Marine current energy conversion: the dawn of a new era in electricity production

Bahaj, A.S.

doi:10.1098/rsta.2012.0500

Cited by 37 publications

(18 citation statements)

References 17 publications

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“…Innovative energy harvesting devices are being developed to extract energy from geophysical flows such as wind or marine currents. The most common way to extract this energy is to convert it into the rotary motion of a dedicated structure, as wind turbines or marine turbines [2,5,24]. Even if these technologies are now mature from an industrial point of view, several other mechanisms to harvest this energy are currently being studied.…”

Section: Introductionmentioning

confidence: 99%

On the efficiency of energy harvesting using vortex-induced vibrations of cables

Grouthier

Michelin

Bourguet

et al. 2014

Journal of Fluids and Structures

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Many technologies based on fluid-structure interaction mechanisms are being developed to harvest energy from geophysical flows. The velocity of such flows is low, and so is their energy density. Large systems are therefore required to extract a significant amount of energy. The question of the efficiency of energy harvesting using vortex-induced vibrations (VIV) of cables is addressed in this paper, through two reference configurations: (i) a long tensioned cable with periodically-distributed harvesters and (ii) a hanging cable with a single harvester at its upper extremity. After validation against either direct numerical simulations or experiments, an appropriate reduced-order wakeoscillator model is used to perform parametric studies of the impact of the harvesting parameters on the efficiency. For both configurations, an optimal set of parameters is identified and it is shown that the maximum efficiency is close to the value reached with an elastically-mounted rigid cylinder. The variability of the efficiency is studied in light of the fundamental properties of each configuration, i.e. body flexibility and gravity-induced spatial variation of the tension. In the periodically-distributed harvester configuration, it is found that the standing-wave nature of the vibration and structural mode selection play a central role in energy extraction. In contrast, the efficiency of the hanging cable is essentially driven by the occurrence of traveling wave vibrations.

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Section: Introductionmentioning

confidence: 99%

On the efficiency of energy harvesting using vortex-induced vibrations of cables

Grouthier

Michelin

Bourguet

et al. 2014

Journal of Fluids and Structures

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“…The UK Total Resource alone was estimated at approximately 110 TWh annually, a large proportion of which is from presently known locations. A comprehensive overview of the recent developments in the technology used to extract power from tides can be found in the study by Bahaj [1].…”

Section: Introductionmentioning

confidence: 99%

Simulating the Wake Downstream of a Horizontal Axis Tidal Turbine Using a Modified Vorticity Transport Model

Vybulkova

Vezza

Brown

2016

IEEE J. Oceanic Eng.

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Vybulkova, L., Vezza, M., and Brown, R. (2016) Simulating the wake downstream of a horizontal axis tidal turbine using a modified vorticity transport model. IEEE Journal of Oceanic Engineering, 41(2), pp. 296-301.There may be differences between this version and the published version. You are advised to consult the publisher's version if you wish to cite from it.http://eprints.gla.ac.uk/119684/ In order to decrease the need for fossil fuels, the alternative energy resources must be not only economically viable but also sustainable in the long-term. One of the most promising alternatives is the marine renewable energy resource.The relatively young marine energy industry is presented with two challenges. Firstly, to deliver a continuous reliable power supply and secondly, to minimize potentially harmful effects of the power extraction on the marine environment.The requirement to understand the interactions between a tidal turbine and the surrounding flow environment motivated the present work. A tidal turbine mounted on the seabed induces a wake that extends far down-stream of the device.As the direction of tidal flow changes so does the position of the wake with respect to the device The detailed study of the turbine wake has been conducted by means of computer simulations. An existing finite-volume computer model called the Vorticity Transport Model has been modified to suit the purpose of simulating the wake of a horizontal-axis tidal turbine subjected to a non-uniform flow typical of that close to the seabed. High-resolution computer simulations suggest that a progressive fragmentation of the vortical structure occurs during the development of the wake of a tidal turbine. The predicted fragmentation generates small-scale unsteady flow phenomena beyond five rotor diameters down-stream of the device in the area previously thought unaffected by the presence of a tidal turbine. The effects of non-uniform flow on the vorticity structure down-stream of a tidal turbine and the fragmentation process are analysed in this work.

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“…Marine current turbine commercial prototypes have now been deployed and significant progress has been made in recent years, with many devices now in development [1][2][3]. The next phase of development will include the design and planning of multiple device arrays [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

“…The next phase of development will include the design and planning of multiple device arrays [2][3][4]. Estimating the extractable power from an array of turbines in a tidal channel may be estimated using simple analytical expressions [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Influence of turbulence on the wake of a marine current turbine simulator

2014

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Marine current turbine commercial prototypes have now been deployed and arrays of multiple turbines under design. The tidal flows in which they operate are highly turbulent, but the characteristics of the inflow turbulence have not being considered in present design methods. This work considers the effects of inflow turbulence on the wake behind an actuator disc representation of a marine current turbine. Different turbulence intensities and integral length scales were generated in a large eddy simulation using a gridInlet, which produces turbulence from a grid pattern on the inlet boundary. The results highlight the significance of turbulence on the wake profile, with a different flow regime occurring for the zero turbulence case. Increasing the turbulence intensity reduced the velocity deficit and shifted the maximum deficit closer to the turbine. Increasing the integral length scale increased the velocity deficit close to the turbine due to an increased production of turbulent energy. However, the wake recovery was increased due to the higher rate of turbulent mixing causing the wake to expand. The implication of this work is that marine current turbine arrays could be further optimized, increasing the energy yield of the array when the site-specific turbulence characteristics are considered.

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Marine current energy conversion: the dawn of a new era in electricity production

Cited by 37 publications

References 17 publications

On the efficiency of energy harvesting using vortex-induced vibrations of cables

On the efficiency of energy harvesting using vortex-induced vibrations of cables

Simulating the Wake Downstream of a Horizontal Axis Tidal Turbine Using a Modified Vorticity Transport Model

Influence of turbulence on the wake of a marine current turbine simulator

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