Concluding RAScue
The Baltic Sea connects multiple Northern European countries. For Flexens, a company with offices in both Helsinki and Mariehamn, making a positive impact on the Baltic Sea is essential.
Due to high nutrient loads over a long time, the Baltic Sea is afflicted by eutrophication. To take part in tackling this problem, Flexens initiated a project called RAScue ("Recirculating Aquaculture Systems cutting eutrophication"), taking an integrated approach to land-based fish farming through nutrient recovery and improving energy efficiency. The project received funding from the Bank of Åland through their Baltic Sea Project.
In brief, Flexens wanted to demonstrate whether it would be feasible for offshore fish farmers to transition their business inland, thereby decreasing nutrient emissions to the sea. The team examined the question through two studies: First, a study on making the leading nutrient recovery system, Recirculating Aquaculture System (RAS), more cost-effective and energy-efficient; second, a feasibility study on producing fertiliser from fish sludge. RAScue was achieved through desktop studies and visits to the Åland islands.
Process highlights: Encounters on Åland
RAScue project coordinator Szilvia Haide and energy specialist Edvard Nordlund, Flexens Oy Ab, visited the Fifax fish farm on Åland, learning more about RAS operation and energy consumption.
Intern Mukesh Basnet visited the Åland Islands, meeting with local stakeholders to discuss agricultural fertiliser production from fish sludge. During the visit, Basnet conducted semi-structured interviews with the CEO of the waste management company Svinryggens Deponi Ab, the CTO of the fish farming company Fifax Abp, crop and fruit growth advisors, agricultural inspectors from the Government of Åland, as well as local farmers.
The RAScue project: Main takeaways
The RAScue team showed that it is techno-economically feasible for offshore fish farmers to decrease nutrient emissions by moving their facilities inland. While coupling RAS with renewable energy technologies is a capital investment, the effort yields annual savings and increased energy self-sufficiency in the long run. Energy self-sufficiency and decreased harmful emissions are all the more important due to the state of the world today.
RAScue also concluded that the sector coupling of RAS is excellent for promoting a circular economy and benefiting all involved parties. For example, the study investigated sourcing oxygen from electrolytic hydrogen production and sourcing heat from industrial waste heat (e.g., from steel and paper industries).
In terms of fertiliser production, it was concluded that by drying the fish sludge, a granular form of fertiliser could be produced and potentially applied to crops on the Åland islands, such as potatoes, onions and apples.
"Working within the RAScue project has been an extremely rewarding experience. I have gained new insights into Recirculating Aquaculture Systems from energy and nutrient recovery perspectives, " RAScue project coordinator Szilvia Haide says.
"As Flexens is advancing the energy transition through the development of green hydrogen production plants, we will have by-product oxygen available. I am open to exploring further cooperation with RAS developers to utilise this oxygen in a circular way."
The RAScue team is grateful for the discussions and assistance from the following parties:
Ålandsbanken Abp
Fifax Abp
Svinryggens Deponi Ab
Ålands Hushållningssällskap
Ålands Landskapsregering
Furthermore, the RAScue team thanks all advisors, including local farmers and researchers, who contributed to the project.
Links to RAScue publications and project presentations: