhao ◽  
Chi Zhang ◽  
Haiyan Xu
Keyword(s):  
Wave Height ◽  
Wave Energy ◽  
Yellow Sea ◽  
Significant Wave Height ◽  
Bohai Sea ◽  
The Yellow Sea ◽  
Wave Power ◽  
Power Flux ◽  
Significant Wave ◽  
The Bohai Sea

A wave hindcast, covering the period of 1979–2018, was preformed to assess wave energy potential in the Bohai Sea and the Yellow Sea. The hindcase was carried out using the third generation wave model TOMAWAC with high spatio-temporal resolution (about 1 km and on an hourly basis). Results show that the mean values of significant wave height increase from north to south, and the maximum values are located at the south part of the Yellow Sea with amplitude within 1.6 m. The magnitudes of significant wave height values vary significantly within seasons; they are at a maximum in winter. The wave energy potential was represented by distributions of the wave power flux. The largest values appear in the southeast part of the numerical domain with wave power flux values of 8 kW/m. The wave power flux values are less than 2 kW/m in the Bohai Sea and nearshore areas of the Yellow Sea. The seasonal mean wave power flux was found up to 8 kW/m in the winter and autumn. To investigate the exploitable wave energy, a wave energy event was defined based on the significant wave height (Hs) threshold values of 0.5 m. The wave energy in south part of the Yellow Sea is more steady and intensive than in the other areas. Wave energy in winter is more suitable for harvesting wave energy. Long-term trends of wave power availability suggest that the values of wave power slightly decreased in the 1990s, whereas they have been increasing since 2006.

Basic Characteristics of the Primary Conversion of an OWC Type WEC Installed on a Wave Dissipating Double-Caisson

2018 ◽  
Author(s):  
Tomoki Ikoma ◽  
Koichi Masuda ◽  
Hiroaki Eto ◽  
Shogo Shibuya
Keyword(s):  
Wave Height ◽  
Basic Property ◽  
Wave Energy ◽  
Wave Power ◽  
Oscillating Water Column ◽  
Type Wave ◽  
Wave Energy Converters ◽  
The World ◽  
Fixed Type ◽  
Basic Characteristics

Several types of oscillating water column (OWC) type wave energy converters (WECs) are researched and developed in the world. They are floating types and fixed types. In case of a fixed type, wave dissipating caissons could be replaced to WECs of an OWC type. On OWC types, installation of the projecting-walls (PWs) is useful in order to improve PTO performance. In this study, it was considered that a double dissipating caisson was used as an OWC type WEC with PWs. A front caisson of the double caisson seems the area surrounded by PWs and a back caisson can be seen as an OWC. The paper studied basic property of the primary conversion from wave power to power of air from model tests in a wave tank. As a result, wave height strongly effects on behaviours of OWC motion as well as air pressure. Finally, the primary conversion was affected by wave height. Besides, the concept of use of a double caisson was useful from the primary conversion over 80 % evaluated using test data.

scholarly journals Kajian Energi Gelombang Laut Di Daerah Abrasi Serangai, Bengkulu Utara Melalui Pengamatan Tinggi Gelombang Laut

2021 ◽  
Vol 11 (2) ◽  
pp. 143
Author(s):  
Ashar Muda Lubis ◽  
Yosi Apriani Putri ◽  
Rio Saputra ◽  
Juhendi Sinaga ◽  
M Hasanudin ◽  
...  
Keyword(s):  
Wave Height ◽  
Wave Energy ◽  
Seasonal Variations ◽  
Coastal Area ◽  
Significant Wave Height ◽  
Ocean Waves ◽  
Wave Period ◽  
Maximum Wave Height ◽  
Significant Wave ◽  
Sea Wave

<p class="AbstractText"><span lang="EN-AU">The Serangai area, Batik Nau District, North Bengkulu has the highest average abrasion speed of 20 m/year. The abrasion could cause the coastal area to erode the coastline till several tens of meters. The purpose of this study was to determine the height of the ocean waves and to determine the energy of the ocean waves that has the potential to accelerate the abrasion process in the Serangai area. The research was carried out on November 5-7, 2018 in the Serangai beach area at a depth of 5 m using SBE 26 Plus Seagauge Wave equipment. The results showed that the observed wave height was between 0.8-1.6 m with a significant wave height (Hs) of 1.38 m. In addition, the wave period ranges from 5-11 s with a significant wave period (Ts) of 8.2 s. The result also shows that the maximum wave height of 1.6 m occurred on November 7, 2018 with maximum wave energy of 1800 J/m<sup>2</sup>. This result can perhaps accelerate the abrasion process in the Serangai area. It can also be seen that the wave height in the Serangai region is higher than in several other areas in Indonesia. However, it is necessary to continue observing the wave height to see the seasonal variations in sea wave height in Serangai area.</span></p>

Characteristics of Hydrodynamics and Generating Output of Offshore Floating Wave Energy Device “Mighty Whale”

2004 ◽  
Author(s):  
Hiroyuki Osawa ◽  
Tsuyoshi Miyazaki ◽  
Shogo Miyajima
Keyword(s):  
Wave Energy ◽  
Wave Power ◽  
Hydrodynamic Behavior ◽  
Extraction Technology ◽  
Energy Device ◽  
Technology Center ◽  
Ocean Wave Energy ◽  
Open Sea ◽  
Theoretical Investigations ◽  
Floating Type

Japan Marine Science and Technology Center (JAMSTEC) has been engaged in research and development of ocean-wave energy extraction technology for many years now. In particular, work began in 1987 an offshore floating type wave power device called “Mighty Whale”. Theoretical investigations and model tests led to an understanding of the hydrodynamic behavior of device, and provided information of constructing for the prototype of Mighty Whale. The open sea tests were started on the 10th of September 1998. Tests were conducted until March 2002. In this paper, firstly, the characteristics of hydrodynamics with “Mighty Whale” have been examined comparing with the results of experiments and calculations approving a numerical method being developed. Secondly, using developed numerical analyze method, the displacements of water level inside air chambers of “Mighty Whale” have been calculated. The generating outputs of “Mighty Whale” have been estimated using these results, the efficiency of primary conversion and the efficiency of secondary conversion of “Mighty Whale” getting through the experiments that had been carried out.

scholarly journals A Study on Characteristics of Generated Output of the Offshore Floating Type Wave Power Device “Mighty Whale”

2001 ◽  
Vol 2001 (190) ◽  
pp. 395-405 ◽  
Author(s):  
Washio Yukihisa ◽  
Osawa Hiroyuki ◽  
Ogata Teruhisa ◽  
Nakagawa Hiroyuki ◽  
Okayama Shuzou ◽  
...  
Keyword(s):  
Power Device ◽  
Wave Power ◽  
Type Wave ◽  
Floating Type

Comparative wave measurements at a wave energy site with a recently developed low-cost wave buoy (Spotter), ADCP and pressure loggers

2021 ◽  
Author(s):  
Orrin Lancaster ◽  
Remo Cossu ◽  
Sebastien Boulay ◽  
Scott Hunter ◽  
Tom E. Baldock
Keyword(s):  
Wave Height ◽  
Wave Energy ◽  
Significant Wave Height ◽  
Low Cost ◽  
Wave Period ◽  
Wave Direction ◽  
Mean Values ◽  
Significant Wave ◽  
Wave Measurements ◽  
The Mean

AbstractWave measurements from a new, low-cost, real-time wave buoy (Spotter) are investigated in a comparative study as part of a site characterization study at a wave energy candidate site at King Island, Tasmania, Australia. Measurements from the Sofar Ocean Spotter buoy are compared with concurrent measurements from a Teledyne RD Instrument (RDI) 1200 kHz Work Horse ADCP and two RBRsolo3 D wave16 pressure loggers. The comparison period between 8th August – 12th October 2019 provides both the shallowest and longest continuous published comparison undertaken with the Spotter buoy.Strong agreement was evident between the Spotter buoy and RDI ADCP of key wave parameters including the significant wave height, peak wave period, and mean wave direction, with the mean values of those parameters across the full deployment period agreeing within 3%. Surface wave spectra and directional spectra are also analyzed with good agreement observed over the majority of the frequency domain, although the Spotter buoy records approximately 17% less energy within a narrow frequency band near the peak frequency when compared to the RDI ADCP. Measurements derived from the pressure loggers routinely underestimated the significant wave height and overestimated the mean wave period over the deployment period. The comparison highlights the suitability of the Spotter buoy for low-cost wave resource studies, with accurate measurements of key parameters and spectra observed.

The backward bend duct buoy-an improved floating type wave power device

2003 ◽  
Author(s):  
Y. Masuda ◽  
T. Yamazaki ◽  
Y. Outa ◽  
M.E. McCormick
Keyword(s):  
Power Device ◽  
Wave Power ◽  
Type Wave ◽  
Floating Type
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