In-situ wave energy harvesting for unmanned marine devices: A review

It is promising and interesting to supply unmanned marine devices (UMDs) such as data buoys, unmanned surface vessels, and unmanned underwater vehicles with sustainable energy by in-situ wave energy harvesting. However, there is a lack of a comprehensive survey about the state of the art. This review summarizes the fundamentals, research status, comparisons, applications, challenges, and future trends of wave energy har-vesters (WEHs) incorporated into the UMDs. Various in-situ wave energy capture mechanisms are categorized into external and internal types according to the positional relation, including hydrofoils, floating bodies, tur-bines, pendulums, spring masses, and gyroscopic mechanisms. Also, they are divided into series and parallel types according to the principle of motion generation. Transducers convert the captured mechanical energy into electricity, including electromagnetic, piezoelectric, triboelectric, dielectric elastomer, liquid metal magneto -hydrodynamic, and hybrid transducers. Existing applications of the in-situ WEHs are reviewed and discussed. Finally, the main challenges are summarized. It is found that there is a gap between fully powering the UMDs and using the WEHs. A list of potential solutions, including nonlinear methods, are proposed to promote the further development of this topic.

Automated summary

This paper provides a comprehensive review of wave energy harvesters incorporated into unmanned marine devices, including categorization of mechanisms, analysis of applications, and identification of challenges. It highlights the gap between fully powering unmanned marine devices and utilizing wave energy harvesters, and proposes potential solutions for further development.