Estimation of the Energy Potential of the Euripus' Gulf Tidal Stream Using Channel Sea-surface Slope

2015 ◽  
Vol 3 (4) ◽  
pp. 23-42 ◽  
Author(s):  
Aphrodite Ktena ◽  
Christos Manasis ◽  
Dimitrios Bargiotas ◽  
Vasilis Katsifas ◽  
Takvor Soukissian ◽  
...  
Keyword(s):  
Sea Level ◽  
Tidal Energy ◽  
Energy Yield ◽  
Energy Extraction ◽  
Low Velocity ◽  
Energy Potential ◽  
Yield Data ◽  
Island Communities ◽  
Tidal Stream ◽  
Harmonic Analysis Method

Potential energy extraction from tidal currents is investigated in this work. Recordings on the streams' velocity and the sea level in the Euripus' strait in Evia, Greece are used to calculate the energy yield. Data on sea level measurements were used to extract information for the current velocity profile through harmonic analysis method. Requirements, limitations and possible new designs that will improve the energy extraction from the low velocity tidal current of the area are discussed. Also, exploitation of tidal energy in cooperation with RES microgrid is proposed for areas where the abundance of sun, wind, island communities and coast areas such as the Mediterranean.

scholarly journals The energy yield potential of a large tidal stream turbine array in the Alderney Race

2020 ◽  
Vol 378 (2178) ◽  
pp. 20190502 ◽  
Author(s):  
D. S. Coles ◽  
L. S. Blunden ◽  
A. S. Bahaj
Keyword(s):  
Large Scale ◽  
Tidal Energy ◽  
Yield Potential ◽  
Energy Yield ◽  
Ambient Flow ◽  
Flow Speeds ◽  
Tidal Stream ◽  
Original Array ◽  
Array Performance ◽  
Tidal Stream Turbine

This research provides an updated energy yield assessment for a large tidal stream turbine array in the Alderney Race. The original array energy yield estimate was presented in 2004. Enhancements to this original work are made through the use of a validated two-dimensional hydrodynamic model, enabling the resolution of flow modelling to be improved and the impacts of array blockage to be quantified. Results show that a range of turbine designs (i.e. rotor diameter and power capacity) are needed for large-scale development, given the spatial variation in bathymetry and flow across the Alderney Race. Array blockage causes a reduction in flow speeds in the array of up to 2.5 m s −1 , increased flow speeds around the array of up to 1 m s −1 and a reduction in the mean volume flux through the Alderney Race of 8%. The annual energy yield estimate of the array is 3.18 TWh, equivalent to the electricity demand of around 1 million homes. The capacity factor of the array is 18%, implying sub-optimal array design. This result demonstrates the need for turbine rated speed to be selected based on the altered flow regime, not the ambient flow. Further enhancement to array performance is explored through increases to rotor diameter and changes to device micro-siting, demonstrating the significant potential for array performance improvement. This article is part of the theme issue ‘New insights on tidal dynamics and tidal energy harvesting in the Alderney Race’.

Effects on hydrodynamics and ecological costs of climate change and tidal stream energy extraction in a shelf sea

2020 ◽  
Author(s):  
Michela De Dominicis ◽  
Judith Wolf ◽  
Dina Sadykova ◽  
Beth Scott ◽  
Alexander Sadykov ◽  
...  
Keyword(s):  
Climate Change ◽  
Large Scale ◽  
Climate Scenario ◽  
Tidal Energy ◽  
Ocean Model ◽  
Future Climate ◽  
Biogeochemical Model ◽  
Energy Extraction ◽  
Shelf Sea ◽  
Tidal Stream

<p>The aim of this work is to analyse the potential impacts of tidal energy extraction on the marine environment. We wanted to put them in the broader context of the possibly greater and global ecological threat of climate change. Here, we present how very large (hypothetical) tidal stream arrays and a ''business as usual'' future climate scenario can change the hydrodynamics of a seasonally stratified shelf sea, and consequently modify ecosystem habitats and animals’ behaviour.</p><p>The Scottish Shelf Model, an unstructured grid three-dimensional ocean model, has been used to reproduce the present and the future state of the NW European continental shelf. While the marine biogeochemical model ERSEM (European Regional Seas Ecosystem Model) has been used to describe the corresponding biogeochemical conditions. Four scenarios have been modelled: present conditions and projected future climate in 2050, each with and without very large scale tidal stream arrays in Scottish Waters (UK). This allows us to evaluate the potential effect of climate change and large scale energy extraction on the hydrodynamics and biogeochemistry. We found that climate change and tidal energy extraction both act in the same direction, in terms of increasing stratification due to warming and reduced mixing, however, the effect of climate change is ten times larger. Additionally, the ecological costs and benefits of these contrasting pressures on mobile predator and prey marine species are evaluated using ecological statistical models.</p>

Implementation of Tidal Stream Turbines and Tidal Barrage Structures in DG-SWEM

2019 ◽  
Author(s):  
Andrea M. Schnabl ◽  
Tulio Marcondes Moreira ◽  
Dylan Wood ◽  
Ethan J. Kubatko ◽  
Guy T. Houlsby ◽  
...  
Keyword(s):  
Numerical Models ◽  
Shallow Water Equation ◽  
Tidal Energy ◽  
Head Loss ◽  
Equation Model ◽  
Energy Extraction ◽  
Tidal Hydrodynamics ◽  
Low Head ◽  
Tidal Stream ◽  
Two Sides

Abstract There are two approaches to extracting power from tides — either turbines are placed in areas of strong flows or turbines are placed in barrages enabling the two sides of the barrage to be closed off and a head to build up across the barrage. Both of these energy extraction approaches will have a significant back effect on the flow, and it is vital that this is correctly modelled in any numerical simulation of tidal hydrodynamics. This paper presents the inclusion of both tidal stream turbines and tidal barrages in the depth-averaged shallow water equation model DG-SWEM. We represent the head loss due to tidal stream turbines as a line discontinuity — thus we consider the turbines, and the energy lost in local wake-mixing behind the turbines, to be a sub-grid scale processes. Our code allows the inclusion of turbine power and thrust coefficients which are dependent on Froude number, turbine blockage, and velocity, but can be obtained from analytical or numerical models as well as experimental data. The barrage model modifies the existing culvert model within the code, replacing the original cross-barrier pipe equations. At the location of this boundary, velocities through sluice gates are calculated according to the orifice equation. For simulating the turbines, a Hill Chart for low head bulb turbines provided by Andritz Hydro is used. We demonstrate the implementations on both idealised geometries where it is straightforward to compare against other models and numerical simulations of real candidate sites for tidal energy in Malaysia and the Bristol Channel.

scholarly journals On Tidal Current Velocity Vector Time Series Prediction: A Comparative Study for a French High Tidal Energy Potential Site

2019 ◽  
Vol 7 (2) ◽  
pp. 46 ◽  
Author(s):  
Tony El Tawil ◽  
Nicolas Guillou ◽  
Jean-Frédéric Charpentier ◽  
Mohamed Benbouzid
Keyword(s):  
Time Series ◽  
Numerical Model ◽  
Linear Approximation ◽  
Current Velocity ◽  
Tidal Current ◽  
Tidal Energy ◽  
Energy System ◽  
Energy Potential ◽  
Tidal Current Velocity ◽  
Tidal Stream

Estimating the energy potential of tidal stream site is a key feature for tidal energy system deployment. This paper aims to compare two methods of prediction of tidal current velocities. The first one is based on the use of a fully three-dimensional (3D) numerical approach. However, while being accurate, the numerical model is highly time-consuming. The second method is based on a linear approximation of the tidal current, which only requires preliminary knowledge of local current velocities time series during two typical tidal cycles. This second method allows a very quick evaluation of the tidal stream resource during a long time period. The proposed comparison is done in three different locations of a high potential tidal energy site in west of France. It is carried out in terms of current velocity and energy harnessing for several turbines technology options (with and without yaw). The achieved results show that the linear approximation gives satisfactory evaluation of the tidal stream potential and can be a very interesting tool for preliminary site evaluation and first technology options selection. However, the fully 3D numerical model can obviously be very useful in more advanced steps of a project.

scholarly journals Reassessment of tidal energy potential in India and a decision-making tool for tidal energy technology selection

2017 ◽  
Vol 8 (2) ◽  
pp. 85-97 ◽  
Author(s):  
K Murali ◽  
V Sundar
Keyword(s):  
Energy Conversion ◽  
Clean Energy ◽  
Tidal Energy ◽  
Technology Selection ◽  
Tidal Range ◽  
Energy Technology ◽  
Ocean Energy ◽  
Tidal Power ◽  
Energy Potential ◽  
Tidal Stream

Oceans have significant renewable energy options to provide environmental friendly and clean energy. Technology for ocean energy systems and the feasibility for extraction of the same is an important area on which research is being focused worldwide. This article covers a detailed review of available tidal energy conversion technologies and case studies, with specific focus on tidal power potential in India. The proven option for tidal energy conversion is barraging. Recently, open-type turbine (usually known as tidal stream turbines) has been studied by several researchers and pilot demonstrations have been made. While conventional turbines of 10–20 MW rating are used in barrages, the application of tidal stream turbines of 0.5–2.0 MW has been demonstrated in water depths between 40 and 60 m. A new scale is proposed for categorizing the tidal energy potential in terms of tidal velocity and tidal range which could be used to categorize the potential sites and their ranking. A new systematic approach proposed for the assessment of tidal energy conversion potential can facilitate the suitability of either tidal stream energy or tidal barrage for a location. Within this, one could also decide the site could be developed as a major project or minor project. Therefore, the present work will be useful for engineers and decision makers in technology selection investment potential identification.

High-resolution numerical survey of potential sites for tidal energy extraction along coastline of China under sea-level-rise condition

2021 ◽  
Vol 236 ◽  
pp. 109492
Author(s):  
C.B. Jiang ◽  
Y.T. Kang ◽  
K. Qu ◽  
S. Kraatz ◽  
B. Deng ◽  
...  
Keyword(s):  
High Resolution ◽  
Sea Level Rise ◽  
Sea Level ◽  
Tidal Energy ◽  
Energy Extraction

scholarly journals Effect of tidal stream power generation on the region-wide circulation in a shallow sea

2010 ◽  
Vol 7 (5) ◽  
pp. 1785-1810 ◽  
Author(s):  
G. I. Shapiro
Keyword(s):  
Kinetic Energy ◽  
Ocean Circulation ◽  
Fold Increase ◽  
Tidal Energy ◽  
Energy Extraction ◽  
Shallow Sea ◽  
Residual Currents ◽  
Tidal Stream ◽  
Generation Capacity ◽  
Extracted Power

Abstract. Ocean tides are deemed to become a stable source of renewable energy for the future. Tidal energy has two components, the first is the potential energy due to sea level variations and the second comes from the kinetic energy of the tidal streams. This paper is concerned with the backward effect on the ocean currents by a tidal stream farm located in the open shallow sea. Recent studies in channels with 1-D models have indicated that the power potential is not given purely by the flux of kinetic energy, as has been commonly assumed. In this study, a 3-D ocean circulation model is used to estimate (i) maximum extractable energy at different levels of rated generation capacity of the farm, (ii) changes in the strength of currents due to energy extraction, and (iii) alterations in the pattern of residual currents and pathways of passive tracers. As water flow is influenced both by tidal and non-tidal currents, the model takes into account wind-driven and density-driven currents generated by meteorological forcing. Numerical modelling has been carried out for a hypothetical circular farm located in the Celtic Sea north of Cornwall, an area known for its high level of tidal energy. Modelling results clearly indicate that extracted power does not grow linearly with the increase in the rated capacity of the farm. For the case studies covered in this paper, a 100-fold increase in rated generation capacity of the farm results only in 7-fold increase in extracted power, this loss of efficiency is much greater than was estimated earlier with 1-D models. In case of high rated capacity of the farm, kinetic energy of currents is altered significantly as far as 10–20 km away from the farm. At high levels of extracted energy the currents tend to avoid flowing through the farm, an effect which is not captured with 1-D models. Residual currents are altered as far as a hundred kilometres. The magnitude of changes in the dispersion of tracers is highly sensitive to the location. For the drifters analysed in this study, variations in the end-to-start distance due to energy extraction range from 13% to 238%.

scholarly journals Dispatchability, Energy Security, and Reduced Capital Cost in Tidal-Wind and Tidal-Solar Energy Farms

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8504
Author(s):  
Peter Osman ◽  
Jennifer A. Hayward ◽  
Irene Penesis ◽  
Philip Marsh ◽  
Mark A. Hemer ◽  
...  
Keyword(s):  
Case Studies ◽  
Energy Content ◽  
Capital Expenditure ◽  
Energy Resource ◽  
Tidal Energy ◽  
Solar Pv ◽  
Stream Power ◽  
Low Velocity ◽  
Power Generators ◽  
Tidal Stream

The global tidal energy resource for electricity generation is small, and converting tidal kinetic energy to electricity is expensive compared to solar-photovoltaic or land-based wind turbine generators. However, as the renewable energy content in electricity supplies grows, the need to stabilise these supplies increases. This paper describes tidal energy’s potential to reduce intermittency and variability in electricity supplied from solar and wind power farms while lowering the capital expenditure needed to improve dispatchability. The paper provides a model and hypothetical case studies to demonstrate how sharing energy storage between tidal stream power generators and wind or solar power generators can mitigate the level, frequency, and duration of power loss from wind or solar PV farms. The improvements in dispatchability use tidal energy’s innate regularity and take account of tidal asymmetry and extended duration low-velocity neap tides. The case studies are based on a national assessment of Australian tidal energy resources carried out from 2018 to 2021.

scholarly journals One year of measurements in Alderney Race: preliminary results from database analysis

2020 ◽  
Vol 378 (2178) ◽  
pp. 20190625 ◽  
Author(s):  
L. Furgerot ◽  
A. Sentchev ◽  
P. Bailly du Bois ◽  
G. Lopez ◽  
M. Morillon ◽  
...  
Keyword(s):  
Wave Height ◽  
Tidal Energy ◽  
Significant Advance ◽  
Strong Wind ◽  
Mean Flow ◽  
Database Analysis ◽  
Energy Potential ◽  
Wide Range ◽  
Tidal Stream ◽  
One Year

The Alderney Race is assumed to have the largest tidal-stream energy potential in the north-western European coastal seas. Interaction of the powerful tidal stream with strong wind, high waves and irregular bathymetry creates hydrodynamic conditions of extreme complexity, with high levels of turbulence. A comprehensive dataset has been created to improve the understanding of physical processes, turbulence, tidal stream and resource variability at the site. The database contains a large amount of oceanographic and meteorological measurements acquired in Alderney Race in 2017–2018. This exceptionally long period of observations (nearly one year) became possible due to modern tools and strategies of data acquisition. The paper presents some significant results from the database analysis. Among many results, we would like to underline the following: (i) a wide range of variability of mean flow and sea state parameters was documented; (ii) exceptionally large values of current velocity (7 m s −1 ) and significant wave height (8 m) were measured during extreme meteorological conditions; (iii) high-frequency variability of current speed during storm events was also found to be very large, with the standard deviation of velocity reaching 0.3 m s −1 in the bottom boundary layer, and 0.6 m s −1 in the surface layer; and (iv) predominant wind and wave direction relative to the flow impacts the wave height and significantly increases the turbulence kinetic energy of the flow. To our knowledge, this is the largest multi-variable database available on potential tidal energy sites. The results of database analysis can represent a significant advance in environmental conditions and resource characterization and provide advanced information to turbine developers. This article is part of the theme issue ‘New insights on tidal dynamics and tidal energy harvesting in the Alderney Race’.

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