Session: 12-02-03 Wave-Structure Interactions III

Paper Number: 125355

125355 - An Experimental Study of a Dual-Function Slotted Barrier Integratred With Oscillating Water Column for Wave Energy Extraction and Shore Protection 

Wave energy conversion is a promising technology to provide renewable energy, but its commercialization is limited mainly due to high initial investment and maintenance cost (Lopez et al., 2013). One way to improve the economic feasibility of wave energy utilization is to integrate wave-energy converters (WECs) into shore-protection structures to form dual-function structures, which have the capability to harness wave energy for electricity generation and provide coastal protection (Xu and Huang, 2018). Among different types of existing WECs, oscillating water columns (OWCs) have the power take-off (PTO) system out of water, which greatly reduces the influence of befouling on PTO performance and lowers maintenance cost. This study introduces a such dual-function design by integrating an OWC-type WEC with a bottom fixed slotted barrier, which can provide shore protection and minimize potential environmental impacts by allowing water, marine life, and sediment to move across the structure. For these types of dual-function structures, the main design objectives are to achieve the designed transmission coefficient, maximize the wave power extraction, and minimize the wave loading on the structure. In this study, we present results of an experimental study of the proposed dual-function structure in a small wave flume equipped with a piston-type wave generator. In the experiment, a circu- lar orifice at the top of the pneumatic chamber is utilized to emulate the PTO system. Wave power extraction is measured using a differential pressure sensor. Wave loading on the structure is measured using a three-axis force balance. The focus of this study is the effects of tide level and the porosity of the slotted barrier on wave power extraction, wave transmission and wave loading under different wave conditions. Four values of slotted barrier porosity (0.1,0.15,0.2 and 0.25) and three tide levels (mean, low and high tides) were studied. For the mean tide scenario, maximum extraction efficiencies obtained for the four slotted bar- riers ranged between 20% and 27%, while the transmission coefficients ranged between 0.2 and 0.6: a larger porosity gives a larger transmission coefficient but a smaller extraction efficiency. The findings from this study demonstrate the potential for cost-sharing between wave energy utilization and shore protection projects.

References

Lopez, I., Andreu, J., Ceballos, S., Mart ́ınez de Alegr ́ıa, I., Kortabarria, I., 2013. Review of wave energy technologies and the necessary power-equipment. Renewable and Sustainable Energy Reviews 27, 413–434.
Xu, C., Huang, Z., 2018. A dual-functional wave-power plant for wave-energy extraction and shore protection: A wave-flume study. Applied Energy 229, 963–976.

Presenting Author: Zhenhua Huang University of Hawaii at Manoa

Presenting Author Biography: Zhenhua Huang is a professor in the Department of Ocean and Resouces Engineering, University of Hawaii at Manoa. His research interests include wave-structure interaction, coral reef hydrodynamics, coastal sediment transport and shore protection.

Authors:

Zhenhua Huang University of Hawaii at Manoa
Mayah Walker University of Hawaii at Manoa
Clint Reyes University of Hawaii at Manoa
Patrick Cross University of Hawaii at Manoa