Pilot Model Tests on the ‘Green Water Concept’ for Wave Energy Conversion With Model Scale Power Take Off (PTO) Modelling

2010 ◽  
Author(s):  
Bas Buchner ◽  
Haite van der Schaaf ◽  
Koos Hoefakker
Keyword(s):  
Energy Conversion ◽  
Wave Energy ◽  
Model Tests ◽  
Green Water ◽  
Wave Energy Conversion ◽  
Mean Power ◽  
Model Scale ◽  
Pilot Model ◽  
Hydrodynamic Behaviour ◽  
Set Up

This paper presents the pilot model tests on the ‘Green Water Concept’ for wave energy conversion. These tests also included the initial modelling of an electric and hydraulic Power Take Off (PTO). The accurate modelling of a PTO is an important aspect in testing of wave energy conversion concepts numerically and in a wave tank: at the moment that energy is converted into electricity in the PTO, the hydrodynamic behaviour of the structure is changing. The present tests confirmed the high motions and large amount of green water of the Green Water Concept as predicted in previous simulations. The application of a real PTO gave important insight in the possibilities and challenges of PTO modelling at model scale. For the present concept a mean Power (at full scale) close to 1MW was generated in a regular wave of H = 3.0m for the maximum possible setting in the chosen test set-up. This setting was limited by the chosen mechanical and electronic motor set-up in this pilot test series, not the actual maximum of the Green Water Concept itself. Considering the test results, it is clear that the potential of the system is significantly larger.

On the Further Optimization of the “Green Water Concept” for Wave Energy Conversion

2012 ◽  
Author(s):  
Joop A. Helder ◽  
Christian Schmittner ◽  
Bas Buchner
Keyword(s):  
Energy Conversion ◽  
Wave Energy ◽  
Green Water ◽  
Wave Energy Conversion ◽  
Pilot Model ◽  
Wide Range ◽  
Water Columns ◽  
Relative Water ◽  
Entrapped Air ◽  
The Time Domain

This paper presents initial results from the following-up study of the ‘inverse’ or ‘green water concept’ for wave energy conversion. Initially presented in 2009, the ‘inverse concept’ was developed by MARIN as a vehicle for open discussion and exchange of ideas in the field of wave energy conversion. Pilot model tests presented in 2010 showed the great potential of the concept, but also revealed the challenges associated with Power Take Off design. The present study aims to further optimize the inverse concept. A new PTO system has been incorporated, based on robustness and effective use of the structure’s (de)optimized hull. The resulting renewed concept combines maximized vessel motions with OWC-type of wave energy conversion. This paper focuses on the motion response of the renewed concept. Frequency domain calculations show the response of the concept with water columns (moonpools) at the bow and stern. Remarkably, the already maximized motions of the hull become even more extreme when moonpools are incorporated. Special attention is given to the relative motions of the water inside the moonpools, as these give an indication of the wave energy conversion potential of the concept. The relative water motions inside the moonpools show a large response that is characterized by multiple peaks. This indicates the concept’s ability to convert energy in a wide range of sea states. Results from additional diffraction analysis show that through proper tuning, the water columns inside the moonpools can be modeled as solid water-bodies. This allows for a future numerical modeling of the hydrodynamic interaction between structure, water columns, entrapped air and PTO damping in the time domain.

‘Inverse’ Concept: Wave Energy Generation by Motion and Green Water Maximisation

2009 ◽  
Author(s):  
Bas Buchner ◽  
Frederick Jaouen
Keyword(s):  
Renewable Energy ◽  
Energy Conversion ◽  
Frequency Domain ◽  
Water Flow ◽  
Wave Energy ◽  
Volume Of Fluid ◽  
Green Water ◽  
Wave Energy Conversion ◽  
Energy Concept ◽  
The Waves

This paper presents the initial investigations into the ‘Inverse’ concept for wave energy conversion, based on the maximisation of motions and green water. The ‘Inverse’ concept combines aspects of ‘overtopping’, ‘heaving’ and ‘pitching’ wave energy conversion concepts, but also adds specific aspects such as the use of green water. Instead of reducing the motions and green water as is done in normal offshore hydrodynamics, the ‘Inverse’ concepts tries to maximise the motions and green water to generate energy from the waves. Results are presented of frequency domain calculations for the motion (de-) optimisation. Improved Volume Of Fluid (iVOF) simulations are used to simulate the green water flow on the deck. It is concluded that the potential of the ‘Inverse’ concept is clear. As a result of the double connotation of the word ‘green’, this renewable energy concept could also be called the ‘green water’ concept. Further work needs to be carried out on the further optimisation of the concept.

Numerical Modelling of Fixed Oscillating Water Column Wave Energy Conversion Devices: Toward Geometry Hydraulic Optimization

2015 ◽  
Author(s):  
Irene Simonetti ◽  
Lorenzo Cappietti ◽  
Hisham El Safti ◽  
Hocine Oumeraci
Keyword(s):  
Energy Conversion ◽  
Water Column ◽  
Wave Energy ◽  
Stokes Equations ◽  
Fluid Dynamic ◽  
Experimental Models ◽  
Multiphase Model ◽  
Oscillating Water Column ◽  
Wave Energy Conversion ◽  
Set Up

The Oscillating Water Column (OWC) is one of the simplest and most studied concepts for wave energy conversion. The commercial scale diffusion of the OWC technology is, however, strongly dependent upon the device optimization. Research at a fundamental level is therefore still required. Analytical, numerical and experimental models are necessary tools for advancing in the knowledge of the system and thus promoting its passage at the commercial level. In this work, a simplified frequency domain rigid piston model has been applied to preliminary select expected ranges of air pressures and air velocities for the instrumental set up of laboratory experiments. The set up of a Computational Fluid Dynamic (CFD) model implemented in the open source OpenFOAM®1 environment is then presented. The multiphase model solves incompressible 3D Navier-Stokes equations, using Large Eddy Simulation (LES) for turbulence modelling, and adopts a Volume of Fluid method (VOF) to track the air-water interface. A preliminary validation of the model with physical tests data is conducted. The numerical approach seems to be promising for an accurate simulation of the OWC device energy conversion process. Hence, the validated model can be a useful research tool for different problems, particularly for systematic parameter studies to extend the range of conditions tested in the laboratory.

scholarly journals WAVE ENERGY CONVERSION AN EMERGING MODE OF RENEWABLE AND SUSTAINABLE POWER GENERATION

2013 ◽  
pp. 78-84
Author(s):  
DIGVIJAY SINGH RAGHUVANSHI ◽  
JAYESH L. MINASE
Keyword(s):  
Power Generation ◽  
Energy Conversion ◽  
Wave Energy ◽  
Ocean Waves ◽  
Future Research ◽  
Extensive Literature ◽  
Wave Energy Conversion ◽  
Power Requirement ◽  
Wave Energy Converters ◽  
Set Up

Ocean waves, if employed efficiently for generation of electricity, could result in the most economic green process (minimal carbon emission). This paper, based on the extensive literature survey conducted as a part of a B.Tech Project provides an overview of the current scenario of power generation and consumption in India thereby emphasizing on the progressively increasing power requirement and a lagging behind share of renewable energy. A scientific clarity is drawn on the basic theory behind wave generation and the key factors for assessing and deploying wave energy converters. Further, a few successful wave energy conversion techniques are discussed briefly, which posses the potential scope of future research and development and are presently employed under pre-commercial and commercial stages around the globe. A special emphasis is laid on the point absorber section which has been the area of research for the authors‘ project thereby detailing its constructional and working aspects and also discussing briefly an experimental procedure to set up a wave generator, to calculate mechanical conversion efficiency, and its scope of applicability. The conclusion is drawn in favor of the coastal communities which still rely on costly diesel for generating electricity.

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