Assessment of the energy extraction potential at tidal sites around the Channel Islands

Coles, Daniel; Blunden, Luke; Bahaj, A.S.

doi:10.1016/j.energy.2017.02.023

Cited by 67 publications

(79 citation statements)

References 15 publications

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“…Several studies related to tidal current energy have been conducted across the world, such as in Scotland [1], France [2], Canada [3], the USA [4], Brazil [5], China [6], Taiwan [7], Korea [8], Japan [9], and India [10]. There have also been some studies of tidal energy in Indonesia.…”

Section: Introductionmentioning

confidence: 99%

Field Measurement and Numerical Modeling of Tidal Current in Larantuka Strait for Renewable Energy Utilization

Ajiwibowo¹

2017

GEOMATE

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ABSTRACT:The amount of electricity consumed is growing rapidly, along with population growth and technological development. Meanwhile, Indonesia's energy supply is predominantly supported by nonrenewable sources, so an approach to renewable energy is urgently needed. This study uses a numerical model to determine the potency of tidal current power at Larantuka Strait, East Nusa Tenggara Province, Indonesia. The output of the study is the electricity generated with a conversion device at several locations. The numerical model is generated using MIKE 3. In order to validate the numerical model, field measurements are conducted to obtain the detailed bathymetry, tidal surface elevation, and tidal current velocity data. The numerical model shows good agreement with the field measurement data; the average errors of tidal surface elevation and tidal current velocity are 4.04 and 9.79%, respectively. Furthermore, the tidal current model is analyzed and two potential sites are found at the narrowest part of the strait. The generated power is calculated for a D10 Sabella turbine. The calculation shows that the amounts of power generated are 522.972 and 324.12 MWh for the two sites, respectively, in 2014. The study shows that Larantuka Strait is very promising and suitable as a site for a tidal current power plant with its tidal current and water depth. A detailed analysis, including financial, navigation, and environmental studies, needs to be conducted to present the feasibility of the realization.

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Section: Introductionmentioning

confidence: 99%

Field Measurement and Numerical Modeling of Tidal Current in Larantuka Strait for Renewable Energy Utilization

Ajiwibowo¹

2017

GEOMATE

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“…The northern part of the "Raz de Sein" is thus characterized by a separation of the flow between the northeastern and northwestern directions, in relation to channels formed on both parts of the islet of Tévennec (Section 2.1, Figures 1 and 4 Following the resource criteria adopted by the Carbon Trust [42], mean kinetic power density should exceed 2.5 kW m −2 for a reasonable economic viability in the setting up of first-generation devices. Along the coasts of France, such power density is found in the Alderney Race (western English Channel) and in the Fromveur Strait (western Brittany) [19,20,43]. In the "Raz de Sein", locations where this power density exceeds 2.5 kW m −2 are restricted to the vicinity of shoals and rocky islets and headlands bordering the strait (Figure 5a).…”

Section: Evaluation Of Model Predictionsmentioning

confidence: 99%

“…Furthermore, significant tidal recirculations with a diameter of around 2 km appear during flood and ebb peak periods, on both sides of the flow emerging from the strait. As local assessments of tidal stream power around France have primarily focused on the two prominent sites of the Alderney Race ("Raz Blanchard") in the western English Channel [18,19] and the Fromveur Strait [20,21] in northwestern Brittany, a reduced number of investigations was conducted in the "Raz de Sein". However, the values of the tidal velocities (>2.5 m s −1 ) and the water depths (>25 m) match the basic conditions required for the implementation of first-generation turbine technologies, covering the great part of existing prototype devices in pre-commercial demonstration stages [22].…”

Section: Study Sitementioning

confidence: 99%

Tidal Turbines’ Layout in a Stream with Asymmetry and Misalignment

Guillou

Chapalain

2017

Energies

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A refined assessment of tidal currents variability is a prerequisite for successful turbine deployment in the marine environment. However, the numerical evaluation of the tidal kinetic energy resource relies, most of the time, on integrated parameters, such as the averaged or maximum stream powers. Predictions from a high resolution three-dimensional model are exploited here to characterize the asymmetry and misalignment between the flood and ebb tidal currents in the "Raz de Sein", a strait off western Brittany (France) with strong potential for array development. A series of parameters is considered to assess resource variability and refine the cartography of local potential tidal stream energy sites. The strait is characterized by strong tidal flow divergence with currents' asymmetry liable to vary output power by 60% over a tidal cycle. Pronounced misalignments over 20 • are furthermore identified in a great part of energetic locations, and this may account for a deficit of the monthly averaged extractable energy by more than 12%. As sea space is limited for turbines, it is finally suggested to aggregate flood and ebb-dominant stream powers on both parts of the strait to output energy with reduced asymmetry.

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“…This (spatially averaged) turbine representation implies that the interactions between the turbines' wakes are negated [5][6][7][8][9][10][11]. Such regional approach has been used at sites located in West Brittany such as the Sein Race [7] and the Fromveur strait [8], at Scottish sites such as the Orkney archipelago [9], at the Ramsey Sound strait [10], and at the Normand site of the Raz Blanchard [1].Recent works [11][12][13][14] deal with the implementation of methods developed (based on numerical results or experimental mapping) to optimize the identification of suitable sites for energy extraction. To simulate a realistic momentum extraction by turbine arrays, Coles et al (2017) [12] introduced a drag over the energy extraction zones of a site.…”

mentioning

confidence: 99%

“…Recent works [11][12][13][14] deal with the implementation of methods developed (based on numerical results or experimental mapping) to optimize the identification of suitable sites for energy extraction. To simulate a realistic momentum extraction by turbine arrays, Coles et al (2017) [12] introduced a drag over the energy extraction zones of a site.…”

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confidence: 99%

Effects of the Current Direction on the Energy Production of a Tidal Farm: The Case of Raz Blanchard (France)

et al. 2019

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This study aims to investigate the influence of the current direction on the energy production of a tidal turbines array. It is based on a three-dimensional (3D) numerical simulation of the flow where the turbines are represented with actuator disks. The case study consists of modelling the energy extraction of a small array of turbines (staggered and aligned layouts) placed in the Raz Blanchard (Alderney Race, France). The simulations are performed with hydrodynamic data (current magnitude and direction) representative of a mean tide, with several resistance forces and ambient turbulence intensities. The influence of the current direction on the energy production is highlighted by comparing the simulations forced with the real current direction with those in which the angle of incidence between the incoming flow and the turbine's axis is "switched off" (bi-directional flow). When the flow is aligned with the turbines' axis (misalignment "switched off"), the staggered layout produces more than the aligned arrangement. Comparison of the two types of simulations (misalignment switched off or not) shows that the misalignment of the flow around a predominant direction reduces the energy produced by the staggered layout and increases the production of the aligned layout. Furthermore, it suggests that the mean energy produced per machine is almost the same for both layouts. Higher turbulence intensity reduces the positive effect of the directional spreading on the aligned layout production and limits the negative effect on the staggered layout production.The hydrodynamics of tidal energy sites is intricate and often shows an asymmetry in tidal current direction. As an example, the current of the Raz Blanchard, which is located between the Alderney Island and La Hague Cape (Normandy, France), is quasi bidirectional in the Southern part of the Race but is characterized by a high directional spreading in the Northern part. At some locations, the current incidence with respect to the predominant direction reaches up to 30 • [4]. Thus, the multi-directionality of the flow should be considered when optimizing the turbines' arrangement.Numerous numerical modelling studies investigated the effect of the current asymmetry (amplitude and direction) on the production of tidal farms. However, previous studies were essentially performed with regional models where the turbines' thrust was spatially averaged over the area occupied by the tidal farm. This (spatially averaged) turbine representation implies that the interactions between the turbines' wakes are negated [5][6][7][8][9][10][11]. Such regional approach has been used at sites located in West Brittany such as the Sein Race [7] and the Fromveur strait [8], at Scottish sites such as the Orkney archipelago [9], at the Ramsey Sound strait [10], and at the Normand site of the Raz Blanchard [1].Recent works [11][12][13][14] deal with the implementation of methods developed (based on numerical results or experimental mapping) to optimize the identification of suitable sites for ene...

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Assessment of the energy extraction potential at tidal sites around the Channel Islands

Cited by 67 publications

References 15 publications

Field Measurement and Numerical Modeling of Tidal Current in Larantuka Strait for Renewable Energy Utilization

Field Measurement and Numerical Modeling of Tidal Current in Larantuka Strait for Renewable Energy Utilization

Tidal Turbines’ Layout in a Stream with Asymmetry and Misalignment

Effects of the Current Direction on the Energy Production of a Tidal Farm: The Case of Raz Blanchard (France)

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