By Neil Jaques, UK correspondent

Out of sight, out of mind. While the ever-increasing size and technological accoutrements of turbines draw the publicity, the cables that siphon their hard-won energy from offshore to land occupy a distinctly under-appreciated quarter of a frontier industry.

Yet as the next generation of deepwater wind farms edge towards logistically daunting commercial realities, the cabling sector will irrevocably tend toward the spotlight.

Cables may serve as an offshore wind farm’s umbilical cord but it doesn’t take much neglect, inexperience, substandard planning or lack of resources to suddenly transform them into cost-sapping Achilles heels.

According to Rob Grimmond, managing director of multi-disciplinary marine solutions provider Offshore Marine Management and vice chairman of Renewable UK’s Offshore Wind Delivery Group, there are three main problems to contend with.

These include breaks “caused by vessel movements and inexperienced crew”; cable loops “due to vessel movements, lack of control or bad equipment and software”; and cables being cut short “due to people not using the right measurement techniques and methodology to install the second end – when you get to the second end you should know how much to the meter is required”.

Cable gridlock?

A recent report by RenewableUK, UK Offshore Wind: Building an Industry, a healthy industry scenario calls for array cable requirements to soar from 400km installed to an additional 800km in 2015, peaking at 1,000km in 2016, and averaging around 850km per year for the next four years.

A similarly sanguine projection for export cables calls for high-voltage, direct current (HVDC) installation) to peak in 2020 at just below 1,000km a year.

Clearly, an abundance of new kit is in order.

“We need large sized dynamic positioning vessels with good station keeping capabilities, good stability, combined with sufficient accommodation capacity, large cable storage and free work deck to handle cables and cable protection provisions,” says Ton Geul, Business Development Manager at Visser and Smit Marine Contracting.

“Typical dimensions would be between 70-90 m long, with a beam between 16-18m. For crew transfers and rotation a helideck should be considered.”

ABB recently made a proactive play to stay ahead of the curve, teaming up with Aker Solutions earlier this year to charter the Aker Connector, which will be kitted out to install long, heavy power cables and subsea umbilicals during 2012 and 2013.

French cable giant Nexans, meanwhile, is quick to trumpet its Skagerrak as “one of the world’s most advanced cable-laying vessels”, with a 7,000 tonne capacity turntable, a state-of-the-art global positioning system, and multiple cranes.

“The industry needs to move away from barges,” advises Grimmond.

“The biggest problem with barges is the anchor moves. The cable installers will tell you they are very efficient and they can lay 120m an hour. That is correct. They are not lying. The problem is they won’t inform you that you lose about 10 hours out of 24 in anchor moves.”

The specific installation requirements for the UK’s fertile Round 3 hotspots can also throw up operational quandaries for some developers.

Nexans, for example, will supply its cables in the UK but decline the installation job as the need to bury them in soil at depths between 2-3m calls for the use of ploughs.

“Ploughing is a rather risky way to bury cables as shown by experiences and track records,” says Olivier Angoulevant, Nexans Sales Manager for offshore cables.

“You create difficulties with this method. As far as I can see there is no need to have the cables buried deeper in UK waters than in the North Sea, where the norm is between 0.7 – 1m. Maybe a more detailed risk assessment could be performed in order to define the optimised level of protection.”

According to Angoulevant, the soil in the UK is “stronger”, so with regards to protection it could “in principle” be buried at a shallower depth.

When Nexans trenches a cable it uses its proprietary Capjet system, which is based on the water jetting principle and solidifies the soil above the cable.

“It’s the volume that’s the tricky thing – which is a good problem to have when you think about it,” says Joel Whitman, director for corporate strategy, marketing and communication at Global Marine Systems.

“We feel very comfortable with the technology, the state of the technology, the ability to do it, the quality of the cable, the coordination with the cable manufacturers.”

Best practice yet to be demonstrated

Amidst all the excitement of future visions where Round 3 will putatively yield up to 23.2GW of offshore wind by 2020, it is easy to forget that this is still a young industry, particularly when it comes to cabling best practice.

Telecommunications has it, oil and gas has it but as it stands, there are currently no universal standards for offshore wind cabling. 

That is something the RenewableUK Offshore Wind Delivery Group hopes to remedy in the coming years.

“For the industry to become cost-effective we have to move away from a project by project basis, and the clients and the contractors have to work in partnership,” says Grimmond.

This is where good planning comes into play, meticulously mapping out survey works, dealing with route engineering issues and defining robust response plans.

“If you have a damaged export cable and you don’t have a maintenance model in place – what are the vessels that are going to repair it, is there spare cable around, do you have jointing expert available – if that hasn’t been worked out you could be down for months,” Whitman warns.

But while technological necessity, planning and implementation methodologies and industrial up-scaling will inevitably evoke all manner of capital complexities, the real issue is likely to be people. Or rather the distinct lack of them.

“I’m starting to feel like a woman – ‘where have all the good men gone?’,” Grimmond bemoans.

“The cable industry always trained up people in a structured way, with experience being passed on. At the moment, we’re trying to do good quality work with the same amount of people from the earlier days, but now we’re trying to spread them across 8 different vessels. It is the biggest issue out there.”

“We can build as many cable vessels as it wants. I could go out and buy five tomorrow and convert them, but if we don’t have the skillset the quality of work is going to slip.

Moving forward, Offshore Marine Management’s is investing heavily in training via its offshore marine academy where it is devoting £250,000 to training six to eight graduates over 12 month periods. Currently based Bristol and Cambridge, there are plans to roll out the scheme nationwide.

“We’ve got to really push this and put our money where our mouths are to ensure these kids come into the industry,” says Grimmond, who feels staff levels for the offshore wind cabling industry need to treble.

Geul echoes this sentiment.

“With technology everything can be resolved,” he says.

“We can fly to the moon or mars. It is a matter of putting money in the basket and talking to the right people. But with cable laying we have a relatively small group of people and activities are rapidly increasing, and we all want 10 years experience on the back deck.”

And while oil and gas industry can often synergistically cross over to offshore wind, both are often fishing for talent in the same pool.

To respond to this article, please write to: Neil Jaques

Or write to the editor: Rikki Stancich

Image: Nexans