Rising wind

Offshore wind installations have seen component sizes driven up at an increasing rate; the turbine output first doubling, then tripling in power over a decade with blades becoming longer than an Airbus A380.

Unfortunately, as Peter Robinson of MPI explains, the leap in scale has thrown the supply chain off-kilter and is keeping everyone on the hop: “Instead of it all being known well in advance, developers are still finalising the engineering and where they will source the components while they are working out the deployment. So, they now come to us and say, ‘we have a series of ports in mind’….”.

Of course, in the past it was a little easier: components were generally classed as general multipurpose cargo. However, bigger and better turbines have piled on the pressure: 2014 saw 6MW turbine deployments with nacelles of over 300 tonnes and a blade diameter of around 155 metres; just two years later, the industry welcomed an 8MW version which added another 25 metres on top.

All this has pushed up the size of installation vessels coming into the ports: in 2012, the 80 metre long, 300 tonne–lift Kraken was still considered large. But, as Chris Garrett of DNV GL explains, the industry is now using the likes of the 139 metre Seajacks Scylla; capable of lifting 1,540 tonne, it also exerts several thousand tonnes of downward pressure on each foot.

Keeping pace

The rise in scale has pressed a number of fast-paced changes. “Just two or three years ago availability and flexibility were the main drivers,” says Jesper Bank of the Port of Esbjerg in Denmark. “Today you still have to deliver availability and flexibility, but on top of that, you need to create a suitable hinterland and quayside.”

Having attracted the eye of players like Siemens and Vestas, Esbjerg has reclaimed in total around 100 hectares (1,000,000 metres square) of land and topped it with granite to support crawler cranes carrying 1,000-tonne loads, plus it’s also constructing two ro-ro ramps to handle the new breed of customised turbine transporters. According to Mr Bank, turbines are even more demanding than the big foundations “as getting anything wrong is extremely expensive”.

Scale is also adding complexity to logistics. Rather than a one-stop-shop marshalling yard, “you might now get three or four ports involved in different legs of the supply chain” he explains; for example, Esbjerg regularly sends components through to Hull in the UK, the installation port for the 402MW Dudgeon project.

Even having finalised the plans there’s no sitting back: working out a response to the next challenge is an ongoing process and not particularly straightforward. Although Mr Bank spends a lot of time listening to customers he admits “while they can give you a lot of information, they still can’t give you the answers”. In his view “you have to follow the market and be part of all that commotion in order to develop the necessary foresight… the only thing that’s certain in this business is change”.

Unfortunately, that includes the politics. Withdrawal of support has put an end to something of a gold rush, dealing a heavy blow to some facilities. A couple of years ago the port of Bremerhaven pulled in manufacturers like Areva, Weserwind and Powerblades with hundreds of millions of Euros of investment. Then came the austerity cuts and both Germany and the UK throttled back hard on their commitments: as one source put it, “if it had been a commercial contract, people would have sued”.

Despite this, the industry may soon have enough momentum to leave these difficulties behind. With the dropping of the strike price to below €50 per MW, wind could be off the subsidies and into commercial business by 2020. Further, with lower costs “offshore wind farms which were not viable may come back from the dead”, says Mr Garrett.

To help get there, manufacturers are poised for yet another big jump: “10MW turbines which will have cost-parity with fossil fuel power production are just around the corner,” he adds. Further, larger blade lengths of around 100 metres are necessary for locations which have to make the most of lower wind speeds, resulting in 125 metre high towers with a diameter “probably over 10 metres base diameter”.

Find your level

So according to Mr Garrett, there are now firm bets to be made and DNV GL has developed practical solutions to help ports future-proof themselves. Among them is a wrap-around hammer-head berth – potentially with a removable concrete ‘T’ end – to give the installation ships more quay to load from.

It’s also developed a ‘Fast Feeder Vessel’ concept which keeps the installation jack-up supplied with components without the heavier ship clambering back to port to restock. Typical high winds, a problem for crane transfer, are overcome by a nifty retractable bridge connecting the two lift vessels; component-holding frames (called Twisties after the twistlocks they use) simply roll from one to the other, mounted on the back of self-propelled modular transporters.

This solution, explains Mr Garrett, “could turn back the clock”, firstly as ports could return to hosting smaller but still capable mid-range jack-ups that would run back and forth to nearshore wind farms without too much interruption and secondly because the Twisties can store components vertically, making the most of yard space. Despite this, Mr Garrett points out you still have to get the components to the quay. An analysis of the new parameters including turning radii, road inclines, immovable street furniture and load weight may well show up a number of shortcomings. And at that point, it might be wise for facilities to decide how far they want to pursue the new supersized industry.

As Mr Bank says: “You have to find your level. Obviously ports will have constraints, whether these are physical or financial.” Not everyone will want to try to keep up and he adds it’s a decision worth thinking through: “If you are going to be a major league offshore port, you have to be able to follow the needs of the market… and it is one that is still immature and still growing.”

Buffer zone

There are already developments on the cards that promise to change the game even further. As Mr Robinson explains, at some point after crossing into double-digits “monopiles will tend to be swapped for jacket foundations”. Jackets presently only account for around 5% of all deliveries; these are far larger than their simpler cousin, an 8MW monopile measures less than 8 metres across while a four-legged jacket foundation would have a footprint roughly 25 metres a side. However, many agree that they are the way forward: “Monopiles have been cost effective, but it’s a pole with a big mass on top. Jackets will probably be necessary for deeper water,” he explains.

Although some components could avoid touching the quay by being transferred straight from barge to installation vessel, Mr Robinson points out there is often a need for a buffer zone whether that’s in the construction plant or at a port: “The rate of installation of these jacket foundations is far faster than the manufacture… so you need a stock, somewhere, to draw on.”

It’s not a stock that is easy to keep tucked away. For example, the BOW Terminal at Vlissingen will need to take between 12 ha and 14 ha of the port’s 25 ha of storage space for the 102 jackets and 306 fastening pins needed by the East Anglia One wind farm. Although they won’t be turning up all at once it’s a heavy job – the jackets weigh 900 tonnes apiece.

Interestingly, Mukran – the deployment facility for the Wikinger farm – stores foundations on the concrete transport barges they arrive on, if necessary mooring them up just outside the port entrance. the port’s Fabian Hoppe explains it’s a strategy which “gives the port flexibility” and allows Mukran to keep no less than 15 in stock at a time. However, Mukran has been thinking hard about the future, so it’s bringing in 12ha of land for storage and pre-assembly work as well as strengthening a quay to 50t/m2 for both future wind components and heavier project cargo.

A matter of scale

So, will component scale just keep rising – or are there factors which could apply the brakes?

As Esbjerg’s Mr Bank points out, wind farms are now doing more with less: “A few years ago you’d have 100 turbines of 4MW filling a wind farm. Although they are bigger pieces, the wind farm can reach the same output with half the amount.”

Further, it wouldn’t be practical to expect the same tripling of capacity to continue every decade and as MPI’s Mr Robinson explains, not all developers will be keen on size but prefer to spread the load: “You don’t want a tenth of your wind farm’s capacity to be knocked out by a single failure.”

It may also be possible to carve out a fairly stable niche. DNV GL’s Mr Garrett makes the point that if a port manages to prove itself capable there’s decommissioning operations to consider. “These turbines are going to be taken down and replaced on a ‘one in, one out’ basis,” he explains, adding that this market hasn’t yet really been explored.

However, the nascent wind industry is still spreading its wings. While Europe may have been first out of the gate other regions may soon catch up, leapfrogging the smaller size turbines and hitting the big stuff straight away. Despite this, it won’t all follow the same development pathway since there are a huge range of locations with wildly varying requirements: some like the US have regulatory elements like cabotage laws to deal with, a number have lower wind speeds requiring even larger blades and a few, like Taiwan, have an even greater wind resource – but the Taiwan Strait is paired with conditions “which are even livelier than the North Sea” explains Mr Garrett. On top of this, many are faced with plunging coastal shelves.

ATTRECTIONS OF SWIMMING, NOT SINKING

Floating turbines promise to liberate the technology from the challenges of piling in 40 metre-plus depths and make it possible for regions with limited shallow waters to join the wind energy party.

Despite Japan’s early start with demonstrators in Nagasaki and Fukushima, the first commercial wind park, due to come onstream later this year, will be the Scottish Hywind development: a fairly modest 30MW generated by five, 6MW turbines. Just a little behind, Portugal is looking to launch its own first 25MW floating park in 2019.

But the first two developments of any real scale may be a 400MW to 700MW wind farm positioned off Hawaii and another marked out for a huge 1GW capacity off California, both due out around 2022, says Principle Power’s chief technical officer Dominique Roddier.

These structures promise to be large: an 8MW turbine will have 80 metre blades and towers of over 100 metres on a triangular base that could be 50 metres-a-side he explains, putting pressure on fabrication facilities.

But even given this, according to Dr Roddier “the beauty of a floating foundation is you don’t need the usual offshore crane vessels – everything is assembled at the quayside with a huge cost saving”.

He explains the most efficient approach may be to construct larger pieces in a modular fashion at nearby facilities then bring these prefabricated sections together at the port. The next job is to float the completed hull “from a dry dock, ramp or even submersible barge” and tow it round to a turbine crane sitting on a heavily strengthened quay.

This last lift will be the most difficult, he explains, “because while the columns sections may be heavy, they can be managed by a sturdy crawler unit”. By contrast, the turbine crane will have to bring a 500-tonne nacelle up to a height of 100 metres or more. After this, it’s towed to site; another reason to make sure distances are as short as possible.

The potential gains are large but competition could prove stiff with some new entrants. Dr Roddier explains that as the ‘hulls’ will typically be built in value shipbuilding locations such as Finland, Eastern Europe and Asia, a well-positioned shipyard could take over the whole show. In fact, WindFloat 1 was deployed directly from the Portuguese Lisnave yard. Further oil and gas facilities hungry for work since the slump could be positioned to snatch a piece of the action: Statoil’s Stord facility has recently been hired to assemble Hywind’s project.

However, as with a lot of port business it’s a matter of location, location, location: “In the end, so much depends on logistics” concludes Dr Roddier.