Vasiliki Stratigaki, Peter Troch, Tim Stallard, David Forehand, Jens Peter Kofoed, Matt Folley, Michel Benoit, Aurelien Babarit, Jens Kirkegaard


Experiments have been performed in the Shallow Water Wave Basin of DHI (Hørsholm, Denmark) within the EU FP7 Hydralab Programme, on large farms of up to 25 heaving point absorber type Wave Energy Converters (WECs). For a range of geometric lay-out configurations and wave conditions (regular, polychromatic, long- and short-crested irregular waves), WEC response and modification of the wave field have been measured to provide data for the understanding of WEC farm interactions and for the evaluation of farm interaction numerical models. A first extensive wave farm database is established. The experimental arrangement and the obtained database are presented, as well as results for wave height attenuation downwave of the farms. For long-crested irregular waves, up to 18.1 % and 20.8 % reduction in significant wave height is observed downwave of the 5x5-WEC rectilinear and staggered farm, respectively. Wave height attenuation is expected to be larger, since in practical wave farm applications WECs will be controlled to extract a large amount of power from the waves, and therefore the array will cause larger wave height dissipation. These findings present the ability to combine the harvesting of energy from sea waves with coastal defence systems, resulting in cost reduction for both applications when WECs operate as multi-purpose devices.


coastal protection, wave energy converters, WEC farms, WEC parks, wave height attenuation, floating structures, point absorber WECs, EU FP7 HYDRALAB IV, DHI Shallow Water Wave Basin

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Alexandre, A., T. Stallard, and P.K. Stansby (2009): “Transformation of Wave Spectra across a Line of Wave Devices”. Proceedings of the 8th European Wave and Tidal Energy Conference, Uppsala, Sweden.

Allsop N.W.H. (2014): “Failures of seawalls – what do we learn from Dawlish?” Presentations to ICE Maritime Board meeting on 8 May 2014.

Budal, K., Falnes, J., Kyllingstad, A., Oltedal, G. (1979). “Experiments with point absorbers in regular waves”. Proc. of the 1st Symposium on Wave Energy Utilization, 1979; pp. 253–282, Gothenburg.Sweden.

Babarit, A. (2013): “On the park effect in arrays of oscillating wave energy converters”. Renewable Energy. 58, 68-78.

Babarit A. (2010): “Impact of long separating distances on the energy production of two interacting wave energy converters”. Ocean Engineering; vol. 37:718-29.

Beels, C., Troch, P., De Backer, G., Vantorre, M., De Rouck, J. (2010a): “Numerical implementation and sensitivity analysis of a wave energy converter in a time-dependent mild-slope equation model”. Coastal Engineering; 57(5), 471-492.

Beels, C., Troch, P., Kofoed, J.P., Frigaard, P., Vindahl Kringelum, J., Carsten Kromann, P., Heyman Donovan, M., De Rouck, J., De Backer, G. (2010b): “A methodology for production and cost assessment of a farm of wave energy converters. Renewable Energy”; 36(12), 3402-3416.

Borgarino B, Babarit A, Ferrant P. (2011): “Impact of wave interactions effect on energy absorption in large arrays of wave energy converters”. Ocean Engineering;vol. 41:79-88.

Eurosion. 2004: “Living with coastal erosion in Europe: sediment and space for sustainability. A guide to coastal erosion management practices in Europe”. European Commission. Service contract B4-3301/2001/329175/ MAR/B3.

Falnes, J. (2007): “A review of wave-energy extraction. Marine Structures”, 20(4), 185–201. doi:10.1016/j.marstruc.2007.09.001.

Folley, M., A. Babarit, L. O’ Boyle, B. Child, D. Forehand, K. Silverthorne, J. Spinneken, V. Stratigaki, and P. Troch. 2012: “A review of numerical modeling of wave energy converter arrays”, Proc. of 31st Int'l Conf. on Offshore Mechanics & Arctic Engineering, Rio de Janeiro, Brazil.

Goda, Y.; Suzuki, Y. (1975): “Computation of Refraction and Diffraction of Sea Waves with Mitsuyasu’s Directional Spectrum”; Technical Note of the Port and Harbour Research Institute, Ministry of Transport: Tokyo, Japan, 1975; No. 230, p. 45.

Longuet-Higgins, M.S., Cartwright, D.E., Smith, N.D. (1963): “Observations of the Directional Spectrum of Sea Waves Using Motions of a Floating Buoy”. In Ocean Wave Spectra, Prentice Hall:

New York, NY, USA; pp. 111–136.

Mendoza, E., Silva, R., Zanuttigh, B., Angelelli, E., Lykke Andersen, T., Martinelli, L., Nørgaard, J.Q.H., Ruol, P. (2013): “Beach response to wave energy converter farms acting as coastal defense”. Coastal Engineering, Available online 12 November; ISSN 0378-3839,

Nørgaard, J.H., Lykke Andersen, T. (2012): “Experimental and numerical investigation of wave transmission from a floating Wave Dragon wave energy converter”. International Ocean and Polar Engineering Conference, Rhodes (ISOPE).

O’Boyle, L. (2013): “Wave Fields around Wave Energy Converter Arrays”. Ph.D. Thesis, Queen’s University Belfast, Belfast, UK, September.

O’Connor MC, et al. (2009): “Practice versus policy: coastal defence management”. Marine Policy, doi:10.1016/j.marpol.2009.03.007

Stallard, T.J., Stansby, P.K., Williamson, A. (2008): “An experimental study of closely spaced point absorber arrays”. Proceedings of the 18th International Offshore & Polar Engineering Conference, Canada.

Stratigaki, V., Troch, P., Vantorre, M., Folley, M., Stallard, T., Forehand, D., Kofoed, J.P., Babarit, A., Benoit, M. (2013): “Development of a Point Absorber Wave Energy Converter for Investigation of Wake Effects and Wave Energy Absorption”. In Proceedings of the 4th International Coastlab12 Conference, Ghent, Belgium.

Stratigaki, V., Troch, P., Stallard, T., Forehand, D., Kofoed, J.P., Folley, M., Benoit, M., Babarit, A., Kirkegaard, J. (2014): “Wave Basin Experiments with Large Wave Energy Converter Arrays to Study Interactions between the Converters and Effects on Other Users in the Sea and the Coastal Area”. Energies, 7, 701-734.

Stratigaki, V. (2014): “Experimental Study and Numerical Modelling of Intra-Array Interactions and Extra-Array Effects of Wave Energy Converter Arrays”. PhD dissertation, Ghent University, Ghent, Belgium.

Thomas, S., Weller, S. and Stallard, T.J. (2008): “Float response within an array: Numerical and experimental comparison”. Proc. 2nd International Conf. on Ocean Energy (ICOE), Brest, France.

Troch, P. (1998): “MILDwave – A numerical model for propagation and transformation of linear water waves”. Internal Report, Department of Civil Engineering, Ghent University.

Troch, P., Beels, C., De Rouck, J., De Backer, G. (2010): “Wake Effects Behind a Farm of Wave Energy Converters for Irregular Long-Crested and Short-Crested Waves”. In Proceedings of the International Conference on Coastal Engineering, Shanghai, China, 30 June–5 July 2010.

Vantorre M., R. Banasiak, R. Verhoeven. (2004): “Modelling of hydraulic performance and wave energy extraction by a point absorber in heave”. Applied Ocean Research; 26:61–72.

Weller, S.D. Stallard, T.J. and Stansby, P.K. (2010): “Interaction factors for a rectangular array of heaving floats in irregular waves”. IET Renewable Power Generation. 4(6), 628–637.