scholarly journals Turbine Characteristics of Wave Energy Conversion Device for Extraction Power Using Breaking Waves

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 966
Author(s):  
Paresh Halder ◽  
Hideki Takebe ◽  
Krisna Pawitan ◽  
Jun Fujita ◽  
Shuji Misumi ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Wave Energy ◽  
Fluid Dynamic ◽  
Flow Simulation ◽  
Breaking Waves ◽  
Wave Energy Converter ◽  
Constant Thickness ◽  
Prototype Model ◽  
Wave Energy Conversion ◽  
Energy Converter

A new type of wave energy converter which harnesses electricity from onshore breaking waves has been studied at Okinawa Institute of Science and Technology Graduate University (OIST) since 2014. This concept has been demonstrated at a coral beach on the Maldives since 2018. Wave energy conversion is possible when waves approaching the shore steepen due to decreased water depth resulting in wave breaks near the surface. A steepened wave reaches the critical velocity of 4~6 m/sec shoreward before it breaks. A rotating blade takes advantage of this breaking phenomenon to convert the wave energy into electricity. The work presented here includes an experimental and numerical investigation of a prototype model of the wave energy converter. The turbine having five blades of variable chord lengths, twist angles, and constant thickness profile from hub to tip was simulated under similar flow as well as testing conditions, to predict the turbine performance. A commercial computational fluid dynamic tool SolidWorks Flow Simulation 2018 was used for the simulations at various rotation speeds with a uniform inlet velocity. The modified k-ε with a two-scale wall function turbulence closure model was selected. The validation performed for different test cases showed that the present computational results match in good agreement with the experimental results. Additionally, details performance of the turbine running, and generator characteristics have been reported in this paper.

scholarly journals Design and Analysis for a Floating Oscillating Surge Wave Energy Converter

2014 ◽  
Author(s):  
Yi-Hsiang Yu ◽  
Ye Li ◽  
Kathleen Hallett ◽  
Chad Hotimsky
Keyword(s):  
Energy Conversion ◽  
Structure Analysis ◽  
Wave Energy ◽  
Integrated Design ◽  
Design Strategy ◽  
Wave Energy Converter ◽  
Wave Energy Conversion ◽  
Power Performance ◽  
Energy Converter ◽  
The Cost

This paper presents a recent study on the design and analysis of an oscillating surge wave energy converter (OSWEC). A successful wave energy conversion design requires balance between the design performance and cost. The cost of energy is often used as the metric to judge the design of the wave energy conversion (WEC) system, which is often determined based on the device’s power performance; the cost of manufacturing, deployment, operation, and maintenance; and environmental compliance. The objective of this study is to demonstrate the importance of a cost-driven design strategy and how it can affect a WEC design. A set of three oscillating surge wave energy converter designs was analyzed and used as examples. The power generation performance of the design was modeled using a time-domain numerical simulation tool, and the mass properties of the design were determined based on a simple structure analysis. The results of those power performance simulations, the structure analysis, and a simple economic assessment were then used to determine the cost-efficiency of selected OSWEC designs. Finally, we present a discussion on the environmental barrier, integrated design strategy, and the key areas that need further investigation.

Design and Performance Analysis of Anchor System for a Single-Body Wave Energy Converter

2016 ◽  
Author(s):  
Rodrigo L. Banos ◽  
Hirpa G. Lemu
Keyword(s):  
Power Generation ◽  
Energy Conversion ◽  
Wave Energy ◽  
Wave Energy Converter ◽  
Wave Energy Conversion ◽  
Energy Converter ◽  
Practical Solution ◽  
Simulation Tools ◽  
Anchor System ◽  
Single Body

The last couple of decades have observed an increasing interest in development of wave energy conversion technology for both research and commercial purposes. Though slow due to several reasons, the technology shows an evident progress. Because of the oil crisis facing the energy sector in particular, wave energy is currently seen as a good alternative to fossil fuel based power generation. This has marked its footprints on rising industrial ventures in wave energy based power generation and the search for new devices is gearing up. Among the latest invented models, point wave energy converters are attractive and low investment options. These devices are much smaller than the traditional oscillating water column devices and have good performance when combined in arrays of devices, thus placing the technology in the center of industrial and academic research. This article reports the study conducted to understand the mechanics of the energy exchange in a single-body point wave energy converter device model Cape Verde, patented by the Norwegian company Euro Wave Energy. Furthermore, the article intends to give a practical solution for the design of the anchoring problem in the device. In general, the article attempts to present two completely different objectives: an academic part focusing on understanding the wave energy conversion mechanics, and the industrial development part that attempts to find a practical solution for a particular part of the device. The first step involves establishing a model that describes the motion and potential of absorbance of a conic single-body absorber. The anchor system was designed in accordance with standards provided by Det Norske Veritas, the Norwegian regulatory framework. A quasi-static method is used to calculate the load that the absorber would suffer and a pulley and cable system is proposed to drive these loads to the anchor system. After a review of the different solutions offered for offshore facilities at the present time, the model of a suction anchor is chosen. As design verification through physical testing of prototypes of conversion devices is demanding and costly, various simulation tools are appearing in the field. The application range of some of these different simulation tools has been evaluated and reported in this article.

Comparison of Physical Model Tests With a Time Domain Simulation Model of a Wave Energy Converter

2012 ◽  
Author(s):  
Ryan S. Nicoll ◽  
Charles F. Wood ◽  
André R. Roy
Keyword(s):  
Energy Conversion ◽  
Wave Energy ◽  
Time Domain ◽  
Wave Energy Converter ◽  
Ocean Dynamics ◽  
Time Domain Simulation ◽  
Wave Energy Conversion ◽  
Energy Converter ◽  
Energy Conversion Systems ◽  
The Time Domain

Development of wave energy conversion systems may yield many key benefits for society such as the production of electrical power or fresh water for remote communities. However, complex ocean dynamics make it difficult for technology developers to not only address the stability and survivability of their systems, but also to establish energy conversion rates that are fundamental to proving economic viability. Building physical prototypes presents many challenges in terms of cost, accessible facilities, and time requirements. The use of accurate numerical modelling and computer simulation can help guide design and significantly reduce the number of physical prototype tests required and as a result play a primary role in the development of wave energy conversion systems that have to operate in challenging marine environments. SurfPower is an ocean wave energy converter (WEC) that converts wave motion into useful energy through surge and heave motion of a point absorber. The system pumps seawater into a high pressure hydraulic network that generates electricity via a turbine or freshwater via desalination at a facility onshore. The system is nonlinear due to the significant change in draft and mooring reaction load through the energy capture cycle of the device. This makes the use of nonlinear time domain simulation ideal for analysis and design of the system. Furthermore, utilizing a simplified nonlinear hydrodynamic model available in the time domain results in a practical early-stage design tool for system refinement. The focus of this work is to compare the results of scale model testing completed at the Institute for Ocean Technology in St. John’s, Newfoundland, with results produced from an equivalent system simulated in the time domain simulation software ProteusDS. The results give an assessment of the range of error that can be used to assess other experiments of the SurfPower WEC at full scale.

scholarly journals Semi-Analytical Solution of Optimization on Moon-Pool Shaped WEC

2016 ◽  
Vol 23 (s1) ◽  
pp. 25-31 ◽  
Author(s):  
W.C. Zhang ◽  
H.X. Liu ◽  
X.W. Zhang ◽  
L. Zhang
Keyword(s):  
Energy Conversion ◽  
Wave Energy ◽  
Ocean Waves ◽  
Maximum Energy ◽  
Wave Energy Converter ◽  
Wave Energy Conversion ◽  
Energy Converter ◽  
Expansion Matching ◽  
Exciting Forces ◽  
Moon Pool

Abstract In order to effectively extract and maximize the energy from ocean waves, a new kind of oscillating-body WEC (wave energy converter) with moon pool has been put forward. The main emphasis in this paper is placed on inserting the damping into the equation of heaving motion applied for a complex wave energy converter and expressions for velocity potential added mass, damping coefficients associated with exciting forces were derived by using eigenfunction expansion matching method. By using surface-wave hydrodynamics, the exact theoretical conditions were solved to allow the maximum energy to be absorbed from regular waves. To optimize the ability of the wave energy conversion, oscillating system models under different radius-ratios are calculated and comparatively analyzed. Numerical calculations indicated that the capture width reaches the maximum in the vicinity of the natural frequency and the new kind of oscillating-body WEC has a positive ability of wave energy conversion.

Mathematical Modeling and Scaling of the Friction Losses of a Mechanical Gyroscope

2018 ◽  
Vol 10 (03) ◽  
pp. 1850024 ◽  
Author(s):  
Nicola Pozzi ◽  
Mauro Bonfanti ◽  
Giuliana Mattiazzo
Keyword(s):  
Wave Energy ◽  
Fluid Dynamic ◽  
Scaling Law ◽  
Full Scale ◽  
Wave Energy Converter ◽  
Energy Converter ◽  
Friction Forces ◽  
Efficiency Optimization ◽  
Energy Field ◽  
Model Of Friction

Friction is a complicated phenomenon that plays a central role in a wide variety of physical systems. An accurate modeling of the friction forces is required in the model-based design approach, especially when the efficiency optimization and system controllability are the core of the design. In this work, a gyroscopic unit is considered as case study: the flywheel rotation is affected by different friction sources that needs to be compensated by the flywheel motor. An accurate modeling of the dissipations can be useful for the system efficiency optimization. According to the inertial sea wave energy converter (ISWEC) gyroscope layout, friction forces are modeled and their dependency with respect to the various physical quantities involved is examined. The mathematical model of friction forces is validated against the experimental data acquired during the laboratory testing of the ISWEC gyroscope. Moreover, in the wave energy field, it is common to work with scale prototypes during the full-scale device development. For this reason, the scale effect on dissipations has been correlated based on the Froude scaling law, which is commonly used for wave energy converter scaling. Moreover, a mixed Froude–Reynolds scaling law is taken into account, in order to maintain the scale of the fluid-dynamic losses due to flywheel rotation. The analytical study is accompanied by a series of simulations based on the properties of the ISWEC full-scale gyroscope.

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