Wave Energy Converter for Drifter Applications (WECDA)

Abstract

The document is a summary of the activities carried out by the Brno University of Technology (BUT) at the EMSO Regional Facility, OBSEA, under the EMSO ERIC Physical Access Programme. The project investigated innovative, environmentally responsible alternatives to enhance the autonomy and sustainability of oceanographic drifters. By validating a new kinetic energy harvesting technology in real marine conditions, the work contributes to the development of next-generation, low-impact observation platforms.

Access to the EMSO-OBSEA cabled observatory, operated by the UPC, enabled a full evaluation of the device—from controlled laboratory characterisation to short-duration sea deployments and a dedicated long-term test. During field trials, the wave energy converter demonstrated stable and continuous energy harvesting, providing sufficient power to support low-duty-cycle sensing and some periodic wireless data transmission. Dataset available: https://doi.org/10.5281/zenodo.17609900

The requirements of ocean monitoring have driven the continued development of sensor platforms such as Lagrangian drifters, where autonomy remains a key design consideration. Energy harvesting (EH) has proven to be a reliable approach for extending the operational lifetime of these autonomous systems [1]. While solar panels are the most common commercial EH solution for enhancing drifter autonomy (e.g., Sofar: Spotter; Fastwave: Voyager Solar), their applicability is limited. To ensure accurate surface current tracking, drifters must minimize wind influence by remaining mostly submerged, which significantly reduces the effectiveness of solar energy harvesting. Moreover, relying on a single EH source provides only a modest improvement in system autonomy. In this project, we investigated the feasibility of harvesting the oscillatory motion of the drifter induced by ocean waves - a concept that has not been extensively explored to date. The work focused on understanding the dynamic interaction between the drifter and the surrounding water load, which is essential for designing an efficient wave energy converter (WEC). It was found that the captured energy can be maximized by properly designing the internal WEC with a natural frequency close to that of the drifter’s movement [2]. The aim was to achieve resonance between the WEC and the drifter’s motion in order to maximize the amplitude of the former’s moving parts and increase the harvested energy.

Postprint (published version)