IXSEA Sponsors Ampelmann Project
IXSEA has sponsored the award winning Ampelmann project. In this project are a number of other leading worldwide companies working together, like Shell WindEnergy, Econcern, Smit and the Delft University of Technology. The objective of the Ampelmann project is to improve offshore access. The project is initiated by Dr. Jan van der Tempel, of Delft University of Technology, Holland and is funded by the Dutch Government through NOVEM under the BISK framework in the We@Sea consortium.
Today, access to offshore wind turbines for maintenance or replacing crew at platforms and supplying offshore structures is hazardous and expensive. Access to the offshore wind turbines is by helicopter or ship and involves the safe transfer of personnel with maintenance equipment from the moving vessel to the fixed turbine. In the North Sea it is currently limited to 50 to 75% of the year as opposed to onshore wind turbines which have accessibility for maintenance 98% of the year. Offshore access should be easy as crossing the street, hence the project is called Ampelmann (the pedestrian crossing symbol used in Germany). The Ampelmann solution will provide safe and easy access to all offshore structures. The principle is based on a movable platform on the deck of the vessel that compensates the wave induced movements of the vessel. The top platform will stand still in relation to the fixed object (for example a wind turbine) providing a stable transfer in rough seas. The six-legged flight-simulator on top of the vessel, offers all six degrees of freedom of the vessel, which are simultaneously and continuously compensated by all six individual hydraulic legs providing a stable platform on the moving vessel. The connection between the platform and the deck of the ship is provided by IXSEA's OCTANS, an IMO-certified gyrocompass and complete motion sensor. An Ethernet output facilitates OCTANS to send real-time information about the six motions of the vessel to a computer (true heading, roll, pitch, SAFE HEAVE TM, surge, sway, as well as speed, acceleration and rate of return). Using specially designed software the computer then calculates the required movements of the Motion System in order to keep the top platform steady. To give the system a required workability of more than 90%, the system must be able to work up to and including a sea state with a significant wave height of 2.5m.
The 108 MW near shore Wind Park off the Dutch coast has been selected as reference site. The project to date has been both dry and wet tested using a scale model; the next phase now involves building a full size prototype, ready for offshore testing at the end of the summer of 2007. At this site, the system could be operational 93% of the year, which is a monthly downtime of a little over 2 days.
