Offshore windfarms are booming in Europe. Installation and operational costs are falling fast, while the amount of power generated is growing.
It’s all thanks to the advent of bigger turbines – but there’s one downside: bigger also means heavier. Luckily, advances in lifting and installation technology are playing a significant part in helping to overcome the challenge and drive costs down further. In one notable case, Gleistein DynaOne® slings made with Dyneema® SK78 fiber helped reduce transport time by three-and-a-half days.
The need for stronger synthetic slings
Over the past few years, slings made with synthetic fibers have become the norm in offshore and windfarm installations. And it’s no surprise when you consider their advantages over traditional steel wire lifting slings – which are heavy, hard to handle, and potentially dangerous, bringing a risk of damage to people as well as high-value loads.
Polyester slings are a well-known alternative. These may be lighter, but their downsides become more significant as the weight and size of payloads increase. The latest offshore wind turbines are pushing polyester slings to their practical limits, to the point where slings that can in theory lift a turbine are in practice becoming too thick to handle.
Dyneema® goes where polyester can’t
For Dyneema®, though, the new generation of larger windfarm installations pose no problem. Slings made with Dyneema® SK78 fiber are significantly stronger than polyester, at just one-fifth of the weight. They’re also easy to maintain, inspect, and repair, which increases uptime and reduces costs. Lifting slings containingDyneema® SK78 fiber can also be recertified, allowing them to be used on multiple projects and therebylowering the cost per lift.
That’s not all. Further advantages include their softness and flexibility, making them safer for crews, loads, and structures. Torque free, they also show similar elongation to steel wire rope, giving full control to the crane operator. Last but not least, they float on water and are resistant to chemicals and salt.
New horizons for offshore wind
The Walney Extension, off the UK coast in the Irish Sea, highlights the speed at which the industry is developing. Built, owned, and operated by Dong Energy, the original windfarm, known as Walney 1 and 2, dates back to 2011 and 2012, when it was the world’s largest operational offshore wind farm. Its 102 turbines max out at 3.6 MW each, providing 367 MW of total power. The 2018 Walney Extension, by comparison, has fewer turbines – 87 – but with ratings of 7 MW and 8 MW they can produce 660 MW of power. That’s enough to run more than 460,000 homes!
So how did the installation team pull off such an enormous feat of construction? It all started with teamwork. Owner/operator Dong Energy chose marine specialist Van Oord to install the seabed foundations and monopiles and contracted SAL Heavy Lift to transport the 87 monopiles from Germany.
Heavy lifting at the Walney Extension
The Walney Extension was the first wind farm to employ turbines rated at over 8 MW (actually 8.25 MW). Of its 87 turbines, 40 are the larger MHI Vestas V164-8.0, and the remainder are Siemens. The Vestas has 80-meter blades, a swept area of 21,124 m2, and a height of 220 meters above the seabed. The monopiles weigh up to 970 tons each, with a diameter of over 8 meters.
Saving time and money with Dyneema®-based slings
Having initially considered polyester slings, SAL soon decided they’d be too heavy, too slow to rig, and simply too thick. The company therefore decided to replace its polyester slings with Gleistein DynaOne® slings, made using Dyneema® SK78 fiber. Significantly lighter and with a small diameter (120 mm), these Dyneema®-based slings would allow SAL to stow two monopiles next to each other – something that would have been impossible with the bigger diameter of the polyester slings.
And the Gleistein slings lived up to their promise. SAL found they reduced the loading and unloading time foreach of the 87 monopiles by 60 minutes – for a total time saving of three-and-a-half days over the whole project. Combined with the lower shipping costs, this meant the costs of the slings were quickly amortized. And there was one final bonus: crews loved the way the lightweight slings handled.
Lightweight lifting slings for a heavyweight operation
Gleistein DynaOne® slings made with Dyneema® SK78 fiber come with an array of advantages over steel and polyester. They can lift up to 325 tons each, with the Gleistein slings as configured for SAL weighing five times less than a polyester sling of the same strength and showing less than 1% elongation at work load. In total, the configuration for the Walney Extension was capable of lifting 1,300 tons (with a safety factor of 3.72), comfortably exceeding the 970-ton weight of each monopile.
What’s more, the softness of the slings makes them less likely to damage the payload, while a replaceable protection sleeve over the rope – also made with Dyneema® – extends the slings’ service life and speeds up rope inspections.
Contact our experts
Interested in learning more about Dyneema® for your project or end-use application? Reach out to our team of experts today.
Get in touch