Wake field study of tidal turbines under realistic flow conditions

Thiebot, Jérôme; Guillou, Nicolas; Guillou, Sylvain; Good, A. J.; Lewis, Michael Alexander Oxenham

doi:10.1016/j.renene.2019.11.129

Cited by 41 publications

(54 citation statements)

References 33 publications

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“…7). Confirming previous studies [3,21,24,31], predicted maximum magnitudes ranged from 4.1 m s −1 within the Fromveur Strait to 5.1 m s −1 within the Pentland Firth. The increased value in North Scotland resulted mainly from a strong hydraulic gradient across tidal channels associated with the increased phase lag in tidal free-surface elevation [26].…”

Section: Results and Discussion (A) Tidal Range Current Magnitude Ansupporting

confidence: 87%

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Spatio-temporal variability of tidal-stream energy in north-western Europe

Guillou

Neill

Thiebot

2020

Phil. Trans. R. Soc. A.

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Initial selection of tidal stream energy sites is primarily based on identifying areas with the maximum current speeds. However, optimal design and deployment of turbines requires detailed investigations of the temporal variability of the available resource, focusing on areas with reduced variability, and hence the potential for more continuous energy supply. These aspects are investigated here for some of the most promising sites for tidal array development across the north-western European shelf seas: the Alderney Race, the Fromveur Strait, the Pentland Firth and the channels of Orkney. Particular attention was dedicated to asymmetry between the flood and ebb phases of the tidal cycle (due to the phase relationship between M 2 and M 4 constituents), and spring-neap variability of the available resource (due to M 2 and S 2 compound tides). A series of high-resolution models were exploited to (i) produce a detailed harmonic database of these three components, and (ii) characterize, using energy resource metrics, temporal variability of the available power density. There was a clear contrast between the Alderney Race, with reduced temporal variability over semi-diurnal and fortnightly time scales, and sites in western Brittany and North Scotland which, due to increased variability, appeared less attractive for optimal energy conversion. 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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Section: Results and Discussion (A) Tidal Range Current Magnitude Ansupporting

confidence: 87%

“…3). Water depth is mainly in the range 25 to 45 m with rocky seabed and coarse seabed sediments including pebbles, gravel and rock outcrops [20,21]. The Alderney Race has a mean spring tidal range of over 7 m and mean spring tidal currents that exceed 3.5 m s −1 [22].…”

Section: Site Descriptionsmentioning

confidence: 99%

Spatio-temporal variability of tidal-stream energy in north-western Europe

Guillou

Neill

Thiebot

2020

Phil. Trans. R. Soc. A.

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“…Indeed, as the power density depends on the cubed velocity magnitude, the errors are magnified. Despite small discrepancies in velocity magnitude, Thiébot et al [20] obtained a RMS error of order 1 kW/m 2 for the power density (Figure 2b), which remains relatively high for the estimation of the exploitable resource.…”

Section: B Regional Scale Studiesmentioning

confidence: 92%

“…Finally, the resource of the AR was also assessed with higher resolution 3D models [19,20]. The investigations of Thiébot et al [20] relied on the hydrodynamic model Telemac3D forced by 11 constituents (TPXO European Shelf 2008 database, [24]). The model domain encompassed the English Channel with a resolution ranging from 10 km at offshore boundaries to 100 m within the area of interest.…”

Section: B Regional Scale Studiesmentioning

confidence: 99%

“…Bennis et al [19] also used a refined 3D model to simulate the current in the AR. Complementary to Thiébot et al [20], they focused on the other side of the Race (French territorial waters) and studied more energetic wind/wave conditions. The main goal of their study was to investigate the influence of the wind and waves on the currents.…”

Section: B Regional Scale Studiesmentioning

confidence: 99%

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Numerical modelling of hydrodynamics and tidal energy extraction in the Alderney Race: a review

Thiebot

Coles

Bennis

et al. 2020

Phil. Trans. R. Soc. A.

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The tides are a predictable, renewable, source of energy that, if harnessed, can provide significant levels of electricity generation. The Alderney Race (AR), with current speeds that exceed 5 m s −1 during spring tides, is one of the most concentrated regions of tidal energy in the world, with the upper-bound resource estimated at 5.1 GW. Owing to its significance, the AR is frequently used for model case studies of tidal energy conversion, and here we review these model applications and outcomes. We examine a range of temporal and spatial modelling scales, from regional models applied to resource assessment and characterization, to more detailed models that include energy extraction and array optimization. We also examine a range of physical processes that influence the tidal energy resource, including the role of waves and turbulence in tidal energy resource assessment and loadings on turbines. The review discusses model validation, and covers a range of numerical modelling approaches, from two-dimensional to three-dimensional tidal models, two-way coupled wave-tide models, Large Eddy Simulation (LES) models, and the application of optimization techniques. The review contains guidance on model approaches and sources of data that can be used for future studies of the AR, or translated to other tidal energy regions. 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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A DMST-based tool to establish the best aspect ratio, solidity and rotational speed for tidal turbines in real sea conditions

Pucci

Zanforlin

Bellafiore

et al. 2022

J. Ocean Eng. Mar. Energy

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A Double Multiple Stream Tube (DMST) routine to predict the performance of cross-flow hydrokinetic turbines in real environments is presented, along with a site assessment application to identify the most efficient turbine aspect ratio, solidity and configuration (single, or paired) for a selected area of the Northern Adriatic Sea. The peculiarity of this DMST tool is its 3D character, since it allows to reproduce the vertical distribution of the torque generated by the turbine. To this end, correlations for fluid dynamic phenomena, based on high-fidelity fully CFD simulations, were implemented. The marine circulation code SHYFEM is adopted to obtain velocity profiles for a half lunar cycle period. The sites with the highest mean kinetic power were identified. The DMST routine is equipped with an iterative process able to establish which rotational speed maximizes the power output. Indeed, a spatially non-uniform velocity profile requires to determine the flow velocity more suitable to obtain the rotational speed via Tip Speed Ratio (TSR) definition. To this end, the section of the blades working at optimal TSR varies from top to bottom, until the maximum power is reached. It works as a virtual Maximum Power Point Tracking system able to adapt the turbine operating conditions for the different turbine geometries, and for changes in flow conditions. The results show that for the case study, the performance curve shape influences the optimal TSR blade section: the latter is often located in the upper part of the turbine for the low solidity, whereas, for high solidity turbines, in the bottom half part.

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Wake field study of tidal turbines under realistic flow conditions

Cited by 41 publications

References 33 publications

Spatio-temporal variability of tidal-stream energy in north-western Europe

Spatio-temporal variability of tidal-stream energy in north-western Europe

Numerical modelling of hydrodynamics and tidal energy extraction in the Alderney Race: a review

A DMST-based tool to establish the best aspect ratio, solidity and rotational speed for tidal turbines in real sea conditions

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