Bigger Blades and Better Designs in Wind Energy

Among those unveiling new or updated designs this year comes evidence of this trend towards expanding the operational wind speed ranges in the 3 MW-class of wind turbines. For example, Enercon has focused the spotlight on its new 3 MW-class wind turbines which are based on its E-82/2.0 MW machine. With the same rotor diameter and tower height (between 78 and 138 metres), it can achieve a yield increase of 3%–6% depending on the wind speed – at the same location, the German manufacturer claims.

Expanding its product portfolio by adding the 82 metre diameter E-82/2.3 MW and E-82/3 MW for strong-wind sites rated as Class I and II wind sites (IA and IIA) by the International Electrotechnical Commission (IEC) and the 101 metre rotor diameter E-101/3 MW for relatively low wind speed inland sites (up to IEC II A), the company says it intends to use these new models to satisfy the growing demand for wind turbines in this capacity range.

Stefan Lütkemeyer, sales manager at Enercon, explains the company strategy, saying: ‘We think it will be this capacity class above all that will exploit the European potential of 80 GW of rated power to be installed by the year 2013.’

The first E-101/3 MW is due to be installed later this year while series manufacturing is scheduled to start in 2011. The E-101 is available with precast concrete towers only and hub heights are 99 or 135 metres. Meanwhile, the prototype of the 2.3 MW machine has been running since February 2009 at a site in Fiebing in north-western Germany and the remaining prototypes are expected to be installed this year. Series manufacturing of the E-82/3 MW is scheduled to start towards the end of this year.

According to Enercon, the turbine design is characterized by more advanced cast iron components, including the main carrier and stator shield – as well as an optimized cooling system, which Enercon says allows the machine to operate at a rated power of 3 MW while largely maintaining the same component sizes, as well as the transport and manufacturing dimensions of the E-82/2 MW machine. ‘We‘ve improved the design of the cast iron components in the nacelle and optimised the air cooling system’, said Arno Hildebrand, engineering manager at Wobben Research & Development (WRD). The previously used stator support star of the generator has been replaced with a stator shield that is shaped in such a way as to protect the generator mechanically, and to allow further components to be fitted directly to it, the designers explain. In contrast to the E-82/2.3 MW, the E-82/3 MW is also suitable for locations where average wind speeds exceed 8.5 m/s, Class II, (at hub height). The generator is somewhat longer than the one in the E-82/2.3 MW. However, Hildebrand adds that the diameter of the generator has not changed.

By way of contrast, REpower Systems AG presented two new variants of their 3.XM series for less windy locations at the European Wind Energy Conference and Exhibition (EWEC 2010) held in Warsaw, Poland in April.

Left: Nordex' latest Gamma generation N100 2.5 MW machine.  Credit: Nordex

With a 104 metre rotor diameter, the 3.4M104 is part of the 3.XM series turbine type introduced in 2008 and which is now available in three different hub heights as a new 128 metre concrete and steel hybrid tower joins two existing steel tower variants with hub heights of 96.5–100 metres and 78–80 metres respectively. Now, the Hamburg-based manufacturer has also announced that it plans to start selling a second variant of the machine, the 114 metre rotor diameter 3.2M114.

Rated at 3.2 MW, compared with the 3.4 MW of the 104 metre version, the newest turbine of the 3.XM series is designed for use in less windy locations in inland areas and is set to be launched in the German market from autumn 2010, with installation of a prototype of the machine planned for 2011. Due to the significantly larger rotor area the 3.2M114 can increase the energy yield at less windy locations, in comparison with the 3.4M104, by up to 10%, REpower says.

The 3.2M114 is initially to be offered with a steel tower and a hub height of 93 metres, though additional variants are planned. The company’s CTO Matthias Schubert observed: ‘We are expanding our product range with the new turbine types in the 3.XM series. Both the 3.4M104 with hybrid tower variant and high hub heights as well as the new 3.2M114 with its 114 metre rotor diameter are optimally suited for less windy locations.’

REpower also unveiled a UK market-specific machine with its 3.4M104 on a 93 metre tower. This meets the 145 metre maximum height requirement for UK planning terms and it is designed for class as IEC1b, the company says, making it suited to the windier conditions in the UK and in particular, Scotland. The turbines are already being actively sold in the UK market with the first installations expected in summer of 2011.

Together with Renewable Energy Systems Canada Inc. (RES Canada) and the Wind Energy TechnoCentre, REpower have also recently announced the installation of two prototype cold climate versions of REpower’s MM92 machines in the Canadian province of Québec. Rated at 2.05 MW each they will be tested intensively in the cold and moist climate of eastern Canada in the following months.

Alstom, too, has launched a larger diameter rotor version of its flagship machine with the unveiling of the ECO 110 wind turbine – a 3 MW rated machine with a rotor diameter of 110 metres designed to maximize energy yield on low to medium wind sites with its 53 metre-long blades.

According to the company, the ECO 110 has been designed to reduce its installation, operation and maintenance costs while its modular design allows the use of industry standard transport and installation equipment. Furthermore, says Alstom, the ergonomic design of its nacelle leaves room to perform easy maintenance. The ECO 110 has also been designed to minimize noise by keeping the rotor speed below 13.7 rpm.

Left: A cutaway of the G10X nacelle.  Credit: Gamesa

The first unit was installed in autumn 2009 at the Loma Viso II wind farm in Albacete, Spain. ‘With the commercial introduction of the ECO 100 wind turbine last year, and now the ECO 110, Alstom confirms its determination to lead the field in large onshore wind turbines’, said Alfonso Faubel, vice president at Alstom Wind.

Among novel turbine concepts presented at EWEC comes a one bladed wind turbine from ADES. With a power range from 100 to 250 kW the medium-sized turbines are currently being tested in Spain, and are due to be available to the market in 2011. The design, a pendular wind turbine with adjusted motor torque, includes a swiveling single-blade rotor, a pendulum power train and a self-steering nacelle. According to the manufacturer, its particular design compensates, accumulates and reinstates wind speed variations, preventing them from affecting the evenness of generator rotation and subsequently diminishing structural overload and power peaks caused by wind gusts.

Generator Concepts

Among the new machines showcased in 2010 was Gamesa’s G10X-4.5 MW platform and specifically the G128-4.5 MW wind turbine, both rated at 4.5 MW. Currently engaged in the marketing and installation of the first pre-series of the G10X-4.5 MW, the machine has a 128 metre rotor diameter and a 120 metre concrete and steel hybrid tower. The turbine offers lower energy costs and ease of transport and installation similar to that of a 2 MW turbine, Gamesa says, adding that the design is the company’s most ambitious project ever.

Turning to the company’s G128-4.5 MW, Gamesa says features include a more easily transported sectional Innoblade, with a new design which minimizes noise. The Innoblade’s structure and materials substantially reduces blade weight, Gamesa adds. The drive train features a semi-integrated main shaft in a two-stage gearbox with mid-speed range output. The integrated design makes the drive train more compact, with fewer components, the designers say, while a permanent magnet synchronous generator using a full converter handles the electrical end.

Earlier in April Gamesa announced that it will deliver 90 permanent magnet generators with a combined capacity of 48 MW for the Ashta hydroelectric project on the Drin River in Albania following an agreement with Andritz Hydro. The generator technology was developed by Gamesa for its G10X-4.5MW turbines and the plant is scheduled to begin operation in 2012.

Elsewhere, Siemens Energy chose EWEC to launch its new SWT-3.0-101 Direct Drive wind turbine for sale, the new SWT-3.0.101 with a rated power of 3 MW. Offering a Direct Drive concept using a permanent magnet generator, the first prototype machine’s generator, which was installed in Denmark in 2009, was produced by the Large Drives Business Unit within the Siemens Industry Sector. With half the parts of a conventional geared wind turbine, and much less than half the number of moving parts, the new wind turbine will require less maintenance and increase profitability for customers, Siemens claims. The new Direct Drive wind turbine features a rotor diameter of 101 metres, and is now available for sale in both onshore and offshore configurations.

‘Our new SWT-3.0-101 will offer 25% more power than our present 2.3 MW machine, but with a lower weight and only half the parts’, said Henrik Stiesdal, CTO of the Siemens Wind Power Business Unit, adding: ‘The nacelle of SWT-3.0-101 weighs only 73 tonnes, which is less than the nacelle of our standard 2.3 MW wind turbine.’ A major advantage of the new machine is its compact design, Siemens says. With a length of 6.8 metres and a diameter of only 4.2 metres, the nacelle can be transported using standard vehicles commonly available in most major markets. Stiesdal added, ‘Our main target for the new machine was to reduce complexity in order to increase reliability and profitability.’

As a next step, the zero-series with up to 10 SWT-3.0-101 wind turbines will be installed in various parts of the world during 2010. Commercial serial production is expected to commence in 2011. ‘Like with our previous machines, we will run a controlled ramp-up program with the SWT-3.0-101’, continued Stiesdal.

Meanwhile, Nordex SE unveiled a new generation of its 2.5 MW turbine series – the third, Gamma, generation. Comprising the N80, N90 and N100 turbines. Nordex has redesigned the nacelle, hub and rotor blades in the new generation to be both lighter and more robust. This also simplifies transportation and installation, while simultaneously reducing the static and dynamic loads on the overall turbine, they say.

The rotor shaft and integrated slip ring have also been redesigned to protect the slip ring from the weather and mechanical influences, Nordex says. Furthermore, the slip ring is now heated to stop condensation from forming. In the yaw system Nordex has also further developed its proprietary control system with an improved concept for temperature control, which the company says ensures maximum yield in both permafrost and desert climates.

Monitoring, Operations and Maintenance

Another key area for development is the drive to improve energy output through a range of measures comprising forecasting, reliability, efficiency and ease of operation and maintenance.

For instance, Spanish wind major Gamesa has launched an online weather forecasting and condition monitoring service.

Its so-called Mega system provides detailed information on wind farms to enhance their performance and better integrate the energy they generate into electricity markets, the company says.

The Mega system allows subscribers to access seven-day forecasts for hourly wind conditions and wind farm output. The Basic option offers forecasts based on customised statistical meteorological modelling for each wind farm. This information is updated five times a day.

The Premium version builds on the Basic version with hourly updates via a real-time connection to wind farm data. By using short-term forecasting models, this system provides greater precision and enhanced assessment of likely conditions and output at wind farms, minimising the risk of deviations between expected and actual generation.

Gamesa plans to add new features to the Mega service in the medium term, including precipitation, temperature and relative humidity forecasts. Gamesa says it has spent more than seven years investing in wind pattern forecasting and wind farm output modelling systems.

Similarly, GL Garrad Hassan – the new name for the renewable energy business segment of Germanischer Lloyd Group – launched its new Online Data Management (ODM) service at the EWEC event. The new tool helps windpark operators, investors and developers in maximizing the value of their wind resource measurement investment via stable, accurate and continuous data collection and review, the company says. The service allows 24/7 secure online access to summary statistics compiled from the data recorded, including energy estimates and other critical information pertinent to the early stages of project development.

Left: The latest version of the 3X.M is designed for low wind speeds. Credit: Repower

More recently Vestas announced an R&D project to impove wind farm management. The so-called Intelligent Energy Management System for a Virtual Power Plant, this project will introduce energy storage into a wind power plant as an optional component for enhanced power generation control. The project will run for 3–5 years, Vestas said in a statement.

‘Storage embedded in the wind power plant allows the power to be regulated without compromising any capture of available wind energy. Such a balancing mechanism opens for even higher amounts of wind power on the grid and for added value of the generated wind power to the transmission system operator. In turn, this makes our wind power plants an even better investment for our customers’, explained Finn Strøm Madsen, president of Vestas Technology R&D.

Other Developments

With evidence of increasing demand for wind turbines despite the economic downturn, it is clear from the spread of recent announcements that the OEMs supplying the wind sector are responding to demands for machines which are more versatile, more robust and reliable, and more economic to operate and maintain. But perhaps the key development does not come from a technology company.

According to a comprehensive assessment of studies of the impact of wind energy on electricity prices – carried out by the independent consultancy Pöyry AS on behalf of the European Wind Energy Association (EWEA) – wind power generation already reduces electricity prices for consumers.

The review, ‘Wind Energy and Electricity Prices’, brings together findings of case studies in Germany, Denmark and Belgium and finds that electricity prices were reduced by €3–€23/MWh depending on the amount of wind power installed. It concludes that the three case studies ‘essentially draw similar conclusions’ and that ‘an increased penetration of wind power reduces wholesale spot prices.’

That OEMs are continuing to hone their chosen instruments is inevitable in a competitive market and consumers will surely benefit as a result. That wind is already directly curbing European electricity prices is perhaps less obvious, and all the more significant for it.

Sidebar: Wind Continues Explosive Growth

Global wind energy markets are expected to continue their rapid growth, with installed capacity increasing by 160% over the coming five years, according to the annual industry forecast presented by the Global Wind Energy Council at EWEC.

Assuming an annual average growth rate of 21%, which GWEC argues is conservative compared with the 29% seen over the past decade, the trade group says it expects global installed wind capacity to reach 409 GW by 2014, up from 158.5 GW at the end of 2010. During 2014, the annual market will be more than 60 GW, up from 38.3 GW in 2009, the GWEC analysis forecasts.

According to the document, the US and China will continue to be the two markets leading global wind power expansion, having exceeded all expectations in recent years.

Indeed, in China growth is set to continue at a breathtaking pace. Already in 2009, China accounted for one third of total annual wind capacity additions, with 13.8 GW worth of new wind farms installed. This took China’s total capacity up to 25.9 GW, thereby overtaking Germany as the country with the most installed wind power capacity by a narrow margin.

China will remain one of the main drivers of global growth in the coming years, with annual additions expected to be over 20 GW by 2014, GWEC predicts. This development is underpinned by a very aggressive government policy supporting the diversification of the electricity supply and the growth of the domestic industry. The Chinese government has an unofficial target of 150 GW of wind capacity by 2020, and with the current growth rates, it looks likely that this ambitious target will be met well ahead of time, the analysis adds.

In the US, development for 2010 will be hampered by continued tightness in the financial markets and the overall economic downturn, but the provisions of the US government’s Recovery Act, and in particular the grant programmes, will continue to counteract the impacts of the crisis, GWEC says. Nonetheless, coupled with legislative uncertainty at the federal level in Canada, the result is that the North American market is forecast to stay flat for the next couple of years, and then pick up again in 2012, to reach a cumulative total of 101.5 GW by 2014 (up from 38.5 GW in 2009). This would translate into an addition of 63 GW in the US and Canada over the next five years.

Until 2013, Europe will continue to host the largest wind capacity. However, GWEC expects that by the end of 2014. Europe’s installed capacity will stand at 136.5 GW, compared to Asia’s 148.8 GW. By 2014, the annual European market will reach 14.5 GW, and a total of 60 GW will be installed in Europe over this five year period.

Commenting on the analysis, Arthouros Zervos, GWEC’s chairman noted: ‘Despite the absence of a global price on carbon, wind energy will continue to grow due to national energy policy in the main markets and also because many governments have prioritized renewable energy development in their economic recovery plans. All of the fundamental drivers that have made wind power the technology of choice are still in place. Neither the threat of climate change nor the macroeconomic insecurity due to reliance on imported fossil fuel is going to go away.’

GWEC’s findings echo those of Denmark’s BTM Consult ApS – see page 32 of this edition for more details – whose latest analysis reports that the booming worldwide market for wind power capacity is expected to grow to 447 GW within five years, almost three times its present level. Within 10 years it could expand to nearly 1 TW and meet 8.4% of the world’s electricity demand, BTM says. BTM points to record levels of new wind power capacity installed during 2009 – 38 GW – despite the economic crisis.