Utilization of Wave Dissipating Caissons as an OWC Type Wave Energy Convertor

2015 ◽  
Author(s):  
Tomoki Ikoma ◽  
Koichi Masuda ◽  
Hiroaki Eto ◽  
Kazuyoshi Kihara ◽  
Hisaaki Maeda ◽  
...  
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Theoretical Calculations ◽  
Low Cost ◽  
Vertical Movement ◽  
Compressed Air ◽  
Linear Potential ◽  
Oscillating Water Column ◽  
Column System ◽  
Air Turbine

Wave energy convertors (WEC) of oscillating water column (OWC) types make compressed air due to vertical movement of a part of water column, which are surrounded by some walls in water. As a result, the compressed air works to rotate an air turbine which also works for an electrical generator. If a structural system can make to move water such like a water column, a shape of a structure would not matter. Wave dissipating caissons installed in or on the existing production line can make to transfer a water wave to a flow and to reduce wave energy by making to overflow them. The caissons which can be overflowed by the water would actuate a water region vertically such like an oscillating water column system. This study investigated if we can utilize wave dissipating caissons as a WEC. Wave dissipating caissons also decrease wave energy due to passing through themselves. Even so, when an air turbine can be installed onto the caisson in order to harvest wave energy, it would be possible to produce electricity at low cost. The study conducted model experiments using the model assumed that wave dissipating double-caissons were remodelled to OWC type WECs with side walls and evaluated performance of the primary conversion of them. In addition, effects of how to arrange the number of the WECs on the primary conversion efficiency were investigated with theoretical calculations based on the linear potential theory and the possibility of utilization of wave dissipating caissons as a WEC was examined in the study.

Scale and Configuration Effects of an Airchamber on PTO of Oscillating Water Column Type Wave Energy Converters

2021 ◽  
Author(s):  
Tomoki Ikoma ◽  
Shota Hirai ◽  
Yasuhiro Aida ◽  
Koichi Masuda
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Water Surface ◽  
Air Pressure ◽  
Scale Model ◽  
Linear Potential ◽  
Oscillating Water Column ◽  
Wave Energy Converters ◽  
Air Chamber ◽  
Energy Converters

Abstract Wave energy converters (WECs) have been extensively researched. The behaviour of the oscillating water column (OWC) in OWC WECs is extremely complex due to the interaction of waves, air, and turbines. Several problems must be overcome before such WECs can be put to practical use. One problem is that the effect of the difference in scale between a small-scale experimental model and a full-scale model is unclear. In this study, several OWC models with different scales and geometries were used in forced oscillation tests. The wave tank was 7.0 m wide, 24.0 m long, and 1.0 m deep. In the static water experiment, we measured the air pressure and water surface fluctuations in an air chamber. For the experiments, models with a box shape with an open bottom, a manifold shape with an open bottom, and a box shape with a front opening, respectively, were fabricated. Furthermore, 1/1, 1/2, and 1/4 scale models were fabricated for each shape to investigate the effects of scale and shape on the air chamber characteristics. Numerical calculations were carried out by applying linear potential theory and the results were compared with the experimental values. The results confirmed that the air chamber shape and scale affect the air pressure fluctuation and water surface fluctuation inside the OWC system.

scholarly journals Effect of wall inclination on the dynamic behaviour of an oscillating water column system

2020 ◽  
Vol 307 ◽  
pp. 01021
Author(s):  
Abdelhamid El Barakaz ◽  
Abdellatif El Marjani ◽  
Hamid Mounir
Keyword(s):  
Water Column ◽  
Natural Frequency ◽  
Wave Energy ◽  
Maximum Efficiency ◽  
Oscillating Water Column ◽  
Wave Energy Converters ◽  
Column System ◽  
Resonance Domain ◽  
Pneumatic Chamber ◽  
Chamber Model

The Oscillating Water Column device (OWC) is one of the most used Wave Energy Converters (WECs) for wave energy harvesting. It consists essentially of two parts: the pneumatic chamber made of concrete and the bidirectional turbine linked to a generator group for energy production. In this study we are interested in the water motion oscillation inside the chamber resulting from the water level perturbation. This process is characterized by its own natural frequency and global damping. The vertical OWC chamber model is limited by the number of parameters defining the natural frequency and the global damping. The objective of this paper is to improve the performances obtained for the vertical OWC by considering an OWC with inclined sidewalls. For maximum efficiency, the device must operate in the resonance domain where the damping is low and the frequency of incoming waves matches with the natural frequency of the OWC. This will theoretically amplify the pneumatic energy to be converted to a mechanical one in the turbine.

A Numerical Study of Wave Energy Converter in the Form of an Oscillating Water Column Based on a Mixed Eulerian-Lagrangian Formulation

2010 ◽  
Author(s):  
Chunrong Liu ◽  
Zhenhua Huang ◽  
Adrian Law Wing Keung ◽  
Nan Geng
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Numerical Study ◽  
Integral Equation Method ◽  
Boundary Integral ◽  
Lagrangian Formulation ◽  
Oscillating Water Column ◽  
Extraction Chamber ◽  
Air Chamber ◽  
Air Turbine

A desingularized boundary integral equation method (DBIEM) is employed to study the wave energy extraction by an oscillating water column (OWC) device. The method is based on a mixed-Eulerian-Lagrangian formulation. We examine the effects of the relative draught on the efficiency of 2D OWC energy converters. The oscillating air pressure inside the OWC chamber is modeled by assuming that the air is incompressible and the air-turbine mass-flow rate is proportional to the pressure difference (a linear turbine). For shallow draughts the numerical results agree well with available analytical results. The wave-excited seiching inside the extraction chamber is discussed and the variation of extraction efficiency with dimensionless air-chamber width for different immersion depths is reported.

Air turbine choice and optimization for floating oscillating-water-column wave energy converter

2014 ◽  
Vol 75 ◽  
pp. 148-156 ◽  
Author(s):  
António F.O. Falcão ◽  
João C.C. Henriques ◽  
Luís M.C. Gato ◽  
Rui P.F. Gomes
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Oscillating Water Column ◽  
Energy Converter ◽  
Air Turbine

A detailed analysis of the unsteady flow within a Wells turbine

2017 ◽  
Vol 231 (3) ◽  
pp. 197-214 ◽  
Author(s):  
Tiziano Ghisu ◽  
Pierpaolo Puddu ◽  
Francesco Cambuli
Keyword(s):  
Detailed Analysis ◽  
Water Column ◽  
Wave Energy ◽  
Oscillating Water Column ◽  
Renewable Energy Resources ◽  
Wells Turbine ◽  
Column System ◽  
Flow Parameters ◽  
Important Interaction ◽  
Acceleration And Deceleration

Sea wave energy is one of the main renewable energy resources. Its exploitation is relatively simple and determines a minimum impact on the environment. The system that is most often used for wave energy harvesting is composed of an oscillating water column device together with a Wells turbine. When designing the Wells turbine, its interaction with the oscillating water column system must be taken into account, if the energy collected is to be maximized. The most important interaction phenomenon is the so called hysteresis effect, i.e. the time delay between the piston-like motion of the air water interface and the torque developed by the turbine. This work presents a detailed analysis of the flow within an oscillating water column system, focusing on the differences in performance and in secondary flow structures between acceleration and deceleration, and between the inflow and outflow phases. This analysis demonstrates how the hysteresis between acceleration and deceleration is caused uniquely by compressibility effects within the oscillating water column system, while differences in the flow parameters and secondary structures near the rotor are negligible, if equivalent flow conditions are compared. The effects of the oscillating water column system configuration on the performance are also highlighted.

scholarly journals TURBINE−CHAMBER COUPLING IN AN OWC WAVE ENERGY CONVERTER

2012 ◽  
Vol 1 (33) ◽  
pp. 2 ◽  
Author(s):  
Ivan Lopez ◽  
Gregorio Iglesias ◽  
Mario Lopez ◽  
Francisco Castro ◽  
Miguel Ángel Rodríguez
Keyword(s):  
Numerical Modeling ◽  
Water Column ◽  
Wave Energy ◽  
Wave Power ◽  
Optimum Level ◽  
Oscillating Water Column ◽  
Wave Energy Conversion ◽  
Energy Converter ◽  
Air Turbine ◽  
Pneumatic Power

Oscillating Water Column (OWC) systems are one of the most popular technologies for wave energy conversion. Their main elements are the chamber with the water column and the air turbine. When studying the performance of an OWC system both elements should be considered together, for they are effectively coupled: the damping exerted by the air turbine affects the efficiency of the conversion from wave power to pneumatic power in the OWC chamber, which in turn affects the air flow driving the turbine. The optimum level of damping is that which maximizes the efficiency of the conversion from wave to pneumatic power. In this work the turbine-chamber coupling is studied through a combination of physical and numerical modeling.

A novel twin-rotor radial-inflow air turbine for oscillating-water-column wave energy converters

Energy ◽  
2015 ◽  
Vol 93 ◽  
pp. 2116-2125 ◽  
Author(s):  
António F.O. Falcão ◽  
Luís M.C. Gato ◽  
João C.C. Henriques ◽  
João E. Borges ◽  
Bruno Pereiras ◽  
...  
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Oscillating Water Column ◽  
Wave Energy Converters ◽  
Air Turbine ◽  
Twin Rotor ◽  
Energy Converters

Air Turbine and Primary Converter Matching in Spar-Buoy Oscillating Water Column Wave Energy Device

2013 ◽  
Author(s):  
J. C. C. Henriques ◽  
A. F. O. Falcão ◽  
R. P. F. Gomes ◽  
L. M. C. Gato
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Rotational Speed ◽  
Time Domain Analysis ◽  
Wave Climate ◽  
Numerical Code ◽  
Oscillating Water Column ◽  
Wave Direction ◽  
Power Performance ◽  
Air Turbine

The oscillating water column (OWC) equipped with an air turbine is possibly the most reliable type of wave energy converter. The OWC spar-buoy is a simple concept for a floating OWC. It is an axisymmetric device (and so insensitive to wave direction) consisting basically of a (relatively long) submerged vertical tail tube open at both ends and fixed to a floater that moves essentially in heave. The air flow displaced by the motion of the OWC inner free-surface, relative to the buoy, drives an air turbine. The choice of air turbine type and size, the regulation of the turbine rotational speed and the rated power of the electrical equipment strongly affect the power performance of the device and also the equipment’s capital cost. Here, numerical procedures and results are presented for the power output from turbines of different sizes equipping a given OWC spar-buoy in a given offshore wave climate, the rotational speed being optimized for each of the sea states that, together with their frequency of occurrence, characterize the wave climate. The new biradial self-rectifying air turbine was chosen as appropriate to the relatively large amplitude of the pressure oscillations in the OWC air chamber. Since the turbine is strongly non-linear and a fully-nonlinear model of air compressibility was adopted, a time domain analysis was required. The boundary-element numerical code WAMIT was used to obtain the hydrodynamic coefficients of the buoy and OWC, whereas the non-dimensional performance curves of the turbine were obtained from model testing.

scholarly journals Wave energy capture by an omnidirectional point sink oscillating water column system

2021 ◽  
Vol 304 ◽  
pp. 117795
Author(s):  
Robert Mayon ◽  
Dezhi Ning ◽  
Chongwei Zhang ◽  
Lifen Chen ◽  
Rongquan Wang
Keyword(s):  
Water Column ◽  
Wave Energy ◽  
Oscillating Water Column ◽  
Energy Capture ◽  
Column System

Peluang Peluang dan tantangan pengembangan teknologi Oscilating Water Column (OWS) di Indonesia.

2021 ◽  
Vol 4 (01) ◽  
pp. 37-42
Author(s):  
Sigit Arrohman ◽  
Dwi Aries Himawanto
Keyword(s):  
Renewable Energy ◽  
Water Column ◽  
Wave Energy ◽  
Ocean Waves ◽  
Primary Energy ◽  
Energy Development ◽  
Ocean Wave ◽  
Oscillating Water Column ◽  
Column System ◽  
Ocean Wave Energy

Renewable energy is one of the government's efforts to increase the source of the national electricity supply and reduce fossil energy sources. Indonesia has the potential to develop renewable energy in the fields of ocean waves, sunlight, water, and geothermal. But of all these, the most promising to become renewable energy development opportunities are water energy, geothermal energy and ocean wave energy. Indonesia as an archipelagic country with an area of ​​1,904,556 km2 which consists of; 17,508 islands, 5.8 million km2 of ocean and 81,290 million km of beach length, the potential for marine energy, especially ocean waves, is very potential to be empowered as new and renewable alternative primary energy, especially for power generation. This ocean wave power plant has been widely developed, including: buoy type technology, overtopping devices technology, oscillating water column technology. Oscillating Water Column (OWC) is an alternative technology to convert ocean wave energy using an oscillating water column system. The ocean wave conversion technology of the OWC system was chosen because it is suitable in areas with steep coastal topography and has a wave height value between 0.2 m to 1.19 m and even exceeds so that the electricity generated is greater. OWC technology which will be developed for the territory of Indonesia has several opportunities and challenges. Opportunities and challenges that will be faced include the potential for waves, the application of OWC to waterways in Indonesia, OWC systems, and technology investment for the prospect of long-term energy development in Indonesia.  

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