scholarly journals Effective Mooring Rope Tension in Mechanical and Hydraulic Power Take-Off of Wave Energy Converter

2021 ◽  
Vol 13 (17) ◽  
pp. 9803
Author(s):  
Ji Woo Nam ◽  
Yong Jun Sung ◽  
Seong Wook Cho
Keyword(s):  
Energy Conversion ◽  
Wave Energy ◽  
Mechanical Energy ◽  
Electrical Energy ◽  
Energy Conversion Efficiency ◽  
Wave Energy Converter ◽  
Hydraulic Motor ◽  
Energy Converter ◽  
The Individual ◽  
Conversion Efficiencies

The InWave wave energy converter (WEC), which is three-tether WEC type, absorbs wave energy via moored cylindrical buoys with three ropes connected to a terrestrial power take-off (PTO) through a subsea pulley. In this study, a simulation study was conducted to select a suitable PTO when designing a three-tether WEC. The mechanical PTO transfers energy from the buoy to the generator using a gearbox, whereas the hydraulic PTO uses a hydraulic pump, an accumulator, and a hydraulic motor to convert mechanical energy into electrical energy. The hydraulic PTO has a lower energy conversion efficiency than that of the mechanical PTO owing to losses resulting from pipe friction and the individual efficiencies of the hydraulic pumps and motors. However, the efficiencies mentioned above are not the efficiency of the whole system. The efficiency of the whole system should be analyzed considering the tension of the rope and the efficiency of the generator. In this study, the energy conversion efficiencies of the InWave WEC installed the mechanical and hydraulic PTO devices are compared, and their behaviors are analyzed through numerical simulations. The mechanics of mechanical and hydraulic PTO applied to InWave are mathematically expressed, and the issues of the elements constituting the PTO are explained. Finally, factors to consider for PTO selection are presented.

Modeling and Experiment of a Novel Micro Wave Energy Converter

2017 ◽  
Vol 863 ◽  
pp. 175-182
Author(s):  
Yi Ming Zhu ◽  
Zi Rong Luo ◽  
Zhong Yue Lu ◽  
Jian Zhong Shang
Keyword(s):  
Output Power ◽  
Wave Energy ◽  
Mechanical Energy ◽  
Vertical Motion ◽  
Electrical Energy ◽  
Wave Energy Converter ◽  
Design Parameters ◽  
Energy Converter ◽  
Drive Power ◽  
Continuous Rotation

This paper proposed a novel micro wave energy converter which can convert irregular wave energy into rotating mechanical energy, then into electrical energy. The device consists of an energy absorption part and an energy conversion part. In details, the blades are installed on the absorber circumferentially and averagely, which are capable of converting the vertical motion of the surface body to continuous rotation of the absorber and leading to a great increase in efficiency. A physical prototype was built to test the performance of the novel generator and optimize the design parameters. In the experiment part, a linear motion electric cylinder was used as the drive power to provide the heaving motion for the device. And the experiment platform was built for modeling a marine environment. Also, a data acquisition program was edited in Labview. Thus, the experiment analyzed the influence of amplitude, frequency, blade angle and resistance value to the output power, and then obtained the optimum parameters combination which can maximize the value of the output power. The result will provide reference for the device’s further application.

Research on the Hydrodynamic Performance of a Wave Energy Converter

2014 ◽  
Vol 986-987 ◽  
pp. 956-962
Author(s):  
Xiong Bo Zheng ◽  
Yu Nong Yang
Keyword(s):  
Energy Conversion ◽  
Conversion Efficiency ◽  
Wave Energy ◽  
Energy Conversion Efficiency ◽  
High Energy ◽  
Wave Energy Converter ◽  
Hydrodynamic Performance ◽  
Mechanical Transmission ◽  
Energy Converter ◽  
Wave Energy Conversion Efficiency

Under the pressure of fossil energy shortage, rational exploitation of ocean wave energy is propitious to establish an environmentally friendly society. This paper presents the results of a practical research done in a test tank, on the hydrodynamic performance of a wave energy converter with swing arms and floaters designed purposely. Fixed on a trailer, the converter was composed of two floaters, two swing arms, mechanical transmission devices and generators. The method of this research was to measure the floater’s acceleration and the output voltages of the generator under the movement of waves, analysis the influence of wave height and period on floaters’ movement, then compute the wave energy conversion efficiency. At last, the research findings show that the converter performed well with heaving motion performance and high energy conversion efficiency.

Frequency Response Analysis of an Ocean Wave Energy Converter

1983 ◽  
Vol 105 (1) ◽  
pp. 30-38 ◽  
Author(s):  
M. Masubuchi ◽  
R. Kawatani
Keyword(s):  
Wave Energy ◽  
Wave Train ◽  
Mechanical Energy ◽  
Energy Conversion Efficiency ◽  
Wave Energy Converter ◽  
Response Analysis ◽  
Floating Bodies ◽  
Energy Converter ◽  
Ocean Wave Energy ◽  
Basic Equations

A theoretical analysis is presented for the dynamic behavior and energy conversion efficiency of a wave energy converter which is oscillating and absorbing power in an incident sinusoidal wave train. The energy converter consists of two floating bodies which have different configuration and are connected by a rigid link. Basic equations governing the floating bodies contained in the energy converter are obtained by assuming two dimensional motions and by considering the interactions between the two bodies and hydrodynamic and damping forces, and they have been solved numerically by using Lewis form as the configuration of the floating bodies. Energy absorption is assumed to be proportional to the square of the relative velocity between the oscillating body and the connecting link. It is shown that nearly 100 percent of wave energy is converted into mechanical energy in a wide frequency band.

scholarly journals Study on Optimum Power Take-Off Torque of an Asymmetric Wave Energy Converter in Western Sea of Jeju Island

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1449
Author(s):  
Haeng Sik Ko ◽  
Sangho Kim ◽  
Yoon Hyeok Bae
Keyword(s):  
Energy Conversion ◽  
Conversion Efficiency ◽  
Wave Energy ◽  
Energy Conversion Efficiency ◽  
Wave Energy Converter ◽  
Jeju Island ◽  
Energy Converter ◽  
Load Torque ◽  
Extracted Power ◽  
Asymmetric Wave

This study primarily investigates an optimum energy conversion efficiency of asymmetric wave energy converter (WEC). A power take-off (PTO) system that provides a constant load torque opposite to pitch motion was implemented. Incident wave conditions were selected based on the measured data in the western sea of Jeju Island, South Korea. An optimum torque was calculated by comparing the time-averaged extracted power with various PTO load torque. InterDyMFoam solver based on Reynolds-averaged Navier-Stokes (RANS) equations were used in an OpenFOAM v4.0 framework—an open-source computational fluid dynamics model—against the experimental results derived from the wave flume. The upward pitch excursion was induced by wave force due to the asymmetric WEC characteristics; however, the downward pitch excursion depends on its weight. Numerically, the PTO torque was only loaded in uni-direction against the upward pitch motion. Moreover, the optimum PTO torque was estimated by comparing the time-averaged extracted power. Finally, the optimum PTO torque was evaluated by an irregular wave as a function of significant wave height. The optimum PTO provides design information about the asymmetric wave energy converter to improve energy conversion efficiency.

scholarly journals Sea Wave Energy. A Review of the Current Technologies and Perspectives

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6604
Author(s):  
Domenico Curto ◽  
Vincenzo Franzitta ◽  
Andrea Guercio
Keyword(s):  
Wave Energy ◽  
Power Plants ◽  
New Technologies ◽  
Morphological Characteristics ◽  
Electrical Energy ◽  
Wave Energy Converter ◽  
Tidal Range ◽  
Ocean Current ◽  
Energy Converter ◽  
Ocean Thermal Energy

The proposal of new technologies capable of producing electrical energy from renewable sources has driven research into seas and oceans. Research finds this field very promising in the future of renewable energies, especially in areas where there are specific climatic and morphological characteristics to exploit large amounts of energy from the sea. In general, this kind of energy is referred to as six energy resources: waves, tidal range, tidal current, ocean current, ocean thermal energy conversion, and saline gradient. This review has the aim to list several wave-energy converter power plants and to analyze their years of operation. In this way, a focus is created to understand how many wave-energy converter plants work on average and whether it is indeed an established technology.

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.

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