Tidal power Research Papers - Academia.edu (original) (raw)

In this project we are going to take deep look on tidal energy in the coastal line of India, about how tidal energy is a solution for our currents situation in this world with this climate and how tidal energy works it's basically deep knowledge on tidal energy in the basis of civil engineering work. The development of renewable energy around the world has been given increased importance due to concerns regarding energy supply and climate change. Wave and tidal energy are very important components of the renewable energies that can be extracted from the oceans. Different locations around the India have good natural conditions for one of these forms of energy, with some locations even being suitable for both.

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- Tidal power

Renewable energy can be used to decrease global dependence on natural resources, and tidal power can be the primary form of renewable power utilized. Built upon steam turbine knowledge, tidal turbines draw on innovative technology and design to operate on both the inflow and outflow of water through them. Tidal power utilizes twice the daily variation in sea level caused primarily by the gravitational effect of the Moon and, to a lesser extent by the Sun on the world's oceans. The Earth's rotation is also a factor in the production of tides.

- by Jacob Barnett
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- Control Systems Engineering, Renewable Energy, Control Systems, Automation
- by Richard Sanders
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- Tidal power

Abstract
In recent years, there have been growing international challenges relating to climate change and global warming, with a conflict developing between the need to create a low-carbon economy and rapid depleting reserves of fossil fuels. In addition to these challenges there continues to be the added complexity of a significant global increase in energy demand. Marine renewable energy from tidal barrages is carbon-free and has the potential to make a significant contribution to energy supplies now and in the future. Therefore, it is appropriate to evaluate the total energy that can be extracted from such barrages. In this study two different methods are proposed to estimate the total annual energy output from a barrage, including a theoretical estimation based on the principle associated with tidal hydrodynamics, and a numerical estimation based on the solutions obtained from a 2D hydrodynamic model. The proposed Severn Barrage in the UK was taken as a case study, and these two methods were applied to estimate the potential annual energy output from the barrage. The predicted results obtained using the two methods indicate that the magnitude of the annual energy output would range from 13 to 16 TWh, which is similar to the value of 15.6 TWh reported by the Department of Energy and Climate Change, in the UK. Further investigations show that the total annual energy output would increase by about 15% if a higher discharge coefficient were to be adopted for the sluice gates, or if the turbine performance were to be improved. However, the estimated
annual energy output could exceed the value of 16 TWh if future technological advances in both sluice gate construction and turbine performance are included.

- by Roger A Falconer
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- Renewable Energy, Numerical Modelling, Severn Barrage, Tidal power

52165111763 Dosen: Kadarusman, PhD 081210220725 PROGRAM SARJANA TERAPAN JURUSAN TEKNOLOGI PENGELOLAAN SUMBERDAYA PERAIRAN PROGRAM STUDI TEKNOLOGI PENGELOLAAN SUMBERDAYA PERAIRAN SEKOLAH TINGGI PERIKANAN JAKARTA 2017 BAB I PENDAHULUAN 1.1.... more

- by Delio Da Costa
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- Marine Ecology, Marine Conservation, Ecology, Tidal power

— This work presents a numerical simulation of a Vertical Axis Marine Current Turbines (VAMCT) in both steady and unsteady current velocities. Three different turbines were examined in this study in order to investigate the relationship between the current fluctuation frequency, the number of turbine blades and turbine frequency. Three, four and five blades turbines were numerically simulated. Fluent is used to solve the 2-D model using the time-accurate incompressible Unsteady Reynolds-averaged Navier-Stokes (URANS) equation with k-ω SST turbulence mode. The simulation results showed that there existed a significant relationship between the number of turbine blades, the turbine Tip Speed Ratio and the current fluctuation frequency. In an unsteady current the increase in the number of blades led to a reduction in the turbine's instability; however it might not increase the power performance especially at high TSR..

A survey of Early Christian sites, artefacts and monuments in County Down in English and Polish, tracing in particular the sites associated with St Patrick and his followers. This project has been funded by the European Union's PEACE III Programme, managed by the Special EU Programmes Body and delivered by the North Down, Ards and Down Councils' Cluster.

- by Michael King
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- Archaeology, Tidal Stream Energy, Early Christianity, Cultural Heritage Conservation

This thesis address ecological risks associated with the possible growth of marine renewable energy. Tidal power, wave power, ocean thermal energy conversion (OTEC) and currently expanding offshore wind power are likely to become common components of future seascapes. The world ocean is strongly affected by other marine activities and it is essential that the possible expansion of marine renewables takes place without causing further detriment to the ecosystem. Identifying possible ecological risks at an early stage of technical development facilitates adaptation and supports apposite regulation.

- by Linus Hammar
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- FISH, Ocean Energy, Environmental Impact, Tidal power

Tidal currents provide a significant energy source in many locations worldwide,
particularly at coastal areas where bathymetric conditions intensify their magnitudes.
Potential sites for tidal-stream energy resource harvesting require realistic assessments
and reliable simulations of effects of turbine arrays on tidal dynamics. Accuracy of
the analysis has direct implications on economic and technical aspects of tidal energy
project developments.
An alternative approach for simulating turbine array energy capture, momentum
sink-TOC, was developed to improve conventional methodologies for assessing tidalstream energy resource. The method uses a non-constant thrust force coefficient calculated based on turbines operating-conditions, and relates turbine near-field changes
produced by power extraction to turbine thrust forces. Sink-TOC combines linear momentum actuator disc in open channel flows theory with the momentum sink method.
Momentum sink-TOC was implemented in two depth-average complex hydrodynamic models to simulate different marine turbine configurations and to perform tidalstream energy resource assessments. The first model solves smooth and slow flows
(SSF) with an alternating direction implicit scheme. The second model solves rapidly
varying flows (RVF) combining MacCormack and total variation diminishing schemes.
The RVF solver incorporates a computational less expensive approach for simulating
sharp gradients produced by power extraction than existing techniques. Benchmarking
of numerical results against analytical solutions indicates that both models correctly compute momentum extracted by turbines.
Calculation of turbine velocity coefficients and head drops across turbine arrays
enabled the calculation of turbine efficiency, total power extracted, power dissipated
by turbine wake-mixing, and power available for electricity generation. These metrics
represent an advantage over traditional methodologies used to assess resources. As
sessment of bounded flow scenarios through a full fence configuration performed better
using the SSF solver, because head drop was more accurately simulated. However,
this scheme underestimates velocity reductions due to power extraction. Evaluation
of un-bounded flow scenarios through a partial-fence was better performed by the
RVF solver as the head drop was more correctly approximated by this scheme. The
free-surface flow simulations led to identification of non-uniform upstream conditions
for the partial-fence configuration. Computational performance comparisons indicated
that the RVF solver requires higher computational cost independently of domain-size,
and whether energy extraction procedure is incorporated or not.
Tidal-stream energy resource evaluations with fence and partial-fence configurations indicate that a computationally economical pre-assessment can be adequately
performed using an SSF solver. However, more accurate evaluation requires solution of
the discontinuities produced in the tidal-stream by power extraction. The methodol
ogy and numerical models obtained in this research could be use to determine realistic
upper limits of available power with turbine arrays in farm format in real-world coastal
environments.

h i g h l i g h t s " A new series of bi-directional HATT rotors was developed. " A generic wind/tidal turbine rotor design and optimization procedure was developed. " An unsteady, time-domain, and efficient panel method was developed and validated. " The code finished over 15,000 runs in 3 months while a RANS CFD will take 50 years. " A 53% power efficiency was achieved to produce extra energy of 1230 MW h/year. a b s t r a c t A series of bi-directional horizontal axis tidal turbine (HATT) rotors was prototyped. The geometry and motion parameters of the turbine series cover a wide range of tidal turbine operating conditions targeted to the tidal flow speed probability distribution of the Bay of Fundy, NS Canada. A generic yet novel wind/ tidal turbine rotor design and optimization procedure was developed and used for the optimization process. In the process, optimum annual energy production, as a benchmark, was obtained and used for comparison by taking into account both rotor hydrodynamic power production performance characteristics and annual tidal inflow speed probability distribution. The diameter of the full-scale bi-directional HATT rotor series developed is 20-m. Optimum values of various variables were obtained for maximum annual energy production. These optimum values include: uniform pitch-diameter-ratio (p/D) distributions, nominal pitch values with different curve forms of non-uniform p/D distributions, shaft rotational speeds under fixed rotor diameter, diameter at fixed tip-speed-ratio (TSR), a combination of optimum shaft speeds at corresponding inflow speeds and optimum uniform p/D distribution at a fixed rotor diameter, number of rotor blades at fixed chord length, rotor solidity at fixed number of blades, and the combination of number of blades and solidity for both optimum constant pitch distribution and optimum linear pitch distribution. For the 20-m bi-directional HATT, a substantial improvement in power coefficient C pow was obtained, from 0.28, as a result of the primary optimization process (for both optimum uniform p/D distribution and shaft speed n), to the final maximum of 0.43. This corresponds to a 56% increase in annual energy production of 1230 MW h, from 2188 to 3418 MW h, an improved energy production equivalent to the energy generated from 600 tonnes of coal (at 2 kW h per 1 kg coal from a standard thermal power plant). The annual energy production from the optimized 20-m bi-directional HATT before the deduction of mechanical and electrical conversion loses, is 3418 MW h, equivalent to the electric energy generated from 1550 tonnes of coal.

- by Neil Bose
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- Engineering, Economics, Tidal turbine, Tidal power

In December 2021, the US Department of Energy (DoE) unveiled the Office of Clean Energy Demonstrations with 21.5bninfederalfundingtodeploytheadvancedgreentechnologies.Themostsignificantportionofthebudget,21.5bn in federal funding to deploy the advanced green technologies. The most significant portion of the budget, 21.5bninfederalfundingtodeploytheadvancedgreentechnologies.Themostsignificantportionofthebudget,9.5bn, has been dedicated to renewable hydrogen to commercialize innovative technologies and establish four regional hubs and a recycling and manufacturing program. Green hydrogen is already the focus of the DoE's energy initiatives, which aims to mitigate the cost of renewable hydrogen production by 80% over the next decade.

- by Seyed Ehsan Hosseini
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- Renewable Energy, Wind Energy, Hydrogen, Fuel Cell

Tidal stream energy is a low-carbon energy source. Tidal stream turbines operate in a turbulent environment, and the effect of the structure between the turbine and seabed on this environment is not fully understood. An experimental study using 1:72 scale models based on a commercial turbine design was carried out to study the support structure influence on turbulent intensity around the turbine blades. The study was conducted using the wave-current tank at the Laboratory of Maritime Engineering (LABIMA), University of Florence. A realistic flow environment (ambient turbulent intensity = 11%) was established. Turbulent intensity was measured upstream and downstream of a turbine mounted on two different support structures (one resembling a commercial design, the other the same with an additional vertical element), in order to quantify any variation in turbulence and performance between the support structures. Turbine drive power was used to calculate power generation. Acoustic Doppler velocimetry (ADV) was used to record and calculate upstream and downstream turbulent intensity. In otherwise identical conditions, performance variation of only 4% was observed between two support structures. Turbulent intensity at 1, 3 and 5 blade diameters, both upstream and downstream, showed variation up to 21% between the two cases. The additional turbulent structures generated by the additional element of the second support structure appears to cause this effect, and the upstream propagation of turbulent intensity is believed to be permitted by surface waves. This result is significant for the prediction of turbine array performance.

A metamodel simulation based optimisation approach for the tidal turbine location problem is introduced. The method comprises design of experiments, computational simulations, metamodel construction and formulation of a mathematical optimisation model. Sample plans with different number of data points are used to fit 2nd and 3rd order polynomial as a function of two design parameters: longitudinal and lateral spacing, with a view to approximating the power output of tidal turbine farms with inline and staggered layouts, each Aquatic Science and Technology ISSN 2168-9148 2015 34 of them with a fixed number of turbines. The major advantage this method has, in comparison to those reported in the literature, is the capability to analyse different design parameter combinations that satisfy optimality criteria in reasonable computational time, while taking into account complex flow-turbine interactions.

- by Paulo Rosman and +1
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- Renewable Energy, Marine Renewable Energy, Tidal Stream Energy, Design of Experiments

Tuning wind and tidal turbines is critical to maximizing their power output. Adopting a wind turbine tuning strategy of maximizing the output at any given time is shown to be an extremely poor strategy for large arrays of tidal turbines in channels. This impatient-tuning strategy results in far lower power output, much higher structural loads and greater environmental impacts due to ow reduction, than an existing patient-tuning strategy which maximizes the power output averaged over the tidal cycle. This paper presents a smart patient tuning strategy, which can increase array output by up to 35% over the existing strategy. This smart strategy forgoes some power generation early in the half tidal cycle in order to allow stronger flows to develop later in the cycle. It extracts enough power from these stronger flows to produce more power from the cycle as a whole than the existing strategy. Surprisingly, the smart strategy can often extract more power without increasing maximum structural loads on the turbines, while also maintaining stronger flows along the channel. This paper also shows, that counter-intuitively, for some tuning strategies imposing a cap on turbine power output to limit loads can increase in a turbine's average power output.

- by Ross Vennell
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- Renewable Energy, Tidal Stream Energy, Tidal Stream Turbine Modelling, Tidal turbine

The UK is an internationally important area for tidal energy, with half of the extractable European tidal resource estimated to be in UK territorial waters [1]. Marine (wave and tidal) energy resources are said to have the potential to supply up to 20% of national electricity demand [2], and now is a critical time in the development of tidal energy, with a wide range of devices at the design and testing stage, some in the water, and a few generating meaningful amounts of electricity. The recent announcement of an increase in financial support for tidal devices is also a very positive development [3]. Many people believe that the UK tidal energy industry is currently in a similar position to the wind energy industry in the mid-1980s, and lies at the bottom of a very steep and exciting development curve.

- by Stuart Walker
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- Renewable Energy, Tidal power

Definition Renewable energy (RE) resources are those energy types that are replaced by natural processes over time. However, the noted definition is not complete. After the Industrial Revolution, the rate of energy resources utilization jumped, and as an example annual per capita energy consumption has been increased about 170% during 1750s to 1850s in England (Wrigley 2010). As a result, the definition of an RE resource has evolved to incorporate the replacing period, such that the consumption rate of an RE should be slower than the rate of which nature can replace them, unless the gap can be filled by human activities.

- by Reza Hafezi and +1
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- Renewable Energy, Wave Energy, Sustainable Development, Biomass

—This paper looks at how channel constriction affects the available power in a channel and the optimal turbine array design that maximises power production. Constricted channels have lower potentials than unconstricted channels but can generate more power from fewer turbines. Turbines placed in the constricted zone can achieve a higher blockage ratio as well as take advantage of the high velocity flow. These turbines must tolerate greater loads compared to turbines placed outside of the constriction. Using the power to load ratio as a crude indicator of array economics, we show that the most constricted part of the channel may also be the most economic place to build a turbine farm. For arrays consisting of multiple rows, constraints such as the minimum spacing between rows and the necessity of leaving a navigable area open, free of turbines, greatly affect the optimal array configuration. Compromises must be made between the average power per turbine and the total row power. The best array design depends on the final number of rows that will be in the array. Turbine power diminishes with the addition of each row and the significance of this effect is correlated to the degree of constriction in the channel.

- by Malcolm Smeaton and +2
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- Tidal Stream Energy, Tidal Stream Turbine Modelling, Tidal Renewable Energy, Tidal energy

Tidal energy is on the verge of commercial viability and full scale prototypes are meeting the challenges of the marine environment. The primary focus of the sector has concerned Horizontal Axis Tidal Turbines (HATTs); comprising a turbine supported by a tubular stanchion operating on a bi-directional, or yaw system. The direction of tidal flow, however, varies over the ebb or flood phases of a tidal cycle. This pa-per utilises tidal velocity data measured in Ramsey Sound (Pembrokeshire, Wales, UK), a macrotidal strait and proposed HATT installation site and combines with Computational Fluid Dynamics (CFD) to assess the impact of misalignment between a HATT and its surrounding free stream velocity. The majority of the veloci-ties within the northern area of Ramsey Sound tend to fall within a misalignment of ±20° for velocities greater than the economic viable threshold of 2 ms-1. However, bathymetry and coastline configuration influence both flow magnitude and direction. At the outer margins for the Sound, the velocities are acted upon by various promontories, reefs and shelving areas, which deflect and retard the flow, resulting in a flow direction greater than 20°, particularly towards the outer edges of the Sound. Utilising field data for numerical simulations will help inform the industry and increase investor confidence in this technology, whilst avoiding costly scaled ex-perimentation. It was found that an axial flow misalignment of ±10° results in approximately a 7% reduction in peak power, 3% in peak torque and 5% in peak thrust. The axial wake recovery length was shorter for the ±10° cases, recovering to 90% by 7D downstream, as opposed to 10D downstream for the aligned turbine.

- by Tim O'Doherty and +3
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- Mechanical Engineering, Oceanography, Tidal Stream Energy, Marine Science

Tidal and Wave energy devices are often discussed as a future contributor to the UK's energy mix, indeed marine energy resources are said to have the potential to supply up to 20% of national electricity demand [1]. However, these technologies are currently at development stage and make no meaningful contribution to the national grid. There are a number of companies working on devices which extract energy from the tides and waves, using various methods. This paper aims to compare two promising devices, one wave device and one tidal device, and assess the life cycle properties of each.

- by Stuart Walker
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- Renewable Energy, Tidal power, Wave Power

Computations of the blade loading and the local flow field around the Model Rotor Experiments In Controlled Conditions (MEXICO) rotor are presented using an actuator line method, implemented within the open source code OpenFOAM. The nacelle and near wake mesh refinement are shown to have little influence on the computed blade loads but a significant impact on the near wake flow field. In addition, the blade loads and near wake flow field calculated with 3 different distributions of the Gaussian smearing parameter ǫ are compared with experimental measurements. Local chord and lift coefficient scaled smearing distributions are shown to yield a significant improvement in the representation of the computed tip vortices and also a small improvement in the blade loading prediction, when compared with a spanwise constant smearing distribution. Despite these improvements in performance prediction, the performance of the rotor is shown to be more strongly influenced by the tip correction fac...

- by Aidan Wimshurst
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- Geology, Computational Fluid Dynamics, Tidal Stream Energy, Rotordynamics

This paper presents preliminary efforts in developing a rapid evaluation tool for tidal in-stream energy (TISE) in the Philippines. We study the possibility of using an energy density metric based on the sea surface elevation (SSE) or tide height difference at the boundaries of a site of interest as a gauge for the TISE potential of that site. Results show good correlation with high potential sites and the proposed metric. Verde Island Passage was assessed, through a combination of DELFT3D simulation and Matlab-based power computations, to have four potential TISE sites with a total energy density of 271.90 kW-h /m 2 in a month.

- by Enrico Paringit
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- Resource Allocation, Renewable energy resources, Tides, renewable Energy sources

h i g h l i g h t s " Tidal power extraction introduces far-field effects on flow speeds and water levels. " Potential power and impacts can be described with a 3-D hydrodynamic model. " Numerical model results should be calibrated and... more

- by Zafer Defne
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- Engineering, Economics, Tidal power, Applied Energy

Large arrays of tidal turbines are critical to realise the potential of tidal current power. This study is a systematic exploration of large tidal array optimisation in channels with numerically modelled array layouts in 2-D. Crucially, flow along channels is driven by head loss leading to significantly more realistic results than previous models which assume constant velocity. The 2-D adaptive mesh approach bridges the gap between large- and small-scale array models. Hundreds of layouts and turbine tunings have been simulated using LES of turbulent flow in tidally reversing currents to explore channel-scale optimisation and tuning of large arrays. Simulations show that total power capture increases as rows are added to the array although there are diminishing returns on additional turbines. Each turbine in 1 (7), optimally blocked row in a small channel captures 2.5× (0.5×) the power of an isolated turbine. There is an optimum blockage for maximum power per turbine which decreases linearly from 1.0 as the number of rows increases. As array size increases individual turbine wakes become less important than stepped head loss across each row. Free-stream velocity reduces linearly with total power capture, with the gradient increasing with channel size.

When selecting sites for marine renewable energy projects, there are a wide range of economical and practical constraints to be considered, from the magnitude of the resource through to proximity of grid connections. One factor that is not routinely considered in tidal energy site selection, yet which has an important role in quantifying the resource, is tidal asymmetry, i.e. variations between the flood and ebb phases of the tidal cycle. Here, we present theory and develop a high-resolution three-dimensional ROMS tidal model of Orkney to examine net power output for a range of sites along an energetic channel with varying degrees of tidal asymmetry. Since power output is related to velocity cubed, even small asymmetries in velocity lead to substantial asymmetries in power output. We also use the 3D model to assess how tidal asymmetry changes with height above the bed, i.e. representing different device hub heights, how asymmetry affects turbulence properties, and how asymmetry is influenced by wind-driven currents. Finally, although there is minimal potential for tidal phasing over our study site, we demonstrate that regions of opposing floodversus ebb-dominant asymmetry occurring over short spatial scales can be aggregated to provide balanced power generation over the tidal cycle.

Computations of the blade loading and local flow field around the Model Rotor Experiments In Controlled Conditions (MEXICO) rotor are presented using an actuator line method, implemented within the open source code OpenFOAM. The nacelle and near wake mesh refinement are shown to have little influence on the computed blade loads but a significant impact on the near wake flow field. In addition, the blade loads and near wake flow field calculated with 3 different distributions of the Gaussian smearing parameter are compared with experimental measurements. Local chord and lift coefficient based smearing distributions are shown to yield a significant improvement in the representation of the computed tip vortices and also a small improvement in the blade loading prediction, when compared with a spanwise constant smearing distribution. Despite these improvements in performance prediction, the performance of the rotor is shown to be more strongly influenced by the tip correction factor, where considerable improvement is still required before actuator line methods can represent real rotors with sufficient accuracy.

Hydrokinetic turbines, targeting the kinetic energy of fast-flowing currents, are under development with some turbines already deployed at ocean sites around the world. It remains virtually unknown as to how these technologies affect fish, and rotor collisions have been postulated as a major concern. In this study the effects of a vertical axis hydrokinetic rotor with rotational speeds up to 70 rpm were tested on the swimming patterns of naturally occurring fish in a subtropical tidal channel. Fish movements were recorded with and without the rotor in place. Results showed that no fish collided with the rotor and only a few specimens passed through rotor blades. Overall, fish reduced their movements through the area when the rotor was present. This deterrent effect on fish increased with current speed. Fish that passed the rotor avoided the near-field, about 0.3 m from the rotor for benthic reef fish. Large predatory fish were particularly cautious of the rotor and never moved close...

- by Linus Hammar
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- Engineering, Botany, Physics, Chemistry

Because of electricity requirement keep increased and similar type of islands in Indonesian, we proposed to implemented these tidal power plant as a renewable energy that can be useful for our future and to reach the target of... more

- by Brandon Noya
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- Renewable Energy, Power Plants, Tidal power

The Maine Tidal Power Initiative (MTPI), an interdisciplinary team of engineers, marine scientists, oceanographers, and social scientists, is using a transdisciplinary sustainability science approach to collect biophysical and social data necessary for understanding interactions between human and natural systems in the context of tidal power development in Maine. MTPI offers a unique opportunity to better understand how group structure and process influence outcomes in transdisciplinary sustainability science research. Through extensive participant observation and semi-structured interviews we: (1) describe MTPI’s organizational structure; (2) examine MTPI’s research approach and engagement with stakeholders from different sectors of society (i.e., industry, government, and the local community); and (3) identify challenges and opportunities for involving different disciplinary expertise and diverse stakeholders in transformational sustainability science research. We found that MTPI’s holistic mission, non-hierarchical structure, and iterative stakeholder engagement process led to important benefits and significant challenges. Positive outcomes include knowledge development, a transferable research framework, shared resources, personal reward, and a greater understanding of the local environment and community. Challenges identified include balancing diverse interests and priorities, maintaining engagement, managing stakeholder relationships, and limited resources. Lessons learned from the process of integrative collaborative research in Maine can offer guidance on what should be considered when carrying out similar transdisciplinary sustainability science projects in other research contexts.

Citation: Falconer R A, Xia J Q, Lin B J, et al. The severn barrage and other tidal energy options: Hydrodynamic and power output modelling.

Controllers for a pitch and a stall regulated horizontal axial flow, variable-speed tidal stream turbine are developed, and a performance comparison is carried out. Below rated flow speed, both turbines are operated in variable-speed mode so that the optimum tip-speed ratio is maintained. One of the turbines has variable pitch blades, which above rated speed are pitched to feather in order to regulate power. The other turbine has fixed pitch blades and uses speed-assisted stall to regulate power. The control system design behind both strategies is examined in MATLAB, with the performance under turbulent flows, loading and energy yield analysis being evaluated in GH Tidal Bladed. Both strategies provide a satisfactory performance, but the out-of-plane loads on the stall regulated turbine were higher over the entire range of operation. In addition, the dynamic characteristics of the stall regulated turbine require a more complex control design. The results suggest that the pitch regulated turbine would be a more attractive solution for turbine developers.

- by IJERA Journal
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- Renewable Energy, Control, Tidal Stream Turbine Modelling, Tidal power

Many coastal areas around the UK are configured such that tidal currents are accelerated by headlands and islands making them attractive tidal energy sites. Efforts to reduce energy dependency on fossil fuels have prompted examination of these macrotidal and nearshore sites for potential tidal-stream resource development. A number of prospective tidal energy sites have been identified around the UK, however, little is known about the specific, and often complicated, hydrodynamics in many of these systems. Understanding the ways in which coastal features affect tidal velocities at potential tidal stream turbine (TST) development sites will help understand the resource and identify potential constraints on tidal energy output and the key physical parameters to consider when identifying suitable sites for tidal stream turbines.
This paper presents and examines tidal velocity data measured in Ramsey Sound (Pembrokeshire, Wales, UK), a macrotidal strait that accommodates circulation from the Irish Sea with peak spring tide velocities exceeding 3 m s-1. Although this coastal area is soon to become the first tidal-stream turbine (TST) demonstration site in Wales, little known about the intricacies of the local tidal dynamics.
Ramsey Sound exhibits a marked flood-dominated asymmetry. Furthermore, local bathymetric features affect flow fields that are spatially heterogeneous in three dimensions, patterns that depth-averaged velocity data (measured and modelled) tend to mask. By examining physical characteristics including flow velocities across the blade sweep (15 m diameter) of a tidal-stream turbine (TST), estimated power output, water depth, and bed slope, it is shown that spatial and temporal variability in the flow field renders much of Ramsey Sound unsuitable for tidal power extraction. Although first-order appraisals may make energetic tidal straits attractive sites for development, realizing their resource potential depends on flow conditions that are fundamentally local. Tidal-energy developers must therefore rely on detailed characterisation of tidal energy sites prior to device field trials and installation.

- by Paul Evans and +1
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- Hydrology/Hydrography, Oceanography, Hydrodynamics (Physics), Hydrography

Turbines are playing a massive role in our day-today lives in the back-end portion of lifestyles where they have been efficiently providing us energy through tidal, hydrological, and many such other mediums. A dominant explanation for the need for energy production has been introduced in the 1800s since the requirement for a high consumption of energy in various forms has started taking place. A very common method that has been observed in today's innovative mannerism is the use of turbines in dams, undersea, elsewhere at locations where the flow of fluid induces better outputs. Vertical axis turbines, Francis turbines as well as Kaplan turbines have frequently opted for such purposes but after studying over 65 works done by adepts, professionals, and experts; the purposely implemented input that is required to fulfill the output doesn't have to always be a necessity, it seemed to be the new designing restructured platform for users as well as providers. An overture to install micro versioned turbines of macro hydroelectric power plants within a residential or commercial structure at the main water-supply connections either at their junctions or directly near the overhead water tanks cannot just provide subtle but fortifying and tireless inputs since the flow of water will be anticipated naturally by the implicated outcomes through day-today chores performed. Hydrokinetic conversion systems may appear suitable in harvesting energy from such renewable resources, despite the fact that they are still in the early stages of development. Contrary to what has been assumed, there are numerous possibilities for the utilization of this energy for common areas/public zones such as signals, street lights, or any such productive amenities to bestow leading-edge facilities without any hitch regarding external contriving inputs.

- by Aayush Khokhani
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- Renewable Energy, Marine Engineering, Wind Power, Wind turbine

This report focuses on various power generation sources in a remote location, various ways to save power, and combining them using the perfect substation and transformer. This report also focuses on a brief power factor correction.

- by Pratyush Ghosh
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- Power Electronics, Hydro Power, Wind Power, Biofuel

Ocean ice capable of impacting marine operations occurs periodically in the most favorable sites for energy harvest from the tidal currents of the Bay of Fundy in Nova Scotia and New Brunswick. In-stream tidal current harvesting devices deployed at these sites should be engineered to tolerate at least 30% ice cover with 15 cm (6 inch) thick floes at least 100 metres in length. Propelled by tidal currents and prevailing winds, ice floes may achieve velocities in excess of 8 knots in some locations. In very severe winters, in-stream tidal current harvesting devices may be subjected to periods of 90% cover of rapidly moving or packed ice thicker than 30 cm (12 inches).
Markets for ice-tolerant tidal current harvesting devices developed under the moderate ice conditions in the headwaters of the Bay of Fundy may exist in other jurisdictions with energetic tidal flows which experience more severe conditions of ocean ice.

- by Richard Sanders
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- Tidal power

Development of renewable energy affects or is affected by numerous stakeholders. Understanding who the stakeholders are and how they are engaged in the process is necessary for improving the responsible development of renewable energy technologies. Using structured community interviews and in-depth ethnographic research (semi-structured interviews, informal interviews, observations, and document review), we identified and characterized the most salient stakeholders associated with tidal power development in Maine and documented stakeholder perceptions of developer engagement strategies. Stakeholder characterization was facilitated using a framework by Mitchell et al. (The Academy of Management Review 22:853–886, 1997) that characterizes salient stakeholders using attributes of power, urgency, and legitimacy. Key stakeholders identified include fishermen, community members, tribes, regulators, developers, and scientists. Fishermen and regulators are definitive stakeholders, with legitimacy, power, and urgency in the process. Tribes are considered dominant stakeholders; they have legitimacy and power, but their interests are, at this time, not viewed as urgent. Scientists are considered to have urgency and power. The developers viewed their stakeholder engagement strategy as open and transparent. Community stakeholders, regulators, and fishermen generally perceived the developer's approach as effective; they noted the company's accessibility and their efforts to engage stakeholders early and often. Given the dynamic nature of stakeholder salience, our findings highlight the importance of engaging dominant stakeholders so that future conflict can be more easily avoided as new information develops. Our approach can be used to inform stakeholder identification and engagement research in other renewable energy contexts.

- by Teresa R Johnson
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- Tidal power

Tidal currents are a promising source for future power generation given their periodicity and predictability. Therefore, numerical hydrodynamic models are frequently utilized for resource assessments. However, the relevant scales of the simulations and hence modeling techniques depend on the problem at hand. This paper shows the potential of the grid refinement technique for the assessment of tidal current energy for particular sites given its relatively low computational expense and high accuracy for the regions with the refined resolution. Example applications are described for mapping the tidal resources near two facilities (Portsmouth Naval Shipyard in Maine and Key West Naval Station in Florida) for possible future deployments of Marine Hydro-Kinetic technologies. The grid refinement capability in the coupled ocean-atmosphere-wave-sediment transport modeling system is used to improve the spatial resolution in the regions of interest, and has shown significant advantage over the original simulation results for the tidal power assessment. The numerical simulation results from both the original coarse grids and the refined grids are validated with measured tidal constituents at available locations. This study demonstrates how the enhancement of a model system for a regional tidal energy with grid refinement can assist with the performance of site specific resource assessments with modest computational expense.

- by Xiufeng Yang
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- Tidal Stream Energy, Tidal Renewable Energy, Tidal energy, Tidal power

Wales supports the use of fish recovery and return (FRR) systems at thermal power station cooling water intakes as part of fish protection measures. New guidance on eel (Anguilla anguilla) screening to meet the latest regulatory requirements also proposes possible modification of existing travelling band and cup screens at raw-water pumping stations for FRR as a means of eel screening. While FRR technology has been available for many years, its use and operational experience are still quite limited, and there are few existing examples that would meet current BAT guidance. Operators trying to introduce FRR are having to push the boundaries of existing knowledge to meet BAT standards. Some of the issues are explored and solutions discussed.

- by andy turnpenny
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- Fish Migration, Tidal power, Fisheries Engineering

Much of the global tidal current energy resource lies in the accelerated flows along narrow channels. These channels have the potential to produce 10s -1000s of MW of electricity. However, realizing 100 MW of a channel's potential is much more complex than installing 100 one MW turbines because large scale power extraction reduces tidal currents throughout the channel, changing the resource. This synthesis and review gives an overview of the issues and compromises in designing the layout of the large tidal turbine arrays required to realize this potential. The paper focuses on macro-and micro-design of arrays. Macro-design relates to the total number of turbines and their gross arrangement into rows, while micro-design adjusts the relative positions of the turbines within a grid and the spacing between rows. Interdependent macro-design compromises balance the total number of turbines, array power output, the power output of each turbine, the loads turbines experience, turbine construction costs, maintaining navigability along the channel and any environmental impacts due to flow reduction. A strong emphasis is placed on providing physical insights about how "channel-scale dynamics" and the "duct-effect" impact on the compromises in array design. This work is relevant to the design of any "large" array which blocks more than 2%-5% of a channel's cross-section, be it 2 turbines in a small channel or 100 turbines in a large channel.

- by Tim Divett
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- Tidal Stream Energy, Tidal energy, Tidal power

Tidal stream turbines deployed in large arrays will need to be optimally arranged for maximum energy extraction to operate economically. Large Eddy Simulations are used to explore the channel scale optimisation and tuning of large array layout. Adaptive mesh and idealisations reduced the simulation time, allowing simulation of hundreds of tuned layouts with reasonable computational cost. Flow is driven by an elevation gradient, so the velocity reduces as turbines are added, allowing comparison of large arrays that remove a significant fraction of the natural velocity. If the array is restricted to only partially block the channel's width then the optimum layout depends on the number of packed rows in the array. Turbines should be packed densely on one side of the channel for one row and less densely packed for increasing rows. Greater total power is captured as rows are added to the array although the power that each turbine captures reduces as rows are added. The adaptive approach bridges the gap between large and small scale models of arrays and this may be the first paper to numerically model array layout with packed rows or tuning at a channel scale.

- by Ross Vennell and +1
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- Fluid Dynamics, Tidal power, Tidal Energy Arrays, Adaptive Mesh Modelling

Abstract
The Severn Estuary has a spring tidal range approaching 14 m and is regarded as having one of the highest tidal ranges in the world. Various proposals have been made regarding the construction of a tidal barrage across the estuary to enable tidal energy to be extracted. The barrage scheme originally proposed by the Severn Tidal Power Group (STPG) would be the largest project for tidal power generation in the world if built as proposed. Therefore, it is important to study the impact of different operating modes for this barrage on the tidal power output and flood inundation extent in the estuary. In this paper, an existing two-dimensional hydrodynamic model based on an unstructured triangular mesh has been integrated with a new algorithm developed for the estimation of tidal power output, which can account for three barrage operating modes, including ebb generation, flood generation, and two-way generation. The refined model was then used to investigate the impact of different barrage operating modes on the tidal power output and the associated extent of flood inundation along the Severn Estuary. Predicted results indicate that the mode of flood generation would produce the least electricity energy and cause a larger reduction in the maximum water levels upstream of the barrage. Two-way generation would provide an improvement to these conditions, and produce an equivalent amount of electricity to that from ebb generation, with a low installed capacity and a small loss of intertidal zones. Therefore, the mode of ebb generation or two-way generation would appear to be a preferred option for power generation, because both would offer benefits of acceptable electricity energy and reduced flood risk.

- by Roger A Falconer
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- Flood modelling, Adaptation to Coastal Flooding, Severn Barrage, Tidal power

ABSTRACT Much of the global tidal current energy resource lies in the accelerated flows along narrow channels. These channels have the potential to produce 10s -1000s of MW of electricity. However, realizing 100 MW of a channel’s potential is much more complex than installing 100 one MW turbines because large scale power extraction reduces tidal currents throughout the channel, changing the resource. This synthesis and review gives an overview of the issues and compromises in designing the layout of the large tidal turbine arrays required to realize this potential. The paper focuses on macro- and micro-design of arrays. Macro-design relates to the total number of turbines and their gross arrangement into rows, while micro-design adjusts the relative positions of the turbines within a grid and the spacing between rows. Interdependent macro-design compromises balance the total number of turbines, array power output, the power output of each turbine, the loads turbines experience, turbine construction costs, maintaining navigability along the channel and any environmental impacts due to flow reduction. A strong emphasis is placed on providing physical insights about how channel-scale dynamics” and the “duct-effect” impact on the compromises in array design. This work is relevant to the design of any “large” array which blocks more than 2%-5% of a channel’s cross-section, be it 2 turbines in a small channel or 100 turbines in a large channel.

- by Tim Divett
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- Engineering, Renewable Energy, Marine Renewable Energy, Tidal Stream Energy

The suggested project aims at evaluating the potential for a successful implementation of renewable energy sources in the coastal zone of tropical developing countries integrating results from different scientific disciplines (ecology, social science and technology) into a useful support for development policy. Its emphasis will be on remote areas where poor infrastructures raise the demand for independent electricity supplies. Moreover, the project intends to identify key-issues and sociotechnical pathways for a future integration of suitable renewable energy sources in such areas. The research will be based on analyses of the relationships between technical, ecological and social systems and focus on applying adequate technology in a socially and ecologically feasible way. The energy sources considered will be selected from local natural flowing resources, i.e. mainly tidal, stream, and wave energies. With funding from Sida (SAREC Planning Grant) and Adlerbertska Forskningsstiftel...

- by Linus Hammar
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- Geography, Renewable Energy, Developing Countries, Tidal power
- by Enrico Paringit
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- Environmental Science, Resource Allocation, Renewable energy resources, Tides

Several approaches can be used for estimating tidal power potential. From a theoretical point of view, others have shown that the problem can be reduced to a single or multiple boundary problem with simple geometry where each case has a well defined maximum power potential. From a practical point of view, the potential can be approximated from the ambient flow. Questions naturally arise whether the theoretical approach can be applied to a typical field-scale problem, and whether the practical approach has any validity. In order to provide more insight into these questions, form drag representing tidal turbines has been introduced into a numerical flow model. This is an unstructured grid model with an implicit treatment of wetting and drying that has been shown to be robust, accurate, and efficient for highly irregular coastal ocean environments and is well suited for this problem. The field site that has been examined is Minas Passage in the Bay of Fundy which provides an interesting practical perspective for this problem. In the end, only a fraction of the theoretical maximum power potential can be realized in practice because of physical constraints on the maximum form drag for tidal turbines.

- by Clayton Hiles
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- Mechanical Engineering, Renewable Energy, Tidal power, Form Drag

- by Raad Qassim
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- Renewable Energy, Marine Renewable Energy, Tidal Stream Energy, Design of Experiments

- by Eduardo González-Gorbeña and +1
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- Renewable Energy, Marine Renewable Energy, Tidal Stream Energy, Design of Experiments

Tidal energy is one of the important form of marine Energy. The tidal energy is extracted from naturally occurring phenomena of rise and fall of the ocean's water level. When the angle made by sun, and moon with respect to earth is zero degree the highest and lowest tides produced due to adding up of pulling forces, called spring tides. When the angle made by moon and sun with respect to earth is 90 degree, the tides produced are not as high or low as at other times of the month, called neap tides. Tidal energy is one of the most predictable and promising form of ocean energy due to its non-polluting, clean, reliable, and non-depleting nature. Number of techniques like Tidal barrages, tidal stream turbines to harness tidal energy are under development. Thus, they provide the best opportunity to harness energy from the oceans. In this paper, the Indian tides location and some tide location all over the world, tidal power plants all over the world are discussed.

- by Prerna Goswami
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- Renewable Energy, Electricity, Tidal power