Marine renewable energy for hydrogen production: Advancing towards a sustainable future through technological, economic, and environmental frontiers– a review

The accelerating urgency to mitigate global climate change has intensified research into cleaner, more sustainable energy solutions. This review explores the convergence of marine renewable energy (MRE) and green hydrogen production as a promising pathway toward a decarbonized energy future. It provides a comprehensive analysis of MRE technologies including tidal, wave, ocean thermal energy conversion (OTEC), and salinity gradient power detailing their working principles, recent technological advancements, and current deployment status. Special attention is given to the integration of these resources with hydrogen production via water electrolysis, focusing on technologies such as proton exchange membrane (PEM), alkaline, and solid oxide electrolyzers (SOEC), which have demonstrated conversion efficiencies of up to 90 % under optimal conditions. The review assesses the technical feasibility of these hybrid systems, highlights key operational challenges (e.g., intermittency, offshore infrastructure, corrosion), and discusses potential advantages such as proximity to coastal hydrogen markets and energy security. The economic dimension is critically examined, with current green hydrogen production costs ranging from $2.50 to $6.80 per kilogram, and future targets aiming for $1/kg by 2030. Case studies including the Sealhyfe offshore pilot project in France, capable of producing up to 400 kg/day of hydrogen are presented to illustrate real-world progress. Environmental impacts, regulatory frameworks, and marine spatial planning considerations are also addressed. By synthesizing technical, economic, and environmental perspectives, this review offers a strategic overview of the role marine energy can play in large-scale hydrogen production. It aims to support researchers, policymakers, and industry stakeholders in identifying opportunities, addressing barriers, and accelerating the deployment of MRE-to-hydrogen systems. Ultimately, the study contributes to outlining pathways for a resilient, low-carbon, and integrated energy future.