Ocean Current Power Generation Research Articles

Marine current power with cross-stream active mooring: Part II

This is the second of three papers that propose and study a new concept of mooring turbine generators with the aim of resolving key difficulties in realizing ocean current power generation. The concept of Cross-stream Active Mooring (CSAM) features a hydro sail system that allows deployment of generator turbines, from anchoring points on shore or on shallow seafloors, across current stream to access current core flowing over deep seas or over seabed not suitable for anchoring construction. The CSAM can increase system power capacity by changing horizontal positions of generator turbines to track meandering current core, and can also change system depth to avoid storms. New anchoring designs of improved efficiency and implementation methods for resolving seafloor geological issues in the Kuroshio off southeast Taiwan are also included. This second paper discusses conceptual design and construction of the tethers, mooring implementations and reduction of flow drag, mooring of power cable and design of linear array and 2D formation. Model tests were conducted to demonstrate and observe the feasibility of the basic concept and its stability. Formation stability under the influences of waves and other possible perturbations was analyzed and discussed.

Study on characteristics of contra-rotating turbine for ocean current power generation

Study on characteristics of contra-rotating turbine for ocean current power generation

Motion Model and Speed Control of the Cross-Stream Active Mooring System for Tracking Short-Term Meandering to Maximize Ocean Current Power Generation

ABSTRACTThis paper analyzes the speed of lateral movement of the Cross-stream Active Mooring (CSAM) system in an ocean current and its control methods in order to study the system's capability of tracking short term meandering of ocean currents for maximizing power generation capacity. The CSAM concept for marine current power features a hydro sail system that can deploy generator turbines transversely across streams in a marine current. The hydro sail system can further adjust the horizontal position of the turbines, by changing the angle of attack of the hydro sail, to actively track fast streams in the marine current to increase power generation capacity. A two-step motion model with analytical formulas was developed and analysis based on mechanics indicated that the simplified model is adequate to estimate the system speed. Using an example system, it was estimated that the proposed active mooring system is capable of matching typical lateral speed of short term meandering and tracking fast streams in an ocean current without any external propulsion other than controlling the angle of attack of the hydro sails. Methods of controlling the system speed of moving from one location to another were also developed.

High-resolution modeling of the Kuroshio current power south of Japan

Ocean current power near the Japanese coast was estimated using a high-resolution, three-dimensional ocean model. Two experiments were conducted to distinguish the impact of the Kuroshio large meander. The simulation results were validated by comparison with measurements. To choose the proper site for ocean current power generation experiment, we quantitatively analyzed the variation of the current field for three candidate areas: around the Tokara Strait, south of Cape Ashizuri (AS), and south of Cape Shionomisaki (SH). The results show that the current around the Tokara Strait is the weakest among the three candidates. The current south of SH is strongest for the non-large-meander period. The area south of AS is promising for ocean current power generation, because the current is stable and strong regardless of the large meander, and the average ocean current power density can reach 1 \(\hbox {kW/m}^{2}\).

Marine current power with Cross-stream Active Mooring: Part I

This is the first of three papers that propose and study a new concept of mooring turbine generators with the aim of resolving key difficulties in realizing ocean current power generation. The concept of Cross-stream Active Mooring (CSAM) features a hydro sail system that allows deployment of generator turbines, from anchoring points on shore or on shallow seafloors, across current stream to access current core flowing over deep seas or over seabed not suitable for anchoring construction. The CSAM can increase system power capacity by changing horizontal positions of generator turbines to track meandering current core, and can also change system depth to avoid storms. New anchoring designs of improved efficiency and implementation methods for resolving seafloor geological issues in the Kuroshio off southeast Taiwan are also included. This first paper presents the basic concept, basic analytical model and prediction of key performance parameters, conceptual designs of the hydro sail and multiple-unit linear array, and potential benefits of the proposed system. The second paper discusses construction of the tethers, mooring of power cables and 2D formation designs. The third paper discusses anchoring designs and constructions, large scale deployment, failure mode designs and system costs.

Site selection of ocean current power generation from drifter measurements

Site selection of ocean current power generation is usually based on numerical ocean calculation models. In this study however, the selection near the coast of East Asia is optimally from the Surface Velocity Program (SVP) data using the bin average method. Japan, Vietnam, Taiwan, and Philippines have suitable sites for the development of ocean current power generation. In these regions, the average current speeds reach 1.4, 1.2, 1.1, and 1.0 m s−1, respectively. Vietnam has a better bottom topography to develop the current power generation. Taiwan and Philippines also have good conditions to build plants for generating ocean current power. Combined with the four factors of site selection (near coast, shallow seabed, stable flow velocity, and high flow speed), the waters near Vietnam is most suitable for the development of current power generation. Twelve suitable sites, located near coastlines of Vietnam, Japan, Taiwan, and Philippines, are identified for ocean current power generation. After the Kuroshio power plant being successfully operated in Taiwan, more current power plants can be built in these waters.

ICOPE-15-1118 Evaluation of material degradation in sea-water for development of ocean current power generation system

ICOPE-15-1118 Evaluation of material degradation in sea-water for development of ocean current power generation system

潮流·海流発電

潮流·海流発電

潮流・海流発電に向けた津軽海峡の流況特性及びエネルギー賦存量に関する研究

潮流・海流発電に向けた津軽海峡の流況特性及びエネルギー賦存量に関する研究

双発タービン式海流発電装置の運動シミュレーションに関する研究

Recently, research and development (R&D) of marine renewable energy becomes very popular all over the world. In this paper, a twin-type turbine is adopted as an ocean current power generator. The twin turbine system is theoretically torque free, since the left blade counters the right blade torque. Therefore, a floating body with a single point mooring concept can be used as a support of twin turbines. A computer code, which represents motions of the twin type current turbine with 6 degrees of freedom together with the non-linear mooring effect, is developed. The numerical code simulates fully coupled motions of the main body, two turbines and two mooring lines. The numerical results are validated with experiment in which a newly developed small size turbine-generator model is used. The results show that the numerical results are in good agreement with the experimental results. Some numerical and experimental results show that the current turbine is stably moored even when the flow speed or direction is suddenly changed. The weather vane function of the mooring system is also demonstrated in the experiment.

海底占有面積が狭小な沖合浮体係留方式に関する基礎研究

In this study, the concept of "vertically movable tension leg mooring system" is proposed for the purpose that an offshore floating body subject to comparatively large static horizontal loads for its scale, which is represented by floating wind power generator, ocean current power generator, etc., is moored so that the occupied plane area of the mooring system may become as small as possible. In the system, a gravity type template is hung from the floating body with vertical lines and the template is moored with relatively short catenary chains to seabed anchors. The advantages of the proposed system are discussed comparing mainly with the tension leg mooring, and the fundamental mooring characteristics are shown with model calculations.

J055013 双発式海流発電タービンへ作用する非定常流体力の評価(〔J055-01〕流体機械の研究開発におけるEFD/CFD(1))

A novel ocean current power generation system is considered which has two major features: underwater floating configuration and two counter-rotating turbines. From the comparison of the CFD results for single turbine and twin-turbine with in-phase rotation, the time variation of the thrust due to the effects of beam wake and turbines interaction is estimated to be approximately 4% of the steady single turbine. It is found the thrust variation is also about 4%, when the two turbine models rotate with 90° phase shift. Furthermore, CFD with linear vertical velocity profile is carried out to simulate the actual oceanic condition. It is found that the velocity profile almost does not influence the thrust acting on the turbines.

Design of the Shape of Blade of the Semi-Submersible Ocean Current Power Generation Device Based on Fluent

The semi-submersible ocean current power generation device is a new power generation device which can absorb the energy of marine currents. The shape of blade determines the absorbing efficiency which is one of the core technologies. To get force status of the different shape of the blade under the currents by using Fluent software simulate these blades. Then analyze the impacts of the blade shape on the power generation efficiency, the simulation results provide guidance for the design of the actual blades.

Development of Tidal Current and Ocean Current Power Generation System Using Elastic Turbine

High power generating cost is an important problem in a sustainable energy. In order to reduce the cost for the power generation, passive power control using elastic turbine blade made of composites is adopted. In this study, the performance evaluation system with fluid-structure interaction analysis and water tank tests has been developed to design the passive power control property and evaluate its performance. First, we made rigid blade models and elastic blade models to compare the calculated deformation by fluid-structure interaction analysis. The deformation of blade is measured by a noncontact optical stereo camera. Consequently we confirmed that we can predict the deformation with fluid-structure interaction analysis. By using some numerical optimization methods, we try to design elastic turbine blade in actual sea condition.

D101 弾性タービンを用いた潮流・海流発電システムの開発(OS2 再生可能エネルギー(潮流・波力・洋上))

D101 弾性タービンを用いた潮流・海流発電システムの開発(OS2 再生可能エネルギー(潮流・波力・洋上))

OS2-05 マリーンタービンによる海流発電システムの開発(OS2 自然エネルギー)

It might be predicted that the recent progress of Japanese technology of sea-water turbo-machinery will make the utilization of ocean current energy practical, because the recent development of technology for seawater turbo-machinery and the progress of ship propulsion-machinery seem to provide solutions to the technological problems which were pointed out 30 years ago. Also, it is encouraging that recently, two research projects have been started individually in the United Kingdom, and in Norway for development of technologies for large-scale generation of clean electricity from the seas using submarine turbines. With the prospect of establishment of hydrogen energy society in the near future, the faculty members of Yokohama National University have started their cooperative works to develop the basic technology for the utilization of the ocean current energy for the hydrogen generation. In this paper, the basic concept of the ocean current power generation system using marine turbines is introduced.