Cables for offshore wind - steady as she goes

Materials World magazine
,
2 Jun 2014
Offshore turbines

The offshore wind industry is growing fast and learning from its mistakes even faster. Rachel Lawler reports from the 2014 Subsea Power Cables conference in London.

Those working in the offshore industry are perhaps the most aware of our crippling inability to predict the future and the weather. Matt Hodson, Business Development Manager at UK firm Mojo Maritime, explained, ‘The biggest risk to marine projects is weather’. Mike McLachlan, Associate Director of London-based Offshore Consultants Ltd echoed these thoughts, stating that during the winter months, downtime can increase to as much as 50% of working hours. While little can be done to mitigate this, both speakers suggested allowing more time for this at the planning stage.

Antony Zymelka, Director of UK-based ZYTECH Subsea Cables, raised another contentious issue for the subsea cable industry – fishing. Cables laid in areas where large trawler nets are used must be stringently covered and protected from potential damage. He said, ‘I would like to encourage fishing in offshore wind farms, but the right sort of fishing – commercial trawling is a safety hazard in these areas. I would not have a blanket ban on fishing in wind farms, but limit it to smaller vessels. Then we could be potentially more cost-effective from day one.’

Another issue that emerged was a possible clash with the offshore dredging industry – a sector that now has more than 70 approved sites off the coast of England and Wales, many of which overlap with areas near to offshore wind farms. Alison Houghton, Principal Consultant at ABPmer, a marine environmental consultancy based in the UK, explained the possible problem. She said, ‘Effectively, what [the dredging industry is] doing is digging a hole in the seabed and any disturbance to the seabed has an effect on cables’. Traditionally, there is little interaction between these two industries, but as the marine environment becomes increasingly crowded, this is going to have to change. Houghton added, ‘There is going to be a level of detriment and compromise on both sides’.

The importance of resolving cabling issues was something all speakers seemed to agree on. Commonly cited problems included faulty spooling, twist and taping of cables during fabrication, excessive pulling during installation, cracks in tubes and damage caused by supports.

Also causing some contention was the issue of insurance. Jonny Allen, Offshore Underwriter at insurance firm GCube, headquartered in London, suggested that cable problems are also more costly than other offshore issues. Around 50% of claims for cables relate to problems with installation. Other common problems include faulty repairs and incorrect operation, which could be solved with better training. Allen suggested greater planning and preparation as well as more interaction between engineers and insurers to increase underwriters’ understanding of potential complications. He said, ‘We need to work harder and collaborate more to be a part of the solution, and not just be a chequebook when things go wrong’.

Approaching the topic from a slightly different angle was Emilie Reeve, Delivery Associate at Offshore Wind Accelerator at the UK’s Carbon Trust. ‘Our main aim is to reduce the cost of offshore wind,’ she explained. Reeve believes that cabling is a crucial part of this. She said, ‘Cables can often be an afterthought. We want to see them considered from the start.’

Stressing the importance of cabling was one of the day’s main take-home messages. Rob Grimmond, Chief Executive Officer at Offshore Marine Management, headquartered in Cambridge, explained, ‘You can have a thousand turbines offshore, but if you break the cable, you haven’t got any electricity’.  

Did you know?

8–10% of a wind farm’s volume is cabling but 90% of wind farm insurance claims relate to cables

UK offshore wind industry facts

22 offshore wind projects
1,075 offshore turbines
3,653MW offshore capacity

Visit materialsworld.tumblr.com to read Rachel’s blog about the conference and see the results of a poll of delegates’ thoughts on four key subsea issues.