Tidal Power Generation Research Articles

Flow field estimation analysis based on the Kalman filter FEM for selection of tidal stream power generator locations

In this paper, we present a shallow water flow field estimation analysis, based on the Kalman filter FEM, for locating the optimal positions for tidal stream power generation systems. In our flow field analysis, we adopt the shallow water equation as the governing equation. The Galerkin and the selective lumping methods are employed as discretization techniques in space and time, respectively. The Kalman filter theory is applied to estimate the flow field. As a numerical example, we carry out a flow estimation analysis for Tokyo Bay. The high estimation accuracy of the flow field estimation based on the Kalman filter FEM is confirmed by comparison with conventional FEM. The electric power generation potential is also computed using the estimated flow field.

日本沿岸潮流発電の資源量推定に対する潮流の長期変動の影響

Tidal currents have two types of intrinsic long-term fluctuations. The one is single tidal constituent such as Ssa and the other one is interferences between tidal constituents. The effect of the long-term fluctuation of tides on the resource assessment for tidal current energy generation system near Japan has been described based on the predictions using data-assimilative global barotropic tide model results. It is shown that monthly mean tidal energy flux varies by more than 20% over a year in the most of the prospective areas. The result indicates the intrinsic long-term fluctuations need to be considered in the resource assessment of tidal current power generation system.

A Review on Tidal Power & Its Scope in Indian Peninsular Area

Now days and in the coming years, increased attention is being given to the tidal current energy development all over the world. This article is about tidal power generation. It describes tidal power and the various methods of utilizing tidal power to generate electricity. The paper focuses on the potential of this method of generating the electricity and why this could be a common way of producing electricity in the near future. It also focuses on the scope of tidal power in coastal areas of India and their comparisons.

Reliability evaluation for islanded microgrid with tidal power generation and battery energy storage system

Reliability evaluation for islanded microgrid with tidal power generation and battery energy storage system

Reliability evaluation of tidal and wind power generation system with battery energy storage

This paper presents a method for reliability evaluation of a hybrid generation system of wind and tidal powers with battery energy storage. Such a system may widely exist in coastal areas and islands in the future. A chronological multiple state probability model of tidal power generation system (TPGS) considering both forced outage rate (FOR) of the TPGS and random nature of tidal current speed is developed. In the evaluation of FORs of TPGS and WPGS (wind power generation system), the delivered power related failure rates of power electronic converters for TPGS and WPGS are considered. A chronological power output model of battery energy storage system (BESS) is derived. A hybrid system of tidal and wind generation powers with a BESS is used to demonstrate the effectiveness of the presented method. In case studies, the effects of various parameters on the system reliability are investigated.

조류발전 지지구조시스템 설계 및 성능평가

조류발전 지지구조시스템 설계 및 성능평가

Design of Supporting Structure for Tidal Current Power Generation Using Tidal Bladed

The importance of tidal energy has increased steadily throughout the world, and it is recognized as the most reliable energy resource from the ocean. It has great advantages compared to other renewable energy resources due to high energy density in sea water, reliability and predictability. There are many suitable sites for the application of tidal current power (TCP) in Korea because the strong current water area are located in the western and southern coasts with high tidal range up to 10m. Even though many tidal turbines are demonstrated to increase the power efficiency, the cost-saving technologies are still required for economical design of the device. Since the structure and installation cost is dominant in development expense of TCP system, economical supporting structure and installation procedure should be developed. Because the ground conditions of most installation site are rocky bed due to its rapid current, gravity structures are regarded as the most competitive solutions than any other piled structures. Gravity base caisson support structure can be installed with small equipment and the stability can be increased by the injection underwater concrete after the installation. To design the caisson structure which is suitable for the TCP system, integrated load analysis has been carried out using Tidal Bladed considering various design load cases. Multi-body dynamic method was used for interaction between components and dynamic loading on the TCP system was simulated. Calculated load was applied to the design of caisson structure and findings have been summarized in this paper.

Reliability Evaluation of a Tidal Power Generation System Considering Tidal Current Speeds

This paper presents a reliability evaluation method for a tidal power generation system (TPGS) with a doubly-fed induction generator (DFIG). The key to the method is the modeling of the tidal current speed-dependent failure rates of the rotor side converter (RSC) and grid side converter (GSC). The models for calculating the rotor currents through the RSC and GSC and the rotor current state related failure rates are presented. Based on the Wakeby distribution of tidal current speed, a multistate discrete probability distribution technique for rotor current is developed. Case studies are described using tidal current speed data from four coastal sites in North America. The results indicate that the failure rates of the RSC, GSC, and the entire TPGS vary with tidal current speeds and the probability distributions of tidal current speed. The TPGS suffers a much higher failure risk in the super-synchronous mode than in the idle and subsynchronous modes. The failure rate of the RSC is much higher than that of the GSC. The change trends in the failure rates of RSC and GSC in the operation modes are different. The probability distributions of tidal current speed have significant impacts on the reliability of the TPGS.

Optimisation and targeting of supply-demand of biogas system through gas system cascade analysis (GASCA) framework

Biogas decentralised energy system is an important technology in developed countries nowadays as one of the energy efficient and eco-friendly techniques for production of bioenergy besides giving significant impact towards reduction of disposed waste volume and greenhouse gas (GHG). The aim of this article is to present a new numerical method, i.e., Gas System Cascading Analysis (GASCA), based on Time Based Pinch Analysis (TBPA) principle. GASCA is capable of targeting the biogas supply-demand chain, as well as optimal capacities of anaerobic digestion (AD) and biogas storage systems for a known total demand profile, with the consideration of energy conversion efficiency for different biogas qualities, charging and discharging efficiencies and losses. In the illustrative case study, the optimal capacity of AD was 4629.52 MJ/h, with initial energy content and maximum energy capacity at biogas storage of 8737.19 MJ/h and 16,988.61 MJ/h. The simulation study also revealed that application of GASCA-optimised biogas energy system could potentially reduce carbon emission by up to 138 t CO2 eq/d. Moreover, a sensitivity analysis was conducted to examine the impacts of demand variations on biogas system design and regional feedstock selection.

Mapping Synergy of Erosion Mechanisms of Tidal Turbine Composite Materials in Sea Water Conditions

Tidal energy, of all marine renewables energy, possesses higher persistency and predictability over long-time scales. Moreover, the higher density of water than air also results in greater power output from a tidal turbine than a wind turbine with similar dimensions. Due to the aggressive marine environment, there are barriers in the development of tidal power generation technology. In particular, with regard to increased rotor diameter, the selection of material presents significant challenges to be addressed including the tribological environment, such as solid particle erosion, cavitation erosion, the effect of high thrust loading on the turbine blade tips and the synergy between sea water conditions and such tribological phenomena. This research focuses on producing and testing a variety of composite materials with different fibres and reinforcement layouts to evaluate two main tribological issues in tidal environments: matrix cutting and reinforcement fracture. A slurry pot test rig was used to measure the effects of different impact angles and particles sizes at constant tip speeds.

A coastal ocean model with subgrid approximation

A wide variety of coastal ocean models exist, each having attributes that reflect specific application areas. The model presented here is based on finite element methods with unstructured grids containing triangular and quadrilateral elements. The model optimizes robustness, accuracy, and efficiency by using semi-implicit methods in time in order to remove the most restrictive stability constraints, by using a semi-Lagrangian advection approximation to remove Courant number constraints, and by solving a wave equation at the discrete level for enhanced efficiency. An added feature is the approximation of the effects of subgrid objects. Here, the Reynolds-averaged Navier–Stokes equations and the incompressibility constraint are volume averaged over one or more computational cells. This procedure gives rise to new terms which must be approximated as a closure problem. A study of tidal power generation is presented as an example of this method. A problem that arises is specifying appropriate thrust and power coefficients for the volume averaged velocity when they are usually referenced to free stream velocity. A new contribution here is the evaluation of three approaches to this problem: an iteration procedure and two mapping formulations. All three sets of results for thrust (form drag) and power are in reasonable agreement.

Current tidal power technologies and their suitability for applications in coastal and marine areas

A considerable body of research is currently being performed to quantify available tidal energy resources and to develop efficient devices with which to harness them. This work is naturally focussed on maximising power generation from the most promising sites, and a review of the literature suggests that the potential for smaller scale, local tidal power generation from shallow near-shore sites has not yet been investigated. If such generation is feasible, it could have the potential to provide sustainable electricity for coastal homes and communities as part of a distributed generation strategy, and would benefit from easier installation and maintenance, lower cabling and infrastructure requirements and reduced capital costs when compared with larger scale projects. This article reviews tidal barrages and lagoons, tidal turbines, oscillating hydrofoils and tidal kites to assess their suitability for smaller scale electricity generation in the shallower waters of coastal areas at the design stage. This is achieved by discussing the power density, scalability, durability, maintainability, economic potential and environmental impacts of each concept. The discussion suggests that tidal kites and range devices are not well suited toward small-scale shallow water applications due to depth and size requirements, respectively. Cross-flow turbines appear to be the most suitable technology, as they have high power densities and a maximum size that is not constrained by water depth. Oscillating hydrofoils would also be appropriate, provided comparable levels of efficiency can be achieved.

Estimation of annual energy output from BCM tidal barrage and the corresponding marine environmental impact

Based on the finite-volume coastal ocean model (FVCOM), a three-dimensional numerical model FVCOM was built to simulate the ocean dynamics in pre-dam and post-dam conditions in Bachimen (BCM). The domain decomposition method, which is effective in describing the conservation of volume and non-conservation of mechanical energy in the utilization of tidal energy, was employed to estimate the theoretical tidal energy resources and developable energy resources, and to analyze the hydrodynamic effect of the tidal power station. This innovative approach has the advantage of linking physical oceanography with engineering problems. The results indicate that the theoretical annual tidal energy resources is about 2×108 kWh under the influence of tidal power station; Optimized power installation is confirmed according to power generation curve from numerical analysis; the developable resources is about 38.2% of theoretical tidal energy resources with the employment of one-way electricity generation. The electricity generation time and power are 3479 hours and 2.55×104 KW, respectively. The power station has no effect on the tide pattern which is semi-diurnal tide in both two conditions, but the amplitudes of main constituents apparently decrease in the area near the dam, with the M2 decreasing the most, about 62.92 cm. The tidal prism shrinks to 2.28×107 m3, but can still meet the flow requirement for tidal power generation. The existence of station increases the flow rate along the waterway and enhances the residual current. There are two opposite vortexes formed on the east side beside the dam of the station, which leads to pollutants gathering.

Modelling, control and frequency domain analysis of a tidal current conversion system with onshore converters

To optimise a tidal energy conversion system, the operation, maintenance and power generation aspects have to be taken into account. As a result the key focus of this study is to propose and investigate an alternative method of implementing a tidal energy conversion system using a pitch-regulated turbine and a variable-speed squirrel cage induction generator with long distance converters. The generator power output can be optimised by utilising variable-speed control strategies allowing the system to operate at maximum power coefficient while availability can be increased by reducing the components installed offshore by using long three-phase cables between the generator and onshore voltage source converters. The tidal current energy conversion system is investigated by developing a full resource-to-grid model in MATLAB/SIMULINK and by performing system analysis regarding the effects of harmonics in the long subsea cables. Simulation results show that optimised filter design and the choice of suitable operating frequency for the generator controller can minimise the overvoltages associated with the harmonics and the reflecting voltage waves in the cables.

Performance investigation of a counter-rotating tidal current turbine by CFD and model experimentation

Global warming is one of the issues in the world, which is mainly due to the burning of fossil fuels. Thus, alternative energy is now paramount in the 21st century. In Korea, the tidal currents in the southwestern sea have a wide range of currents that are available for tidal current power generation. Single rotor turbines can obtain a theoretical maximum power coefficient of 59.3%, whereas dual rotor turbines can attain a maximum of 64%. In this study, the performance and efficiency of a counter-rotating tidal current turbine is investigated when changing the front and rear blade angles at different water velocities. The investigation was conducted by using Computational fluid dynamics (CFD) and experimental methods highlighted in this study. When varying these parameters, changes in the streamlines were observed in the CFD results. The changes in flow stability over the blade surfaces observed in the numerical results were reflected in the power and power coefficient graphs presented in this study. The results obtained by the experiments were also shown to be in good agreement with the CFD results.

Experimental study on hydrodynamic characteristics of vertical-axis floating tidal current energy power generation device

To study the characteristics of attenuation, hydrostatic towage and wave response of the vertical-axis floating tidal current energy power generation device (VAFTCEPGD), a prototype is designed and experiment is carried out in the towing tank. Free decay is conducted to obtain attenuation characteristics of the VAFTCEPGD, and characteristics of mooring forces and motion response, floating condition, especially the lateral displacement of the VAFTCEPGD are obtained from the towing in still water. Tension response of the #1 mooring line and vibration characteristics of the VAFTCEPGD in regular waves as well as in level 4 irregular wave sea state with the current velocity of 0.6 m/s. The results can be reference for theoretical study and engineering applications related to VAFTCEPGD.

Tidal power generation in the glaciated, macrotidal Minas Scour Trough, Bay of Fundy, Atlantic Canada

The configuration of the Bay of Fundy results in large tides (up to 17 m) which give rise to strong currents (Fig. 1d). Harnessing these currents to generate electricity has been the focus of engineering schemes dating from 1910. Fundy tidal power generation has garnered attention periodically throughout the twentieth century (Gordon et al. 2014). The seabed and water column conditions in the Minas Scour Trough at the NE head of the Bay of Fundy (Fig. 1a, d) are now the subject of engineering studies to characterize the site for electricity generation. Test installations have been deployed on the seabed, the subsea cable to collect and transmit power to the electrical grid on land has been laid and future infrastructure instalments are planned. Fig. 1. Multibeam swath bathymetry and geophysical profile of the main Minas Scour Trough, Bay of Fundy. ( a ) Sun-illuminated multibeam-bathymetric image showing the tidal scour system developed in, from west to east, Minas Channel, Minas Passage and Minas Basin. Inset interpretation shows the extent of the scour trough. Acquisition system Kongsberg EM1000. Frequency 95 kHz. Grid-cell size 5 m. ( b ) Seismic-reflection profile in Minas Channel showing eroded glacimarine sediments and exposed bedrock cropping out in Minas Scour Trough. VE×67. Acquisition …

マグロの遊泳特性を利用した潮流発電

マグロの遊泳特性を利用した潮流発電

Properties Variation of Carbon Fiber Reinforced Composite for Marine Current Turbine in Seawater

Turbine blade which are generally made of composite is a core device among components of tidal current power generator that converts the flow of tidal current into a turning force. Recent years, damages of composite turbine blades have been reported due to reasons like seawater degradation, lake of strength, manufacture etc. In this paper, water absorption, tensile, bending, longitudinal transverse shearing properties of carbon fiber reinforced plastic (CRP) composite which would be applied to fabricate the marine current turbine blade has been investigated. Furthermore, the variations of properties with seawater immersion period were studied. The results indicated that the water absorption increased almost linearly at the beginning of immersion and then became stable. Tensile strength of specimen tended to decrease firstly and then recovered slightly. However, the longitudinal transverse shearing strength showed reverse variation trend comparing to tensile strength. And the bending property of specimens was depressed significantly. The properties variations in seawater shall be referenced to design and fabrication of composite marine current turbine blade.

潮流発電技術を応用した小水力発電システムの開発

After the Great East Japan Earthquake devastated the Fukushima Daiichi nuclear power plant, many nuclear plants in Japan have been closed and now we depend on fossil fuel. The lack of energy will be better to be compensated by solar power and wind power, which are directly affected by the weather. Therefore, the output remains unstable. This study focuses on the tidal power generation system, which is not much affected by the weather, to build it up as the small hydroelectric system which can generate a stable power. The system is multi-level and each level is a combination of Savonius type hydraulic turbine and Darrieus type hydraulic turbine, which are mostly used in tidal power generation systems. Therefore, we can obtain a stable and more efficient power even at low tidal speed current. We carried out research on efficiency of turbines under low current such as rivers and agriculture canals in order to choose the best type of them.