A question mark hangs over the long-term stability of Europe’s shallow-water turbines, after research linked to the Horns Rev 1 wind farm found that high-powered currents were causing the stone “armour” around the base of monopile foundations to collapse.
Exposed from behind this layer of shielding stone, turbines could potentially be dangerously destabilised by the effect of scour — the wave- and tide-driven sediment that can eat away at the seabed around fixed structures.
A team from the Technical University of Denmark (DTU) carried out model tests designed to mirror the impact of offshore conditions on the three-layer cover of “scour protection” placed around the 80 turbines at Horns Rev 1, which, three years after installation, had sunk by as much as 1.5 metres.
Experiments in the current flume at the DTU testing facility in Lyngby established that “horseshoe vortices” — twisting flows created by a change in water pressure at the surface of the monopile — were working their way around the stones and carrying off soil from around the foundation, causing the stone armour to sink into the sea floor.
In the dash for Green cash any design was rushed out, just as long as the money could be grabbed and the Green zealots assured that CO2 emissions would be reduced.
No prizes for guessing who will end up paying the bill for sorting this latest Green energy fiasco.