BARD Engineering GmbH is a highly ambitious wind industry newcomer, now building its ‘own design’ 5 MW BARD VM offshore wind turbine (including 60-metre rotor blades) in-house. Other key developments include a novel Tri-Pile deep-water foundation for the company’s future North Sea projects, and an innovative self-propelled deep-water wind turbine installation barge. Eize de Vries visited the company’s impressive facilities, where he talked to managing directors Anton Baraev and Heiko Roszlig; about BARD’s plans and visions – and watched the huge prototype taking shape.
Founded in 2004, BARD Engineering – with the financial backing of a Russian investor – has set out to become one of the world’s largest integrated offshore wind plant developers. From its bases in Germany’s North Sea towns of Emden and Bremen, BARD is planning to install, during the next few years, offshore wind farms of about 400 MW each in the Deutsche Bucht – the span of the North Sea that reaches out from Hamburg westwards towards the Netherlands and northwards towards Denmark.Building permission
In April this year, the company received a building permission for its first 400 MW offshore wind farm named BARD Offshore 1. This challenging project, with a water depth that reaches 39-41 metres in parts, comprises 80 BARD VM turbines. It is to be built during 2009 and 2010, with commissioning planned for the same period.
The plan is to erect two land-based prototypes between the middle of October and the end of December this year about 25 km west of Emden in a 500-hectare chunk of wasteland named Rysumer Nacken. Development of the BARD VM wind turbine began in November 2005, which means there will have been only a two-year interval between the start of the design process and prototype erection.
Artist’s impression of the 400 MW BARD Offshore 1 wind plant bard engineering
The two test turbines will be put on a tubular steel tower and a ‘common’ state-of-the-art concrete foundation. The hub height of the two prototypes is 90 metres, and the average wind speed at this height is about 8 m/s. BARD Engineering’s Managing Director Anton Baraev says: ‘Offshore at the same hub height, we expect a considerably higher wind speed value. But the turbulence level as a key factor that much contributes to wind turbine fatigue loading is substantially lower offshore. When the prototype testing and optimizing proceeds according to plan, we expect a Germanischer Lloyd (GL) Type Certificate by the end of 2008.’
Series production is to begin next year, with a planned 20 wind turbines and up to another 40 installations in 2009, all designated to the BARD Offshore 1 project. Production will be scaled up again in 2010 to 50-60 units. Of this total number manufactured in 2010, 20 units will complete the 80-turbine total for BARD Offshore 1. The remaining units will either flow into one of BARD’s next offshore projects or – as an alternative – they can be sold to third-parties in the global wind market.
Rotor blade production in Emden bard engineering
BARD Engineering’s envisaged in-house capabilities include management of the entire onshore and offshore process chain from planning to manufacturing, installation and long-term wind plant maintenance. The company’s current workforce comprises about 180 persons spread over the two locations in Emden and Bremen. While Emden is responsible for all technical issues concerning the wind power plant, Bremen deals with all financial issues and project development. The number of staff is expected to expand rapidly to about 600 as the offshore wind project business grows during the coming years. Managing Director Heiko Roß continues: ‘BARD Engineering’s overall company strategy aims at fast growth combined with an independence from third parties where no market is available.’Goldhofer
The two large manufacturing halls in Emden – with direct access to the water of the North Sea – can be clearly distinguished by their bright blue lower wall sections and white-painted upper wall sections. The separation lines between the two colours have been drawn in an artistic wave pattern, clearly emphasizing the company’s key focus on offshore wind power development. One of the halls, fitted with large overhead cranes and featuring a high ceiling, is new and purpose-built for wind turbine series assembly. It has a maximum annual capacity of a hundred turbines. During the second week of August, engineers and technicians were busy completing the first BARD VM prototype nacelle, while some components and sub-assemblies for the second unit were already waiting inside the hall.
When series production gets into full swing – from 2008 – the hall will be able to accommodate five nacelles at different stages of completion, a moving working station process that is physically organized as a single-line assembly. As part of an integrated assembly and transport logistics chain philosophy, BARD developed a novel transportable welded steel platform with a roughly 1.5 metre high vertical tubular steel section located in the centre. These platforms represent an essential time- and money-saving part of the working station process, and each of them serves as an individual link in the assembly line.
Drawing of the installation barge Wind Lift I bard engineering
Any new nacelle assembly process takes five weeks of throughput once series production begins. It always starts by bringing in a new steel platform through the rear door into the hall and into position at the back of the assembly line (five positions). The next step is to bolt the yaw bearing on top of the tubular part of this platform (in analogy to the tower top section), which as an entity is then elevated on ‘blocks’ on the factory floor. The cast main chassis is then assembled on top of the yaw bearing, followed by the fitting of the fabricated welded steel rear generator sub-frame to the main frame.
During assembly, the platforms are moved several times to the next position in the hall with the aid of a so-called Goldhofer vehicle. This is a precision-manoeuvrable low-bed tractor with up to 100 individually steered wheels that is capable of moving extreme loads. (Goldhofer is a German company that manufactures these specialist vehicles.)
Once all components – including main bearing, gearbox, generator and turbine control unit – have been fitted, the completed nacelle (without rotor) plus mounting platform are moved to a pontoon as one assembly. The short distance from the hall to the waiting pontoon is again covered with the aid of the Goldhofer. Once on board the pontoon, the nacelle/platform assembly is offloaded and firmly fixed to her deck, ready for safe sea transport to the offshore wind plant construction site. On arrival at the site, the crane of the Wind Lift I wind turbine installation barge hoists the nacelle up to the top of the wind turbine tower, after disassembly from the transport platform.Electric power module
Back in the same hall, the electric power modules are being assembled. These compact modules, each three storeys high, accommodate the transformer, frequency converter and power cabinets. Internal stairs have been incorporated to access the two upper levels of the module. A ready assembly fits in the lowest part of the tubular tower and is put on the offshore foundation prior to lowering the tubular tower bottom section over it. Baraev explains: ‘We purposely decided to put the power electronics in the tower foot and not in the nacelle, as service and maintenance are much easier and less time consuming. A second advantage is the physical conditions – the electrical components are not exposed to dirt and vibrations.’
Next to the mechanical assembly hall is an unused plot of land large enough to double the present assembly area in future.
A second hall, with adjoining offices, already exists and has an even bigger floor space. It is set up for series manufacture of the huge – nearly 60 metre long – rotor blades and the spinners. These spinners are made of glass fibre reinforced epoxy (GFRE) composite material and they fit over the hub as a kind of nose cone. The aesthetic and protective cover also contains three large holes where the blade roots pass through. This second hall also houses several huge moulds designed for vacuum-assisted rotor blade production technology, and various blade-handling equipment to tackle final assembly of rotor blades. In addition are blade sections, a huge coned blade flange and other GFRE composite components.
Computer image of barge Wind Lift I hoisting a BARD VM rotor blade by crane bard engineering
The BARD VM rotor blades were developed in close co-operation with the renowned engineering consultancy aerodyn Energiesysteme GmbH of Rendsburg, Germany, which was also responsible for the design of the actual turbine. The mass of one rotor blade is 26 tonnes. This specification qualifies them easily as the heaviest pieces in the current 5-6 MW class. By comparison, the rotor blade mass of an Enercon E-112 (rotor diameter 114 metres, blade length 52 metres) is 20 tonnes. The Multibrid M5000 (rotor diameter 116 metres; blade length 56.5 meters) rotor blade weighs 17 tonnes, and the REpower 5M (rotor diameter 126 metres, blade length 61.5 metres) 18 tonnes. Both Multibrid (aerodyn design) and REpower (LM blade) apply carbon fibres in the GFRE composite.
Baraev explains the key objectives behind the rotor blade design: ‘From the manufacturing hall, finished rotor blades are transported directly onto a pontoon for sea transport and from there to the offshore construction site. We therefore do not face any transport logistics limitations. This situation is perhaps different for some of the market participants that transport rotor blades of this length or sometimes even longer by road. Secondly, our primary objectives are maximized for energy capture under demanding IEC Wind Class I conditions combined with a high reliability and a relatively easy series production process. This together resulted in a relatively deep rotor blade with a maximum chord size of 5.94 metres and a blade foot flange diameter of 4 metres. And in order to limit the risk of faults in the laminate during series production, we decided not to apply carbon fibres in highly stressed blade cross-sections, and opted instead for GFRE only.’Conventional
The ‘conventional’ pitch-regulated, variable-speed-geared BARD VM wind turbine features a 122 metre rotor, a multi-stage gearbox, a doubly fed induction generator and a single main bearing (no main shaft). The single-bearing rotor support solution is enjoying increasing popularity in the wind industry. However, it has already been commercially applied for the first time many years ago in a 250 kW turbine of the former HSW of Germany. Today it is applied in – among others – the Harokasan Z72 (former Zephyros Z72), Vestas V90-3 MW, Fuhrländer FL 2500 and the (1-5 MW) Multibrid models originating from both Finland and Germany.
The BARD VM’s Top Head Mass (THM), comprising nacelle and rotor, is comparable to the THM of the other German 5 MW design that has a conventional drive train layout: the REpower 5M (see Table 1).
The BARD VM is not the first 5 MW offshore wind turbine to be designed by aerodyn Energiesysteme. Earlier, the German wind technology specialists successfully developed the patented 5 MW Multibrid wind technology, a highly compact wind turbine concept that features a fully integrated drive train combined with a slow speed generator. A first prototype of the Multibrid M5000 has been operational since the end of 2004 and a second unit from the end of 2006.
The BARD VM drive concept enabled the designers to position the huge 65 tonne gearbox directly in front of the cast main chassis and to flange it directly to the single main bearing with the aid of a short, hollow shaft. The gearbox thereby ‘hangs’ on the main bearing, while two supports on each side of the gearbox rear absorb torsion (impact) loads. The concentric flange arrangement between main bearing and gearbox input shaft further eliminates the risk of misalignment faults occurring between the two components. The main chassis casting, which weighs about 70 tonnes, is – according to Baraev – one of the heaviest single cast pieces ever applied in the wind industry. The generator is positioned in a line arrangement behind the gearbox. A cardan shaft connects the gearbox output shaft with the generator input shaft, while a fail-safe disc brake is positioned at the fast-speed gearbox output shaft. The BARD VM drive solution has the advantage of having a sturdy, relatively compact nacelle with a total length of only 14 metres. The nacelle width is 7 metres. This combination provides ample space for service personnel to carry out their work inside.Proven technology
‘In order to achieve the required short time to market from prototype development to full testing and certification, we deliberately went for proven wind technology only,’ explains Baraev. ‘This means that all 5 MW class key components, such as the gearbox, generator with converter, and single main bearing, are practice-proven. Despite their size, they are already mostly available from more than one supplier.’
Winergy of Germany supplied the gearboxes for the two prototypes, as well as the doubly-fed induction generators and frequency converter system. The electro-mechanical rotor blade pitch system and bearings are state of the art wind technology.
Offloading the 70 tonne cast main chassis bard engineering
The new turbines are fitted with redundant systems and a condition monitoring system. These complementary systems are essential, says Baraev, as major unexpected repairs at sea are by definition very costly and should therefore be limited to an absolute minimum. The long-term objective is to develop a predictive, continuous maintenance strategy aimed at maximized availability and optimized output of the wind plant for acceptable costs.
Wind turbine access is another important related issue for BARD’s offshore wind turbine upkeep specialists. At the moment, they consider a number of alternative access options, including the Ampelmann technology developed by the technical university of Delft in the Netherlands, and a second Dutch OAS concept. A third relatively simple offshore wind turbine access method already in wide use offshore comprises a transport vessel with a rubber friction lining at the bow. For turbine access, the service vessel manoeuvres its bow against one or two vertical steel piles attached to the wind turbine (monopile) foundation. The next and final step is to give full throttle, and the friction between the rubber and steel slows the vessel motion as it rides the waves. When the vessel reaches a wave top and seems to stop in that position for a split second, one steps quickly to the receiving wind turbine ladder/platform or the other way.
Pitch motor drives bard engineering
With regard to offshore foundation technology choices, Baraev says that BARD Engineering conducted a benchmark study which compared various steel and concrete foundation options based on multiple criteria: ‘Gravity-based concrete foundations scored well in terms of total costs, for instance, but we have worries about lifetime performance. The study results earmarked our Tri-Pile foundation to be the superior overall solution for our most common operational environment, German North Sea locations with water depths from 35-50 metres. For water depths of 30-35 metres, overall economics of a Tri-Pile is comparable to Monopile type foundations. A Tri-Pile foundation comprises three independent steel pipes that are all rammed into the seabed. As a second step, the piles are joined together at the top, and well above the seawater surface, into a rigid assembly with the aid of a special “transition bracket” on which the bottom wind turbine tower flange is then bolted.’Breakthrough
Today in Germany, only one genuine offshore installation is operational, a 2.5 MW Nordex N90/2500 that was erected in Rostock harbour early in 2006. This solitary installation is likely to be joined in future by a substantial number of large offshore wind farms as part of the long-awaited German offshore wind boom. So far, Germany’s offshore wind portfolio contains 15 approved offshore projects with an estimated total volume of a thousand multi-megawatt class wind turbines, mainly in the 5-6 MW class.
In what is seen as a genuine breakthrough in November 2006, Germany’s Federal Council of Ministers passed a law aimed at speeding up the planning procedure for infrastructural projects. Central to this new legislation package is that the grid connection of offshore wind farms in Germany (that have started construction by the end of 2011) has to be provided by the responsible grid operators. This is highly significant news because grid connection costs for offshore turbines can add up to 30% of total investment costs, say experts. Thanks to the new legislation, the costs for grid connection of offshore wind farms will – as is the case with all other types of power plant – be distributed over total grid operation.
Hoisting the compact cast rotor hub bard engineering
The set of new rulings has also positive implications for BARD Offshore 1, explains Roß: ‘It is our responsibility to install all 80 BARD VM turbines plus the 33 kV infield cables that electrically interconnects the individual turbines in strings and to the BARD Offshore High Voltage Station (B-OHVS). These activities are all at our expense. What is new is that the responsible utility, E.ON Netz, at its own expense, will install a 150 kV export cable from shore to a central distribution Offshore High Voltage Station (E.ON-OHVS). Under the new legislation, E.ON is also obliged to make the final cable connection between the B-OHVS and the E.ON-OHVS, again at its own expense.’Market
Roß concludes that BARD Engineering is confident of what it has achieved so far and what it is doing at the moment, with well thought out strategies focused on the long term. He therefore welcomes professional market participants in the growing international offshore wind market: ‘Competition is attractive to us for more than one reason. First it keeps us sharp in our own performance as a new company dedicated to large-scale offshore wind plant development. Second, we are able to make an objective comparison with what others in the market are doing. Third, a higher overall activity including necessary successes is good news for everybody and gives a confidence boost to financial parties like banks and other institutions. Last but not least, an increased supply of state-of-the-art components gives us more and better choices and, equally importantly, offers sourcing for more attractive prices.’
Eize de Vries is Wind Technology Correspondent, Renewable Energy World
e-mail: [email protected]
Wind Lift I
In June, Lithuanian shipyard PC Western Shipbuilding Yard was commissioned by BARD Engineering to build a four-legged self-propelled jack-up barge to be named Wind Lift I. The 8000-tonne vessel will accommodate a 50-person crew. The total length is about 102 metres (actual hull length 90 metres) and the hull is 36 metres wide. By comparison, the Jumping Jack, now Danish owned, (see REW May-June 2007) is 91 metres long and 33 metres wide but has no internal propulsion system. Despite a 1520 kW diesel-electric Azipod type propulsion system featuring four turnable propeller units, Wind Lift I can operate in shallow water of depths of only 4.5 meters, necessary for instance when visiting a supply harbour for foundation and/or wind turbine (top head) loading.
Azipod is a trade name registered by ABB and a so-called podded propulsion system for marine applications that can turn in azimuth through 360°C. It incorporates an electric motor mounted directly on an extremely short propeller shaft in a highly compact housing. The motor drives a fixed-pitch propeller and is controlled by a frequency converter that produces full nominal torque. It is smooth and stepless in either direction over the entire speed range, including standstill. Propeller rotation speed can be optimized according to the varying hydrodynamics of the drive propulsion system.
As a unique feature, the barge can also operate in water depths of up to 45 metres (as compared with 32-35 metres for the Jumping Jack). ‘When the legs under this maximum water depth conditions stand firmly onto the seabed [including a given reserve length for unavoidable soil penetration], the hull will still be elevated at 5-7m above the waves,’ says Baraev. Under normal conditions, the hull bottom will be elevated about 10 metres above the waves.’Market segments
Baraev adds that there are in principle two different market segments for jack-up type wind turbine installation vessels. One is for shallow water applications. Many such vessels are available. The second segment is for water depths of 35 metres and up, and characterized by a very limited availability in supply.
Wind Lift I will be fitted with a 500 tonne main crane that has a 125 metre maximum lifting height. The heaviest single load to be hoisted will be the 400 tonne transition piece, but a certain reserve capacity is required under demanding maritime conditions – such as a rough sea with high waves. If not delivered at the wind plant construction site by pontoon, the barge can carry either a complete Tri-Pile foundation or a complete top head, comprising the tower, nacelle and rotor.
Wind farm installation is split into two phases. During summer, when wind speeds and waves are generally low, the top heads will be installed. Installation of the foundations is less dependent on good weather and therefore less critical. These operations can be performed almost year-round. For the pile ramming, the rear of the barge deck can be fitted with a removable pile-guiding system. A 275 tonne hydraulic hammer finally drives each pile about 30 metres into the seabed.
Wind Lift I will be commissioned by March 2009.
‘Job motor’ wind industry
The two BARD Engineering manufacturing halls are not the only commercial structures in the Emden-Ost industrial area dedicated to the growing wind industry and with a local ‘job motor’ function. The unemployment rate in Emden is improving but still 11.1 %. Across the water of the Jarssumer Hafen inland harbour and opposite the BARD buildings stands Enercon’s modern Emden-based reinforced concrete tower manufacturing plant. And just behind the nearby North Sea dyke, a 6 MW Enercon E-112 near-shore turbine towers over the building – an unmistakable sign of changing times in support of a massive renewable energy development drive.
Other (coastal) German cities are aiming to create new wind jobs by co-operating with suppliers keen to build new facilities with direct or close access to water to encourage growth and/or ease transport logistics. Among the cities that have already welcomed wind companies with these ambitions are: Bremerhaven (Multibrid and REpower 5-6 MW; WeserWind – steel Tripod foundations), Magdeburg-Rothensee (Enercon E-126) and Rostock (Nordex). In addition the town of Cuxhaven houses DEWI-OCC, an organization that since 2003 has operated a test site for multimegawatt-class wind turbines at a location characterized by strong winds and marine-type climate conditions.
The new production facility for BARD’s Tri-Pile offshore foundations is owned and operated by a sub-supplier. It will also be inaugurated in Cuxhaven on 6 September under the trade name Cuxhaven Steel Construction GmbH.