Offshore Wind Moves Soar with Potential

By Helen Campbell

The drive for a lower-carbon future has seen the wind sector truly take off in the last few years. According to the Global Wind Energy Council, there is more than 18.8 gigawatts of wind power installed offshore in 17 markets around the world.

This boom has been ably assisted by a creaking shift in regulatory systems, and is beginning to see the first developments without subsidies, in Germany and the Netherlands, for example.

The bulk of offshore wind is fixed to the seabed by piles securing turbine towers many meters tall, but the concept of floating wind parks is emerging as a reality. Until the start-up of the 30-megawatt Hywind development off Scotland in October 2017, floating wind had been limited to demonstration and pilot projects. Operated by Norway’s Equinor (formerly named Statoil), the world’s first floating offshore windfarm has proved that floating wind is no longer just a vision; it is quickly edging closer to full commerciality, and becoming a real challenger in the scramble to shape the renewable energy future.

As operational performance data for floating wind is scarce, prospective investors in renewable energy will be watching Hywind closely. Equinor rates the potential for floating offshore wind as “vast,” and says that growth is exponential. So far, Hywind is outperforming expectations and this bodes well for construction of additional floating wind parks elsewhere in the world.

According to a report from the Offshore Renewable Energy Catapult, the most likely markets for deployment of floating wind are countries with deeper water close to large cities, remote island communities with high electricity prices and, rather ironically, oil and gas platforms whose power could be provided by wind rather than gas. Analysts highlight Asia, the West Coast of North America and Europe in particular, as the hotspots for growth. France already has a number of prototypes underway, and the UK, Portugal, Spain and Norway also hold high potential.

In Asia, Japan and China are expected to deploy floating wind from about 2030, with Taiwan and South Korea to follow. In the U.S., the West Coast carries higher potential than the East, the latter presenting a higher degree of competition from bottom-fixed offshore wind, at least until 2030. Hawaii is another key market.

Space to Breathe

Building wind capacity offshore, as opposed to onshore, carries many benefits: most obviously, offshore has the space for installations, and the ability to scale up is central to the growth potential. Not only are wind developments offshore, fixed or floating, likely to be larger overall than their onshore relations, they are likely to comprise bigger turbines, to produce more energy more efficiently. Moreover, wind conditions are significantly more abundant out at sea than on land.

All of this, combined with the drive for a lower carbon future, has helped offshore wind develop its position as a credible renewable energy source, and floating wind really builds on these benefits. Floating wind parks mean seabed contact and intrusion is limited to chains and anchors instead of piles as with fixed wind, bringing clear environmental benefits. At the same time, floating wind does not require all turbine towers in a development to be individually adjusted to fit the contours of the seabed below, so each tower can instead be mass-produced to the same dimensions. This ability to standardize, and the consequential economic and supply chain advantages, is one of the biggest drivers behind the projected growth in floating wind development.Moreover, it follows that without the need to be built on the seabed, floating windfarms are freed from the relatively shallow waters that constrain the fixed wind sector — the Hywind concept is appropriate for water depths of up to 800 meters. This relative freedom means lower degrees of aesthetic objection to projects, as they can be located further out to sea, in addition to the technical benefits of designing projects around shipping lanes, fisheries and other fellow users of the water.

Catering to Wind Resources

A new specialist report from Wind Intelligence estimates that up to 80 percent of all global wind resources are located in waters deeper than 60 meters where bottom-fixed systems are not an option. So the difference that floating wind could make to the renewable energy sector’s drive to access this resource is enormous.

Bigger wind parks, larger turbines and increased wind conditions, combined with the lack of need to impact the seabed and the ability to standardize, make floating wind very attractive indeed. Wind Intelligence expects floating wind costs to follow the same downward trajectory that onshore and fixed offshore wind have followed over the last several years, putting the potential for cost decreases achievable by floating wind at 40 percent to 50 percent by 2030. Price decreases of that magnitude are expected to see floating wind become a real contender in the renewable fuels market.

Supply chain development is also a prerequisite; it’s not yet there, but confidence that it will develop is high.

“The supply chain for this has not been matured,” an Equinor spokesperson said. “The supply chain for offshore wind is starting to mature in Europe, but not other places in the world. This will change when development increases in other places. We believe that this will change as we scale up and see more deployment of floating wind.”

According to Sweden’s Hexicon, a specialist developer of floating multiturbine wind technology, there will be 500 floating turbines “out there” by 2030. That kind of development signifies a real opportunity, and also a challenge, for project cargo movers looking to transport outsize components like turbines, towers and blades.

Typical Hywind Journey

A look at the origin and location of manufacture of the Hywind components and how these were moved from manufacture to quayside for assembly demonstrates the breadth of the possible opportunities all over the world. It should, however, be noted by project cargo carriers that, as regional supply chains develop, the distances between manufacturer and project site will gradually decrease, so the job of transporting wind components is likely to become much more about the equipment, the know-how and driver skill, if on road, than it is about mammoth distances by any transportation method.

Hywind’s blades, each weighing 25 tonnes and measuring 75 meters in length – a wingspan almost the same as an Airbus 380 – were moved from Denmark, as were the nacelles, which equate to the size of two double-decker buses. Hywind’s towers were made in Bilbao, Spain, and, at 83 meters high and with a maximum diameter of 7.5 meters, weigh close to 670 tonnes each. These were constructed in four segments before being shipped for assembly at Stord, Norway.

The substructures that provide the platform on which buoyant wind turbines float were made in Spain. At 91 meters long and 14.5 meters in diameter at their widest point, they are formidable pieces of outsize kit themselves, each weighing 2,300 tonnes. The wind park’s mooring chains were also fabricated in Spain, while its suction anchors, each 16 meters tall, 5 meters in diameter and weighing about 300 tonnes each, were transported from Isleburn, Scotland.Moving wind towers and turbines is no small feat; the job requires considerable planning, paperwork, expense and care. It also requires increased communication and cooperation between all parties involved, from client and manufacturer to carrier and logistics provider, with highway and port authorities, forwarder and customs broker in between. Options range from trucks, rail and barge, as well as some newer, less-conventional methods.

The major physical challenges of trucking these outsize components include driving with overhead objects; height requirements; weight limits; bridges and tunnels; a lack of suitable roads; and administrative and regulatory constraints. Rail options, meanwhile, are frequently non-starters in many regions, owing to limitations related to dimensions and/or, more likely, lack of access to final project sites. If the end of the line is nigh, a turbine or tower section will have to be transferred to an alternative mode to complete its journey, adding in another major operation. Wind components have certainly been moved by rail, but the ability is closely reliant on local circumstances. Vestas is a manufacturer that has been using rail in Europe for several years – with trains of railcars up to 700 meters long – and rail has also been used in the U.S., but not yet for floating in either case.

Still Risks to Consider

As a still-nascent technology with immense potential, the floating wind market is not without other risks. Cargo movers wanting to prepare to move floating wind components will need to familiarize themselves with the array of design options present in the floating market; whereas Hywind is of a spar design, others in the market are semi-submersible, barge, or tension leg platform (TLP), all presenting specific requirements and considerations.

Within the four basic designs mentioned above, there are more than 30 floating wind concepts in existence or under development globally, presenting a significant degree of variation in dimensions and a further challenge to logistics planners when taking ports, quays and drafts into consideration. For example, spar and TLP designs can cope with water depths of minimum 9 meters, but semi-submersible concepts would be more problematic in the same circumstances.

“Another important consideration is the width of the port entrance,” the Carbon Trust said in a recent report. “Most port facilities have been designed to accommodate long and slender naval vessels; however, floating wind platforms are often very wide structures with beams reaching up to 100 meters in some concepts.” The report also points to a possible shortage of drydock facilities should floating wind boom as predicted.

Other challenges are storage and laydown considerations for the large number of components that make up a large wind park offshore — the Catapult report noted that modular designs that can be pre-manufactured away from the assembly port will be preferable once floating wind starts approaching commerciality, to avoid dockside bottlenecks and the resultant health and safety issues. Those sections and modules will need moving.

As the energy industry continues to creak toward a more renewable future, increased innovation and creativity would serve project cargo carriers well; those wanting to take advantage of a market predicted to boom should be ready for floating wind.

Helen Campbell is a freelance journalist based in London who has specialized in energy, environment, sustainability and technology for more than 20 years.

Image: Illustrated rendering of Equinor’s floating Hywind Wind Farm off the coast of Scotland, UK. / Credit: Equinor

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