WinSeaFuel aims to product biomethane (and bioproducts) from seaweeds cultivated in offshore conditions. Today, both the culture of marine biomass in offshore conditions in huge quantities and its associated valorizations are not well controlled. The project presents technical and scientific issues which require research and development in order to start a new industry economically viable and sustainable. Regarding the marine resource mobilization the goal is to develop our knowledge of the physiology of seaweeds (growth, reproduction...) and to design culture and harvest offshore technologies in order to gain our technical know-how. Regarding the seaweed valorizations, the aim is to study and develop bioenergy production (biogas by methanization) for biomethane fuel/grid injection applications. It presents research issues mainly on the pre-treatment, the yield optimization and co-digestion. Due to the richness of interesting molecules from the seaweeds and in order to ensure the economic viability of the industry, the study of the potential bioproducts and associated extraction process will be led within the biorefinery concept. The global target of WinSeaFuel is to evaluate the technical and economic feasibility of this new sustainable production with a view to developing a gradual industrial exploitation from 2015 on an off-shore wind farm site.