Contact
For more information, please contact Christian Baresel.
christian.baresel@ivl.se
+46 (0) 8 598 564 06

Construction

The wave-powered oxygen demonstration pump is designed in a way that makes it suitable for the projects demonstration and evaluation purposes. The design of a full-sclae wave-powered oxygen pump may differ from this pilot (see e.g. the design on the left side image). This is partly because the current pilot has to be equipped with sensitive measuring equipment and a reliable electricity supply that would not be required at a full-scale implementation.

Main structure
The main structure is a hull divided into a floating wedge with the edge facing the incoming waves, a basin to gather the overtopping water and a rear vertical wall on the front of a floater. The hull is divided into two times nine tanks. Twelve of them are floater-tanks and the rest trim-tanks. At the bottom of the basin there is an 1800 mm hole to which the vertical tube is connected (see next section). At the lower end of the edge there is a plane to make the sloped part longer in order to capture a greater part of the incoming waves. Also the mooring is connected to this plane.

The design implies that incoming waves will stream upwards the sloped surface of the structure and fill the basin by overtopping. The higher water head in the basin compared to the sea surface will make the water flow through the hole in the bottom of the basin. The trim-tanks facilitate the adjustment of the draft and the slope of the prototype in order to get a better total water flow.

Vertical tube
The vertical tube that is used for transporting the oxygen-rich surface water to deep waters suffering of oxygen depletion has no bearing task except for its own weight and the diffuser that is located at the end of the tube. The tube is 75 m long and consists of a plastic material (polyester) with a high tear and tensile strength produced by the Finnish company Scantarp Oy. At the end a diffuser plate is attached that also acts as the weight for preventing horizontal movement of the tube. The tube is reinforced at a depth of 10 m where a flow meter will be installed inside the tube.
 
The connection to the outflow from the main structure is done by dynamic wires that allow a tube movement that does not have to follow the movements of the main structure. This is important as the main structure will behave in a different way as the tube as it will be exposed to wind and waves whereas the tube will be mainly exposed to currents. In order to enable this flexibility but to prevent leakage this connections is enclosed by a bendable mantle made of the same material but with a larger diameter that allows flexibility of the connection.

The diffuser plate is attached to the tube with help of chains. In addition a wire outside the tube connects the diffuser plate with the prototype. This provides the access to the tube end in case of required service etc. The main function of the diffuser plate is to prevent damaged on the sediments at the sea bottom by the vertical flow from the pump. At the same time, the diffuser will distribute the oxygen-rich water around the tube.

Necessary equipment for operation during demonstration period
The design of the prototype includes the possibility to adjust its position in terms of the draft and the slope of the prototype in order to get a better total water flow. This requires the monitoring of the current position, placement, water levels in the trim tanks, pumping effect and external conditions. Therefore, the prototype is equipped with both a GPS and an automatic tracking system that report position and direction of the prototype. Pressure gauges outside and inside the prototype basin provide information about the angle and water level inside the structure, respectively. Visual equipment will facilitate the observation of general condition of the prototype and the nearby environment. A flow meter inside the tube provides current flows for various positions of the prototype. The sum of this information can be used to fill or empty all or some of the trim tanks which will result in a adjustment of the prototype t local conditions.    

For safety reasons the prototype is further equipped with both GPS and AIS systems as well as various seamarks which identify the approximate position of the pilot. This marking consists of both special marks and lights attached to the prototype.

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