Tripod (foundation)
This section allows to be outfitted onshore with all functionalities needed in terms of boat landing, cable guiding and last but not least corrosion protection systems.
The first tower section, called S3, is foreseen to be mounted offshore on top of the Tripod with a bolted flange connection.
This was the beginning of a long lasting collaboration between the turbine developer and manufacturer Multibrid, the foundation designer OWT and the fabricator WeserWind.
Meanwhile, the design covers the demands of an offshore turbine foundation to sufficient extent, the fabrication was even challenging regarding size and shape of the structure.
[3] The first steps in condition monitoring have been undertaken including the determination of stress curves, the so-called "Hot spot" Survey, in order to enable the comparison with calculation models.
Alpha Ventus was planned as a first test field for the exploration of offshore wind energy in German waters.
A broad basis of experience and knowledge was gained for the construction, commissioning and operation for future offshore wind farms.
Anticipating this demand WeserWind has developed a serial production approach for Tripods in the years before, together with Dr. Möller GmbH / IMS Nord,[4] Bremerhaven.
Based on this concept Georgsmarienhütte released the investment program building this assembly shop with two parallel lines at Lunedeich, Bremerhaven.
In December 2011 the pontoon was baptised and the offshore terminal ABC-Peninsula was commissioned by BLG Logistics Solutions GmbH & Co. KG after essential upgrading.
The Offshore Construction Jack Up “Innovation” by HGO InfraSea Solutions GmbH & Co. KG was commissioned in 2012 and did her first job for Global Tech 1 carrying three Tripods and pile sets per sail.
The crane ships “Stanislaw Yudin” and “Oleg Strassnow” by SHL Seaway Heavy Lifting were in operation for Borkum West II.
Hot spots are avoided in the aggressive environment of splash zone by design allowing a free corrosion fatigue assessment.
In the wind energy, the coordination of the dynamics of the structure, characterized by the frequencies it mainly swings, is of special importance due to the excitation by the turbine rotor.
Finally the dedicated suitability of the Tripod to corrosion protection systems will remain a significant difference to the Monopile.
The number of three legs results in sufficient stability in the unpiled or ungrouted situation what comes back with a reliable weather window for installation.
It was born within a creative nut shell of German offshore wind pioneers and it expanded its potential gaining further partners to a large multidisciplinary team realising the vision.
The fact, that 126 turbines founded on top of Tripods are nowadays operational, is the result of a long lasting reliable collaboration of a number of stakeholders.
A desk top study has been performed in 2014 assessing the feasibility of the foundation concept to the next turbine generation with 8MW and rotor diameter beyond 160m.
It was essential to demonstrate the limited weight increase carrying the even higher loads and thus approving all the existing fabrication and installation processes from the projects done before.
