Legless when installing turbine foundations
The proposed vessel will be based on the conversion of an existing shuttle tanker.
Two major players in the world of offshore wind and energy shipping have joined forces to develop a wind turbine foundation installation vessel.
It features a departure from the current trend of jack-ups, instead using a free-floating vessel based around the conversion of an existing shuttle tanker.
Danish company A2SEA A/S, and the Vancouver based Teekay Corporation in Canada have signed a Memorandum of Understanding to design, deliver and operate transportation and installation vessels capable of handling the next generation tripod and jacket type foundations which are expected to dominate developments such as the UK Round 3 schemes as they the progressively march into deeper, more hostile waters.
As reviewed in MJ (April 2011) there are now around 15 firm orders and options for installation vessel worldwide, all jack-ups. This proposal however involves conversion of an existing shuttle tanker into a dynamically positioned, free-floating transportation and installation vessel. At 242m LOA, 42m beam and 6,500m2 of deck space along with 1,000 ton crane capacity, there will be space for seven jacket foundations per round trip. Reduced weather down-time due to the size of the vessel, along with fewer restrictions from water depth and seabed conditions will result in significant cost savings for foundation installation, it is claimed. The target date for delivery of this innovative vessel to the market is 2014.
The cooperation agreement involves Teekay owning and operating the vessel with A2SEA providing project management and operational expertise, an arrangement that reflects the individual expertise of the two partners, particularly from Teekay, with the introduction of the DP, free-floating aspect.
Owned by DONG Energy and Siemens Wind Power, A2SEA currently owns four installation vessels. Sea Power and Sea Energy were converted from ro-ro cargo vessels in 2002, each provided with four semi-jacked stabilising legs. A2SEA took over ownership of the conventional jack-up Sea Worker in 2008 and embarked on a major upgrade programme including the addition of a leg penetration water jetting system. Particularly suited for shallow water work (3.6m draft), Sea Worker is capable of operation at sites that dry out at low water. Another jack-up, Sea Jack, is now a regular sight in European waters and was recently also upgraded in an operation involving the replacement of its accommodation with a new module, including 23 single en-suite cabins. Currently under construction in China and due for delivery in the third quarter of 2012, the newbuilding jack-up vessel Sea Installer will be based on a conventional ship’s hull, capable of operating in water depths up to 45m. The vessel will feature an 800 ton ‘wrap around’ Gusto crane.
For Teekay Corporation, involvement in the marine renewable industry may be a new venture, but is not so far removed from its core activity of being a major player in the global energy supply chain. Transporting over 10% of the world’s seaborne oil, Teekay has a fleet of around 150 vessels and operates in both the conventional oil and LNG markets. More than just owning and operating tankers however, it is involved in connecting oil and gas producer’s upstream operations with their downstream refining and distribution facilities, services involving conventional tankers, lightering, shuttle tankers, floating storage and offloading (including FPSOs) and LNG shipment. Teekay’s experience in operating large vessels equipped with DP will obviously be an important contribution to the concept of using free-floating vessels for turbine foundation installation.
By Peter Barker
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