scholarly journals Arrays of Point-Absorbing Wave Energy Converters in Short-Crested Irregular Waves

Energies ◽  
2018 ◽  
Vol 11 (4) ◽  
pp. 964 ◽  
Author(s):  
Malin Göteman ◽  
Cameron McNatt ◽  
Marianna Giassi ◽  
Jens Engström ◽  
Jan Isberg
Keyword(s):  
Wave Energy ◽  
Large Scale ◽  
Ocean Waves ◽  
Irregular Waves ◽  
Electricity Production ◽  
Design Parameters ◽  
Scattering Method ◽  
Active Research ◽  
Park Design ◽  
Multiple Scattering Method

For most wave energy technology concepts, large-scale electricity production and cost-efficiency require that the devices are installed together in parks. The hydrodynamical interactions between the devices will affect the total performance of the park, and the optimization of the park layout and other park design parameters is a topic of active research. Most studies have considered wave energy parks in long-crested, unidirectional waves. However, real ocean waves can be short-crested, with waves propagating simultaneously in several directions, and some studies have indicated that the wave energy park performance might change in short-crested waves. Here, theory for short-crested waves is integrated in an analytical multiple scattering method, and used to evaluate wave energy park performance in irregular, short-crested waves with different number of wave directions and directional spreading parameters. The results show that the energy absorption is comparable to the situation in long-crested waves, but that the power fluctuations are significantly lower.

Wave Propagation in Continuous Sea Ice: An Experimental Perspective

2020 ◽  
Author(s):  
Giulio Passerotti ◽  
Alberto Alberello ◽  
Azam Dolatshah ◽  
Luke Bennetts ◽  
Otto Puolakka ◽  
...  
Keyword(s):  
Sea Ice ◽  
Wave Energy ◽  
High Frequency ◽  
Large Scale ◽  
Low Frequency ◽  
Ocean Waves ◽  
Continuous Model ◽  
Ice Cover ◽  
Irregular Waves ◽  
Ice Melt

Abstract Ocean waves penetrate hundreds of kilometres into the ice-covered ocean. Waves fracture the level ice into small floes, herd floes, introduce warm water and overwash the floes, accelerating ice melt and causing collisions, which concurrently erodes the floes and influences the large-scale deformation. Concomitantly, interactions between waves and the sea ice cause wave energy to reduce with distance travelled into the ice cover, attenuating wave driven effects. Here a pilot experiment in the ice tank at Aalto University (Finland) is presented to discuss how the properties of irregular small amplitude (linear) waves change as they propagate through continuous model sea ice. Irregular waves with a JONSWAP spectral shape were mechanically generated with a very low initial wave steepness to avoid ice break up and maintain a consistent continuous ice cover throughout the experiments. Observations show an exponential attenuation of wave energy with distance. High frequency components attenuated more rapidly than the low frequency counterparts, in agreement with a frequency-cubed power-law. The more effective attenuation in the high frequency range induced a substantial downshift of the spectral peak, stretching the dominant wave component as it propagates in ice.

scholarly journals Modeling and Validation of an Electrohydraulic Power Take-Off System for a Portable Wave Energy Convertor with Compressed Energy Storage

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3378
Author(s):  
Hao Tian ◽  
Zijian Zhou ◽  
Yu Sui
Keyword(s):  
Energy Storage ◽  
Wave Energy ◽  
Large Scale ◽  
Ocean Waves ◽  
Small Scale ◽  
Test Results ◽  
Traditional Architecture ◽  
Power Circuit ◽  
Lumped Parameter ◽  
Efficient Power

Small-scale, portable generation of electricity from ocean waves provides a versatile solution to power the ocean sensors network, in addition to the traditional large-scale wave energy conversion facilities. However, one issue of small-scale wave energy convertor (WEC) is the low capturable power density, challenging the design of the efficient power take-off (PTO) system. To tackle this challenge, in this paper, an electrohydraulic PTO system with compressed energy storage was proposed to boost output power of a portable WEC. Lumped-parameter kinematics and dynamics of the four-bar mechanism, the fluid dynamics of the digital fluid power circuit, and the mechanical and volumetric power losses were modeled and experimentally validated. Initial test results of the 0.64 m2 footprint prototype showed that the inclusion of storage improved the averaged electric power output over 40 times compared to the traditional architecture, and the proposed device can deliver up to 122 W at peaks.

Experimental Investigation of Irregular Wave Cancellation Using a Cycloidal Wave Energy Converter

2012 ◽  
Author(s):  
Stefan G. Siegel ◽  
Casey Fagley ◽  
Marcus Römer ◽  
Thomas McLaughlin
Keyword(s):  
Wave Energy ◽  
Deep Ocean ◽  
Ocean Waves ◽  
Wave Energy Converter ◽  
Irregular Waves ◽  
Energy Converter ◽  
Irregular Wave ◽  
Wave Measurements ◽  
Wave Heights ◽  
Significant Wave Heights

The ability of a Cycloidal Wave Energy Converter (CycWEC) to cancel irregular deep ocean waves is investigated in a 1:300 scale wave tunnel experiment. A CycWEC consists of one or more hydrofoils attached equidistant to a shaft that is aligned parallel to the incoming waves. The entire device is fully submerged in operation. Wave cancellation requires synchronization of the rotation of the CycWEC with the incoming waves, as well as adjustment of the pitch angle of the blades in proportion to the wave height. The performance of a state estimator and controller that achieve this objective were investigated, using the signal from a resistive wave gage located up-wave of the CycWEC as input. The CycWEC model used for the present investigations features two blades that are adjustable in pitch in real time. The performance of the CycWEC for both a superposition of two harmonic waves, as well as irregular waves following a Bretschneider spectrum is shown. Wave cancellation efficiencies as determined by wave measurements of about 80% for the majority of the cases are achieved, with wave periods varying from 0.4s to 0.75s and significant wave heights of Hs ≈ 20mm. This demonstrates that the CycWEC can efficiently interact with irregular waves, which is in good agreement with earlier results obtained from numerical simulations.

Wave Energy Extraction Maximization in Irregular Ocean Waves Using Pseudospectral Methods

2013 ◽  
Author(s):  
Daniel R. Herber ◽  
James T. Allison
Keyword(s):  
Optimal Control ◽  
Resonance Frequency ◽  
Wave Energy ◽  
Energy Production ◽  
Early Stage ◽  
Wave Spectrum ◽  
Ocean Waves ◽  
Irregular Waves ◽  
Energy Extraction ◽  
Control Approach

Energy extraction from ocean waves and conversion to electrical energy is a promising form of renewable energy, yet achieving economic viability of wave energy converters (WECs) has proven challenging. In this article, the design of a heaving cylinder WEC will be explored. The optimal plant (i.e. draft and radius) design space with respect to the design’s optimal control (i.e. power take-off trajectory) for maximum energy production is characterized. Irregular waves based on the Bretschneider wave spectrum are considered. The optimization problem was solved using a pseudospectral method, a direct optimal control approach that can incorporate practical design constraints, such as power flow, actuation force, and slamming. The results provide early-stage guidelines for WEC design. Results show the resonance frequency required for optimal energy production with a regular wave is quite different than the resonance frequency found for irregular waves; specifically, it is much higher.

A Mathematical Model for a Gyroscopic Ocean-Wave Energy Converter

2013 ◽  
Author(s):  
H. Murakami ◽  
O. Rios
Keyword(s):  
Mathematical Model ◽  
Power Generation ◽  
Wave Energy ◽  
Ocean Waves ◽  
Ocean Wave ◽  
Scale Model ◽  
Design Parameters ◽  
Wave Power ◽  
Power Generator ◽  
Ocean Wave Energy

Global attempts to increase generation of clean and reproducible energy have contributed to considerable progress in ocean-wave power-generation technologies. The efficiency of ocean-wave energy converters has improved by almost an order of magnitude in the last decade. In this report, we consider a floating-type gyroscopic ocean-wave power-generator that has proven to generate 50 kW in a prototype test conducted by a Japanese company in 2012. A gyroscopic power generator consists of a buoy, a gimbal, and spinning rotors mounted on a gimbal. The gimbal is installed on the deck of the buoy and rotates when the buoy oscillates or rocks by ocean waves. The gimbal axis is connected to an electric generator. The objectives of our research are to understand quantitatively the mechanisms of gyroscopic ocean-wave power-generators and to improve the component design of the generator to maximize power output. To this end, we develop a mathematical model and a scale model of a gyroscopic ocean-wave power-generator. This integrated approach is to numerically simulate power generation and to clarify the effect of relevant design parameters.

Ocean Wave Energy Utilization

2002 ◽  
Vol 36 (4) ◽  
pp. 52-58 ◽  
Author(s):  
Michael E. McCormick ◽  
Oavid R. B. Kraemer
Keyword(s):  
Wave Energy ◽  
Potable Water ◽  
Impedance Matching ◽  
Ocean Waves ◽  
Energy Utilization ◽  
Electricity Production ◽  
Water Production ◽  
Ocean Wave Energy ◽  
Resonant Systems ◽  
Conversion Technologies

The exploitation of ocean waves in electricity production, potable-water production, waterbody revitalization and farming is discussed. Those energy-conversion technologies that are now at the prototype stage are described. The systems are those that are resonant in nature, since resonant systems have been found to be the most efficient. The efficiency of these systems is due to both diffraction-induced wave focusing and possible impedance-matching.

scholarly journals Design Optimisation of a Multi-Mode Wave Energy Converter

2020 ◽  
Author(s):  
Nataliia Y. Sergiienko ◽  
Mehdi Neshat ◽  
Leandro S. P. da Silva ◽  
Brad Alexander ◽  
Markus Wagner
Keyword(s):  
Wave Energy ◽  
Average Power ◽  
Clean Energy ◽  
Wave Energy Converter ◽  
Irregular Waves ◽  
Viscous Drag ◽  
Design Parameters ◽  
Energy Converter ◽  
Design Optimisation ◽  
Anchor System

Abstract A wave energy converter (WEC) similar to the CETO system developed by Carnegie Clean Energy is considered for design optimisation. This WEC is able to absorb power from heave, surge and pitch motion modes, making the optimisation problem nontrivial. The WEC dynamics is simulated using the spectral-domain model taking into account hydrodynamic forces, viscous drag, and power take-off forces. The design parameters for optimisation include the buoy radius, buoy height, tether inclination angles, and control variables (damping and stiffness). The WEC design is optimised for the wave climate at Albany test site in Western Australia considering unidirectional irregular waves. Two objective functions are considered: (i) maximisation of the annual average power output, and (ii) minimisation of the levelised cost of energy (LCoE) for a given sea site. The LCoE calculation is approximated as a ratio of the produced energy to the significant mass of the system that includes the mass of the buoy and anchor system. Six different heuristic optimisation methods are applied in order to evaluate and compare the performance of the best known evolutionary algorithms, a swarm intelligence technique and a numerical optimisation approach. The results demonstrate that if we are interested in maximising energy production without taking into account the cost of manufacturing such a system, the buoy should be built as large as possible (20 m radius and 30 m height). However, if we want the system that produces cheap energy, then the radius of the buoy should be approximately 11–14 m while the height should be as low as possible. These results coincide with the overall design that Carnegie Clean Energy has selected for its CETO 6 multi-moored unit. However, it should be noted that this study is not informed by them, so this can be seen as an independent validation of the design choices.

scholarly journals Dynamic Response of Coupled Mooring Lines and Floating Wave Energy Devices in Waves / Currents

2019 ◽  
Vol 8 (12) ◽  
pp. 5539-5545
Keyword(s):  
Renewable Energy ◽  
Dynamic Response ◽  
Wave Energy ◽  
Degrees Of Freedom ◽  
Ocean Waves ◽  
Irregular Waves ◽  
Mooring Lines ◽  
Energy Devices ◽  
Six Degrees Of Freedom ◽  
The Government

Various global studies have shown that ocean waves energy have large potential in renewable energy sector. Their role within renewable energy gets high priority in the future by the government of United Kingdom. The principle concept of wave energy is when wave energy is converted into potential energy by the wave energy devices to generate electricity. An understanding of the dynamic response of the devices and mooring lines is important for this paper. This paper deals with the analysis of the various effects that influence the different design of wave energy converter devices. The mooring design idea is also analyzed to show which mooring layout is suitable to fulfill the requirement. The design of mooring configuration also influence how wave power is extracted and how such system are operated and maintained. The effects investigated in this paper are regular and irregular waves, motion @ six degrees of freedom, maximum and minimum mooring tension, different waves direction, wave current, energy and power take off.

scholarly journals Modelling and testing of a wave energy converter based on dielectric elastomer generators

2019 ◽  
Vol 475 (2222) ◽  
pp. 20180566 ◽  
Author(s):  
Giacomo Moretti ◽  
Gastone Pietro Rosati Papini ◽  
Luca Daniele ◽  
David Forehand ◽  
David Ingram ◽  
...  
Keyword(s):  
Wave Energy ◽  
Large Scale ◽  
Dielectric Elastomer ◽  
Wave Energy Converter ◽  
Irregular Waves ◽  
System Response ◽  
Small Scale ◽  
Energy Converter ◽  
Operational Conditions ◽  
Analysis And Design

This paper introduces the analysis and design of a wave energy converter (WEC) that is equipped with a novel kind of electrostatic power take-off system, known as dielectric elastomer generator (DEG). We propose a modelling approach which relies on the combination of nonlinear potential-flow hydrodynamics and electro-hyperelastic theory. Such a model makes it possible to predict the system response in operational conditions, and thus it is employed to design and evaluate a DEG-based WEC that features an effective dynamic response. The model is validated through the design and test of a small-scale prototype, whose dynamics is tuned with waves at tank-scale using a set of scaling rules for the DEG dimensions introduced here in order to comply with Froude similarity laws. Wave-tank tests are conducted in regular and irregular waves with a functional DEG system that is controlled using a realistic prediction-free strategy. Remarkable average performance in realistically scaled sea states has been recorded during experiments, with peaks of power output of up to 3.8 W, corresponding to hundreds of kilowatts at full-scale. The obtained results demonstrated the concrete possibility of designing DEG-based WEC devices that are conceived for large-scale electrical energy production.

scholarly journals Correction to: Methane and Electricity Production from Poultry Litter Digestion in the Amazon Region of Brazil: A Large-Scale Study

2021 ◽  
Author(s):  
Marcelo Mendes Pedroza ◽  
Wanderson Gomes da Silva ◽  
Luciene Santos de Carvalho ◽  
Alice Rocha de Souza ◽  
Girlene Figueiredo Maciel
Keyword(s):  
Large Scale ◽  
Poultry Litter ◽  
Amazon Region ◽  
Electricity Production ◽  
Large Scale Study
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