Offshore wind markets are growing rapidly around the world.
The offshore wind industry, once a niche market in Northern Europe, is now rapidly expanding worldwide. While the North Sea is the most established market, new markets are opening in China, Taiwan and North America.
Generating power where winds are more powerful
Most of the offshore wind market is developed close to shore, with fixed foundations. However, industry analysts have long noted that if the wind industry is going to generate a significant portion of the global power mix, it needs to move into deeper water where average wind speeds are higher and more consistent.
Today, new designs are opening up deep-water offshore wind sites. Since these technologies are still largely unproven, their associated risks have yet to be fully quantified.
Explore the risk profiles of different types of wind turbines
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- Sea level
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up to145 feet
Monopile
The preferred foundation solution for shallow water, monopile installations have been used in depths of up to 145 feet. A rolled steel cylinder is drilled or hammered into the seabed. The wind turbine tower is then bolted onto a transition piece which sits on top of the monopile.
Perils facing monopile installations
- Established, “one-size-fits-all” offshore wind farm design used on many Gigawatts (GW) of projects
- Larger turbines and deeper water are pushing the limits of this technology
- Gravity based solutions (GBS) and suction bucket foundations may be used if ground conditions permit.
- Ground investigations required to determine optimal installation methods
- Availability of vessels and equipment large enough to install monopiles is high.
- Major component replacements require vessels that are costly to hire
- Working in an offshore environment exposed to weather conditions always poses risks
- Scour protection around monopile base is vital to maintain foundation integrity.
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100-200 feet
Jackets
Common in the oil and gas industry, jackets are truss-like steel structures with three or four legs. At the base of the legs are piles—essentially smaller monopiles inserted into the seabed using the same techniques as a full-size monopile—providing great structural strength. Jackets are a cost effective solution in depths of up to 200 feet.
Perils facing jacket installations
- Custom-built for each turbine location
- Require a detailed understanding of ground conditions
- More intricate design requires excellent quality control during fabrication
- While jackets are lighter and easier to handle than monopiles, installation times are longer
- Multiple legs per jacket increases risk of unsuitable ground conditions.
- Custom built for each turbine location, providing more flexible access options
- More prone to corrosion than monopiles if not coated and maintained.
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200–3,000+ feet
Floating foundations
Consisting of a floating substructure tethered to the seabed using a mooring system, floating foundation designs include: spar buoys, semi-submersibles, tension leg platforms (TLP) and barges. No design has achieved market dominance yet. Floating foundations target water depths from 200 feet to more than 3,000 feet.
Perils facing floating installations
- Limited or no track record on all four design installation types
- Supply chain is not commercialized to date
- Dis-connectable mooring lines and cables are a new technical challenge
- Requires anchors installed in the seabed attached to the turbine foundation
- Small anchor footprint expected to reduce risk of unsuitable ground conditions.
- Turbines are towed to site pre-installed on their foundations, which removes the need for expensive crane vessels.
- Since depths are too great for jack-ups, entire turbine will likely be towed back to port to replace major components
- Mooring lines may be at risk for vessel collision or anchor trawling
- Limited or no operational data from some designs makes risks difficult to accurately quantify at this time.
As the wind industry grows, so does the associated risk.
Until recently, the majority of the wind industry's growth could be attributed to onshore installations. However, we've begun to see the rapid growth of offshore projects. As wind turbines increase in size and projects are built in harsher environments, understanding the potential risks will be critical in helping the industry achieve its goals.
Cover your wind project’s entire lifecycle.
Planning
Wind projects face challenges long before installation. They start in the factory. So it’s critical owners and operators consider their insurance options in the planning stages.
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1 https://gwec.net/global-wind-report-2022/
