Unlocking Offshore Freshened Groundwater Potential: Assessing Feasibility in EU COST Member Countries

Coastal aquifers, situated at the interface of oceanic and hydrologic systems, provide vital freshwater resources for over one billion people. However, these systems are increasingly stressed due to overexploitation, urbanization, and climate change, necessitating innovative solutions to address freshwater scarcity. Offshore freshened groundwater (OFG) represents a promising yet largely untapped resource, but its technological and economic feasibility remains uncertain. This study focuses on evaluating the feasibility of OFG utilization in EU COST Member countries, considering critical criteria such as water quality and treatment requirements, sustainability and resource longevity, infrastructure and logistics, availability of alternative water sources, and site-specific conditions. A comprehensive database was compiled, integrating OFG occurrences, desalination capacity, oil and gas infrastructure, and seafloor properties. An initial assessment was conducted to evaluate technical feasibility, focusing on the proximity of OFG reservoirs to treatment capacity and existing infrastructure. Key findings indicate that the Adriatic Sea offshore Rimini, Italy offers the highest feasibility for OFG utilization, due to the proximity to desalination facilities and existing offshore platforms. Other regions, including southern Spain and Belgium, warrant further exploration to determine their potential for sustainable OFG exploitation. This study provides a regional feasibility assessment and lays the groundwork for more detailed case studies. By addressing technological and logistical challenges, this research contributes to the broader effort to unlock OFG’s potential as a critical resource in water-stressed regions.