Energy chains tame the tide

Published:  10 December, 2014

Ensuring a safe and productive solution to providing electrical, water, and fuel connections to a jetty is challenging at the best of times. But when that jetty is floating in the harbour at Barrow-in-Furness with rough seas and an 11 metre tide, the problems are compounded. That was the situation facing Cameron Forecourt, who installed a floating pontoon for DONG Energy that is used to service their wind farm just off the rugged North West coast of England. ODEE reports.

The 90MW Barrow Offshore Wind Farm, developed by DONG Energy and Centrica, is located in the East Irish Sea approximately 7km south west of Walney Island, near Barrow-in-Furness. The wind farm consists of 30 3MW turbines covering an area of approximately 10km².

The annual production is around 305 GW/h, enough to meet the demand of around 65,000 British households. Electricity generated by the wind farm is delivered to the National Grid at a substation in Heysham, Lancashire via 27km of buried subsea transmission and onshore cables.

“Our traditional approach to such floating pontoons would be to run all the cabling and service pipes along the side or floor of the access ramp,” Dennis West, manager at Cameron Forecourt, explained. “The arrangement is both unsightly, and more importantly could present safety issues. There has to be enough spare cable on the floor at the bottom of the bridge to allow for the movement of the pontoon between low and high tides. This cable and piping is often coiled at the foot of the walkway and as the pontoon rises and falls the cables can become untidy and present a trip hazard. When you consider that the tide at Barrow-in-Furness is 11 metres, so at high tide the pontoon raises 11 metres – that is a lot of slack hose.”

The route taken by West and his team to overcome the aesthetic, safety and operational challenges was to use igus energy chains. The energy chain cable carriers (also known as drag chains) became the umbilical cord of the operation.

West commented: “By using the igus energy chains all the services are accommodated in one place in a very neat, professional and safe arrangement.” This track was fastened at both ends – on the harbour wall at the top, fed from a 60,000 litre double-skin bunded tank, and on the pontoon at its lower end. When the pontoon lifts with the tide, its movement is accommodated by the curve in the igus track.

He continued: “All the wires, cables and piping were enclosed together within the energy chain, safe from damage and presenting no hazards for those working on the pontoon or boarding the ships.”

The services within the energy chain were two feed lines for the two dispensers that allow the boats to be loaded, a water hose, a bilge hose for the sewerage and the cabling required for the pontoon for lights and electric hose reels. Also included within the enclosure was a 100mm thick fuel line of double contained marine pipework with leak detection on the outer pipe.

Installing the energy chains was also a trouble free operation. All the cabling and amenities were fitted into the track on the harbour side before it was swung into position and fastened to the pontoon. The length was set to accommodate the low tide position, approximately an 18 metre run. As the tide comes in and the pontoon rises, the flexible e-chain doubles back on itself.

In this way, the energy chain guides and protects the hoses and cables from the often violent movements of the pontoon as it rocks with the tide and is buffeted by the waves crashing into the harbour wall.

igus energy chains are modular and therefore can be assembled quickly and easily to accommodate any length of travel, which enables engineers to save installation time. They are tested against the environmental elements, high loads, high speeds and noise. Being corrosion resistant and self-lubricating they reduce downtimes whilst increasing the service lives of the cables and hoses.

“They are a unique solution,” Justin Leonard, director at igus explains. “If you need to get cables across the gap and the gap moves, they are the only way to go. They are unique in that you can have any mix of services such as electrical, hydraulic or fibre optic all together in one compact system. In addition, you can quickly add or replace services whenever you need without changing the system itself.”

Cameron Forecourt’s managing director, Barry Jenner, is convinced that the use of energy chains had delivered a safe and cost effective solution in a very challenging application. “The installation has made the servicing of the pontoon far more professional and removed any safety hazard,” he says. “It has also allowed the cables and pipelines to be fully enclosed which offers protection from accidental damage, giving us confidence that whatever the environmental conditions the installation can continue to service our client’s boats and keep the power flowing back to land from the offshore wind farm.”

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