Offshore Energy and Storage 2023 Malta ‐ Sea Opportunity

The years 2023 and 2024 marked a pivotal period for global climate and energy policy. The European Union was advancing its REPowerEU plan to accelerate renewable energy deployment and reduce reliance on imported fossil fuels. More globally, nations around the world have been ramping up efforts to meet clean energy targets under the Paris Agreement. Subsequently, the spotlight has increasingly turned to offshore renewable energy and long-duration storage systems as essential pillars of a resilient, low-carbon global economy. Offshore wind, in particular, offers vast untapped potential, especially when integrated with emerging technologies such as green hydrogen production, wave energy harvesting and compressed air energy storage. Given that nearly half of the world's population resides in coastal regions, the development of scalable offshore energy solutions is not just an environmental imperative—it is an economic one. In this context, the Offshore Energy and Storage Society (OSES) has emerged as a vital force in mobilising the international research community, industry stakeholders, and policy leaders towards the realisation of integrated offshore energy systems. The contributions in this Special Issue reflect the Society's mission and demonstrate the technical ingenuity, interdisciplinary thinking and systems-level insight required to advance offshore energy and storage innovations in support of global climate goals. This Special Issue has attracted high-calibre contributions at the intersection of offshore renewable energy systems, energy storage integration, and diagnostic methodologies. Of the papers received, seven have been accepted following a rigorous peer-review process. Together, they offer valuable insights into the techno-economic, operational and control challenges and opportunities emerging in offshore wind, hydrogen systems, wave energy and compressed air energy storage technologies. These selected papers can be broadly clustered into three thematic categories: (1) techno-economic optimisation of renewable-hydrogen systems, (2) storage technologies and system-level controls and (3) diagnostics and reliability of offshore wind components. The papers by Guichard et al. and Travalgini et al. explore the integration of offshore wind energy with hydrogen production. Guichard et al. use the PyPSA power system modelling tool to optimise reversible solid oxide cell (rSOC) configurations coupled with a 600 MW offshore wind farm. Their parametric sensitivity study highlights how combinations of electricity and hydrogen prices influence system profitability—showing potential improvements in profit margins of up to 908% over baseline cases. Travalgini et al. complement this by focusing on the Mediterranean context, where floating offshore wind turbines (FOWTs) are evaluated with green hydrogen production under curtailment. Their comparative modelling approach—combining statistical and time-dependent methods–yields levelised hydrogen costs between 3.79 and 5.47 €/kg, establishing critical benchmarks for floating hydrogen systems in constrained grid environments. Four papers in this collection examine novel storage integration strategies across wind, wave and compressed air systems. Mokhtare et al. investigate battery energy storage systems (BESS) in Turkish offshore wind farms under strict grid code constraints. Their techno-economic model demonstrates that flexible integration strategies can increase delivered energy and profitability compared to strict regulatory compliance. Sang et al. focus on wave energy, proposing a nonlinear coordinated control scheme using multiple feedback linearisation for systems combining direct-drive linear permanent magnet generators with supplementary electrochemical storage. The proposed control methodology improves dynamic performance under fluctuating wave conditions. Meanwhile, Cardenas et al. present a combined heat store and heat exchanger (HSX) for compressed air energy storage (CAES). Through a case study involving a 15 MW offshore wind-driven CAES system, they show that the proposed salt-based HSX design achieves a round-trip exergy efficiency of 93.7% and a reduced levelised cost of storage (≈31.5 £/MWh), suggesting a cost-effective path for thermally integrated CAES systems. Finally, Barbour et al. perform a detailed exergy analysis of both isobaric and isochoric adiabatic CAES systems. Their results indicate that isobaric systems deliver higher energy density and round-trip efficiency but demand more complex pressure management. The analysis emphasises compressor and cooler losses as primary exergy sinks, guiding future system design for improved performance. To conclude, Huan et al. provide a comprehensive review of fault diagnosis approaches for wind turbine generators, highlighting that hybrid diagnostic models currently offer the highest accuracy in real-time detection. Their structured comparison of stator, rotor, air gap and bearing failures underlines the operational vulnerabilities of wind systems and the need for robust predictive maintenance. Carriveau drafted this Editorial Article. Article was reviewed by Sant and Garvey. The authors have no conflicts of interest. Dr. Rupp Carriveau is the director of the Environmental Energy Institute and co-director of the Turbulence and Energy Lab, and co-lead of AgUWin at the University of Windsor. His research activities focus on energy systems futures and advanced agricultural systems. Dr. Carriveau serves on several editorial boards, including Wind Engineering, Advances in Energy Research, and the International Journal of Sustainable Energy. He is a recipient of the University Scholar Award and has acted as a research ambassador for the Council of Ontario Universities. He is a Founder of the Offshore Energy and Storage Society (OSES) and co-chaired recent OSES Events in Ningbo, China; Brest, France; and recently chaired OSES2024 New Bedford. Dr. Carriveau represents Canada in the International Energy Agency Wind Task on Digitalization. He is the chair of the IEEE Ocean Energy Technology Committee and has been named to Canada's Clean50 for his contributions to clean capitalism. Dr. Tonio Sant is a professor of fluid mechanics at the University of Malta and a leading expert in offshore renewable energy systems. He is the co-founder of FLASC (Floating Liquid-piston Accumulator using Seawater under Compression), a pioneering start-up focused on offshore energy storage solutions that integrate directly with floating renewable platforms. Dr. Sant's research bridges fluid dynamics, ocean engineering and energy systems, with a particular emphasis on sustainable offshore infrastructure. He has played a central role in advancing compressed energy storage technologies for marine environments and has published extensively on wave-structure interaction, offshore hydrodynamics and system integration. In addition to his academic leadership, Dr. Sant actively collaborates with industry and international consortia to advance offshore energy innovation in Europe and beyond. His work supports the global transition to net zero by enabling scalable, cost-effective storage solutions that address the intermittency and spatial challenges of offshore renewable energy. Dr. Seamus Garvey is a professor of dynamics at the University of Nottingham and a leading authority on mechanical energy storage and offshore renewable systems. With a background in dynamics and aero-mechanical engineering, he has spearheaded numerous research initiatives focused on scalable, low-carbon technologies that support global decarbonisation efforts. Professor Garvey is the founder of two innovative start-ups: Tetrafloat, which develops novel floating platform technologies for offshore wind, and Cheesecake Energy Ltd., a company pioneering compressed air-based energy storage solutions for grid and industrial applications. His interdisciplinary work blends theoretical insight with practical engineering, aiming to overcome the spatial and temporal mismatches inherent in renewable energy production. A vocal advocate for holistic energy system thinking, he contributes regularly to public and policy discourse on sustainable energy futures. Professor Garvey's contributions continue to shape the direction of offshore infrastructure, storage integration, and systems-level approaches to enabling a net-zero economy.