A review of impulse turbines for wave energy conversion
TL;DR: In this article, the state of the art in self-rectifying impulse air turbines is reviewed and the optimum parameters for the fixed-guide-vane impulse turbine are also presented.
Abstract: Oscillating Water Column based wave energy plants convert wave energy into low pressure pnuematic power in the form of bi-directional air flows. Air turbines which are capable of rotating uni-directionally in bi-directional air flow, otherwise also known as self-rectifying turbines, are used to extract mechanical shaft power which is further converted into electrical power by a generator. This paper reviews the state of the art in self-rectifying impulse air turbines. New results on optimum parameters for the fixed-guide-vane impulse turbine are also presented. Starting characteristics and conversion efficiencies of two types of impulse turbines are compared with the well known Wells turbine.
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TL;DR: In this article, the development of wave energy utilization since the 1970s is discussed, with a focus on the characterization of the wave energy resource; theoretical background, with especial relevance to hydrodynamics of wave absorption and control; how a large range of devices kept being proposed and studied, and how such devices can be organized into classes; the conception, design, model-testing, construction and deployment into real sea of prototypes.
Abstract: Sea wave energy is being increasingly regarded in many countries as a major and promising resource. The paper deals with the development of wave energy utilization since the 1970s. Several topics are addressed: the characterization of the wave energy resource; theoretical background, with especial relevance to hydrodynamics of wave energy absorption and control; how a large range of devices kept being proposed and studied, and how such devices can be organized into classes; the conception, design, model-testing, construction and deployment into real sea of prototypes; and the development of specific equipment (air and water turbines, high-pressure hydraulics, linear electrical generators) and mooring systems.
2,115 citations
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TL;DR: A comprehensive review of wave energy converters and air turbines can be found in this paper, together with a survey of theoretical, numerical and experimental modelling techniques of OWC converters.
Abstract: The ocean waves are an important renewable energy resource that, if extensively exploited, may contribute significantly to the electrical energy supply of countries with coasts facing the sea. A wide variety of technologies has been proposed, studied, and in some cases tested at full size in real ocean conditions. Oscillating-water-column (OWC) devices, of fixed structure or floating, are an important class of wave energy devices. A large part of wave energy converter prototypes deployed so far into the sea are of OWC type. In an OWC, there is a fixed or floating hollow structure, open to the sea below the water surface, that traps air above the inner free-surface. Wave action alternately compresses and decompresses the trapped air which is forced to flow through a turbine coupled to a generator. The paper presents a comprehensive review of OWC technologies and air turbines. This is followed by a survey of theoretical, numerical and experimental modelling techniques of OWC converters. Reactive phase control and phase control by latching are important issues that are addressed, together with turbine rotational speed control.
594 citations
TL;DR: In this paper, the background of wave energy harvesting technology, its evolution, and the present status of the industry is reviewed, and solutions are suggested while discussing the challenges in order to increase awareness and investment in wave energy industry as a whole.
Abstract: Wave energy is substantial as a resource, and its potential to significantly contribute to the existing energy mix has been identified. However, the commercial utilization of wave energy is still very low. This paper reviewed the background of wave energy harvesting technology, its evolution, and the present status of the industry. By covering the theoretical formulations, wave resource characterization methods, hydrodynamics of wave interaction with the wave energy converter, and the power take-off and electrical systems, different challenges were identified and discussed. Solutions were suggested while discussing the challenges in order to increase awareness and investment in wave energy industry as a whole.
175 citations
TL;DR: A survey of wave energy converters can be found in this paper, where the most important criteria that have to be kept in mind when designing a WEC are described and evaluated.
Abstract: The utilization of renewable energy sources is a vital aspect for development of sustainability. Currently, an unexploited energy source is ocean waves. Various types of wave energy converters (WECs) are able to transform the motion of the waves into electricity. During the last 30 years, a wide range of prototypes was presented with different rates of success. The aim of this survey is to give an overview of how WECs are categorized [operation principle and power takeoff (PTO) system] and show what are the most important criteria that have to be kept in mind when designing a WEC. A few important WECs are described and evaluated.
159 citations
Cites background from "A review of impulse turbines for wa..."
...The impulse turbines [25], [26] are self-pitched, controlled...
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TL;DR: The power take-off systems of the wave energy converters (WEC) based on the different working methods of their power take off systems are reviewed, showing that the mechanical direct drive system is the most popular.
Abstract: Ocean waves contain one of the world's largest untapped and predictable renewable energy sources that can be used to fulfil the energy demand in the present energy crises situation. There are many devices that have been proposed and prototyped in different countries all around the world to harness wave energy based on different power take-off (PTO) systems. The aim of this article is to review the power take-off (PTO) systems of the wave energy converters (WEC). The review starts with a brief introduction and background of wave energy. Following this, a novel classification of WEC systems is introduced. Then, the WECs based on the different working methods of their power take off systems are briefly reviewed. This includes an analysis and comparison of advantages and challenges of the power take off systems. Aspects of current international research and development activities and networks for wave energy is also discussed. The current market of wave energy technologies is also assessed, showing that the mechanical direct drive system is the most popular. Hybrid PTO systems are seen as an important development for the future.
143 citations
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TL;DR: In this article, an experimental investigation of the aerodynamic performance of a high-solidity Wells turbine for a wave power plant is presented, and the results show that the presence of guide vanes can provide a remarkable increase in turbine efficiency.
Abstract: The paper describes an experimental investigation, and presents the results of the aerodynamic performance of a high-solidity Wells turbine for a wave power plant. A monoplane turbine of 0.6 m rotor diameter with guide vanes was built and tested. The tests were conducted in unidirectional steady airflow. Measurements taken include flow rate, pressure drop, torque, and rotational speed, as well as velocity and pressure distributions. Experimental results show that the presence of guide vanes can provide a remarkable increase in turbine efficiency.
84 citations
Journal Article•
TL;DR: In this article, the performance of an impulse turbine with self-pitch-controlled guide vanes for wave power conversion has been investigated, and the results show that a high-efficiency impulse turbine can be developed by these of guide vane connected by link motions.
Abstract: Experimental investigations directed towards improving the performance of the impulse turbine with self-pitch-controlled guide vanes for wave power conversion are reported. The turbine presented and tested here has an upstream and a downstream guide vane row connected by link motions. The behavior of guide vanes in the reciprocating flows is shown in connection with the axial flow velocity. The results show that a high-efficiency impulse turbine can be developed by these of guide vanes connected by link motions. Furthermore, it is found that the running and starting characteristics of this turbine in the reciprocating flow can be estimated from the performance of the turbine with fixed nozzle and diffuser vanes in a unidirectional steady flow.
59 citations
Journal Article•
TL;DR: In this paper, an impulse turbine with self-pitch-controlled guide vanes was investigated experimentally by the use of turbine test equipment in which the sinusoidally reciprocating flow conditions are simulated.
Abstract: An impulse turbine with self-pitch-controlled guide vanes was proposed by the authors in a previous paper. The unsteady characteristics of this turbine have been investigated experimentally by the use of turbine test equipment in which the sinusoidally reciprocating flow conditions are simulated. The results have been compared with those of a Wells turbine. Furthermore, in order to clarify the usefulness of quasi-steady analysis of this turbine, they have been also compared with the analytical results calculated on the basis of the experimental data obtained by the model testing of a turbine rotor with fixed guide vanes under steady unidirectional flow conditions. As a result, it has been clarified that the impulse turbine presented here is superior to the Wells turbine in overall characteristics, and the quasi-steady analysis is available for this turbine.
48 citations
01 Nov 1988
39 citations