Award for Hereon researcher Nils Christiansen

The Hamburgische Wissenschaftliche Stiftung gives the Kurt Hartwig Siemers Science Award every two years to researchers who have made an outstanding scientific achievement beyond their doctoral thesis. This year's recipient is Dr Nils Christiansen, who graduated from the University of Hamburg and is researching renewable energies at the Helmholtz Zentrum Hereon in the Cluster of Excellence „Climate, Climatic Change, and Society (CLICCS)”. The award is endowed with 30.000 euros.

„Our modeling shows changes in the physical processes of the sea and suggests possible ecological consequences - both negative and positive,” explains Christiansen. In his doctoral thesis, which he wrote at Hereon and the University of Hamburg, he discovered that wind turbines create resistance in the atmosphere and underwater, thereby affecting ocean currents. On one hand, the resistance of the rotor reduces the wind speed behind the wind turbine and the influence of the wind on the sea surface decreases. On the other hand, turbulence is created in the water at the pillars, which strongly mix the local water layers. These two effects change current speeds and the density distribution at the wind parks and beyond their boundaries.

Following his doctoral thesis, Christiansen worked at Hereon on the question of the impact of offshore hydrogen production in the North Sea. This does not yet take place in reality; technologies are currently being tested. The German government has designated areas for this in the German Bight. In the production of hydrogen, the seawater is desalinated. This produces brine and heat at higher temperatures. Using modern technologies, both are led back into the sea. This input increases both the salt concentration and the temperature of the water within a radius of several hundred meters around the platform. Local temperature fluctuations of more than 2 degrees Celsius can occur. "This can have a significant impact on the local ecosystem," says Christiansen.