Ocean Current Power Generation Research Articles

The Influence of Structural Parameters on the Ultimate Strength Capacity of a Designed Vertical Axis Turbine Blade for Ocean Current Power Generators

An ocean current power generator is a power plant that uses kinetic energy from ocean currents to generate electricity. Considering that the blade is the component that receives the biggest load from seawater currents, its structural design should be strong enough to sustain the applied load. Therefore, this research seeks a suitable design and material for turbine blades using the finite element method (FEM). A NACA 0021 blade with a total length of 3600 mm is used for the base geometry. A parametric study was conducted by varying the spacing between the supports, the pitch angle, the material, and the frame model. Considering a high load, the suitable amount of space between the stiffeners was 2200 mm. It was found that a pitch angle variation between −20° and +20° did not significantly affect the strength of the blade structure. The frame geometry variation caused the rigidity and cross-section area of the blade to differ. Therefore, web-shaped or bar-shaped frames are preferable because they have optimal maximum load-to-weight ratios. The material variation analysis resulted in CFRP material being chosen because it had a high maximum load/weight ratio and a high maximum stress.

MARITIME DEPLOYMENT PLANNING AND EXECUTION FOR FIELD TESTING OF OCEAN CURRENT POWER GENERATOR

To develop ocean current power generation, this study explored the planning and execution of the installation and deployment of a 20kW Floating Kuroshio Turbine (FKT) system and anchoring system for field-testing in the southwest coast of Liuqiu Island. During the experiment, the 20kW FKT and anchoring system were loaded onto a vessel from the Kaohsiung Port Intercontinental Container Center by a barge and tugboat for deployment in the southwest coast of Liuqiu Island. The field testing of the 20kW FKT was conducted during this period, and upon completion, the unit will be retrieved. The deployment and retrieval of marine devices are easily affected by wave conditions, which increase the difficulty of the operation. Therefore, when designing the hanging and unhooking system, under the consideration of safety, the convenience of operation for the operators should be simplified as much as possible and safety, The study aims to further develop Taiwan's domestic ocean current power generation technology and provides maritime engineering experience through the installation of the 20kW FKT unit and field mooring tests. Additionally, this research seeks to facilitate a local marine green energy industry development through the economic benefits and commercialization of ocean current power generation.

MARITIME DEPLOYMENT PLANNING AND EXECUTION FOR FIELD TESTING OF OCEAN CURRENT POWER GENERATOR

To develop ocean current power generation, this study explored the planning and execution of the installation and deployment of a 20kW Floating Kuroshio Turbine (FKT) system and anchoring system for field testing in the southwest coast of Liuqiu Island. During the experiment, the 20kW FKT and anchoring system were loaded onto a vessel from the Kaohsiung Port Intercontinental Container Center by a barge and tugboat for deployment in the southwest coast of Liuqiu Island. The field testing of the 20kW FKT was conducted during this period, and upon completion, the unit will be retrieved. The deployment and retrieval of marine devices are easily affected by wave conditions, which increase the difficulty of the operation. Therefore, when designing the hanging and unhooking system, under the consideration of safety, the convenience of operation for the operators should be simplified as much as possible and safety, The study aims to further develop Taiwan's domestic ocean current power generation technology and provides maritime engineering experience through the installation of the 20kW FKT unit and field mooring tests. Additionally, this research seeks to facilitate a local marine green energy industry development through the economic benefits and commercialization of ocean current power generation.

Characteristics of ocean current meandering and potential efficacy of maximizing power capacity by tracking short-term meanders with hydro sail enabled active mooring

This research studies the characteristics of ocean current meanders from the viewpoint of power generation engineering and the potential of maximizing ocean current power generation capacity by making generator turbines to track the meanders applying a recently proposed Cross-stream Active Mooring concept. The current meanders will hurt capacity factor of marine turbines moored at fixed locations, somewhat like the issue of wind availability for wind farms. The new mooring concept 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 sail angle of attack, to actively track fast streams in an ocean current. This paper first reviews and discusses the characteristics of short-term track variations of the Florida Current and the Kuroshio near Taiwan and then analyzes potential improvement in power generation using measured and simulated current velocity data in the two ocean currents, suggesting a potential increase of 10–40 % power generation achievable by tracking the meanders. Operations of the hydro sail were demonstrated by tests using remote controllable and passive scale models. Control methods are discussed. Approaches to observe, predict and track the meanders are conceptualized.

Hydrodynamic Characteristics of the Lombok Strait During the 2022 West Monsoon Peak and Estimation of Ocean Current Power Generation Potential

The Lombok Strait is one of the crucial straits in the Indonesian area because it falls in the Indonesian Archipelagic Sea Lanes of Communication II (ALKI II), and is considered as a strategic chokepoint. Additionally, it serves as a passage for ARLINDO, facilitating the movement of water masses from the Pacific to the Indian Ocean. This unique attribute creates a diverse ecosystem in the Lombok Strait due to the convergence of marine organisms from both oceans. The Lombok Strait presents an opportunity for harnessing renewable energy from its currents. However, there is a scarcity of direct measurements and oceanographic data for the Lombok Strait, making it impractical and costly to conduct direct observations using oceanographic mooring instruments. Therefore, one approach to better understand natural phenomena in the ocean is to use numerical methods such as Computational Fluid Dynamics (CFD) with the Finite Element Method (FEM) application. In this study, the software Mike3FM was used, which incorporates both Computational Fluid Dynamics (CFD) and the Finite Element Method (FEM). This software used bathymetric data and coastlines to create a triangular mesh in the horizontal plane and a grid mesh in the vertical plane. The simulations conducted in January 2022, for 30 days with hourly intervals around the sill area showed an average current velocity of 1.2 m/s at various depths, including 5, 50, 150, and 250 meters. The current primarily flowed southward in the direction of the Indian Ocean. The conversion of avarage current velocity to electrical power at depths of 5, 50, 150, and 250 meters above the sill yielded values of 0.86 kW, 0.70 kW, 0.34 kW, and 0.19 kW, respectively. Based on the results of the hydrodynamic modeling experiments, it is evident that the Lombok Strait has the potential to develop ocean current power generation.Keywords: Hydrodynamics, the Lombok Strait, CFD, FEM, West Monsoon.

Transient Translational–Rotational Motion of an Ocean Current Converter Mooring System with Initial Conditions

Systems of ocean current power generation are generally moored deep in the seabed. The mooring system is like ropes. The ropes are very long and can provide tension but not compression, and their dynamic displacement is large and unstable, which is different from traditional structures. To generate high-efficiency ocean current power generation, it is necessary to design a stable mooring system. Maintaining the stability and small dynamic displacement of the ocean current invertor is significantly helpful for the high efficiency of the invertor. In addition, the stability of the mooring system and a small dynamic tension, high safety factor, and long life of the mooring ropes are essential. In this study, we investigate the transient behavior of a mooring system composed of an inverter platform, pontoon, and ropes under initial conditions. An analytical method is proposed. The transient translational and rotational displacements are composed of 36 independent normalized fundamental solutions. The composition depends on the initial conditions. Each fundamental solution is derived by using the Frobenius method. This study proposes the replacement of the traditional single-rope mode with the double-rope parallel mode, which can maintain a high fracture strength and low effective spring constant in the rope. It is verified that this design can decrease instantaneous tension and increase the safety factor of the rope. Additionally, high hydrodynamic damping coefficients can significantly increase the stability of the mooring system.

Marine Power Generation Methods and Future Developments

With the continuous advancement of science and technology, ocean energy continues to develop because of its renewable, clean and stable advantages. This paper mainly studies the issue of ocean energy power generation, focusing on tidal energy power generation, wave energy power generation and ocean current power generation. The practical application of tidal energy power generation, and the negative and positive impacts of clean energy such as tidal energy on the marine environment after application, various methods and advantages and disadvantages of ocean current/ocean current power generation are described, and the explanation of many instruments in these power generation methods. For instance, the equipment used in tidal energy, wave energy and ocean current power generation are oscillating water column wave energy converter, mechanical wave energy generation, the diffuser-augmented floating hydro turbine, Darrieus deep-sea vertical axis turbine and so on. At last, from the actual cases of China's use of clean energy such as tidal energy and wave energy to generate electricity, we analyzed the future development trend of ocean energy and concluded that ocean energy will be vigorously developed in the future to replace some fossil energy.

Scale model study of basic functions of the cross-stream active mooring for marine current power systems

The Cross-stream Active Mooring (CSAM) is a recently proposed concept for ocean current power generation featuring serial mooring of multiple submerged floating generator turbines on a long mooring tether with a set of hydro sails to stabilize and adjust the positions of the generator turbines in the sea. This research studies feasibility of deployment, stability under general sea conditions and capability of storm resistance and avoidance of the system through scale model tests and observations in conditions corresponding to the Kuroshio southeast of Taiwan. First, small scale models were designed, made and tested to achieve proper scaling of forces involved, including buoyancy, lifts, drags and thrusts resulted from the models in the flow. Next, single stage CSAM models were experimented to study the deployment angle in relation to sail pitch angle. Finally, multiple stages of models were connected into a CSAM linear array model and tested in a pool with a flow under different wave conditions. Tests and observations show that the model linear array was successfully deployed as designed, was basically not affected by waves in regular sea conditions and kept its formation in its storm avoidance mode under influences of waves of a 10-year recurrence typhoon.

Numerical and experimental analyses of the performance of a vertical axis turbine with controllable-blades for ocean current energy

Phasing out high-carbon-emission fossil fuels and using renewable energy have become a global consensus for mitigating climate change. For the application of renewable energy, this study proposes a high-efficiency controllable-blade vertical axis turbine, which has six blades and a cam plate, for ocean current power generation. A novel design for the turbine using cam to control the opening and closing of blades to enhance the performance of vertical axis turbines. The design feature of the drag-type blade is to be active or open quickly in downstream. The effective area of the blade under thrust is increased to enhance the performance. On the other hand, the blade is designed to be inactive or close quickly in upstream and the drag of blade in upstream can be reduced. A commercial software, ANSYS FLUENT is used to simulate the performance of the vertical turbine. The streamline, velocity, and pressure around the turbines are then obtained. The power coefficients and torques are evaluated at various angular velocities and tip speed ratios and are validated by experimental results. The maximum power coefficient of the proposed turbine occurs at an angular velocity ratio of 4 with quick opening of blades and is higher than that of 3, 5, or 6 by 3.4 %, 2.7 %, or 7.4 %, respectively. In addition, performance comparisons among controllable-blade vertical axis turbine, fixed-blade vertical axis turbine, and Savonius turbine are made. The results show that the maximum power coefficient of the presented controllable-blade vertical axis turbine is 143 % and 103 % higher than that of the fixed-blade vertical axis turbine and Savonius turbine at V = 1 m/s, respectively.

Biomimetic Design of Turbine Blades for Ocean Current Power Generation.

The enhancement of energy technology and innovation play a crucial role in order to meet the challenges related to global warming in the coming decades. Inspired by bird wings, the performance of a bio-inspired blade assembled to a marine turbine model, is examined. Following a biomimetic pathway, the aerodynamic performance of the bird wings of the species Common Guillemot (Uria aalge) was tested in a wind tunnel laboratory. Based on our results, we derived a bio-inspired blade model by following a laser scanning method. Lastly, the bio-inspired blades were assembled to a marine turbine model and tested in a large flow tank facility. We found efficiencies (Cp) up to 0.3 which is around 53% of the maximum power that can be expected from the turbine model according to the Betz approach. Our findings are analyzed in the discussion section as well as considerations for future research.

Numerical Study on the Interaction between Ocean Current Power Generator and Unmanned Underwater Vehicle

The unmanned underwater vehicle (UUV) can effectively utilize marine renewable energy after equipping the UUV with an accompanying power generator that improve its long-range endurance. In order to study the interaction between the UUV and the ocean current power generator, a coupled hydrodynamic model of the counter-rotating type turbine and the UUV hull was established. Based on the RANS model and the sliding grid method, this paper analyzed the influence of the ocean current power generator on the straight-ahead resistance and hydrodynamic coefficient of the UUV in the non-working state, and calculated the UUV yaw moment and its surrounding flow field characteristics with the power generator in the working state. Then, the effect of the drift angle on the performance of the counter-rotating type turbine was explored. The results show that the straight-ahead resistance of the UUV increased slightly after equipping the power generator, but the increase was within 14%, and the characteristics of the surrounding flow field of the UUV did not changed greatly. The difference in the linear hydrodynamic coefficients before and after equipping the UUV with the power generator was within 7%. At most drift angles, when the generator was in the working state, the yaw moment of the hull was greater than the condition when the generator was not equipped. Nevertheless, the overall trend of the two sides was similar, so the rotation of the counter-rotating type turbine did not reduce the stability of the hull in the moored state. In addition, when the drift angle was greater than 50°, the UUV hull had a great impact on the performance of the counter-rotating type turbine; the power coefficient CP and thrust coefficient CT increased by about 35.7% and 17.8%, respectively. This paper provides a good reference value for the design of the power generation mode of the UUV equipped with a counter-rotating type turbine.

海流発電装置の開発と指導過程の提案

This study focuses on ocean current power generation, develops a device for experiential learning, and aims to propose a teaching process. The developed device consists of a hull and a power generation turbine. The hull is stabilized by attaching two styrofoam floats side by side. The power generation turbine was designed and manufactured using 3D CAD. The guidance process consists of (1) confirming the energy situation in Japan and recognizing the need for renewable energy, (2) learning the mechanisms and characteristics of ocean current power generation through experiments, and (3) thinking about Japan's future energy policy. As a result of the experiment, I was able to understand the characteristics of ocean current power generation and consider Japan's energy policy from various points of view.

Development of Ocean Current Power Generation Equipment as Learning Materials

The purpose of this study is to develop teaching materials and teaching tools for raising the ability to think and judge scientifically and to evaluate and utilize them, while encouraging the understanding according to the developmental stage, taking energy situation and environmental problem of Japan and the world which are tense recently as a subject. In this study, the development of the ocean current power generation equipment is proposed with the aim of scientifically recognizing the necessity of the introduction of the renewable energy and technical problems in proportion to the developmental stage, and acquiring the ability to appropriately evaluate and utilize the technology. The developed equipment is composed of a hull and a power generation turbine. On the hull, the hull stabilization is attempted by arranging two floats made of foamed polystyrene side by side. The turbine was designed by 3D CAD and fabricated by 3D printer. Created. On the power generation turbine, after the students themselves designed it using simple 3DCAD and printed it by 3D printer, they intend to improve it so that it becomes more efficient through experiment and measurement in this experimental equipment.

A Simple Nozzle-Diffuser Duct Used as a Kuroshio Energy Harvester

In response to the increasing energy demand in Taiwan and the global trend of renewable energy development, Kuroshio energy is a potential energy source. How to extract this invaluable natural resource has then become an intriguing and important question in engineering practices. This study reported the results of a feasibility study for a nozzle-diffuser duct (NDD) as the Kuroshio currents energy harvester. The computational fluid dynamics (CFD) software ANSYS Fluent was employed to calculate the drag and added mass coefficients of the duct anchored to the seabed. Those coefficients were further imported into Orcaflex to simulate the motion of the duct under normal and storm wave conditions. Results showed that the duct was stable 25 m below the sea surface under normal wave conditions. When the wave condition changed to storm waves, the duct needed to dive into at least 90 m below the sea surface to regain its stability and obtain high power take-off (PTO). An optimal design nozzle-diffuser-duct was reported, and a PTO peak of 15 kW was expectable in the Kuroshio currents. Once a suitable offshore platform can be developed with sixty-six NDDs, a Megawatt Kuroshio ocean current power generation system is feasible in the near future.

Remote Monitoring and Fault Diagnosis of Ocean Current Energy Hydraulic Transmission and Control Power Generation System

The development of clean and environmentally friendly energy is necessary to address significant energy challenges, and abundant sea current energy, which plays a key role in the decarbonization of our energy systems and has attracted increasing attention among researchers. In the present study, a remote monitoring and diagnosis system was designed in accordance with the requirements of a 50 kW hydraulic transmission and control power generation system. Hardware selection and software function requirement analysis were then performed. The causes of system faults were analyzed, the output fault types of the improved model were determined, and effective monitoring parameters were selected. The accuracy of traditional spectra in diagnosing faults is poor; however, the generalization capability of support vector machines (SVM) is robust. Thus, an improved particle swarm algorithm optimized SVM fault diagnosis model for the hydraulic transmission control power generation system was proposed to rapidly and effectively determine the key parameters. Remote monitoring software for the hydraulic transmission and control power generation system was also developed. The results of remote monitoring and diagnostic tests showed that the software was able to satisfy the functional requirements of the hydraulic transmission control power generation remote monitoring system, and the operation effect was consistent with expectations. By comparing the test accuracy of different diagnostic models, the improved PSVM model has the highest test accuracy with a classification accuracy of 99.4% in the case of normal operation, accumulator failure, relief valve failure and motor failure. In addition, the proposed diagnostic method was effective, thereby ensuring safe and reliable operation of the hydraulic transmission control power generation system.

Fast economic model predictive control for marine current turbine generator system

This paper considers the optimal operation of the ocean current turbine power generation system. Based on the model construction of the ocean current turbine system, the model predictive control strategy with economic indicators as the main consideration and the system focusing on real-time control issues are used. It is known that the quadratic form complicates the process to be solved, thereby increasing the solution time. For some complex formulation settings, although the system optimization problem can be solved more effectively, the complexity of the system is increased and the calculation time is increased. Therefore, this paper considers an optimal control that can be obtained fast enough for real-time optimization of the feedback scheme. The economic model predictive control framework is proposed in the paper, with the sensitivity components to solve the formulation, and the paper also consider an iterative optimization algorithm to enhance and improve the response speed of the system without affecting the economics of the system. Finally, all of these concepts are demonstrated on a detailed case study of a marine current turbine generator system.

Design, prototyping, and experiment of the ocean current power generation system using Bach Savoniusrotor

Design, prototyping, and experiment of ocean current power generation system have been carried out using the Bach Savonius rotor. The introduced ocean current power generation prototype is validated on real measurement obtained in the Rupat Strait, Indonesia. In this research, the influence of the velocity of ocean currents, the number of turbine blades, and the blade arc angle of the generator output power are studied. The results showed that the turbine output power is strongly influenced by the velocity of ocean currents where the velocity values of ocean currents varied in the range 0,63-1,98 m/sec. The maximum electrical power of the turbine occurs at a current velocity of 1,98 m/sec of 26,88 Watts. The number of turbine blades has a significant effect on turbine output power. The turbine reaches maximum power is found in the rotor with a number of 3 blades with a power coefficient of 0,1176 on the tip speed ratio of 0,359. The blade arc angle is varied at angles of 90°, 135° and 165°. The blade arc angle 135° gives the best performance with a power coefficient of 0,102 on the tip speed ratio of 0,298.

Optimal Control Design of Generator Systems for Marine Current Turbine Applications Using Economic Model Predictive Control

Economic Model Predictive Control (EMPC) has recently been researched in many areas, especially in terms of energy. The development of advanced control algorithms has promoted the cost reduction of marine energy generation and improved the efficiency and reliability of marine current turbines. By reducing the loss on the marine turbine system, better economic indicators can be achieved. Based on this, the maximum marine power can be captured such that the entire marine current turbine system can obtain maximum economic benefits. In this paper, it is mainly based on the economic model predictive control framework to optimize the ocean current turbine power generation system. The system index is directly used for the objective function of the EMPC problem, as EMPC has the advantage of dealing with system constraints and cost functions. Compare the performance of the proposed control framework with the performance of commonly used basic MPC controllers, simulation results show that the proposed controller can reduce the loss of the turbine system and gearbox, indicating that more energy capture can be obtained for the system to achieve better economic effects.

KAJIAN APLIKASI PANTULAN SINYAL GNSS UNTUK PEMANTAUAN KETINGGIAN PERMUKAAN AIR LAUT

Design and experiment of ocean current power generation system have been carried out using the Bach In Indonesia, the tsunami early warning system only applies the earthquake and hydrosphere relationship model to predict tsunamis. To date, no tsunami detector has used radar or GNSS technology. GNSS technology can be applied as an early warning system for tsunamis, provided that tsunamis are caused by earthquakes greater than 7 magnitudes, occur 70 kilometers below sea level, and are caused by normal faults. This could be an alternative to Bouy GNSS which is expensive to install and maintain, especially for countries with vast oceans such as Indonesia. In this paper, a review of the application of GNSS signal reflection was carried out using one International GNSS Service (IGS) station, JOG2, and one Continuously Operating Reference Station (CORS), CLSA, each located in Java and Sumatra to investigate the availability of sea level monitoring in Indonesia. Determination of sea level is obtained from two methods, the GNSS signal phase data analysis method and the GNSS Signal-to-Noise Ratio (SNR) data analysis method. Both methods use reflected GNSS signals or multipath effects to obtain sea level. The results of the study show that the number of satellites that pass through Indonesia every 15 minutes is enough to get sea-level data every 15 minutes to one hour. This shows that it is possible to apply the multipath effect to obtain sea level information in Indonesia to detect tides and tsunamis as part of the tsunami early warning system in Indonesia.

STUDI EKSPERIMEN TEKNOLOGI PEMBANGKIT LISTRIK TENAGA ARUS LAUT (PLTAL) MENGGUNAKAN SAVONIUS BACH ROTOR

Design and experiment of ocean current power generation system have been carried out using the Bach Savonius rotor. In this research, the influence of the velocity of ocean currents, the number of turbine blades, and the blade arc angle of the generator output power are studied. The results showed that the turbine output power is strongly influenced by the velocity of ocean currents where the velocity values of ocean currents varied in the range 0,63-1,98 m/sec. The maximum elctrical power of the turbine occurs at a current velocity of 1,98 m/sec of 26,88 Watts. The number of turbine blades has a significant effect on turbine output power. The turbine reaches maximum power is found in the rotor with a number of 3 blades with a power coefficient of 0,1176 on the tip speed ratio of 0,359. The blade arc angle is varied at angles of 90˚, 135˚ and 165˚. The blade arc angle 135˚ gives the best performance with a power coefficient of 0,102 on the tip speed ratio of 0,298.