Last January, 5 miles off the English coast in choppy 40-foot-deep water, Siemens quickly installed two of their newest 6MW offshore wind turbines at DONG Energy's Gunfleet Sands wind farm (the first of a 300 turbine order) in just 24 hours. Since these turbines produce twice the power of current models - while weighing much less - they allow Siemens to head further out to sea to catch stronger winds. These revolutionary turbines were installed with the help of a new ship, the A2Sea Sea Installer (press release), which had been designed and built for this job.
Watch its maiden voyage as Sea Installer showed off its built-in cost advantages. First, the dockside loading was quicker: a ramp allowed nacelles to be driven on board, while at the same time a crane lifted and loaded the towers, as another stowed the blades.
Instead of being towed, the ship had diesel-electric propulsion that powered it at 12 knots, using little fuel; and with a 132-meter length and a 39-meter width, it had a payload capacity of 5,000 tons, and could have transported up to eight to ten wind turbines at a time.
The vessel was positioned with uncanny 3 cm accuracy by penetrating the legs with large spud cans into the sea bed. After the installation, the legs were quickly retracted with its special water injection system. A2Sea chief executive Jens Frederik Hansen said: "The installation of the two 6MW turbines is a step into the future of offshore wind. The turbines are getting bigger and the future sites are further out to sea."