Sharing the Space at Sea – integrating low trophic aquaculture, nature restoration and marine monitoring in an off-shore wind farm

The competition for space at sea is increasing, and the need for intelligent solutions for sharing space at sea is pertinent¹. The concept of marine multi-use is emerging as one such solution. With marine multi-use, actors at sea share space and time, services, data, infrastructure and logistics². This concentrates human activities in confined areas, leaving other areas free for Marine Protected Areas, and also allows for synergistic activities, reducing the overall energy use, emissions, labour and increasing safety of operations.

In the WIN@sea project, the project partners have created a marine multi-use prototype in the Danish Kriegers Flak (DKF) offshore windfarm in the Baltic Sea. Here, the partners combine off shore production of fossilfree electricity with low trophic aquaculture (LTA) of seaweed and mussels, restoration of marine ecosystems through nutrient extraction, and data production for the national marine monitoring program.

While the low salinity of the Baltic waters (<10 ppt) limits the yields of seaweeds and blue mussels, the multi-use prototype at DKF has generated valuable outcomes for future multi-use operations: Primarily, the project has demonstrated integration of activities between partners, allowing for reduced fuel use, emissions and labour – as wind farm Crew Transfer Vessels have monitored the aquaculture site on a regular basis, and costly maintenance and repair activities have been combined. Safety in LTA operations has been increased through joint risk assessment procedures and through the wind farm Marine Coordination Centre overseeing all operations in the wind farm 24/7. In the windfarm, technological innovation for marine monitoring with Autonomous Underwater Vehicles has been tested to automatise future monitoring operations.

Site selection tools have been developed to secure optimal positioning of LTA in windfarms for maximal harvest yields and nutrient extraction, and Life Cycle Assessment will further quantify the benefits in saved emissions and identify the emission hot spots for future optimisation of multi-use concepts. Optimising future Marine multi-use operations calls for integration of the concept in the earliest planning phase of future offshore wind farms, aligning Marine Spatial Planning Frameworks across EU and regulating across food, environmental and climate policy sectors.