The concept of a “maintenance-free lattice tower”, first envisioned eight years ago, has now been realized in a pilot project run by the German steel construction and engineering company Butzkies and the Fraunhofer APG Rostock, with the involvement of voestalpine.
The idea of a maintenance-free lattice tower arose in the middle of the 2005 economic crisis as new fields of business needed to be developed for the steel construction industry. Renewable energies were clearly becoming a future market. However, without a turbine manufacturer, it wouldn’t be possible to enter this market. The lattice tower concept initially met with significant opposition from turbine manufacturers. In 2006 the turbine manufacturer Vensys became a partner, interested in developing a lattice tower for its own facilities. Together the first designs and approaches were developed. Using a modified design, in 2007 plans for a lattice tower with rolled profiles were drawn up for the Vensys 77. Although the lattice tower design was similar in price to a tube tower, it was removed from the portfolio in 2008 due to the high costs involved in maintaining the bolts.
By implementing a new connector design, in 2009 the necessary maintenance was reduced, and voestalpine continued to research and develop its tower concept. In a first step the corner profile, made from special rolled profiles, were exchanged for plates. This reduced dependence on suppliers. At the same time, the Fraunhofer Gesellschaft IPA in Rostock was commissioned to test special connectors, and initial contact was made with WTSH GmbH (Business Development and Technology Transfer Corporation of Schleswig-Holstein). Neuenbrook was chosen as the location for a test installation. The advantages of lattice towers become clear at heights of 100 m and above. At the test installation the hub height was limited to 61.5 m, but the tower was constructed in order to prove the suitability of the concept and the tower’s maintenance-free characteristics. The test tower began operations in September 2012 and the DIBt, Germany’s institute of civil engineering, has certified that the tower is indeed maintenance-free.
Three wind energy towers are planned for installation in Bahrenfelth in the summer of 2013, with hub heights of 100 m. In further contrast to the prototypes in Neuenbrook, the lattice tower will be built with four corner posts, instead of three. The first 130 m towers with 2MW turbines are scheduled for construction by the end of the year.