For a variety of reasons offshore wind has so far proved much more difficult to do than its early proponents imagined, but some recent developments, notably in Germany – which still has among the most ambitious offshore wind aspirations of any country, with about 65 GWe planned and 3 GWe permitted – should help.

Particularly significant is a law passed recently in Germany to speed up the planning processes for infrastructure projects. This stipulates, among other things, that, for offshore wind farms connected before the end of 2011, the existing grid operators are responsible for providing the grid connection, with costs distributed over the whole grid system, as is the case for conventional power plants.

Not surprisingly this has gone down well with would-be developers of German offshore wind projects. The potential of the German offshore market has, for example, not been lost on the Irish wind visionaries, Airtricity. Visionary-in-chief, Airtricity CEO Eddie O’Connor, believes that, in his words, the German offshore market “is about to explode” and in December his company announced it was planning to become a partner in the stalled Butendiek project, taking control of financing, construction and operation (see p 21). He believes this project could be producing power by the end of 2009, thus establishing it and his company “in the forefront of German offshore wind farms”, he hopes.

The company presumably anticipates that this project might eventually become a further building block of its European Supergrid concept (see pp 20-21), which is, to say the least, ambitious – but there’s no harm in that. In November Airtricity announced it had been awarded site exclusivity on its West Rijn offshore proposal for the Netherlands, which is also seen as a potential part of the Supergrid. (The Dutch government, incidentally, has a target of 6000 MWe of offshore wind by 2020 and commissioning is currently underway on the country’s first offshore wind farm, the 108 MWe OWEZ facility.)

The new German infrastructure law is also good news for those in a position to supply the wind turbines, which need to have the highest possible installed capacity per unit combined with the lowest mass, as well as demonstrated capability for operating in hostile offshore conditions.

In fact the number of suppliers able to respond to a resurgence of interest in offshore wind with appropriately large offshore-proofed turbines, ie in the 5 MW class, is currently very limited, and with the recent apparent departure of Enercon from the sector, and the postponement by Vestas of its development work on its 4.5 MWe machine, the number has actually been diminishing in recent times.

But one turbine supplier very happy to oblige, and already planning to increase production capacity in anticipation, is REpower of Germany, one of whose 5 MWe 5M wind turbines was deployed this summer in a water depth of about 44m at the Beatrice demonstrator project off the coast of Scotland (the frustrations of offshore installation, incidentally, being illustrated by the fact that the second turbine at Beatrice has yet to be put in place).

This autumn saw two further 5M machines installed at the DEWI-OCC test field in Cuxhaven, Northern Germany, which is designed for the testing of machines in realistic conditions, although it is in fact an onshore coastal site rather than being offshore.

REpower is also supplying six out of the twelve 5 MW class turbines to be installed in the course of 2008 at the government/industry-supported Borkum West offshore demonstration wind farm, in the North Sea, 45 km from the island of Borkum. According to REpower’s CEO, Professor Fritz Vahrenholt, from his company’s point of view, “Borkum is the ‘shop window’ for the 3000 megawatts of wind energy which the German government is targeting in the North Sea and Baltic Sea over the next few years.”

Professor Vahrenholt recently told investors that most of the sixteen German offshore projects consented to date would be using his company’s 5M wind turbine, and since the new infrastructure law was passed he and his colleagues had been in almost daily contact with the developers of these projects, all seeking turbines. It is no wonder therefore that REpower is preparing to embark on serial production of the 5M at its Bremerhaven facility, perhaps as early as 2007.

Another contender in the 5 MW class offshore market is the Multibrid M5000, which has the advantage of a lower top head mass (nacelle plus hub and blades) than the REpower machine, 310t compared with 420 t. The other six turbines in the Borkum West demonstration farm will be of the Multibrid M5000 type. This machine has also been selected by the French for their first, 105 MWe, offshore wind farm, while in December Multibrid announced that it had successfully constructed a second M5000 demonstration unit, onshore, at Bremerhaven, using an innovative tripod foundation structure.

Originally it had been intended that the Borkum West facility would host four Enercon E-112 turbines, together with four M5000 units and four 5M machines. But the E-112 machines will not now be deployed there, following Enercon’s apparent decision to focus on areas other than large offshore turbines. Neither does the E-112, one of which has been operating for several years in an “offshore demonstrator” at Emden, now seem to get a mention on Enercon’s web site. One of the E-112’s drawbacks, particularly in the offshore context, is its relatively large top head mass, over 500t – although its power rating is correspondingly large, 6 or even 7 MWe. Not helping the E-112 was the failure of an innovative suction bucket foundation during installation of a second demonstration machine, at Wilhelmshaven, in 2005.

In contrast, a strikingly low top head mass, of around 220t, is a feature of the 4.5 MWe V-120 turbine that Vestas is developing, but which it delayed in the wake of financial turmoil experienced last year. However, now that the position is recovered, with EBIT margin expectations of 5%, 7-9% and 12% projected for 2006, 2007, and 2008, respectively, one might reasonably expect the V-120 project to be revisited with some urgency.

Looking to longer term deployment, turbines well in excess of 5 MW class are very much on the agenda. GE is, for example, understood to be developing a 7 MWe machine for offshore use in deeper waters, while the EU funded UpWind project is looking towards turbines in the 8-10 MWe range and well above, perhaps 20 MWe or so.

The is the kind of turbine size that will be needed if offshore wind, both in Germany and elsewhere, is going to deliver as promised.