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Choosing cost-effective vessel design

EUROPE: For the successful installation and maintenance of offshore wind farms across Europe, more vessels will be needed. Whether they will be specialised, focusing on one activity, or multipurpose will be largely dependent on cost.

Whether installing or maintaining, offshore wind turbines need a fleet of vessels equipped to carry out a multitude of complex tasks in an often hostile marine environment. European companies know this better than most. In the North Sea, Irish Sea and Baltic Sea 1,247 wind turbines have been installed, generating up to 3.3GW of electricity. And plans for growth are immense.

The availability of offshore installation vessels in particular has become a key concern for the European wind power industry, and a debate is ongoing about whether to turn to the new multi-functional ships, or continue to use different vessels for different needs.

In the past, wind-farm developers have often been forced to make use of vessels not necessarily fit for purpose, whether brought in from the offshore oil and gas industry or from turbine manufacturers. Today, however, that situation is changing.

Aris Karcanias, a managing partner at BTM Consult, a Danish wind industry research consultancy, says the availability and suitability of shipping to support offshore wind has recently improved. "It's got a great deal better, although vessel availability still remains an area of potential concern if the uptake of offshore is as great as is anticipated," he says. "Here the challenge will not only be from the lack of vessels, but from the capacity and availability of adequately trained, highly skilled offshore specialists who lend themselves to both the offshore oil and offshore gas industry. This is during a period when the big take-off in offshore wind energy will likely coincide with the next round of oil and gas decommissioning in the North Sea, around 2014."

Ready for work

Data from BTM Consult shows that today 53 vessels are capable of offshore wind-energy installation, with 42 originating in Europe, mainly from Denmark, the Netherlands and Belgium. This year has also seen the release of ship-shaped self-propelled jack-up vessels from the UK and Germany, with ten such vessels now operating in European waters for A2Sea, Bard, Hochtief, DBB, RWE, Seajacks International and MPI Vroon. Up to 15 new turbine installation vessels are expected to enter the market by 2013, which will help meet demand, but it is estimated that for the UK's Round 3 offshore development alone, ten to 12 new vessels customised for operations and maintenance tasks will be required.

Adapting the design and technology to meet turbine manufacturers' proposed 10-15MW turbines is a challenge, as is securing the necessary investment to build them. If the offshore wind market grows over the next two to three years as predicted, says BTM Consult, then around eight customised self-propelled jack-up vessels could be delivered by shipbuilders, primarily from yards in the far East and Middle East, to Europe.

So far, vessels deployed in all phases of offshore wind activity have tended to be single purpose, specialised vessels, often bringing with them an offshore oil and gas heritage. However, say some industry experts, a new generation of multi-purpose vessels might serve the industry better, particularly wind-farm developers and operators, by bringing the capability of combining more than one activity at a time.

"The offshore wind sector needs vessels that have a multi-role capability," says Stephen Bolton, director of operations and maintenance at Offshore Marine Management. He would like to see vessels that reflect the whole operational cycle of wind farms, beyond construction and installation, and would like developers to have a say in the design.

"Continuing to allow vessel manufacture to be driven by the needs of turbine manufacturers alone could mean that not enough attention is paid to the full maintenance requirements of an offshore wind farm. We need to manage the entire wind farm, not just the turbines, and we need to look at the 20-year life cost, not just the first five years," he says. "We need ships that can facilitate the inspection, maintenance, and repair of the subsea infrastructure - cables, cable-laying systems and foundations - not to mention offshore substations. For a small impact on design and cost this additional capability could be included."

But others believe that sticking to specialism is more cost effective. Flemming Hougaard, chief operating officer at Vestas Offshore is in no doubt. "If you add other capabilities to an installation vessel, such as cable-laying capability, it will immediately become more expensive," he says. "A specialised vessel is an optimum solution, whereas a multi-functional vessel is a compromise. If you want a vessel to double up as a diving platform then you have to add a decompression chamber at extra cost, which you are then paying for every day. Yet a developer or operator will not want a diving capability on a daily basis. You are paying day after day for something you are not using."

Long-term maintenance

Robert Trahan, CEO of offshore services company Sea Energy Marine, says a new generation of multi-purpose vessels with the ability to stay on site for longer periods of time will change the way that operators and contractors service turbines further from shore and in deeper waters. "The UK alone needs to install, operate and maintain 6,000 turbines at sea in the next ten years," he says. "We will have to work night and day to achieve that, with Carbon Trust figures suggesting that 10% of offshore turbines are down at any given time."

The answer is to be stationed on site, but an offshore accommodation platform at a wind farm would have to have all the life support facilities of an oil and gas platform, with the expense involved, and still have to transfer technicians by boat to the turbines, which in effect would double the number of transfers.

The answer, says Trahan, is the Service Operation Vessel, a floating multi-purpose installation ship currently in development. "It will be able to be on location 100% of the time, be able to work 24/7 and could actually be at sea for years at a time if required," he says.

"The costs of turbine downtime are such that an effective access system based offshore can be relatively expensive and still be economically viable. Our economic analysis shows that our vessel is cost effective versus workboats even at near shore sites."

Offshore wind is about producing revenue he says. "If the blades aren't turning the farms aren't earning."

THE ORDER BOOK — THE VESSELS THAT WILL ENSURE THE OFFSHORE BUILD GOES ON

Offshore wind farm installations have up to now largely been shipped to site using existing marine vessels, often those used in the oil and gas industry.

Some 17 vessels are currently in use while another 21 vessels designed for other purposes have been used for wind projects.

Now, however, offshore wind developers and shipping firms are ordering specialist vessels customised for offshore wind.

German offshore wind power company Bard Engineering has been using its own vessel Windlift 1 to construct the 400MW Bard Offshore 1 wind farm. Windlift was ordered five years ago from the Lithuanian Western Shipbuilding Yard at a cost of €60 million. The construction of a second vessel is planned. RWE Innogy will use a vessel that it has ordered from Korean Daewoo Shipbuilding & Marine Engineering for €100 million, and which is due to arrive this year. It has an option for two further vessels.

Norwegian company Fred Olsen Windcarrier has placed orders for two offshore wind turbine installation ships from Dubai-based oil and gas vessel provider Lamprell, worth a total of $320 million. Dutch shipping group Vroon will use two offshore vessels ordered by shipping company MIP Offshore — Adventure and Discovery — both built in China and worth a combined €550 million. Adventure arrived in 2010 and Discovery is expected late this year. They are sister ships to the MPI Resolution.

Danish shipping firm A2Sea is adding to its fleet with an order for a special installation vessel from the Chinese Cosco Shipyard Group at a cost of $139 million. The vessel, the Sea Installer is to be delivered in the second half of 2012, and will be capable of working in 45 metres of water and carrying up to ten wind turbines to the installation site.

Major fleet

The biggest fleet of offshore wind vessels yet assembled, however, is now operating in the Thames estuary off the coast of south-east England at E.on, Dong Energy and Masdar's 1GW London Array offshore wind project, the first phase of which has now reached the stage where foundations can be seen above the water and two sub-stations are in place perched on monopiles.

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