Abstract
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.