Powering the Sea: Challenges and Trends in Tidal Energy Integration, Power Converter Technology, and the Path Forward

The global demand for sustainable energy has shifted interest in Marine Renewable Energy (MRE) sources. Tidal energy is particularly attractive within this domain due to its predictability and high capacity factors. However, practical and large-scale deployment remains constrained by challenges in resource variability, subsea reliability, and grid compliance. This review provides a focused and comprehensive assessment of tidal energy systems, with particular emphasis on Power Electronic Converters (PECs) as the pivotal enabler of efficient energy extraction, control, and grid integration. A structured challenge– mitigation framework is developed across three domains—resource assessment, converter topologies, and grid interaction—revealing unresolved issues in long-term reliability, converter robustness, and system-level stability. Forward-looking research directions are also identified, including hybrid tidal–renewable integration, modular and multiport PEC architectures, and advanced monitoring frameworks, all of which are expected to accelerate technology readiness and support cost-effective scaling. This review offers a roadmap for transitioning tidal energy toward dependable, cost-effective, and sustainable expansion by bridging insights across the resource, converter, and grid domains.