Prospective seaweed systems for North-West European waters

Seaweed is a potential source of sustainable food, feed, cosmetics, biomaterials, and biostimulants. Seaweed is currently mainly grown in Asia, and it is unclear which seaweed systems are best suited for North-West European waters. We use an expert workshop and a written feedback round to identify prospective seaweed systems, including the cultivation site and post-harvest stages, for three different contexts. Independent of the context, there is a preference for cultivating multiple species and having a high level of automation. Depending on the context, the optimal choice with regards to scale, substrate, seeding technique, and the integration of seaweed farming with (shell)fish species differs. Profitability of the systems, availability of (large-scale) processing facilities and ships to go offshore, uncertainty of buyers, and obstacles in seed stock availability, permits, and building infrastructures present key challenges and risks. The identified seaweed systems serve as input to the policy debate around alternative resource production in Europe and can help in developing standards for seaweed system design. Furthermore, researchers and technology providers can use the prospective systems for future profitability assessments and directions for technology developments.