Wave and tidal power

2007 ◽  
Author(s):  
Dean L. Millar
Keyword(s):  
Wave Energy ◽  
Tidal Current ◽  
High Efficiency ◽  
Energy Resource ◽  
Energy Difference ◽  
Tidal Range ◽  
Tidal Power ◽  
Floating Structures ◽  
Wave Energy Converters ◽  
High Tidal Range

This chapter reviews how electricity can be generated from waves and tides. The UK is an excellent example, as the British Isles have rich wave and tidal resources. The technologies for converting wave power into electricity are easily categorized by location type. 1. Shoreline schemes. Shoreline Wave Energy Converters (WECs) are installed permanently on shorelines, from where the electricity is easily transmitted and may even meet local demands. They operate most continuously in locations with a low tidal range. A disadvantage is that less power is available compared to nearshore resources because energy is lost as waves reach the shore. 2. Nearshore schemes. Nearshore WECs are normally floating structures needing seafloor anchoring or inertial reaction points. The advantages over shoreline WECs are that the energy resource is much larger because nearshore WECs can access long-wavelength waves with greater swell, and the tidal range can be much larger. However, the electricity must be transmitted to the shore, thus raising costs. 3. Offshore schemes. Offshore WECs are typically floating structures that usually rely on inertial reaction points. Tidal range effects are insignificant and there is full access to the incident wave energy resource. However, electricity transmission is even more costly. Tidal power technologies fall into two fundamental categories:1. Barrage schemes. In locations with high tidal range a dam is constructed that creates a basin to impound large volumes of water. Water flows in and out of the basin on flood and ebb tides respectively, passing though high efficiency turbines or sluices or both. The power derives from the potential energy difference in water levels either side of the dam. 2. Tidal current turbines. Tidal current turbines (also known as free flow turbines) harness the kinetic energy of water flowing in rivers, estuaries, and oceans. The physical principles are analogous to wind turbines, allowing for the very different density, viscosity, compressibility, and chemistry of water compared to air. Waves are caused by winds, which in the open ocean are often of gale force (speed >14 m/s).

A Power Take-Off (PTO) for Wave Energy Converters Based on the Hybrid Hydraulic-Electric Architecture (HHEA)

2021 ◽  
Author(s):  
Jackson Wills ◽  
Adam Keester ◽  
Perry Y. Li
Keyword(s):  
Wave Energy ◽  
High Efficiency ◽  
Energy Resource ◽  
Check Valve ◽  
Hydraulic Actuator ◽  
Renewable Energy Resource ◽  
Electric Generator ◽  
Energy Capture ◽  
Wave Energy Converters ◽  
Electrical Components

Abstract Wave energy is a promising renewable energy resource for coastal regions around the world, but is not yet an economically competitive source of electricity. More effective power take-off (PTO) designs would help to make wave power a feasible and clean source of energy. To do this, PTOs need to: i) enable controlled actuation, ii) convert absorbed energy into electricity efficiently, and iii) have minimal manufacturing costs. We propose a new PTO architecture that can exert arbitrary control loads on the WEC to maximize energy capture, enabling the downsizing of expensive electrical components while maintaining high efficiency. Our PTO design is based upon a hybrid hydraulic-electric architecture (HHEA). This paper compares the performance of the HHEA PTO against two other PTO designs: 1) a baseline PTO consisting of a system of rectifying check valves and accumulators, and 2) a PTO consisting of an electro-hydraulic actuator (EHA). The HHEA PTO is shown to produce much more power than the check valve PTO and the EHA PTO. Also, the required electric generator sizes for the HHEA are smaller than that of the EHA PTO. The reduced size of these components allows for a WEC which is less expensive to manufacture.

scholarly journals HF Radars for Wave Energy Resource Assessment Offshore NW Spain

2021 ◽  
Vol 13 (11) ◽  
pp. 2070
Author(s):  
Ana Basañez ◽  
Vicente Pérez-Muñuzuri
Keyword(s):  
Wave Energy ◽  
Numerical Models ◽  
Wave Spectrum ◽  
Energy Resource ◽  
Electrical Energy ◽  
Resource Assessment ◽  
Electricity Production ◽  
Statistical Validation ◽  
Wave Energy Converters ◽  
Energy Converters

Wave energy resource assessment is crucial for the development of the marine renewable industry. High-frequency radars (HF radars) have been demonstrated to be a useful wave measuring tool. Therefore, in this work, we evaluated the accuracy of two CODAR Seasonde HF radars for describing the wave energy resource of two offshore areas in the west Galician coast, Spain (Vilán and Silleiro capes). The resulting wave characterization was used to estimate the electricity production of two wave energy converters. Results were validated against wave data from two buoys and two numerical models (SIMAR, (Marine Simulation) and WaveWatch III). The statistical validation revealed that the radar of Silleiro cape significantly overestimates the wave power, mainly due to a large overestimation of the wave energy period. The effect of the radars’ data loss during low wave energy periods on the mean wave energy is partially compensated with the overestimation of wave height and energy period. The theoretical electrical energy production of the wave energy converters was also affected by these differences. Energy period estimation was found to be highly conditioned to the unimodal interpretation of the wave spectrum, and it is expected that new releases of the radar software will be able to characterize different sea states independently.

scholarly journals Sustainable Power Generation by Tidal Current Turbine in Straits of Malacca

2018 ◽  
Vol 198 ◽  
pp. 04004
Author(s):  
P. T. Ghazvinei ◽  
H.H. Darvishi ◽  
A. Bhatia
Keyword(s):  
Tidal Current ◽  
Energy Resource ◽  
Flow Characteristics ◽  
Tidal Power ◽  
Tropical Country ◽  
Marine Current ◽  
Tidal Current Turbine ◽  
Straits Of Malacca ◽  
Sustainable Power ◽  
Current Turbine

Marine current power is a significant energy resource which is yet to be exploited for efficient energy production. Malaysia, being a tropical country is rich in renewable sources and tidal power is one of them. In Malaysia, Straits of Malacca is a potential site to establish a tidal current turbine. In the current study, the potential sites of the Straits of Malacca are discussed. A detailed review about the generator suitable for the Straits of Malacca with the associated challenges has also been discussed. Furthermore, the suitable solution for such challenges is proposed. The role of simulation in choosing an appropriate site and generator has also been reviewed. The focus of the study is to propose a generator suitable for the flow characteristics of the Straits of Malacca.

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.

scholarly journals Weptos Wave Energy Converters to Cover the Energy Needs of a Small Island

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 423 ◽  
Author(s):  
Lucia Margheritini ◽  
Jens Kofoed
Keyword(s):  
Wave Energy ◽  
Energy Resource ◽  
Energy System ◽  
Resource Assessment ◽  
Small Island ◽  
Wave Energy Converters ◽  
Energy Needs ◽  
Battery Bank ◽  
The Individual ◽  
Energy Converters

This paper presents the details of a study performed to investigate the feasibility of a wave energy system made up of a number of Weptos wave energy converters (WECs) and sets of batteries, to provide the full energy demands of a small island in Denmark. Two different configurations with 2 and 4 Weptos machines respectively with a combined installed power of 750 kW (and a capacity factor of 0.2) are presented. One full year simulation, based a detailed hourly analysis of the power consumption and wave energy resource assessment in the surrounding sea, is used to demonstrate that both configurations, supplemented by a 3 MWh battery bank and a backup generator, can provide the energy needs of the island. The proposed configurations are selected on the basis of a forecast optimization of price estimates for the individual elements of the solutions. The simulations show that Weptos WECs actually deliver 50% more than average consumption over the year, but due to the imbalance between consumption and production, this is not enough to cover all situations, which necessitates a backup generator that must cover 5–7% of consumption, in situations where there are too few waves and the battery bank is empty.

Hebridean Marine Energy Resources: Wave-Power Characterisation Using a Buoy Network

2012 ◽  
Author(s):  
Arne Vögler ◽  
Vengatesan Venugopal
Keyword(s):  
Wave Energy ◽  
Site Selection ◽  
Selection Process ◽  
Energy Resource ◽  
Energy Resources ◽  
Wave Power ◽  
Energy Futures ◽  
Wave Energy Converters ◽  
Marine Energy ◽  
Outer Hebrides

The Outer Hebrides of Scotland were identified as an area with a high wave power resource of 42.4kW/m. The Outer Hebrides of Scotland are currently targeted by a range of developers for demonstration and commercial developments of wave energy converters and current planning efforts are based on initial deployments by 2014. Technology providers with well advanced plans to develop the Hebridean wave resource include Aquamarine Power (Oyster) [1], Pelamis (P2) [2] and Voith Wavegen (OWC) [3]; all of these companies are partners in the Hebridean Marine Energy Futures project [4] to help move the industry into the commercialisation stage. As part of the Hebridean Marine Energy Futures project, a three year programme aimed at developing a high resolution wave energy resource map to support the site selection process of marine energy developers, a network of three wave measuring buoys was deployed 15km offshore in a depth of 60m and at distances of 11km between buoys. Measured wind and wave data from this buoy network for autumn 2011 are analysed and presented in this paper along with estimated wave power for the same duration.

scholarly journals A Design Outline for Floating Point Absorber Wave Energy Converters

2014 ◽  
Vol 6 ◽  
pp. 846097 ◽  
Author(s):  
Mohammed Faizal ◽  
M. Rafiuddin Ahmed ◽  
Young-Ho Lee
Keyword(s):  
Wave Energy ◽  
Power Output ◽  
Energy Resource ◽  
Wave Structure ◽  
Floating Point ◽  
Mooring Lines ◽  
Point Absorber ◽  
Wave Energy Converters ◽  
Incident Waves ◽  
Energy Converters

An overview of the most important development stages of floating point absorber wave energy converters is presented. At a given location, the wave energy resource has to be first assessed for varying seasons. The mechanisms used to convert wave energy to usable energy vary for different wave energy conversion systems. The power output of the generator will have variations due to varying incident waves. The wave structure-interaction leads to modifications in the incident waves; thus, the power output is also affected. The device has to be stable enough to prevent itself from capsizing. The point absorber will give optimum performance when the incident wave frequencies correspond to the natural frequency of the device. The methods for calculating natural frequencies for pitching and heaving systems are presented. Mooring systems maintain the point absorber at the desired location. Various mooring configurations as well as the most commonly used materials for mooring lines are discussed. An overview of scaled modelling is also presented.

scholarly journals Wave energy resource variation off the west coast of Ireland and its impact on realistic wave energy converters’ power absorption

2018 ◽  
Vol 224 ◽  
pp. 205-219 ◽  
Author(s):  
Markel Penalba ◽  
Alain Ulazia ◽  
Gabriel Ibarra-Berastegui ◽  
John Ringwood ◽  
Jon Sáenz
Keyword(s):  
Wave Energy ◽  
West Coast ◽  
Energy Resource ◽  
The West ◽  
Power Absorption ◽  
Wave Energy Converters ◽  
Energy Converters ◽  
Resource Variation

Systematic Dynamic Modeling and Simulation of Multibody Offshore Structures: Application to Wave Energy Converters

2013 ◽  
Author(s):  
François Rongère ◽  
Alain H. Clément
Keyword(s):  
Wave Energy ◽  
Kinematic Chain ◽  
Offshore Structures ◽  
Rigid Bodies ◽  
Degree Of Freedom ◽  
Dynamic Simulations ◽  
Floating Structures ◽  
Wave Energy Converters ◽  
Inertia Parameters ◽  
Recursive Techniques

This article presents a framework to model and perform time domain dynamic simulations of offshore structures presenting several interconnected rigid bodies. Both fixed and 6 degree of freedom floating structures are considered. It uses a robotics formalism to parameterize the kinematic chain of the structures and is robust with respect to the number of bodies involved. Direct dynamics algorithms are given, using a consistent notation across offshore engineering and robotics fields. They use efficient recursive techniques based on Newton-Euler equations. The advantage of this framework is that tedious analytical developments are no longer needed. Instead of that, it is sufficient to provide a data parameter table as well as principal inertia parameters of each body to entirely describe the mechanical structure. An example of simulation is given, based on the 7 degree of freedom SEAREV Wave Energy Converter.

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