Design, Fabrication, Simulation and Testing of a Novel Ocean Wave Energy Converter

2015 ◽  
Author(s):  
Changwei Liang ◽  
Junxiao Ai ◽  
Lei Zuo
Keyword(s):  
Wave Energy ◽  
Energy Demand ◽  
Energy Resource ◽  
Wave Energy Converter ◽  
Ocean Wave ◽  
Energy Converter ◽  
Wave Energy Converters ◽  
Ocean Wave Energy ◽  
Linear Electromagnetic Motor ◽  
Energy Converters

The total useful wave resource around the world is estimated to be larger than 2 TW. Harvesting a small portion of the available wave energy resource could contribute significantly to meet the urgent energy demand. Therefore, a lot of wave energy converters have been developed in the past decades. Traditionally, air turbine, hydroelectric motor and linear electromagnetic motor are used in wave energy converters as the power takeoff system. Although these power takeoffs have their own advantages, power takeoffs are still recognized as the most important challenge in ocean wave energy technology. In this paper, a mechanical motion rectifier (MMR) based power takeoff system is proposed and prototyped for wave energy converter. This power takeoff system can convert the bi-directional wave motion into unidirectional rotation of the generator by integrating two one-way clutches into a rack pinion system. A 500W prototype which contains a heaving buoy and MMR-based power takeoff system was designed and fabricated. The models of power takeoff system and the corresponding single-buoy wave energy converter are built and analyzed. Lab testing of power takeoff mechanism and ocean testing of the overall ocean wave converter system are also conducted.

Towards a Definition and Metric for the Survivability of Ocean Wave Energy Converters

2010 ◽  
Author(s):  
Adam Brown ◽  
Robert Paasch ◽  
Irem Y. Tumer ◽  
Pukha Lenee-Bluhm ◽  
Justin Hovland ◽  
...  
Keyword(s):  
Wave Energy ◽  
Energy Content ◽  
Ocean Waves ◽  
Wave Energy Converter ◽  
Ocean Wave ◽  
Energy Converter ◽  
Term Survival ◽  
Wave Energy Converters ◽  
Ocean Wave Energy ◽  
Energy Converters

Survivability is a term that is widely used in the ocean wave energy industry, but the term has never been defined in that context. The word itself seems to have an intrinsic meaning that people understand; this fact often leads to the term’s misuse and its confusion with “reliability”. In order to design systems that are capable of long term survival in the ocean environment, it must be clear what “survivability” means and how it affects the design process and ultimately the device being deployed. Ocean energy is relatively predictable over the span of months, days, and even hours, which makes it very promising as a form of renewable energy. However, the variation of the energy content of ocean waves in a given location is likely high due to the effect of storms and the seasons. Wave energy converters must be built to be reliable while operating and survivable during severe conditions. Therefore, probabilistic design practices must be used to insure reliability and survivability in conditions that are constantly changing. Reliability is used to numerically express the failures of a device that occur while the system is operational, and it is usually expressed in terms of the mean time between failure (MTBF). However, in the context of ocean wave energy converters, the devices are likely to be continuously deployed in conditions that push them beyond their operating limits. During these times it is likely that wave energy converters will be placed in some sort of “survival mode” where the device sheds excess power, reducing system loading. Survivability is focused specifically on failures that occur during these times, when the device is experiencing conditions that surpass its operational limits. Developing a highly survivable wave energy converter is an outstanding goal, but without a standard definition of the term survivability, progress towards that goal cannot be measured. The purpose of this paper is to provide an initial definition for survivability, and to introduce a simple metric that provides an objective comparison of the survivability of varying wave energy converter technologies.

scholarly journals Wave-to-Wire Power Maximization Control for All-Electric Wave Energy Converters with Non-Ideal Power Take-Off

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2948
Author(s):  
Sousounis ◽  
Shek
Keyword(s):  
Wave Energy ◽  
Reactive Power ◽  
Energy Resource ◽  
Wave Energy Converter ◽  
Floating Body ◽  
Maximum Efficiency ◽  
Energy Converter ◽  
Electric Wave ◽  
Wave Energy Converters ◽  
Energy Converters

The research presented in this paper investigates novel ways of optimizing all-electric wave energy converters for maximum wave-to-wire efficiency. In addition, a novel velocity-based controller is presented which was designed specifically for wave-to-wire efficiency maximization. In an ideal wave energy converter system, maximum efficiency in power conversion is achieved by maximizing the hydrodynamic efficiency of the floating body. However, in a real system, that involves losses at different stages from wave to grid, and the global wave-to-wire optimum differs from the hydrodynamic one. For that purpose, a full wave-to-wire wave energy converter that uses a direct-drive permanent magnet linear generator was modelled in detail. The modelling aspect included complex hydrodynamic simulations using Edinburgh Wave Systems Simulation Toolbox and the electrical modelling of the generator, controllers, power converters and the power transmission side with grid connection in MATLAB/Simulink. Three reference controllers were developed based on the previous literature: a real damping, a reactive spring damping and a velocity-based controller. All three literature-based controllers were optimized for maximum wave-to-wire efficiency for a specific wave energy resource profile. The results showed the advantage of using reactive power to bring the velocity of the point absorber and the wave excitation force in phase, which was done directly using the velocity-based controller, achieving higher efficiencies. Furthermore, it was demonstrated that maximizing hydrodynamic energy capture may not lead to maximum wave-to-wire efficiency. Finally, the controllers were also tested in random sea states, and their performance was evaluated.

Optimization of Mooring Configuration Parameters of Floating Wave Energy Converters

2011 ◽  
Author(s):  
Pedro C. Vicente ◽  
Anto´nio F. O. Falca˜o ◽  
Paulo A. P. Justino
Keyword(s):  
Wave Energy ◽  
Oil And Gas ◽  
Wave Energy Converter ◽  
Domain Model ◽  
Floating Point ◽  
Mooring System ◽  
Energy Converter ◽  
Energy Devices ◽  
Wave Energy Converters ◽  
Energy Converters

Floating point absorbers devices are a large class of wave energy converters for deployment offshore, typically in water depths between 40 and 100m. As floating oil and gas platforms, the devices are subject to drift forces due to waves, currents and wind, and therefore have to be kept in place by a proper mooring system. Although similarities can be found between the energy converting systems and floating platforms, the mooring design requirements will have some important differences between them, one of them associated to the fact that, in the case of a wave energy converter, the mooring connections may significantly modify its energy absorption properties by interacting with its oscillations. It is therefore important to examine what might be the more suitable mooring design for wave energy devices, according to the converters specifications. When defining a mooring system for a device, several initial parameters have to be established, such as cable material and thickness, distance to the mooring point on the bottom, and which can influence the device performance in terms of motion, power output and survivability. Different parameters, for which acceptable intervals can be established, will represent different power absorptions, displacements from equilibrium position, load demands on the moorings and of course also different costs. The work presented here analyzes what might be, for wave energy converter floating point absorber, the optimal mooring configuration parameters, respecting certain pre-established acceptable intervals and using a time-domain model that takes into account the non-linearities introduced by the mooring system. Numerical results for the mooring forces demands and also motions and absorbed power, are presented for two different mooring configurations for a system consisting of a hemispherical buoy in regular waves and assuming a liner PTO.

scholarly journals Validation of a CFD-based numerical wave tank model for the power production assessment of the wavestar ocean wave energy converter

2020 ◽  
Vol 146 ◽  
pp. 2499-2516 ◽  
Author(s):  
Christian Windt ◽  
Josh Davidson ◽  
Edward J. Ransley ◽  
Deborah Greaves ◽  
Morten Jakobsen ◽  
...  
Keyword(s):  
Wave Energy ◽  
Power Production ◽  
Wave Energy Converter ◽  
Ocean Wave ◽  
Numerical Wave Tank ◽  
Energy Converter ◽  
Tank Model ◽  
Wave Tank ◽  
Ocean Wave Energy ◽  
Numerical Wave

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.

Ocean Wave Energy Converters - A Perspective

2012 ◽  
Vol 36 (5) ◽  
pp. 707-715 ◽  
Author(s):  
Nanjundan Parthasarathy ◽  
Kui Ming Li ◽  
Yoon-Hwan Choi ◽  
Yeon-Won Lee
Keyword(s):  
Wave Energy ◽  
Ocean Wave ◽  
Wave Energy Converters ◽  
Ocean Wave Energy ◽  
Energy Converters

A review on front end conversion in ocean wave energy converters

2015 ◽  
Vol 9 (3) ◽  
pp. 297-310 ◽  
Author(s):  
Nagulan Santhosh ◽  
Venkatesan Baskaran ◽  
Arunachalam Amarkarthik
Keyword(s):  
Wave Energy ◽  
Ocean Wave ◽  
Wave Energy Converters ◽  
Ocean Wave Energy ◽  
Front End ◽  
Energy Converters

scholarly journals A Survey of Power Take-off Systems of Ocean Wave Energy Converters

2019 ◽  
Author(s):  
Zhenwei Liu ◽  
Ran Zhang ◽  
Han Xiao ◽  
Xu Wang
Keyword(s):  
Energy Conversion ◽  
Wave Energy ◽  
Clean Energy ◽  
Ocean Wave ◽  
Direct Drive ◽  
Wave Energy Conversion ◽  
Drive Power ◽  
Wave Energy Converters ◽  
Ocean Wave Energy ◽  
Energy Converters

Ocean wave energy conversion as one of the renewable clean energy sources is attracting the research interests of many people. This review introduces different types of power take-off technology of wave energy converters. The main focus is the linear direct drive power take-off devices as they have the advantages for ocean wave energy conversion. The designs and optimizations of power take-off systems of ocean wave energy converters have been studied from reviewing the recently published literature. Also, the simple hydrodynamics of wave energy converters have been reviewed for design optimization of the wave energy converters at specific wave sites. The novel mechanical designs of the power take-off systems have been compared and investigated in order to increase the energy harvesting efficiency.

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