Close up - Gamesa's plans for the offshore market

Windpower Monthly technical writer Eize de Vries looks at Gamesa's offshore plans and what its upcoming 5MW and 6/7MW offshore turbines might look like.

Gamesa's G10X 4.5MW turbine will provide the platform for the company's 5MW offshore turbine

Gamesa's offshore plans have been eagerly awaited since the breakdown of negotiations with offshore specialist BARD in July and the announcement it was developing its own offshore turbine.

The clearest indication of Gamesa's plans has come with the announcement that it is joining forces with Northrop Grumman Shipbuilding, the largest US shipbuilder and a defence industry giant, to develop a 5MW offshore turbine in the US. Gamesa is planning to launch the prototype, the G11X-5MW, in the final quarter of 2012, with series production slated for 2013. Gamesa's offshore capacity will be further boosted by plans to build the G14X, a 6/7MW offshore turbine that will go into pre-series production in 2014.

Proven experience

In 2009, Gamesa was ranked sixth among the world's largest suppliers. It has a manufacturing capacity of 4.4GW and a global workforce of 6,300. Northrop Grumman employs 120,000 staff and has wide experience in heavy load logistics in marine environments.

However, the Northrup Grumman deal might never have happened if Gamesa and BARD had come to an agreement. That deal would have incorporated joint marketing and the development of offshore wind turbines and services. Gamesa had been set to make a significant capital investment for a minority stake in BARD and the right to produce its turbines under license.

BARD has a brief but strong offshore background and has already developed one of the wind industry's largest 5MW offshore wind turbines. A total of 80 units are being installed in a major German 400MW North Sea wind plant. The company will also install several scaled-up 6.5MW prototypes this year at its planned German Bight wind farm.

Many wind industry analysts had welcomed the collaboration between the two, which was viewed as a good strategic fit, with potential benefits for both parties. For Gamesa, the main benefit would have been a short-track entrance to the offshore market based on BARD's dedicated, proven 5MW product.

Instead, Gamesa is going it alone. The company is giving little away about the G11X but has conceded it will be based around the innovative, lightweight, medium-speed G10X-4.5MW onshore turbine introduced earlier this year. Notable features include a 250-tonne top head mass, segmented rotor blades, a 128-metre rotor and advanced transport and installation logistics features.

The G11X-5MW offshore wind turbine design will build on technologies already tested and validated in the G10X-4.5MW platform but the specifications other than the power rating have not yet been made available. It seems likely, however, that there will be substantial differences between the G11X and the G10X. First, with construction of offshore turbines expected to take place at or close to ports wherever possible, there seems little need for segmented blades.

There may also be modifications aimed at strengthening the drive system, while another option could be to let the turbines run faster with a reduced rotor diameter, a proven method of raising the power rating without making the drive train heavier.

Next step G14X-6/7MW

While still working on the 5MW turbine model Gamesa and Northrop Grumman are already looking to the medium and long-term, envisaging that offshore wind systems with higher installed capacity will be required to meet the expected growth in market demand.

In its recently released business plan for the period 2011-13, Gamesa reveals its plans for the larger 6/7MW G14X turbine platform. A pre-series is planned for 2014, with series production start by 2015. Gamesa plans to erect its first offshore wind turbines in UK waters by 2014.

Predicting what the G14X might look like is even harder than the G11X. However, it could be medium speed or direct drive as both options appear to be configurations that many suppliers consider for such large offshore turbine developments. Also, going by the nameplate, there is a suggestion that its rotor will be in the range of 130 to 140 metres, although using Gamesa's nameplate to predict product specifications has been misleading in the past.

The probable truth is that the design of each turbine is yet to be firmed up by Gamesa's own design team. And with a first deadline of 2012, it still has time to finalise its plans. In the meantime, competitors like Vestas, Sinovel, Siemens, Samsung, BARD and Clipper – all planning large capacity offshore products – will continue steaming ahead.