Introduction
The continued expansion of offshore renewable energy infrastructure creates new opportunities for multi-use marine systems, in which low-trophic aquaculture can be co-located with offshore wind farms and potentially share spatial, infrastructural, and operational resources. Such integration may increase the efficiency of marine space use, reduce resource requirements and environmental burdens, and improve the economic feasibility of offshore aquaculture. This study evaluated the environmental and economic performance of offshore cultivation of sugar kelp (Saccharina latissima) and blue mussel (Mytilus edulis) as mono- and co-cultivation systems integrated with offshore wind farm operations under Danish offshore conditions. The analysis considered a commercial-scale cultivation area of 18.75 ha and investigated whether operational synergies associated with multi-use offshore systems could improve performance relative to standalone aquaculture.
Methodology
An integrated life cycle assessment (LCA) and techno-economic analysis (TEA) framework was applied to mussel mono-cultivation, seaweed mono-cultivation, and seaweed–mussel co-cultivation. Wind farm integration was modelled through shared offshore operations, including vessel use, diesel consumption, and monitoring activities. Environmental performance was evaluated using the Environmental Footprint (EF) 3.1 method. A separate scenario accounting for nutrient assimilation was evaluated to distinguish production-related impacts from potential ecosystem services benefits associated with nutrient removal. Economic feasibility was assessed over a 10-year project lifetime using Net Present Value (NPV), considering alternative market pathways for food- and feed-grade biomass.
Results and Discussion
Integration with offshore wind farm operations improved environmental performance across the cultivation systems. At farm scale, shared resource use reduced the environmental footprint of the co-cultivation system by approximately 17% relative to standalone cultivation. The carbon footprint decreased by approximately 4% for mussel mono-cultivation and 12% for seaweed mono-cultivation following wind farm integration, demonstrating that sharing infrastructure and offshore operations can reduce burdens associated with offshore logistics and farm management.
Economic viability was strongly influenced by both wind farm integration and the targeted biomass market. The highest economic benefit was obtained for co-cultivation combining high-value seaweed products with food-grade mussels, for which the 10-year NPV increased from approximately ���10.8 million for standalone cultivation to ���12.5 million following wind farm integration. In contrast, systems dependent on wholesale seaweed and feed-grade mussel markets remained economically constrained, indicating that operational synergies alone may not compensate for low biomass market values.
Conclusion
The combined environmental and economic assessment demonstrates that integrating low-trophic aquaculture with offshore wind farms can improve environmental and economic performance, particularly when shared infrastructure and operations are coupled with higher-value biomass applications. Co-cultivation showed the strongest overall benefit, supporting multi-use offshore systems as a pathway towards more resource-efficient and economically resilient marine production. However, market positioning remains a critical determinant of economic viability, highlighting the importance of integrating production-system design with biomass valorisation strategies.
Acknowledgement
This work was supported by the European Union's Horizon Europe research and innovation programme under Grant Agreement No. 101094065 (OLAMUR), WIN@Sea under Grant No. 00037712, SMARTTANG under Grant No. 34009-21-1963