Turbine installation vessel is designed for deeper waters 2

A2SEA has installed more than 500 offshore wind turbines of all types, sizes and configurations, including one and two-piece towers, full rotor lifts and different types of nacelle lifts.

The company, which owns and operates a fleet of four specially designed vessels, is owned by DONG Energy, one of the leading energy groups in northern Europe with a business that is based on procuring, producing, distributing and trading in energy and related products.

The company continues to have more wind turbine installation capacity than any other shipowner and earlier this year gained another major investor in the form of Siemens, which now holds 49 per cent of A2SEA. DONG Energy will, however, continue to be the company’s main shareholder.

At the time that Siemens invested in A2SEA, the company, which is based in Fredericia in Denmark, said it planned to look into the possibility of expanding its installation capacity. In July it announced that it was investing US$139 million in the construction of a new vessel, which is due to be delivered in the second half of 2012 and will bear the name Sea Installer.

Sea Installer will be a self-propelled jack-up vessel optimised for operations in water depths of up to 45m and will thus be well suited for the installation of wind turbines on the windfarms that are planned to be built under the UK’s Round 3 and, of course, on other windfarm projects around the world.

Speaking at the time that the order was announced, Jens Frederik Hansen, A2SEA’s CEO, said he anticipated that there would be a significant increase in the amount of turbine installation work and the type of projects now being envisaged would place greater demands on installation vessels.

“With a new state-of-the-art vessel, A2SEA will be able to meet our customers’ future requirements and hold on to our position as the leading supplier of installation services,” said Mr Hansen, noting that reducing the time it takes to install a turbine is another important factor in the ongoing industrialisation of windfarm construction.

This being the case, Sea Installer has been designed to be able to carry more turbines than first-generation vessels, transporting eight to ten at a time, depending on their size. This is significantly more than can be transported by the vessels which are currently available in the market (although a number of the installation vessels now on order for other companies will approach this capacity).

Sea Installer’s design is based on A2SEA’s experience in the field of offshore wind turbine and foundation installation over the last 10 years. Compared with its existing fleet of vessels, it is intended to operate further offshore, in more challenging conditions than those encountered during construction of offshore windfarms to date.

Because it will operate further offshore in more challenging conditions, carrying more wind turbines than first-generation ships, it will also be somewhat larger than the vessels in A2SEA’s existing fleet and have a higher transit speed in order to be able to relocate between projects more quickly than earlier vessel types. “In many cases,” said A2SEA in information it recently released about the vessel, “this will allow direct feed from component production facilities, eliminating the inefficiency of turbine trans-shipment.”

Longer legs will enable the vessel to work at most of the deepwater sites that are being planned and, in another interesting departure compared with its existing fleet, the main crane has been positioned in such a way that it increases the available deck space and allows for much greater flexibility during lifting operations, during loading and turbine installation.

A2SEA describes Sea Installer as having a length overall of 132m, breadth of 39m and draught of 5.8m. The vessel will have a speed of 12 knots and crane capacity of 900 tonnes, complemented by a loading area of 3,200m² and a loading capacity of 5,000 tonnes.

Able to jack up in water depths of up to 45m, the vessel will be capable of carrying towers, nacelles and blades, and provide accommodation for people including the ship’s crew.

“Sea Installer will take the installation process to a more efficient and cost-effective level,” said the company, “which will give developers greater confidence that their projects will be delivered on time and with maximum profitability.” OSJ