Inflow Measurement in a Tidal Strait for Deploying Tidal Current Turbines: Lessons, Opportunities and Challenges

2010 ◽  
Author(s):  
Ye Li ◽  
Jonathan A. Colby ◽  
Neil Kelley ◽  
Robert Thresher ◽  
Bonnie Jonkman ◽  
...  
Keyword(s):  
Tidal Current ◽  
Laboratory Tests ◽  
Critical Factor ◽  
Tidal Energy ◽  
Background Information ◽  
Commercial Development ◽  
Mean Velocity ◽  
Topic Area ◽  
East River ◽  
Turbine Performance

Tidal energy has received increasing attention over the past decade. This increasing focus on capturing the energy from tidal currents has brought about the development of many designs for tidal current turbines. Several of these turbines are progressing rapidly from design to prototype and pre-commercial stages. As these systems near commercial development, it becomes increasingly important that their performance be validated through laboratory tests (e.g., towing tank tests) and sea tests. Several different turbine configurations have been tested recently. The test results show significant differences in turbine performance between laboratory tests, numerical simulations, and sea tests. Although the mean velocity of the current is highly predictable, evidence suggests a critical factor in these differences is the unsteady inflow. To understand the physics and the effect of the inflow on turbine performance and reliability, Verdant Power (Verdant) and the National Renewable Energy Laboratory (NREL) have engaged in a partnership to address the engineering challenges facing marine current turbines. As part of this effort, Verdant deployed Acoustic Doppler Current Profiler (ADCP) equipment to collect data from a kinetic hydropower system (KHPS) installation at the Roosevelt Island Tidal Energy (RITE) project in the East River in New York City. The ADCP collected data for a little more than one year, and this data is critical for properly defining the operating environment needed for marine systems. This paper summarizes the Verdant-NREL effort to study inflow data provided by the fixed, bottom-mounted ADCP instrumentation and how the data is processed using numerical tools. It briefly reviews previous marine turbine tests and inflow measurements, provides background information from the RITE project, and describes the test turbine design and instrumentation setup. This paper also provides an analysis of the measured time domain data and a detailed discussion of shear profiling, turbulence intensity, and time-dependent fluctuations of the inflow. The paper concludes with suggestions for future work. The analysis provided in this paper will benefit future turbine operation studies. In addition, this study, as well as future studies in this topic area, will be beneficial to environmental policy makers and fishing communities.

scholarly journals A Study on Diffuser Augmentation of a Tidal Turbine

2021 ◽  
Vol 83 (1) ◽  
pp. 170-177
Author(s):  
Evi Elisa Ambarita ◽  
Harinaldi ◽  
Nasruddin ◽  
Ridho Irwansyah
Keyword(s):  
Tidal Current ◽  
Fluid Dynamic ◽  
Tidal Energy ◽  
Power Coefficient ◽  
Optimized Design ◽  
Inflow Velocity ◽  
Cavitation Inception ◽  
Turbine Performance ◽  
Tidal Turbine ◽  
Turbine Design

As tidal energy is progressively earning attention worldwide, there is a lot of existing research about the tidal current potency and the tidal turbine design. Especially on turbine design, existing studies deduced that a diffuser augmentation is a superior choice to increase the turbine performance. However, the research in finding the best diffuser angle whose efficiency is maximum, yet minim cavity risk is still limited. Therefore, this study proposes an innovative, optimized design method on diffuser augmentation of a tidal turbine by comparing four diffuser angles in three inflow velocity circumstances. In particular, three airfoil blades design with a rotor diameter of 0.3 m was developed. The combination of computational fluid dynamic and multi-objective optimization using a general algorithm coupled with the artificial neural network was applied by considering the turbine’s power coefficient and cavitation inception as a trade-off objective. The numerical results display that the different inflow velocity affects the turbine performance insignificantly. The optimization analysis and comparison among four diffuser angles in three variations of inflow velocity show that the tidal turbine's optimal design with diffuser augmentation could be applied to all tidal current speed.

Bridging the Gap With Choosing Wisely Recommendations: What Laboratory Topics Matter Most to Other Medical Specialty Societies?

2019 ◽  
Vol 152 (Supplement_1) ◽  
pp. S143-S143
Author(s):  
Barbara Caldwell
Keyword(s):  
Women’S Health ◽  
Women's Health ◽  
Laboratory Tests ◽  
Pap Smear ◽  
Medical Specialty ◽  
Laboratory Medicine ◽  
Choosing Wisely ◽  
Topic Area ◽  
Medical Specialties ◽  
Smear Testing

Abstract Introduction This study sought to evaluate the nature and frequency of laboratory recommendations made by medical societies other than ASCP. Methods Review of all 2012 to 2018 ABIM Choosing Wisely (CW) non-ASCP laboratory recommendations and categorization of recommendations per topic area. Results There are 107 total recommendations made by other medical specialties that involve laboratory medicine. The most common recommendations are (1) Transfusion Medicine: to minimize transfusion of PRCs (19 recommendations, 18%); (2) Women’s Health: Pap smear testing, other women’s health testing (18 recommendations, 17%); and (3) General Laboratory: reducing repetitive routine laboratory tests (10 recommendations, 9%). Most (64, 60%) recommendations addressed screening while 29 (27%) focused on treatment and 14 (13%) were related to monitoring disease. Conclusion Almost one-half (44%) of all recommendations fell into three common areas and there were more recommendations related to screening for disease than for treatment or monitoring. For Choosing Wisely to achieve increasing success, increasing efforts are needed to disseminate this information, promote multidisciplinary effective test utilization, and encourage continued laboratory medicine recommendations from all medical stakeholders.

scholarly journals ESTIMATION OF ELECTRICITY GENERATED FROM TIDAL ENERGY IN BEDONO VILLAGE OF DEMAK REGENCY

2020 ◽  
Vol 4 (9) ◽  
pp. 13-17
Author(s):  
Agus Margiantono ◽  
Titik Nurhayati ◽  
Wahib Hasbullah
Keyword(s):  
Electric Power ◽  
Current Velocity ◽  
Tidal Current ◽  
Tidal Energy ◽  
Tidal Currents ◽  
Active Power ◽  
Tidal Current Velocity ◽  
The Village

In some places in the village of Bedono Demak Regency there is a location with high tidal current velocity, the coordinates of the Location is 6 ° 55'29.0 "S 110 ° 29'11.4" E. In this study estimated the amount of electric power that can be generated from tidal currents in the village Bedono. Estimates are made by modeling the location and the Darrieus turbine using the CFD (Computating Fluid Dinamyc) Software. From the research that has been done to get the results of electric power that can be produced in the village Bedono highest at 14-16 times 3469.413W and lowest 39.002W at 22-24 hours according to the CFD is the highest active power occurred at 14-16 at 3197.064W and the lowest 35.941W at 22-24 hours.

Advances in Fisheries Bioengineering

2008 ◽  
Keyword(s):  
Swimming Speed ◽  
Critical Factor ◽  
Lake Sturgeon ◽  
Acipenser Fulvescens ◽  
Mean Velocity ◽  
Shovelnose Sturgeon ◽  
Pectoral Fins ◽  
Fish Ladder ◽  
Juvenile Sturgeon ◽  
Sturgeon Species

<em>Abstract</em>.—Fish ladder designs that pass adult sturgeons are poorly studied. This is partly due to difficulties associated with obtaining and testing large adults. To learn about behavior and swimming of sturgeons in fish ladder environments, we observed juvenile lake sturgeon <em>Acipenser fulvescens </em>to determine the type of ladder opening that fish passed best. We also constructed a short fish ladder (6% slope) using the best opening type and determined the general usefulness of the ladder design to pass juvenile lake sturgeon, pallid sturgeon <em>Scaphirhynchus albus </em>and shovelnose sturgeon <EM>S</EM>. <em>platorynchus</em>. Lake sturgeon swam upstream through orifice and vertical openings better than through surface weir or weir and orifice openings. Because 37% of the fish hit the orifice when swimming upstream, and also, sturgeon could be damaged passing downstream through an orifice, we focused on testing a ladder design with vertical openings. A side-baffle ladder design that created vertical openings that alternated from side to side showed promise at passing the three species of sturgeons. All lake sturgeons (<EM>N </EM>= 15), most pallid sturgeons (12 of 22 fish, 55%), and 1 of 3 shovelnose sturgeons ascended the side-baffle design. Also, all sturgeon species moved safely downstream in the side-baffle ladder by passively drifting tail-first. Mean velocity in side-baffle openings was 60–75 cm/s, so sturgeons could use prolonged swimming speed to swim upstream. Vertical openings were wide enough for fish to partially erect their pectoral fins, likely a critical factor for maintaining balance. Our observations suggest that a ladder for adults should have vertical openings, enable fish to swim continuously and not stop at cross-channel barriers, have resting areas, enable fish to safely drift downstream, and enable fish to swim upstream using prolonged swim speed. The study of juvenile sturgeon behavior and swimming ability can contribute to developing a fish ladder for adults. This approach to fish ladder development can be used for other species with large adults.

Modelling Wave-Current-Turbulence Interactions for Tidal Energy Applications

2020 ◽  
Author(s):  
Vengatesan Venugopal ◽  
Arne Vögler
Keyword(s):  
North Atlantic ◽  
Tidal Current ◽  
Current Model ◽  
Coupled Model ◽  
Wave Model ◽  
Tidal Energy ◽  
The North ◽  
Wave Parameters ◽  
The North Atlantic ◽  
Coupled Wave

Abstract This paper presents the nature of turbulence parameters produced from 3-dimensional numerical simulations using an ocean scale wave-tidal current model applied to tidal energy sites in the Orkney waters in the United Kingdom. The MIKE 21/3 coupled wave-current model is chosen for this study. The numerical modelling study is conducted in two stages. First, a North Atlantic Ocean large-scale wave model is employed to simulate wave parameters. Spatial and temporal wind speeds extracted from the European Centre for Medium Range Weather Forecast (ECMWF) is utilised to drive the North Atlantic wave model. Secondly, the wave parameters produced from the North Atlantic model are used as boundary conditions to run a coupled wave-tidal current model. A turbulence model representing the turbulence and eddy viscosity within the coupled model is chosen and the turbulence kinetic energy (TKE) due to wave-current interactions are computed. The coupled model is calibrated with Acoustic Doppler and Current Profiler (ADCP) measurements deployed close to a tidal energy site in the Inner Sound of the Pentland Firth. The model output parameters such as the current speed, TKE, horizontal and vertical eddy viscosities, significant wave height, peak wave period and wave directions are presented, and, their characteristics are discussed in detail.

scholarly journals Geotechnical and Minerology Properties of Marine Clay at the Northeast of Penang Island

2018 ◽  
Vol 203 ◽  
pp. 04005
Author(s):  
Nik Mohd Kamel Nik Hassan ◽  
Suhaizan Wahid ◽  
Mohd Taha Abd Wahab
Keyword(s):  
Laboratory Tests ◽  
Soft Clay ◽  
Field Work ◽  
Design Parameters ◽  
Marine Clay ◽  
Commercial Development ◽  
Cone Penetration Tests ◽  
Subsurface Investigation ◽  
Two Phases ◽  
Clay Layers

A series of subsurface investigation including in-situ and laboratory tests has been carefully planned and executed for a proposed residential and commercial development over soft marine clay at Tg Tokong, Penang Island. This paper presents the approach taken in determining and developing fundamental geotechnical engineering design parameters of the soft clay. The subsurface investigation was carried out in two phases to suit the overall development implementation plan namely subsurface investigation done near-shore with about 70 nos of boreholes, 50 nos of cone penetration tests (CPT) and 100 nos of Mackintosh probes and those that were carried out off-shore with 72 Nos of boreholes. The samples extracted from the field work were subjected to grain size analyses, Atterberg limits, oedometer test and consolidated undrained compression. Subsequently, correlations were established between physical soil properties with undrained shear strength from field vane and laboratory tests. The subsurface investigation has suggested that the soft marine clay at the northeast of Penang island comprises of a very soft upper marine clay layer overlying a stiffer lower marine clay. An intermediate stiff clay is sandwiched between these two marine clay layers. The soft clay was also subjected to x-ray diffraction to observe the minerology make up. The primary clay mineral was kaolinite/chlorite followed by smectite. The clay is anticipated to pose minimum effect onto the swelling and compression behaviour.

scholarly journals Comparative Investigations of Tidal Current Velocity Prediction Considering Effect of Multi-Layer Current Velocity

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6417
Author(s):  
Bo Feng ◽  
Peng Qian ◽  
Yulin Si ◽  
Xiaodong Liu ◽  
Haixiao Yang ◽  
...  
Keyword(s):  
Machine Learning ◽  
Current Velocity ◽  
Tidal Current ◽  
Learning Algorithms ◽  
Critical Role ◽  
Tidal Energy ◽  
Machine Learning Algorithms ◽  
Tidal Current Velocity ◽  
Velocity Prediction ◽  
Prediction Approach

Accurate tidal current prediction plays a critical role with increasing utilization of tidal energy. The classical prediction approach of the tidal current velocity adopts the harmonic analysis (HA) method. The performance of the HA approach is not ideal to predict the high frequency components of tidal currents due to the lack of capability processing the non-astronomic factor. Recently, machine learning algorithms have been applied to process the non-astronomic factor in the prediction of tidal current. In this paper, a tidal current velocity prediction considering the effect of the multi-layer current velocity method is proposed. The proposed method adopts three machine learning algorithms to establish the prediction models for comparative investigations, namely long-short term memory (LSTM), back-propagation (BP) neural network, and the Elman regression network. In the case study, the tidal current data collected from the real ocean environment were used to validate the proposed method. The results show that the proposed method combined with the LSTM algorithm had higher accuracy than both the commercial tidal prediction tool (UTide) and the other two algorithms. This paper presents a novel tidal current velocity prediction considering the effect of the multi-layer current velocity method, which improves the accuracy of the power flow prediction and contributes to the research in the field of tidal current velocity prediction and the capture of tidal energy.

scholarly journals Marine Scour and Offshore Wind: Lessons Learnt and Future Challenges

2011 ◽  
Author(s):  
John M. Harris ◽  
Richard J. S. Whitehouse ◽  
James Sutherland
Keyword(s):  
Hazard Assessment ◽  
Wind Farms ◽  
Tidal Energy ◽  
Offshore Wind ◽  
Commercial Development ◽  
Offshore Wind Farms ◽  
Energy Devices ◽  
Lessons Learnt ◽  
Future Challenges ◽  
Scour Hazard

The drive for developing marine offshore renewables has led to specific requirements for scour hazard assessment relating to the associated foundation structures and the cabling necessary for in-field transmission and power export. To date within the United Kingdom (UK) a number of demonstrator projects have been constructed covering wind, wave and tidal generation. However, only offshore wind has been developed at large-scale at present as part of two rounds of commercial development of offshore wind farms (OWFs). In June 2008, The Crown Estate, responsible for licensing seabed use, announced proposals for a third round of offshore wind farms to develop an additional 25 GW of energy to the 8 GW already planned for under Rounds 1 and 2. The size of these Round 3 developments will vary, but the largest of these zones will involve the construction of around 2500 seabed foundation structures. Under Round 1 and 2 developments monopile and jacket type foundations have been used, although several other European (non UK) wind farms have been built using gravity base foundations. For a wind turbine the foundations may account for up to 35% of the installed cost. Therefore, one of the future challenges for large volume installation of offshore wind is the control and minimization of these costs. For tidal energy devices one of the principal requirements for many of the devices proposed is their placement in areas of strong tidal energy, and this has implications not only for the stability of the foundation option, but also for the construction methodology. Similarly wave energy devices are designed to be located in shallow, coastal environments as either floating or bottom mounted systems. These devices, by design, are intended to be located in environments with strong wave action. This may be substantial during storm events, which has implications for the integrity of the anchoring system keeping the wave device on station or the design of the device if it is seabed mounted. This paper will explore the lessons learnt from existing offshore wind farm developments as this represents the principal body of collected monitoring data. Using these data the paper will outline some of the challenges facing the offshore renewable industry in respect of the foundation designs and specifically the requirements for scour hazard assessment using the combined experience from those developments currently operational or under construction.

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