Comprehensive review of wireless power transfer for autonomous underwater vehicles: technological innovations, challenges, and future prospects

• The review highlights advancements in WPT for AUVs, focusing on resonant inductive coupling, magnetic resonance, and acoustic-based systems. • Hybrid WPT systems address challenges such as energy loss due to water salinity, conductivity, and alignment issues in underwater environments. • Future research areas include adaptive control systems, metamaterials, and integrated energy storage solutions to optimize AUV docking stations and extend mission durations. Autonomous Underwater Vehicles (AUVs) are revolutionizing oceanographic research, military surveillance, and offshore energy maintenance but face the constraint of limited battery capacity and recharging difficulties in terms of endurance during operation. Wireless Power Transfer (WPT) appears to be a promising answer in providing remote, contactless charging, thereby extending mission duration. This review covers recent advancements in WPT technologies for AUVs, focusing on resonant inductive coupling, magnetic resonance, and acoustic-based power transfer systems. Among these, resonant inductive and magnetic resonance coupling methods have demonstrated the highest practical suitability for AUV applications due to their efficiency, misalignment tolerance, and compatibility with submerged operational conditions. The specific problem of energy loss with salinity and conductivity from the water, alignment issues, and the use of durable corrosion-resistant materials are analyzed in detail. This paper reviews the key advancements in inductive coupling techniques, coil configurations, as well as hybrid power transfer modes combining electromagnetic, acoustic and optical methods. No sole WPT technology can solely address the variety of underwater power transfer application needs, but hybrid schemes are promising. Hybrid designs can be used to support short-range, high efficiency transfer modes with complementary long-range acoustic or optical transfer techniques for improved performances. Some future research areas include adaptive control systems, metamaterials, and novel energy harvesting innovations, as well as integrated energy storage and management in AUV docking stations. WPT technologies have advanced significantly, but innovation is still needed to optimize AUVs for long-duration underwater missions that are critical to marine resource management and subsea infrastructure monitoring.