Construction and testing of an upwelling pump
Our focus for the technical implementation of artificial upwelling in Test-ArtUp is on a propeller-driven upwelling system, powered by wind or solar electricity. In collaboration with experts in hydromechanics at Kiel University of Applied Sciences (FH Kiel), we plan to develop an energy-efficient system that can generate flow rates of >100 m3s-1 under offshore conditions, based on the hydromechanical modelling results and many years of experience in the design and use of KOSMOS mesocosms.
This model system serves as the basis for building a 1st generation prototype, initially without a propeller pump, at a scale of 1:10, which is tested under simulated conditions (waves and shear flow) in a wave tank and optimised step by step in an interactive process based on the findings.
The 2nd generation prototype is planned to then be sea-going with 30–40 meter tube length. In this phase, the propeller pump will be integrated into the system. In a first equipment test under realistic conditions, the prototype is to be deployed in the western Baltic Sea and tested with regard to material suitability, seaworthiness, pumping rates achieved and mixing-in properties. For this purpose, the system will be equipped with measuring probes to determine the flow rate, temperature and salinity in the upwelled water. A three-dimensional temperature measuring chain around the outflow opening will provide information on the mixing of the upwelled deep water.
Based on the findings of this 2nd generation prototype test, the construction will be further optimised with regard to the materials used and the technical design. If necessary, more tests in the western Baltic Sea can be planned and carried out at short notice. The tested and iteratively-optimised system will be equipped with a 100 meter-long flexible tube in the next steps.
The now complete upwelling system will finally be deployed in a field validation study and operated over a period of 2–3 weeks). The deployment of the upwelling pump will take place during a research cruise south of the Canary Islands. Based on the hydrographic and biogeochemical data collected during the cruise, we will determine on site the appropriate location to deploy the upwelling pump, to allow operation of the pump in free-drifting mode for a period of two to three weeks. For small-scale characterisation of the hydrography in the vicinity of the upwelling pump during operation, we will (i) deploy a system of temperature measurement probes previously used in the Baltic Sea, (ii) install combined hydrographic measurement systems at the inlet and outlet of the upwelling pump, and (iii) collect high-resolution hydrographic data with AUVs in the wider vicinity of the upwelling pump. These data will form the basis for the validation of the hydromechanical model simulations.