Monobase Wind BV has successfully concluded the model-testing in MARIN.
“All tests were in line with our predictions for all stages of the transport, installation and in-place situations,” Project Director Jan Groot said.
The transportation analysis showed mild accelerations (less than 1.1 m/s2) at nacelle height, even at 6 m significant wave height (12 m maximum waves). This is due to the own period of the Monobase being greater than 20 seconds and the first order movements are therefore not sensitive for waves in the southern part of the North Sea (mostly 4-8 sec waves).
The Monobase also moves within acceptable limits during the installation procedure, with wave limits of 2m (10sec) and/or 2.5m (8 sec). This will allow the operational crew to choose the weather window with the required flexibility. In practise, the operational crew may choose a lower wave height, but these tests show the redundancy in the design and procedure.
Specifically the lowering of the ‘donut’ was much better controllable than expected. This can be seen on this video at 1:25, bearing in mind that due to the scale effect, the actual lowering will be 8 times slower. The donut slows down several meters before engaging with the tower mat and gently sets itself on top of it. The deceleration can be designed for any specific circumstances by tuning the space between ‘donut ‘and ‘tower column’.
The in-place simulated a 100 year storm in 45 m water depth, resulting in massive maximum waves of 32 m, which were withstanded by the Monobase without problems. This should give future clients the confidence that the Monobase can be designed to withstand the heaviest storm conditions. Attached pictures show the 100 year storm waves as simulated in the MARIN test tank.
Next steps for the company are to execute detailed studies for clients, to design the Monobase for specific locations, environmental conditions and turbine specifications.
Press release; Image: Monobase Wind