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Offshore Wind Journal

Service ship of the future will be greener and much more cost-effective

Thu 10 May 2018 by David Foxwell

Service ship of the future will be greener and much more cost-effective
The partners in the Nexus project want to develop a service operation vessel design that is 20% more cost-effective

A European research project to develop a new-generation service operation vessel is examining every aspect of SOV design and operation to help reduce O&M costs and the environmental impact of their operation

The concept of a service operation vessel (SOV) is still a relatively new one. SOV design has evolved since the first units were introduced into service 3-4 years ago, but as the number of offshore windfarms grows cost reduction has come to play an ever-greater role in the industry, creating the need for more cost-effective SOVs.

Operations and maintenance (O&M) costs account for 20-30% of the lifecycle cost for a typical offshore windfarm so a huge opportunity exists to reduce costs by analysing windfarm maintenance as a system. Existing O&M concepts leave room for further cost reduction if enhanced SOVs can be developed, and the number of SOVs in the European market alone is expected to quadruple in the next decade, further highlighting the potential savings if more cost-effective vessels can be developed.

What form an enhanced SOV might take, how its design might be improved, new logistic processes and changes in how windfarm service ships operate are all part of the three-year Nexus project, which is funded to the tune of €3.3M (US$3.9M) by the European Commission’s Horizon 2020 research programme.

With a total budget, including the European funds, of €4.4M, the organisations participating in the project aim to deliver an advanced service vessel concept optimised for maximum performance and safety with minimal lifetime costs – their stated aim is to reduce SOV costs by 20% and reduce CO2 emissions from SOVs by 30% compared to current ‘state-of-the-art’ vessels.

To find out more about the Nexus project and its aims, OWJ spoke to Rolls-Royce chief designer for SOVs Martin de Jongh, one of the main participants in the project, Rolls-Royce technology manager Sverre Torben, and ARTTIC senior consultant David Bone. The project is co-led by ARTTIC, which supports research and technology developments including Nexus, and Rolls-Royce Marine, and also includes Strathclyde Business School, Astilleros Gondán, DNV GL and Global Marine Group. It got under way in November 2017 and is due to be completed by the end of October 2020.

They noted that, as offshore windfarms move further offshore, the challenges placed on operations and maintenance (O&M) providers are growing, and the relatively high cost of windfarm maintenance today has a negative impact on the competitiveness of offshore wind. In addition, they said, current safety requirements limit design and operational flexibility. In short, future SOVs will need to be more significantly more efficient and safer.

Messrs Bone and Torben said that project Nexus recognises that offshore windfarms are only now emerging as a mature source of energy, and to create substantial cost savings a ‘root and branch’ analysis of the inefficiencies in O&M services is required. This process includes an integrated look at the dynamics, uncertainties, costs and gains, and interactions between key players in offshore wind, including the windfarm itself, transport, O&M operations, onshore support, and the environment.

“This kind of indepth analysis has been neglected until now,” they told OWJ. “This has resulted in suboptimum vessels that cost more than they should that have emissions that are higher than they need to be.

“Innovations, such as a service vessel partially powered by batteries that could be recharged from the turbines whilst they are being serviced need to be assessed,” they said, noting that Nexus “has a list of innovations to be analysed to determine which ones can be potential game-changers.

“What is needed is a structured analysis of the situation, so that a clear path forward for specialised wind service vessels can be determined,” they told OWJ. “Larger turbines further offshore create a demand pull for more innovative, specialised ships. By providing an unbiased assessment of the market, the Nexus project will guide the industry towards an optimised, robust solution that will also help the EU capture a significant market share of demand for these new types of ship.”

The aim of Nexus, they said, is to develop and demonstrate a novel, ‘beyond state-of-the-art’ SOV and logistics concepts for safe and sustainable servicing of offshore windfarms.

Mr Bone explained that this will be achieved by designing and validating a reference concept SOV that will integrate new and emerging technology. To allow room for design creativity and flexibility, the project will also recommend new safety regulations for windfarm service vessels. The holistic approach adopted by the project partners will look at every aspect of the design of SOVs, said Mr Torben, including hullforms, propulsion, alternative fuels, energy efficiency and the potential application of hybrid power and propulsion systems. The project also includes simulation, model testing and consideration of the most suitable construction and production principles for vessels of this type.

Apart from enabling the development of more advanced SOVs, the Nexus team believes the project will have a significant impact on the whole value chain, reducing costs and providing industry with a toolset that will give it a competitive edge and the ability to use the same process to expand into new markets. The project will also enable an increase in the professional skills of workers and the capability of the European marine and maritime industry to develop and commercialise specialised vessels and related technology, benefiting SMEs in particular. Apart from reducing lifecycle expenditure and CO2 emissions associated with windfarm service vessels, Nexus also aims to enable more effective management of SOVs, capture overall design requirements for a new windfarm service vessel for operation in the North Sea and develop a new vessel concept to technology readiness level 5.

As Mr de Jongh noted, as the level of subsidies for offshore wind decline and zero-subsidy windfarms become more and more common, so the need for more efficient O&M concepts and more cost-effective SOVs is likely to grow. “This focus on costs makes the design and operation of SOVs quite challenging,” he told OWJ.

Mr Bone emphasised the way the Nexus project focuses on the role that SOVs play as part of a wider O&M strategy. “It is essential to create major savings,” he told OWJ. “One of the most important aspects of Nexus is that it starts with a business analysis of the role SOVs play and systems engineering approach that satisfies the needs of all users and stakeholders.”

As highlighted above, another key part of the project is a review of safety regulations that apply to SOV operations with a view to enabling operations to “go further,” as Mr Bone described it. A key aim is the development of specialised safety regulations for windfarm service vessels, thereby improving cost-effectiveness and operational flexibility that, to some extent, are undermined by current, generic safety rules.

Although there is consensus in the industry that SOVs should be designed in accordance with the IMO 2008 SPS Code, differences in interpretation between flag states and coastal states regarding the status of windfarm technicians servicing wind turbines have resulted in different regulatory regimes. The issue has been recognised at IMO, and work is ongoing on a code for windfarm and other vessels carrying industrial personnel. Class societies have issued guidance for offshore access systems of the type used by SOVs to transfer personnel and equipment, but there are a number of ‘grey areas’ when it comes to SOV operations that need more indepth examination, the project partners believe.

One of the most important that the partners in the Nexus project want to address is the use of gangways while vessels are in dynamic positioning mode.


X-STERN ship makes its mark

The Netherlands-based Acta Marine, which recently took delivery of its second walk-to-work vessel Acta Auriga, has placed a contract for a second ship of the type at the OWJ conference in February.

The new vessel is a dynamic positioning class 2 SX195 design walk-to-work/construction support vessel like Acta Auriga, which was recently awarded a two-year charter for O&M operations on the Bard Offshore 1 windfarm in Germany. The SX195 design is 93.4 m long with a breadth of 18 m. It will have a centrally positioned motion-compensated gangway and elevator tower for personnel and cargo transfers. The gangway and tower are to be supplied by SMST in the Netherlands. Logistics on board will be optimised to enhance workflow and is complemented by significant storage capacity and a ‘stepless’ approach to the offshore installations for windfarm personnel.

The new vessel will differ from Auriga only in a few respects, including the installation from the outset of a helicopter deck, Auriga having been designed and built ‘for but not with’ a helicopter deck. With most of the main equipment and operations in the aft ship, the vessel will operate stern first while in the field, keeping its X-STERN towards the weather, which will mean slamming will be very much reduced and noise and vibration will be minimised.

Speaking exclusively to OWJ in April, Acta Marine’s general manager, commercial offshore Simon Anink, said the first X-STERN ship Auriga had surpassed operating requirements during trials. This included transferring personnel using its gangway in a significant wave height of 2.5 m and wind speed of 40 knots. Mr Anink said it was evident that Auriga could safely undertake transfers in higher sea states, if required.  

Mr Anink said the X-STERN hullform had been demonstrated to have a number of advantages when used on service vessels. Among the most important is that being able to operate bow or stern first significantly reduced cycle times when moving between turbines. “Unlike oil and gas, where a vessel is only serving one offshore installation, SOVs have to service multiple installations. With the X-STERN we save time on the approach to and departure from every turbine. On a large windfarm that can save hours,” he said.


More services ships ordered

In April 2018, Louis Dreyfus Armateurs placed a contract for a second service operation vessel, which will be deployed on Ørsted’s Hornsea Project Two offshore windfarm off the coast of the UK. As sister vessel to Wind of Change, the first SOV ordered by the company in 2017, the second ship will also be designed in close co-operation with Salt Ship Design and will be built by Cemre shipyard in Turkey for delivery in 2021. The 84 m ship will be equipped with an innovative hybrid propulsion system using diesel generators and ABB’s OnBoard DC grid. The vessel will also incorporate an energy storage system using batteries.

In February, Norway’s Østensjø Rederi held a naming ceremony and launched the newbuild Edda Mistral and held a naming ceremony for another, Edda Passat. Both newbuildings are purpose-built for Ørsted’s offshore windfarms off the coast of the UK. Edda Passat was delivered in the last week of February and started operations at the Race Bank windfarm. Edda Mistral will be delivered in August and operate on the Hornsea Project One offshore windfarm.

The keel-laying ceremony for Bibby Marine Services’ second WaveMaster-type SOV took place at Damen Shipyards Galati in Romania on 5 May. The first Damen SOV, Bibby WaveMaster 1, was delivered to Bibby Marine Services in 2017. The new SOV is due for delivery in August 2019 and will carry out maintenance operations on the Hohe See and Albatros windfarms offshore Germany on behalf of Siemens Gamesa Renewable Energy and EnBW.

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