28 April 2003
28 April 2003
Enercon GmbH has recently completed the installation of the world's largest wind turbine, the E-112, at Egelin near Magdeburg in Germany. Now fully operational, it can generate 4.5 megawatts which is sufficient to meet the electricity needs of 15,000 domestic users.
Each of its three rotor blades measures 52 meters in length. The combined weight of the blades, egg-shaped nacelle and ring generator is 500 tonnes. The tower is 120 meters tall. The E-112 was deliberately sited on a wind farm that has existing Enercon E-66 and E-40 wind turbines in order that local people and other interest groups could directly compare its appearance and sound level with that of the smaller machines.
Despite its size, it has been generally agreed that the E-112 fits well into the landscape and the visual differences between the three models is not so significant. For the next year, the performance of the turbine and its individual components will be continuously monitored with particular attention being paid to how it reacts to environmental forces. Both the development and construction of the first E-112 were supported by the German Federal Ministry of Economics and Technology in collaboration with the project sponsor Jülich. A second prototype will be installed this year in Wilhelmshaven and a third unit will be sited 500 meters offshore; also in the Wilhelmshaven area.
The physical weight and size of the various components posed special logistical problems that required detailed planning and co-ordination. For example the three 52 meter blades travelled to the site from Abeking & Rasmussen’s blade production facility in Lemwerder to Egelin by water and road.
Each blade was loaded onto an individual barge measuring 85 meters long x 9 meters wide that would normally carry 1,300 tonnes of wood pulp for papermaking. Despite their size the sandwich composite blades are relatively light, weighing in at just 20 tonnes each. As a result 400 tonnes of ballast had to be added to the barge to ensure that it would be able to safely pass under canal bridges.
At the end of the canal journey the blades then had to be transported a further 30 kilometers by road. For this part of the journey, Enercon designed a special blade transporter that held the blade so that, again, it could pass under bridges.
However, in order to reach the main road, it was necessary for a 170 meter temporary road to be built as the local highways had too many bends. Despite the size and length of the load each blade was transported to the site in just two and half hours on separate nights and with the minimum of disruption to the local community.
Actual assembly of the E-112 also required a different approach. Instead of just a few lifts, as would be the case with the Enercon E-66 wind turbine, a multiple lift sequence was required. First the nacelle components were raised to a height of 124 meters, item by item in pre-assembled sections weighing up to 110 tonnes.
Then the heavier components were lifted and positioned by two 800 tonne cranes working in tandem. After a brief pre-assembly on the ground, the main carrier was lifted together with the nacelle cover. Next followed the stator in two halves. The installation of the disc rotor into the stator was probably the most difficult part of the installation procedure as it had to be located with millimeter-precision. Then the hub and axle journal were lifted up together, followed by the spinner that also required very accurate positioning. Finally the three rotor blades were individually flanged onto the hub adapter.
Although the size and scale of the installation was very much a ‘first ’ for all concerned, the whole procedure took just two and half weeks; a week less than had been originally planned.
The cores for the blades for the E-112 were supplied by DIAB