The cumulative impact of tidal stream turbine arrays on sediment transport in the Pentland Firth

Fairley, Iain; Masters, Ian; Karunarathna, Harshinie

doi:10.1016/j.renene.2015.03.004

Cited by 70 publications

(55 citation statements)

References 54 publications

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“…Changes to hydrodynamic regime can lead to second-order effects. Researchers have also investigated impacts on sediment transport and associated changes to morphology [32][33][34][35]. Wave-current interactions [36] can also be an important process, both in affecting the tidal resource and the changes to currents impacting the wave climate [37][38][39], the water quality [40] or aquatic organisms.…”

Section: Coastal Area Modellingmentioning

confidence: 99%

“…The value used is often based on actuator disk theory with correction factors applied when array scale extraction is considered [43,44]. In three-dimensional models, such an approach would give unrealistic vertical velocity profiles, and thus, an additional sink term must be introduced to the model [35]. A review of the commonly-used methods is presented in [45].…”

Section: Coastal Area Modellingmentioning

confidence: 99%

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A Comparison of Numerical Modelling Techniques for Tidal Stream Turbine Analysis

et al. 2015

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To fully understand the performance of tidal stream turbines for the development of ocean renewable energy, a range of computational models is required. We review and compare results from several models of horizontal axis turbines at different spatial scales. Models under review include blade element momentum theory (BEMT), blade element actuator disk, Reynolds averaged Navier Stokes (RANS) CFD (BEM-CFD), blade-resolved moving reference frame and coastal models based on the shallow water equations. To evaluate the BEMT, a comparison is made to experiments with three different rotors. We demonstrate that, apart from the near-field wake, there are similarities in the results between the BEM-CFD approach and a coastal area model using a simplified turbine fence at a headland case.

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Section: Coastal Area Modellingmentioning

confidence: 99%

Section: Coastal Area Modellingmentioning

confidence: 99%

A Comparison of Numerical Modelling Techniques for Tidal Stream Turbine Analysis

et al. 2015

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“…Their study, however, was undertaken using a two-dimensional, depth-averaged model, which cannot resolve the specific near-bed velocity relevant for sediment transport processes; in particular, the potential exists for flow to be accelerated beneath tidal turbines, as well as around the sides, and this process clearly cannot be simulated with a depth-averaged model. A further study using a three-dimensional (3D) model, by Fairley et al [9], extended the modelled sediment transport in the Pentland Firth into predictions of bed level changes, and again investigated the possible effects of turbines deployed in the Inner Sound on sediment deposition and erosion. They found that currently proposed arrays would have only minimal effect on the baseline morphodynamics of the large sandbanks in the region, but did not consider the smaller sandbanks local to the arrays.…”

Section: Introductionmentioning

confidence: 99%

“…Martin-Short et al [8] and Fairley et al [9] both noted that accurate sediment modelling is inhibited by a lack of detailed knowledge of local sediment deposits and transport in the area. Fairley et al [9] combined a variety of data to construct a map of sediment type through the Pentland Firth and surrounding area, but detail in the Inner Sound was limited.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Simulations of the Effects of a Tidal Turbine Array on Near-Bed Velocity and Local Bed Shear Stress

Gillibrand

Walters²,

McIlvenny

2016

Energies

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Abstract:We apply a three-dimensional hydrodynamic model to consider the potential effects of energy extraction by an array of tidal turbines on the ambient near-bed velocity field and local bed shear stress in a coastal channel with strong tidal currents. Local bed shear stress plays a key role in local sediment dynamics. The model solves the Reynold-averaged Navier-Stokes (RANS) equations on an unstructured mesh using mixed finite element and finite volume techniques. Tidal turbines are represented through an additional form drag in the momentum balance equation, with the thrust imparted and power generated by the turbines being velocity dependent with appropriate cut-in and cut-out velocities. Arrays of 1, 4 and 57 tidal turbines, each of 1.5 MW capacity, were simulated. Effects due to a single turbine and an array of four turbines were negligible. The main effect of the array of 57 turbines was to cause a shift in position of the jet through the tidal channel, as the flow was diverted around the tidal array. The net effect of this shift was to increase near-bed velocities and bed shear stress along the northern perimeter of the array by up to 0.8 m·s −1 and 5 Pa respectively. Within the array and directly downstream, near-bed velocities and bed shear stress were reduced by similar amounts. Changes of this magnitude have the potential to modify the known sand and shell banks in the region. Continued monitoring of the sediment distributions in the region will provide a valuable dataset on the impacts of tidal energy extraction on local sediment dynamics. Finally, the mean power generated per turbine is shown to decrease as the turbine array increased in size.

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Tidal streams, fish, and seabirds: Understanding the linkages between mobile predators, prey, and hydrodynamics

et al. 2022

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Driven by the necessity to decarbonize energy sources, many countries are targeting tidal stream environments for power generation. However, these areas can act as foraging hotspots for marine top predators, such as seabirds. Thus, it is important to understand the ecological interactions influencing predator behavior and distribution in these areas, to determine the potential ecological implications of marine renewable devices. This study used concurrent observations of foraging seabirds, physical hydrodynamics, and prey presence across a tidal stream environment, before and after the installation of a commercial turbine array close to the island of Stroma, Scotland. There were three main findings: First, benthic foraging seabirds showed a clear preference for certain sections around Stroma where sandeels were detected, while pelagic foraging seabirds were seen all around Stroma. Second, there was a positive effect of water velocity on the number of pelagic foragers and common guillemots. Third, there was a positive effect of the presence of fish schools on the number of pelagic seabirds and common guillemots, in both the same and the previous transects. Thus, it is possible that seabirds target areas of predictable food sources during periods where prey might be easily accessed (e.g., periods of fast flows). Given the difference in the distribution between seabird categories, it is likely that marine renewable devices will impact each category differently. We conclude that any impact on sandbank locations, sandeels preferred habitat, due to the presence of tidal turbines is likely to alter the distribution of benthic foraging seabirds. For pelagic foraging seabirds and common guillemot, changes in prey presence and accessibility (depth and level of aggregation/disaggregation) will have a stronger effect on seabird presence. This study highlights the need to include concurrent physical and biological data when assessing the ecological impacts of tidal turbines.

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The cumulative impact of tidal stream turbine arrays on sediment transport in the Pentland Firth

Cited by 70 publications

References 54 publications

A Comparison of Numerical Modelling Techniques for Tidal Stream Turbine Analysis

A Comparison of Numerical Modelling Techniques for Tidal Stream Turbine Analysis

Numerical Simulations of the Effects of a Tidal Turbine Array on Near-Bed Velocity and Local Bed Shear Stress

Tidal streams, fish, and seabirds: Understanding the linkages between mobile predators, prey, and hydrodynamics

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