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Viewpoint: Bigger turbines on land as offshore grows in reach

I remember talking to people 15 years ago about how wind-industry technology was really starting to converge - on three-bladed, upwind rotors driving high-speed, doubly-fed or full variable-speed generators via three-stage gearboxes, with the occasional outlier in direct-drive or with two-bladed rotors.

Life has moved on, and we no longer see such convergence. We now have a range of drivetrain concepts fighting it out for supremacy, and the establishment of a completely separate class of turbine for offshore wind.

This year, we have also seen a rise in the number of competing technology options moving to market in onshore wind. There seems to be gradually growing industry consensus that, if wind is to continue to compete with huge cost reductions in solar technology, it is time, to break through three critical and inter-related constraints.

These are transport limitations that have kept the largest onshore turbines at around 3MW for some time; tip height restrictions coming from both permitting challenges and technical limitations of traditional steel towers and blade designs; and minimum wind-resource requirements for projects to be viable as subsidies recede.

For some years, the largest turbines to be used onshore were rated at around 3MW and with not much more than 100m rotor diameter, constrained by the challenge of transporting heavy nacelles along small roads, large diameter tower sections under bridges and long blades round sharp corners.

Of course, there have been design solutions to each of these problems, such as bolt-together blades and concrete towers to build on site. The additional cost of implementing these, however, has made it more attractive for developers to pursue "easier" sites, even if these have lower wind resource, or use smaller turbines.

Following the industry's experiences with very large turbines offshore, where it has overcome a range of other technical and supply chain hurdles, it seems time to "go large" on onshore projects too. Turbines rated at 4MW and with rotor diameters exceeding 140 metres are already on the market, and a range of more innovative solutions to the logistics challenges are anywhere from the drawing board to in production.

With significantly larger turbines, the equation tips and it becomes worth investing in the work-arounds to be able to use them on more and more sites.

Of course, such turbines aren't right for all sites, for example in hilly terrain and close to dwellings; but on more flat, open and lower-wind sites, where project scale can approach that of offshore, large turbines could offer an attractive solution, reaching up to higher winds.

One prediction, then, as we head for 2017, is that we will see significantly more progress in this area.

Falling prices

What else has changed in 2016 that can give pointers to next year? We've seen the fall and fall of offshore wind prices, with recent European auctions — Borssele in the Netherlands, Vesterhav and Kriegers Flak in Denmark — pushing the boundaries of what is achievable.

We see ample room for further cost reduction based on technology, but we don't see much more room to squeeze margins or gain benefits in supply-chain dynamics in a market that is consolidating, now that the optimistic vision of scale for the next decade has been tamed somewhat.

Examples of that consolidation are evident in some of the big wind supply chain deals of the year, where effectively we have said goodbye to Areva (via Adwen) and Gamesa from the offshore turbine competitive landscape. This potentially leaves current offshore wind markets in an awkward position for two reasons.

First, the small number of players is barely enough to drive competition. Second, the offshore market turnover of each remaining player in the sector may not be enough to facilitate new, much larger turbine development, key to reducing the cost of energy after the next five years or so. C

ompetitive auctions can partly mitigate the first of these, but there is no substitute for the next generation of larger turbines and that needs more market.

Another prediction for 2017 is that, based on recent auction prices and the prospect of further cost reductions, there will be a rapid rise in the number of countries interested in establishing an offshore wind industry as they see that offshore wind is not just a curiosity in northern Europe, but in many cases the most scalable, low-carbon generation source that can be built close to population centres.

The next stage of market growth starts here.

Bruce Valpy is managing director of BVG Associates.

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