Viewpoint: Floating technology taking shape to be next big thing

Although the first offshore wind turbine was installed more than 25 years ago, the onshore industry has continued to grow and dominate. In Europe last year, onshore wind still accounted for 75% of new wind-power capacity installed.

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Yet, the direction of travel is clear. In a number of markets, offshore wind is already seen as a more effective way to get industrial volumes of new capacity online.

This is because onshore wind is held back by smaller project and turbine sizes, saturation of attractive sites and tougher permitting regimes. Total European investment costs in offshore wind over the past five years have been almost the same as in onshore.

So as offshore wind establishes itself as a key source of sustainable electricity generation that can be "subsidy free" within the next ten years, what will be the next "new" market to emerge?

The oil and gas sector moved far offshore in the late 1940s and took a further 50 years to use floating technology at scale to access new markets.

Offshore wind is following in its footsteps, but taking much less time to start addressing those sites with deeper waters that are rich in wind resource and close to shore, through the use of floating foundations.

Currently, there are a number of competing floating platform concepts, often based on different initial engineering hypotheses from designers.

Some designs are based on the principle that it is most cost-effective to provide buoyancy via steel cylinders, others that concrete is best for achieving structural strength, while others focus on maximising hydrodynamic stability.

Each of these concepts involves uncertainty over anticipated costs, making a comparison difficult, and it is not clear if any one concept will become the solution of choice for most sites, or whether different solutions will be used at different types of sites.

Tension-leg platforms may generally have the lowest costs for the support structure, but the highest costs for anchoring and equipment to provide stability during installation, presenting considerable investment challenges.

Semi-submersible platforms are the opposite, with simpler anchoring and installation solutions, and therefore offering the safest early option, but they come with higher fabrication costs. Spar buoys have potentially the lowest cost, but there are limitations on sites and assembly locations, unless more radical installation methods are adopted.

Different approaches

The sector is characterised by a number of technology players focused on specific aspects of the floating wind farm. At some point there will be a move towards a few large installation contractors playing broad EPC roles.

This will lead to more holistic full-system designs that incorporate anchoring, cabling, installation and maintenance solutions.

Wind-farm developers are also taking quite different approaches, with some sponsoring technology in order to help establish it in the market, others playing an active but technologically agnostic game, and the remainder still leaving the floating opportunity alone.

Another uncertainty is where the first floating markets will become established. Japan has been a long-term frontrunner, but its huge research-and-development investment has had limited success so far.

France arguably now has the largest programme of likely demonstration projects, with Scotland not far behind, and the US has the greatest potential.

Established offshore markets are less in need of floating technology, as they generally have plenty of sites in shallower water or have no significant deep-water sites.

Floating technology also has a longer-term chance to compete on price in these existing markets, however, especially on midto deeper water sites, where bottom-founded solutions increase rapidly in cost.

Best of both worlds

But is there an intermediate solution that could do even better? A number of organisations are developing float-out-and-sink designs, where bottom-founded turbines are fully assembled on foundations in port, towed to site, then sunk to the seabed, without the expense and limitations of crane vessels.

The installation challenges are similar to those of floating solutions, but after that, routine operation is the same as on conventional projects.

Industry frontiers are often compelling places to be. Floating offshore wind may still be much of a decade from commercial deployment, but already the playing field is taking shape and early movers are learning lessons. Don't miss out - has your organisation decided on its strategy in floating offshore wind?

Bruce Valpy is managing director of BVG Associates

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