Since the beginning of this year, US states together, have committed to over 8,000MW of offshore wind by 2030. And now, these long-term commitments by states have started to materialize in near term actual projects. PES brings you the latest update from GustoMSC.

GustoMSC NG-8000X design, equipped with telescopic leg crane

Installation solutions for US offshore wind

Building a long-term industry on near term projects

In May this year Vineyard Wind was awarded an 800MW project by the state of Massachusetts followed by two further awards of 400MW by Rhode Island and 200MW by Connecticut to Deepwater Wind. Increasingly these developments provide justification to invest in dedicated and

efficient installation solutions both for a long-term efficient US offshore wind industry and to provide short term solutions to install these first projects.

GustoMSC, a design and engineering company of mobile offshore units and equipment, has designed the vast majority of offshore wind turbine installation jack-ups and vessels operating to date.

Since 2010, these jack-ups with integrated jacking systems and cranes have installed over 4,000 turbines and foundations.

Past developments

GustoMSC has long been aiming to support developments in the US offshore wind market with its expertise. Two years ago, GustoMSC participated in a study, led

PES Wind1

TALKING POINT

by the New York State Energy Research and Development Agency (NYSERDA), aimed at understanding what is required for a wind turbine installation vessel on the US east coast from both technical and financial perspectives.

This report was published last year by the states of Massachusetts, New York and Rhode Island. In that study GustoMSC put forward the NG-9800C-US design as an autonomous and efficient jack-up capable of installing the present size of 8 MW turbines and foundations in water depths of up to 50 to 55m. The proposed design is an evolution of the successful NG-9000C design of which 4 units have been built to date. In addition, GustoMSC proposed a dedicated self-propelled feeder jack-up, the NG-3750C as an alternative solution.

At that time, when the future US pipeline of work was less visible than it is today, the main concern was whether a large investment in a unit like the NG-9800C-US could be justified. In response GustoMSC put forward the SEA-3250-LT as lower cost, non-self-propelled jack-up capable of installing these same turbines (but not foundations) at a minimum investment cost. The projected price was a ¼ to a 1/3 of the price of the NG-9800C-US.

Next generation solutions

With time progressing, the expected size increase of future offshore wind turbines is becoming more and more apparent. Also, newly proposed lease areas of the Massachusetts and New York coasts are in increasingly deeper waters, with water depths averaging over 45m and maximum depths going up to 65m. Dedicated offshore wind turbine installation jack-ups for the US market, which have a lifetime of at least 20 years, need to be able to cope with these expected future turbines and larger water depths. As such GustoMSC’s focus has more and more shifted to its next generation designs; namely the NG-20000X, the NG-14000XL and the NG-8000X.

What these next generation designs all have in common is that they apply jacking systems on truss legs. The open leg structures provide reduced load and increased stiffness in deeper waters, when compared to circular leg designs. As such these designs are capable of working in water depths of up to 60 to 70m meters. These units comprise a GustoMSC telescopic crane with a capacity of 1,250mt in extended mode at hook heights of approximately 150m above main deck, thereby enabling the installation of next generation (>12 MW) turbines. Where these designs differ from each other is their payload capacity and crane capacity in retracted mode.

At the higher end of spectrum (in terms of capacity), the NG-20000X is able to carry 5-6 turbines and install foundations with

weights of 2,500mt with the telescopic crane in retracted mode. On the other end of the spectrum, still capable of meeting installation needs of next generation turbines in deeper water, the NG-8000X is presented as a lean solution, focused on turbine installation only but at a lower cost due to a smaller platform.

Another thing these next generation designs have in common, is that they are pushing the boundaries of wind turbine installation jack-ups, in terms of jacking capacity. Frequent jacking of increasingly heavy platforms, as is common in offshore wind, places high demands on a jacking

system. GustoMSC’s variable speed drive Rack & Pinion Jacking System is specifically designed to minimize wear on the legs and jacking system due to its patented ability for smooth initiation of the jacking procedure. This quality is proven by the many jacking systems operating in the market today.

Increasingly large water depths typically result in higher wave loads on the jack-up legs. In addition, longer legs are required to cover the deeper water and higher waves. Longer legs in general introduce larger flexibility. The combination of larger loads and increased flexibility, if not addressed

Fred. Olsen’s GustoMSC NG-9000C design Brave Tern safely installing the first wind turbines in the USPicture: courtesy FOW

www.peswind.com 2

TALKING POINT

properly, may result in dynamic motions of the jack-up, which as a consequence may induce motions of the crane base, which transfers into unwanted motions at the crane tip and load during installation.

Relative motions between the component being installed and the turbine tower, may cause damage to equipment and poses a serious risk to the crew trying to mate the components at a height of well over 100m above sea level.

It is essential, for safe installation, that the governing parameters are understood and properly addressed, and that the potential risk is mitigated to an absolute minimum. GustoMSC designed jack-ups are renowned to be solid and stable platforms, with outstanding performance based on thorough understanding and an integrated design philosophy between jack-up, jacking system and crane.

A short-term alternative

Although there is an improvingly solid case to be made for US built installation jack-ups, these are challenging platforms to build. There are few US yards that have the experience and capacity to build such a large and complex jack-up, and building in the US comes at a cost. Building a jack-up takes time; a projected 2.5 to 3 years depending on the size and type of jack-up. This is beyond the current timeframes available for the earliest projects. As a result, developers may need to rely on alternative solutions for the first large scale projects.

GustoMSC and Barge Master have joined forces in the development of a motion-compensated feeder solution. This solution offers a flexible and cost-effective alternative for installing the first wave of US projects. GustoMSC and Barge Master adopted an integrated approach in order to comply with the Jones Act and overcome the operational restrictions of US ports.

The motion-compensated platform BM-T700 will be placed on a US flagged seagoing barge, in order to feed the wind turbine components fast and safely to the offshore installation site. On site, the components can be installed by a foreign wind turbine installation jack-up. The motion compensated platform is capable of compensating the vertical, roll and pitch motions whereas a thruster system is used to keep the barge on station.

Barge Master introduced the BM-T700 platform in 2013 and it has proven itself in various projects. By compensating the motions of the vessel, the platform creates a stable lift-off base for a maximum weight of 700 tons in sea states up to Hs 2.5 meter and is Lloyds certified under the lifting appliances rules. As a result, the

operations can continue in more adverse weather enabling completion within the execution timeframe.

The characteristics of this motion compensated barge solution, without tall legs and limited beam, allows it to enter into more ports with bridge or beam restrictions, making it a relatively flexible solution with regard to the existing US port infrastructure.

On the other hand, while a Jones Act compliant, self-propelled, self-elevating platform may be restricted to enter ports with height or beam limitations, the transfer of components to the jack-up can be executed at an inshore location, free of waves and associated risk of weather down time. As such the self-transiting solution minimizes the amount of offshore work, offshore handshakes and thus lowers risks compared to any feeder solution. This avoidance of offshore component transfer from barge to jack-up is a key benefit of the currently used self-transiting jack-ups and is one of the main drivers of their successful and widespread use in offshore wind in Europe.

The future is quickly unfolding and it is clear we are at a decisive point in time for the US offshore wind market. Both the existing experience of the global offshore wind market and local US conditions influence its development. At GustoMSC we see both a near term need for a Jones Act compliant feeder solution, as well as a longer term drive for dedicated US built installation jack-ups, in order to improve efficiency and reduce risk. GustoMSC is committed to use its experience and expertise and provide the US market with safe, solid and stable solutions for the successful development of US offshore wind.

www.gustomsc.com

Seajacks Scylla, a GustoMSC NG-14000X design, installing foundations in the Veja Mate

GustoMSC and Barge Master have joined forces in the development of a motion-compensated feeder solution

PES Wind3

TALKING POINT