It is little secret that efforts to develop and harness new forms of clean power is an ever-present global task to serve the dual purpose of ensuring a cleaner environment and to be less taxing on non-renewable resources. The wind has emerged as a viable, if sometimes unreliable and often more costly*, option to generate power. (see chart next page)
Plans to build the U.K.'s largest offshore wind farm, to provide electricity for 50,000 homes in Wales, has been given the green light. The North Hoyle Offshore Wind Farm will feature 30 wind turbines, located five miles off the Welsh coast between Prestatyn and Rhyl in North Wales. There are currently two additional major offshore wind farm projects under consideration for the UK, and the hope is, by 2010, to power more than three million homes with this renewable energy source.
"The U.K. government has plans that will require the installation of 1,300 new 2MW offshore turbines over the next ten years," says David Donnelly, Chairman of Mayflower Energy. "There are also plans for major installations around other European coasts. We expect demand for this type of specialist vessel to be very high, and we are happy that Graig has helped us to contract with a Chinese shipyard for the construction of this technologically advanced vessel to install the turbines."
Offshore 'wind farms' have thus come into vogue, but the efficient installation of these massive units in the aquatic environment requires a specialty vessel.
Mayflower Energy recognized that there is an emerging market for vessels, which can efficiently install offshore wind turbines, which are likely to be of multi-megawatt size, with tubular towers rising about 100 m above the water surface and blades cutting a 100 m diameter circle.
Mayflower Energy is based in Middlesbrough in England, and is staffed by a small team with experience from the offshore heavy lift industry. It is a subsidiary of Mayflower Corporation, a large U.K.-based company whose main business is producing buses and specialized trucks and manufacturing steel pressings for the motor industry. Recognizing that increased investment in offshore wind energy would require capable installation vessels, Mayflower Energy came
up with the TIV concept. The potential market is considerable, with several hundred-wind turbines to be installed off the coasts of Denmark, Sweden, Ireland, Germany, Holland, Belgium, France and the U.K., over the next few years from 2003. One location alone off Denmark, for example, is scheduled to have 72 wind turbines with a rated total output of 150MW.
The Ship — Mayflower Resolutions
Captain James Cook was born in the village of Marton, Yorkshire on October 27, 1728 and is very much a local hero in these parts close to Middlesbrough and eventually sailed from the Port of Whitby on Wind Powered vessels (Sailing Ships). Therefore it is no coincidence that Mayflower Energy has chosen the name Resolution as that was the vessel appointed by the Admiralty as Captain Cook's flagship, which set sail on July 13, 1772.
The $45 million ship, a world first, will be capable of carrying the parts for up to 10, 3 MW wind turbines and should be able to install them at the rate of one a day. The 426 x 125 x 26 ft. (130 x 38 x 8 m) vessel will have six jack-up legs so it will be able to provide a stable work platform in waters up to as shallow as 9 ft. (3 m), and as deep as 115 ft. (35 m). Mayflower said that the use of its vessel would be cheaper for windfarm construction than current jack-up barge methods.
Mayflower's brief was to design a vessel that will mitigate the risks associated with working in the North Sea, giving an installation solution by focusing on the following criteria: the vessel must be highly maneuverable, dynamically positioned, high speed jacking capability all of which will increase the vessels operating potential.
In transit, carrying wind turbines from base to offshore site, and in maneuvering into position for jacking, the Mayflower Resolution will be driven by a diesel electric system powering four azimuth thrusters and three tunnel thrusters
The Mayflower TIV will be able to carry the components for ten wind turbines of 2 to 3.5MW rating. Typically the towers will be in two tubular sections about 98 - 164 ft. (30-50 m). These will be lowered in turn on to a prepared foundation rising a few meters above sea level and bolted together. The heavy gearbox/generator in the nacelle will then be installed on the tower, using the installation vessel's main crane with a capacity of 300 tons at 25.5 m radius and 110 m hook height. The three blades will be assembled on the hub on board the vessel, using a smaller 50-ton crane, and the unit will then be installed on the nacelle.
A transit speed of 10.5 knots will enable the vessel to shuttle to and from the base collecting the next batch of turbines with the minimum use of time, and also travel between jobs. On site, and jacked up, it will be able to sit out the 100 year storm, and the 50 year wave (Beaufort force 12, and 14 m height). Between wind energy contracts, the TIV is likely to attract offshore oil and gas contracts such as shallow water platform renewals.
The whole of the aft part of the vessel, (1,750 sq. m.), is available for transporting, assembling and manipulating turbine components, with additional space for the tower sections themselves in racks along the sides between the hydraulically operated legs. A total payload of 7,200 tons can be carried, and the working deck is stiffened for 10 t/sq. m. loading and 50-ton forklift trucks. The minimum operating water depth is 7 ft. (2.2 m) with 10 percent cargo on board, increasing to 10 ft. (3.2 m) with a full load.
Mayflower Resolution will have accommodation for 50 people in single berth cabins, and all facilities for a 60-day endurance, arranged in the forward mounted superstructure, with the bridge above. This unusual vessel will be classed by DNV with Self Elevating Unit and Dynpos AUT notation, and will be cleared for worldwide operation.
Graig Shipping has provided a full support package for the supervision of the building of Mayflower Resolution at China's Shanhaiguan yard. "Chinese shipyards are now first choice for new vessel types," says Hugh Williams, CEO of Graig. "Not only are they competitive on pricing, but they are flexible and willing to adapt to new technology and new designs. We are very happy that we have been able to help Mayflower find the right yard, the right designer and the right classification society to get this new offshore industry off to a good start." Graig advised Mayflower on choice of yards, introduced Denmark's Knud E Hansen as the designer and DNV as a suitable class society, and assisted in yard negotiations. Graig's China-based supervision team will now oversee the building and delivery of the first vessel, which is due to enter service in February 2003.
Just as the practice of single-sourcing complete packages of equipment and machinery, albeit long applied, has gathered tremendous pace over the past decade in the commercial marine sector, the uptake of functionally-integrated systems has had a signal bearing in driving ship technology forward. Building on its own track record in the naval field, in particular, and on the longstanding policy of the absorbed Ulstein interests to supply 'coherent' systems to offshore support ships, Rolls-Royce has landed an integrated ship systems deal spanning an innovative vessel designed to install wind turbines offshore.
Ordered by U.K. firm Mayflower Energy in recognition of an emerging market for ships to build up the many offshore windfarms planned by North European countries, the 426-ft. (130-m) Mayflower Resolution will transport and position parts for up to 10 wind turbines at a time. The design has been conceived to minimize the risks associated with year-round deployment in the North Sea, and features a jack-up capability to provide a stable offshore working platform.
Rolls-Royce has been selected to supply the integrated ship systems, including the entire diesel-electric propulsion plant and also the bridge outfit, including navigation, communications, automation and dynamic positioning. Although the broad portfolio of Rolls-Royce products will be accessed for the contract, much equipment is being sourced from other manufacturers.
In fact, the U.K.-owned group considers that the order "fits well with the Rolls-Royce strategy of taking increased responsibility for integrating complete ship systems, building on years of supplying comprehensive equipment packages for offshore support vessels."
Mayflower Resolution, which will be constructed at the Shanhaiguan Shipyard in northern China, will be propelled by four Ulstein Aquamaster azimuth thrusters fitted in nozzles, augmented in maneuvering and dynamic positioning mode by three Kamewa Ulstein controllable-pitch tunnel thrusters. Power for propulsion and shipboard services will be primarily met by four gensets, made up of 1,824-kW Mitsubishi (MBI.F)
high-speed diesels and Newage Stamford alternators.
Mayflower Energy is currently marketing the vessel both to wind energy companies and to the offshore oil and gas industry, and is confident of having contracts in place when the newbuild is ready for operation in spring 2003.