WP6: Sea Farms

The work package will develop tools for design of seaweed farms. Drag forces and deformation of farm systems at different sea states will be determined using towing experiments with live seaweeds at sea and artificial surrogates in lab.

The WP will develop tools for design of seaweed farms. Drag forces and deformation of farm systems at different sea states will be determined using towing experiments with live seaweeds at sea and artificial surrogates in lab. Based on data from the experiments, the numerical model for macroalgal sea farms will be developed within FhSim, a software framework developed at SINTEF Ocean for simulation and visualization of dynamic systems. The model will support design of sea farm concepts at different environmental conditions (e.g. sheltered, coastal, offshore and IMTA).

Status

Status autumn 2019

Towing experiments at sea were conducted in 2016 and 2017. Loads and towing velocities were measured. Towing experiments with artificial sugar kelp were conducted at NTNU in 2017. Drag forces were measured and the movement of the models were recorded by an underwater camera. The study is published in the MSc thesis "Design of Artificial Seaweeds for Assessment of Hydrodynamic Properties of Seaweed Farms" by C. Norvik. A study of mechanical properties and morphology of sugar kelp (Saccharina latissima) has been carried out as part of a SINTEF summer student programe (Norvik 2016). In 2018 tests with cultivated sugar kelp were conducted in a closed test facility containing sea water. Towing velocities, drag forces and tensile forces in the rope were measured (Endresen et al in press). Results from the towing tests have been used in FhSim for simulation of a seaweed farm planned to be deployed in exposed environments in Norway in 2020.

Publications:

  • Endresen PC, Norvik C, Kristiansen D, Birkevold J, Volent Z (2019). Current Induced Drag Forces on Cultivated Sugar Kelp. Proceedings of the ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering OMAE2019 June 9-14, 2019, Glasgow, Scotland. OMAE2019-96375. In press
  • Norvik C (2017). Design of Artificial Seaweeds for Assessment of Hydrodynamic Properties of Seaweed Farms. MSc-thesis, NTNU
  • Norvik C (2016) "Design of artificial seaweeds for assessment of hydrodynamic properties of seaweed farms". SINTEF summer student report

Status autumn 2018

Testing and drag-measurements using different configurations of seaweeds in sea and towing tank, start developing numerical model: Towing experiments have been conducted at the Marine Cybernetics laboratory at NTNU in 2017. Two simplified artificial models of Saccharina latissima were tested. Drag forces were measured at different velocities, while the movement of the models were recorded by an underwater camera. Towing experiments at sea were conducted in 2016 and 2017. In the first set of sea trials a rope with sugar kelp were attached to a rigid frame at the bow of SINTEF ACE's research vessel Torra, while the tests in 2017 were performed by towing a raft – with a 1 m long rope with sugar kelp attached - 100 meters behind the vessel. Loads and towing velocities were measured in both experiments. In 2018 tests with sugar kelp were conducted in a test facility containing seawater – providing the opportunity to perform towing tests in an undisturbed body of saltwater. A special purpose raft with a test rig was constructed and 3 m long ropes with sugar kelp were towed at constant velocities. Plants with two levels of growth were tested. Towing velocities, drag forces and tensile forces in the rope were measured. Data from experiments are to be analysed and used for developing a model for hydrodynamic loads on sugar kelp.

Figure: Tests in 2017 (Top left), tests in 2018 (right) and one of the medium growth samples tested in 2018 (bottom left).


 

Status autumn 2017 (EN)

Testing and drag-measurements using different configurations of seaweeds in sea and towing tank, start developing numerical model (WP6):

Towing experiments have been conducted at the Marine Cybernetics laboratory at NTNU. Two simplified models of L. saccharina were tested. Drag forces were measured at different speeds, while the movement of the models were recorded by a camera under water. Towing experiments at sea have been conducted to add to last year's experiment data. 1 m ropes with seaweed were attached to a raft rig towed 100 m behind SINTEF ACE's research vessel Torra. Currents were measured to record the speed and loads were measured with a load cell. Data from the experiments are to be analysed and used for developing a numerical model for seaweed hydrodynamics.

Workshops

A workshop on seaweed production technology (WP5 and WP6) with contributions from seaweed producers, equipment manufacturers and R&D institutes was arranged at SINTEF Sealab in Trondheim in September 2017, and

Contacts