Field experiments on dielectric elastomer generators integrated on a U-OWC wave energy converter

This paper describes the results of an experimental campaign conducted on a U-Oscillating Water Column (UOWC) wave energy converter equipped with Dielectric Elastomer Generator (DEG) Power Take-Off (PTO) system. The considered PTO technology has the potential for overcoming some of the limitations associated with the use of traditional self-rectifying turbines. Experiments have been performed in the benign sea test site of the Natural Ocean Engineering Laboratory (NOEL), where the DEG/U-OWC was exposed to sea states with a significant wave height in the range of 0.15 m - 0.45 m and peak spectral periods in the range of 1.8 s - 3.3 s. The aim of this work is to analyze the dynamic response of the coupled DEG-PTO and U-OWC system. The analysis of the experimental data shows that the presence of the DEG determines a slight decrease in the natural period of the water column oscillations. Through the tests, we also demonstrate that a relief valve can be successfully used to actively tune the dynamic response of the system to ensure the safety of the DEG in severe sea-states.