NEW DESIGN OPTIONS FOR THE IMPROVEMENT OF THE MUTRIKU POWER PLANT
Authors: Urko Izquierdo , I Urquijo , Iñigo Bidaguren , Gustavo Adolfo Esteban , Miguel Ángel Gómez Solaeche , Juan Luis Larrabe , Jesus María Blanco 
Published: September 2023

The research based on the development of OWC devices continues growing and nowadays there are endless options that have already been studied. From the type of turbine and its control, to the most efficient energy conversion system or design, the OWC technology needs to be further developed in order to be economically attractive.

This research studies several possibilities to improve the efficiency of the Mutriku breakwater wave plant. On the one hand, the L-shape configuration of this plant allows studying a new configuration based on the coupling of the well-known U-shape [1], to create a new L+U-shape breakwater. In addition, the installation of harbor-walls has been proven as a promising option to enhance the interior damping of the camera [2], and this option seems to be very promising because of the design of the Mutriku plant allows its performance. Finally, a design based on the sharp-edges round off its being studied in order to reduce the energy losses and therefore enhance the energy harnessing of the plant.

The experimental work has been carried out in the 12.5 m long wave flume located at the laboratory of Fluid Mechanics of the Energy Engineering Department (UPV/EHU). The physically constructed OWC device corresponds to one of the cameras installed at the Mutriku breakwater wave plant, an isolated camera, according to the construction plan and applying a 1:36 scale. All the experiments were carried out at two tides that correspond to the medium and maximum equinoctial live tides of Mutriku location. According to the information of the Basque Coast sea states [3], a constant incident regular waves of 30 mm were generated at several periods: 0.7<T[s]<1.7 for the medium tide and 0.7<T[s]<2.1 for the maximum tide.

The L+U-shape was created with two lateral walls joined by frontal walls of different heights (W), as shown in Figure 1-left, that were positioned at several distances from the physical model. However, another L+U-shape was considered using a transversal wall of different heights and without lateral walls (TW, Figure 1-right), and placing at several distances form the plant.
The obtained results reveals that the promising configuration corresponds to the one containing lateral walls, so that the influence of harbor walls will be further studied.

References:
[1] C. Xu, Z. Liu, G. Tang, Experimental study of the hydrodynamic performance of a U-oscillating water column wave energy converter, Ocean Eng. 265 (2022) 112598. doi:10.1016/j.oceaneng.2022.112598.
[2] D.H. Yacob, S. Sarip, H.M. Kaidi, J.A. Ardila-Rey, F. Muhammad-Sukki, Oscillating Water Column Geometrical Factors and System Performance: A Review, IEEE Access. 10 (2022) 32104–32122. doi:10.1109/ACCESS.2022.3160713.
[3] Y. Torre-Enciso, I. Ortubia, L.I. López de Aguileta, J. Marqués, Mutriku Wave Power Plant: from the thinking out to the reality, 8th Eur. Wave Tidal Energy Conf. (EWTEC 2009). (2009) 319–328. http://tethys.pnnl.gov/sites/default/files/publications/Torre-Enciso_et_al_2009.pdf.