Photo: Hvalpsund Net

MERMAID: The sea—a treasure trove of energy and food resources

By Lisbeth Lassen
The seas around Europe are used relatively intensively, particularly for wind farms and aquaculture or fish farms, and to a lesser extent for wave energy plants and seaweed farming. This trend is set to continue in the near future. Given that the attractive sea areas are not unlimited and offshore activities are relatively expensive, it can be good idea to utilize the regions for several things at the same time. The EU MERMAID project, a four-year project under the leadership of Professor Erik Damgaard Christensen from DTU Mechanical Engineering, has therefore looked at how to most effectively exploit various marine areas in Europe for different types of offshore power generation and food production industries.

“At the beginning of the project we had many ideas about combining the various functions into a single platform with a very imaginative design,” explains Erik Damgaard Christensen. “But our knowledge of structures at sea made us realise that it would be far too expensive. So we suggested that we should develop sites with several functions instead. We chose to focus on aquaculture and wind in the project, without the two offshore activities having to be integrated into a single structure. Space requirements for the two industries are also different: Wind power needs very large areas and aquaculture can take place in much smaller areas, so it does not make sense to integrate them structurally."

Four different test sites in the European seas
The MERMAID project therefore quickly became focused on investigating opportunities for collaboration between the various offshore industries, and it was decided to set up four test facilities in marine regions with different conditions: the Wadden Sea, the Baltic Sea, the Mediterranean Sea and the Atlantic Ocean. These regions have widely varying environment and climate conditions.

The Baltic Sea is an area where fresh water from the large rivers to the east mixes with salt water, while the Wadden Sea or North Sea has changing seabed conditions. The Atlantic Ocean and Mediterranean Sea are deep water areas, although the Mediterranean has much more coastline protection than the Atlantic.

focused on the challenges that exist in Europe if you want to exploit these marine areas for different offshore activities,” explains Erik Damgaard Christensen, “and we quickly discovered several advantages. The Baltic Sea has a mixture of salt water and fresh water, resulting in quite low salinity, combined with specific temperature conditions. This was found to be a huge advantage for trout production, because the problematic salmon louse cannot survive as easily in this environment as it can in other regions.”

The main reason for placing a test site in the North Sea was that this area is exposed to strong currents and waves, and the seabed is changeable, causing potential challenges for structures. It is also a region where the shellfish industry is on the lookout for new areas for mussel cultures—an industry with large growth potential because the market demand for mussels is twice as large as current Dutch production.
The Gemini test site, as it was called, was located in an area with good conditions for wind power, but also potential for seaweed and mussel farming.

The third test site was the Cantabria Offshore Site in the Atlantic Ocean north of Spain, chosen for good wind conditions and relatively deep water, and the large waves that roll in from the North Atlantic. There are plans to install 77 multi-use offshore platforms here which can extract energy from wind and waves—units based on OWC (Oscillating Water Column) technology.

The fourth test site was located in the Mediterranean Sea, in the Adriatic, to get a test site in deep water but where the waves were not as large. The area is fairly close to Venice, leading to a number of restrictions in relation to new offshore structures. It is also an area where special consideration must be given to bird life and rare marine mammals. It was therefore a challenge to find a location for the multi-use platform. It had to be placed fairly far out to sea, also to avoid conflicting with local traffic routes and fishing. The solution chosen was a platform including wind turbines and fish farms.

Overall, the four test sites helped identify the advantages and challenges of exploiting marine areas for different industries. But the challenges were not only technical in nature.

 Atlantic testsite. image: MERMAID.  Baltic testsite, image: MERMAID.

Collaboration and challenges for offshore industries
“You think of the sea as being large. But when people set aside large areas for a given purpose, such as one new wind farms, I think the operators expect the area not to be used for anything other than wind turbines,” says Erik Damgaard Christensen, highlighting one of the challenges of getting offshore industries to cooperate.“

This is precisely the problem. The interesting marine areas are starting to get filled up. So unless care is taken, it will just be a single industry that is given the rights to large parts of the marine space, which might prevent other industries to develop,” he notes. Several industries, such as aquaculture in Denmark, have enormous growth potential which will mean more jobs. This potential can be aided by a change in legislation and permitting procedures that assists different industries in the corporation on exploitation of ocean resources.

“If you want offshore companies to collaborate, it has to be supported by the legislation and permitting procedures that makes it attractive to the industries to collaborate in the same marine area” concludes Erik Damgaard Christensen.

Facts about MERMAID:

An EU project and part of the 'Oceans of Tomorrow' initiative

Project leader: Erik Damgaard Christensen

Total budget: EUR 7.4 million

Duration: Four years from the beginning of 2012 to the end of 2015
29 participants in total



Erik Damgaard Christensen
Head of Section, Professor
DTU Mechanical Engineering
+45 45 25 13 98
25 FEBRUARY 2020