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The offshore wind turbine industry looks like being a very... [Derived headline]

June 6, 2014

The offshore wind turbine industry looks like being a very good place to be for the next four decades, and big is definitely going to be better. When you are mounting a turbine 30 miles or so off the coast in 30 metres of water you want it to be generating as much power as possible for as much of the time as possible - and the industry is living up to this challenge.

Senvion (rebranded from REpower, a subsidiary of the Suzlon Group) is now in production with its 6.2MW turbine, following the successful testing of its prototype earlier in 2014.

Senvion's Vice-President of Offshore, Norbert Giese, explains this is Senvion's third generation rotor and the emphasis in the design has been on generating reliable power and reducing costs. Giese adds: "The industry is committed to lowering the total lifecycle costs - including manufacture, transport to site, installation and running costs - by 30% by 2020.

"As turbine manufacturers our share of that 30% reduction is potentially 30-40% and the way we will achieve this is through larger turbines with more generation capacity and larger rotors."

Senvion has plenty of experience to prove this. Its earlier generation of turbines had a 2MW turbine that began with a rotor of 82 metres and was then extended to a rotor diameter of 92 metres and later 100 metres. That extension improved the reliability of power output since bigger rotors make more efficient use of the wind.

Next it produced a 5MW generation turbine in 2004, with a 126 metre rotor, and a 6MW turbine in 2009.

The latest model, the 6.15 turbine, has increased the rotor diameter to 152 metres, which means the rotor sweeps out an area larger than three football pitches. The nacelle alone is as big as two detached houses and will be constructed offshore at a height of between 95 and 110 metres.

"Going up from a 126 metre rotor to a 152 metre rotor gives us an increase in energy yield of around 20 per cent at wind speeds of 9.5 metres per second. Each of these turbines can supply around 6000 to 7000 homes with electricity," Giese says.

Headquartered in Hamburg, Senvion's design centre is at Osterronfeld, while it has manufacturing plants at Husum (North Friesland), Trampe (Brandenburg) and Bremerhaven, with additional manufacturing being carried out in Portugal, India and China. The company has more than 3300 employees world-wide, and has more than 5000 wind turbines installed around the world.

Siemens' latest turbine is also a 6MW model and has been tested on SSE's test site at Hunterston and at Dong Energy's Gunfleet Sands offshore wind farm. This is a gearless turbine, which Siemens claims simplifies the drive components and helps bring down total lifecycle costs. In March 2014Siemens announced it was to construct a factory for offshore wind power in Hull, at an investment of pound(s)160 million.

The Hull plant will produce rotors for Siemens' 6MW class turbines and is expected to be at full capacity somewhere around the middle of 2017.

While Siemens' gearless turbine is attracting a good deal of attention with its lower lifecycle costs claim, Senvion's Giese says that what customers are interested in is not whether a turbine is geared or gearless, but how reliably it is going to generate power. The good news from the offshore sector, he adds, is that the "full load hours" numbers for the offshore sector are now right up there with gas fired electricity generation plants.

The term "followed hours" points at the importance of one hour of power generation following on another. There are 8760 hours in a year and the UK's current coal and gas-fired power stations have a full load hours figure of about 4000 to 5000. With the latest generation of offshore turbines, Giese reckons, the offshore sector could match that, which would lay to rest much of the argument about renewables generation being weak on continuity of supply.

Senvion's prototype 6.2MW turbine was installed at an offshore demonstration site for the German utility EWE, which has been the launch customer so far for three of its new models.

So is he confident about the future? "Very confident," he says. "Over the past two years the market has been very quiet in terms of new orders, especially the big markets of the UK and Germany. But now that the UK has fixed the strike price, and Germany has a new feed-in law with a stable market up to 2019, we expect many of the projects that have been stalled to come forward." He points out offshore is really the only renewables option for countries that have small, highly populated land masses, such as Belgium and Holland, so that they can be expected to come in strongly as well. Thereafter, he expects activity in the Far East, India and US. "These countries are about 10 years behind the UK and Germany. Today these are markets for developers, not for manufacturers, but once they have a stable framework for renewables deployment things should move forward," he concludes. *

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Source: Herald, The (Scotland)

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