Tidal turbines in the Eastern Scheldt storm surge barrier generate renewable energy for 1,000 households. Rijkswaterstaat wants to know what impact they have on the environment.
PhD candidate Merel Verbeek presented her hydraulic research on the turbines during the first Ocean Energy Platform lunch lecture of 2017.
The monthly series organised by The Delft Energy Initiative, covers the field of marine renewable energy. During her lecture, Verbeek presented progress of a NWO project dealing with the Eastern Scheldt storm surge barrier. Located between the islands of Noord-Beveland and Schouwen-Duiveland, the barrier protects the Province of Zeeland against the North Sea.
In November of 2015, the Dutch company Tocardo installed five Horizontal Axis Tidal Turbines in one of the sluice gates of the barrier. Dubbed ‘HATTs’ for short, these turbines convert tidal streams into electricity. Verbeek’s research focuses on the hydrodynamic effects on the surrounding environment. Worldwide there is little known about the potential impacts of tidal stream turbines on seabed morphology and enclosed estuaries.
The five turbines, each five metres in diameter, don’t currently pose much of a risk to the reserve. However, if more are added, they could reduce the tidal range and thus impact the intertidal flats. This, in turn, could negatively impact migrating birds that rely on the flats for feeding and resting.
Rijkswaterstaat, the Dutch authority for Public Works and Water Management, is also concerned about impacts on the seabed protection which provides the stability of the foundations of the barrier. Verbeek will investigate whether blockage effects of a gate with turbines can cause increased velocities and turbulence in adjacent sluice gates and if an impact on the soil protection can be expected or not.
Each Tocardo turbine generates up to 250 kilowatts . The actual power depends on the velocity of the tidal flows, which are governed by the rotation of earth and moon. The total electricity production from the five turbines can supply up to 1,000 households.
“You may be wondering why the turbines are at this location,” Verbeek said during her lecture. “It’s because in the barrier, the tidal currents are at their maximum. This is important for tidal energy. You need fast currents in order to generate energy at a competitive price.”
“If the impact on the environment proves to be insignificant, then the Oosterschelde Storm Surge Barrier could indeed fulfil the urgent societal need for clean and renewable sources of energy in order to combat the disastrous effects of climate change,” said Tocardo project manager Peter Scheijgrond.
Verbeek and her colleagues hope to create a numerical model that will analyse the potential impacts of the turbines on the seabed. Utilising hydraulic geometry, she will take a look at how the turbines interact with the turbulent tidal flows. They’ll be combining their observations at the barrier with further research conducted in a laboratory. Verbeek has been working on the project for the past year and expects it to reach completion in 2020.
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