Where the Wind Blows

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There’s a contradiction at the heart of the wind industry: its upward trajectory will add to the downward pressure on costs.  But is the industry ready to respond? Stevie Knight asks around at Offshore Energy 16.

Wind seemed like it could provide welcome relief to those squeezed by the oil and gas market collapse but the industry’s crystal ball has been consistently cloudy of late.

The problem is the pace of change is speeding up: it took till 2007 to get to 3.6MW turbines, but 6MW record-beaters in 2015 gave way to 8MW developments the next year, and now 10MW-plus turbines with towers over 2,000t seem to be on the way.  Unfortunately, there’s still no clear investment pipeline to indicate exactly what the demands will be and construction vessels “are often outdated by the time they are delivered” according to one industry source.

Further, contract prices have plummeted.  Dong Energy’s recent bid of €72.70 per MWh for the 700MW Borssele wind farms “has been a big surprise for everyone” says Pim Nelemans of Boskalis.  “As an industry, we were aiming at something like this figure – by 2020. Nobody guessed it would happen now.” 

Good news for the credibility of wind power – but it means the supply chain is also going to be looking at slashing the total cost of energy further and much faster than originally expected.  As charterers attempt to tighten up operations to save money there may be a renewed impetus toward role differentiation, moving the industry even further away from what some have called ‘multiuseless vessels’.

However, according to Alun Roberts of BVG Associates, the practicalities push back in the other direction “as there’s not enough work to support a vessel with a narrow specialism that only, for example, installs foundations – we’ve already seen there’s not the business case for it”.  So, this means spread betting on solutions that will dovetail with the requirements of other sectors.

Jack-ups, of course, have some advantages.  Feet down, there’s nothing like them for providing a stable platform: this element is as useful for turbine installation and maintenance as it is for well intervention or enhanced recovery work.  And, as Damen’s Staffan Utzon points out “if the vessel is higher off the water, you don’t need such a large onboard crane to reach the top of a wind tower”.  Surprisingly, in order to develop a really tailored solution the company has stepped away from its usual naval architect role, leaving that to longstanding jack-up designer GustoMSC which has developed a very slick jacking device: frequency-converter speed controls stop uncomfortable lurches when the power is engaged.

PARING DOWN ESTIMATES

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So, where can Damen add value? According to Utzon, the designers “stop at the outline, they don’t know what equipment will be put in during construction: the plans are therefore shaped around very broad margins”.

But by focusing on the build and having specific details for each element to be installed, Damen can pare these estimates down and get more onboard for less.  So, while the guaranteed elevated load of the 76m long NG2500X is 1,300t, “by looking at the complete structure we’ve reduced the lightship weight” says Utzon “giving it more capacity”.  A quarter more in fact: the resulting DG Jack 6136P can lift as much as 1,600t.

There are, it seems, other varieties of jack-up to be explored.  Although he won’t say too much at present, Edwin van Leeuwen of Ulstein Design and Solutions explains that despite the steep increase in component sizes “there’s a certain limit to what can be achieved by simply scaling up a conventional design” he says, hinting heavily at the ‘unconventional’ and explains the company is developing a very new idea with SeaOwls BV.  But there’s another issue that mitigates against innovation: “At present vessels are on a day rate – so you finish the job two months early and there goes your income.  It means we will soon have to adapt the contracts to support better efficiency,” he says.

Despite this, it may be tempting to assume that a jack-up could be utilised for everything as they have “real flexibility” says Alun Roberts – but this is where the water gets muddied.

“The key words now are ‘cost reduction’, we have to be smarter and cheaper than we have been,” says Pim Nelemans.  Floating assets that can move between locations, using dynamic positioning to hold station, have a distinct advantage when it comes to deeper water or the repetitive work associated with large wind projects.  Firstly there’s no restriction on depth and secondly no waiting for the legs to extend or retract – a slow business complicated by the need to make sure exactly what the feet will be treading on.

However, Nelemans explains that given the overcapacity of construction vessels in the market, owners still need to offer something extra – and in the case of Boskalis’ F3000 conversion, this ‘extra’ is deck space.

DOUBLING WORKLOAD

The vessel is 216m long and 43m wide and will allow for a free deck space of 173m by 43m. Despite expanding the accommodation to three times the size – from 50 to 150 – there’s still a big clear working area of around 6,500m2 with a 3000t Huisman crane located centrally amidships “so the reach can cover the whole deck” he adds. “The big advantage is while most other lift vessels are limited to take two or three jackets or monopiles, we can double this.”  Combine that with a transit speed of between 11 and 12 knots and an operator will be seeing significantly more time on site and less on pickup runs.

Originally a 2011 Dockwise vessel it was chosen partly because it already had a modern diesel-electric layout, it being much harder work to reconfigure a shaft drive to DP.

“However we had to put in some additional power and thrusters to support the dynamic positioning” he explains: this can be used on its own or work alongside a new eight-point mooring system to stop the ship weathervaning.  Overall, is should be able to work up to 2.5m significant wave heights “depending on wind and so on”.

These changes demand a fair amount of room so several the original semisubmersible ballasting tanks are giving way to the requirements of a hefty pair of 7.5MW Rolls-Royce engines – giving a total installed power of around 25MW – as well as the space associated with four large 3.5MW Rolls-Royce thrusters.  And because the F3000 will have a fair amount of load to carry, the other ballasting tanks must be modified for the new, faster trim requirements.

Wind isn’t the only driving force behind the F3000: there’s the decommissioning market too.

Here the large deck space yields another advantage: “We could handle some of the smaller topsides, but the main point is that we are not restricted by barges taking the old rig sections away as we can load them onto our own deck.  That’s the freedom,” says Nelemans.

Unfortunately as Julian Manning of Baker Hughes explains at OEEC2016, as far as the decom market is concerned although the demands will start to rise next year, it won’t be steady.  He says forecasts show activities clustered into “distinct peaks… with a three-year gap between each one”: this presents a big problem as a supply chain simply can’t sustain a business with three year lulls.

So it’s a happy coincidence that most decom work is not to a fixed-to-the-wall plan and maybe there’s room to slot it in around the repetitive, time-sensitive wind installation requirements – or at least this is what Nelemans hopes “because if we can determine the schedule, then the costs come down”.  A potential win-win for everyone.

BIGGEST IN CLASS

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Going for ‘big is best’ and dwarfing all others is Heerema’s huge semi-sub crane vessel Sleipnir; with a 220m length and at 102m beam it is almost half as wide as it is long. Remarkably, it is also being designed with no less than a dozen 8MW engines giving it a grand total of 96MW of installed power – this is for the benefit of the two bow-mounted 10,000t cranes as much as its dynamic positioning (Class III) system.

This means it has both the O&G decom and installation markets in its sights: it can both pick up and drop in entire jackets, foundations and topsides in one hit.

It’s not only the scale of the engines that make it interesting: they are also dual fuel, adhering to the company’s green agenda.  However Sipke Schuurmans of Heerema explains there was concern that this kind of dual fuel engine wouldn’t cope with the large fluctuations in the onboard power demand, especially when combined with very rough sea conditions.  So different candidates were put through their paces on a test rig: “They had to ramp up to 3.8MW in 20 seconds to simulate a big wind shift, and to satisfy the lift case they had to get up to 2.5MW in 5 seconds while keeping the output in a narrow frequency band.”

Interestingly, he says “they all complied”.

Feeding these giants are eight, vertical type C-type tanks sitting in pairs, held within four of the vessel’s eight column structures.  These were chosen over other varieties as they allow pressure to build up to approximately 6bar, providing more operational flexibility.

As for LNG market conditions, Schuurmans admits that although “things have changed a bit from back in 2013” when the vessel was conceived, “longer term we have a strong belief that LNG will be the future” adding that there’s a downward force on LNG pricing with more streams being added in the near future; on the other hand MGO in 2020 may well fall foul of limited refining capacity “so we think LNG will have a price advantage in the long term”.

There is another element to consider: big ships like Sleipnir and the older Thialf are semisubmersibles so they simply settle themselves down into the water to minimise movement… they don’t rely on motion compensated handling equipment for installation activities.  However, the smaller F3000 doesn’t have the bulk and anyway has given up this characteristic in favour of DP so, in case of installing monopiles, it is going to use motion compensated handling kit – for example an MC gripper frame – to keep its load in position for installation.

Motion compensation may be the way that smaller vessels might make up some ground: while they can’t carry as much, they could do more journeys.

CHANGING MINDSETS

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Although it’s taken a while, “there’s a mindset change happening”, says Herman Groot Beumer of Barge Master.  He adds: “You see more attention being paid to motion compensated systems now – because it means you can continue working in different sea states, without that you can be limited to a few months of the year.  The effect is a reduction of 30% to 50% on the total cost of an operation.”

The Barge Master comes in a couple of different flavours: there’s a complete gangway and cargo transfer device – the system used on Vroon’s walk-to-work VOS Start – a motion compensated offshore crane operating on the Kroonborg (KNVTS Ship of the Year 2015) and a six-cylinder actuated, 700-tonne platform which can be used as a flexible base for various offshore operations.  The model at the show simulated 3m waves, and it was tempting to balance a cup of tea on the motionless plate it presented – just to prove the point.

However, the story isn’t straightforward and there are some interesting alternatives that may prove game changers.

One innovation – affectionately known as ‘Twisties’ – could alter the dynamic.  These, say Chris Garrett of DNV GL, aim at stopping the big installation vessels wasting time and money cycling in and out of port, instead allowing faster feeder vessels to supply them.  According to him, this means the installation ship wouldn’t even have to pause while being loaded from behind.

The reason it hasn’t been done before is because vessel-to-vessel offshore lifts “are an absolute nightmare” he explains, falling under very strict regulations that limit operations to moderate wind speeds; all well and good in other circumstances, but these are windfarms after all, and the ‘acceptable’ conditions are restricted to a few summer months.

By contrast, the DNV GL concept allows for a roll-on roll-off deployment between jackups: Twisties (named after twistlocks, the elements that hold them in place) provide a modular, lock together frame with adaptors to allow for several different foundations and/or towers to be moved across a retractable bridge on the back of SPMTs.

More to the point, this could turn back the clock as “potentially smaller but still capable mid-range jack-ups can be used as they won’t need the carrying capacity,” explains Garrett.  “The feeders can keep them supplied, without the WTIV’s crane stopping operation.”

FLOATING WINDFARMS

The entrance of floating windfarms could also make a difference: “You could create the whole thing in one go at or close to the quayside and tow it out into position,” says Alun Roberts, altering the entire scope of work.

While he says at present floating turbines are “horrendously expensive… about 40% more than current windfarms” he also points out that in certain places around Japan where the demand is, there’s simply no choice, the shelf drops away too steeply to install foundations on the sea bed itself.  Given these drivers, it may be possible to get a batch process running that would lead to economies of scale, and at this point they might be cheap enough “to compete with current technology”.

Floating turbines may, he adds, also provide a method for the US to avoid struggling with the Jones Act: designed to stop foreign vessels trading along the US coast it also, strangely, stops foreign vessels transiting between foundations.

Dutch company TenneT is preparing for a mammoth offshore energy hub.  The company says its ‘Wind-connector’ island will add to the region’s overall efficiency by tying together many wind farms: not only will it absorb incoming power surges it could more evenly distribute energy demand around the North Sea and facilitate an international powertrade.  This element has been on the cards for a while: an integrated offshore transmission grid is also being pursued by the ‘PROgress on Meshed HVDC Offshore Transmission Networks’ (PROMOTioN) project explains Andreas Wagner of the Offshore Wind Energy Foundation.

According to Wagner, something like the TenneT artificial island may also have an impact on support roles as it will be big enough to act as a base, potentially shortening the duty cycles of both installation and maintenance vessels – and possibly changing the size and shape of these vessels once again.

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Source: Motorship

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