In mid-August Max Bögl Wind AG began shipping the first mobile factory for hybrid towers to South East Asia. The hybrid towers will be built on-site in Thailand and are expected to be the tallest in Asia.

 

Promoting the worldwide energy revolution, advancing renewable energy technologies and creating added value at the local level – these were the ideas behind the development of a mobile manufacturing plant. Every day since the middle of August, ten containers have been shipped from the Max Bögl company site in Sengenthal, Bavaria, to Nuremberg and then on to Rotterdam for a 17,000 kilometer journey to Huai Bong, a village about 260 kilometers northeast of Bangkok. The world’s first mobile manufacturing plant for hybrid tower systems will be constructed there by February 2018. Max Bögl AG intends to build 90 hybrid towers for the Korat Wind Farm in the Thepharak District using local resources and labor, but with the same high quality produced in its main factory in Sengenthal.

 

“To better meet the global demand for wind turbine systems with hub heights between 130 and 180 meters, we developed the concept of a mobile production facility,” says Josef Knitl, Board Member of Bögl Wind AG, regarding the innovation. Wind farms in Europe are supplied with hybrid tower systems from production plants in Sengenthal and Osterrönfeld. For international customers, however, the company chose a different strategy: build a mobile manufacturing plant at the wind turbine site itself and use it to produce concrete elements with local materials and labor. This creates added value on site, reduces the cost of material purchases and places significantly less strain on infrastructure compared to heavy transports. The high quality standards for factory manufacturing are maintained in the mobile factory since the equipment and processes from seven years of experience in producing concrete segments remain largely the same and only needed to be adapted for the new precast concrete sizes. The CNC-machined concrete segments are smaller in the mobile manufacturing plant. Max Bögl has thus found a way to offer its hybrid tower systems throughout the world while maintaining the high quality standards it is known for.

 

Logistical masterpiece

A great deal of preparation was needed in order to ship a complete hybrid tower manufacturing plant around the world in containers. “It quickly became clear to us that a stationary manufacturing plant could not simply be packed up and shipped off. We needed to find a logistical solution for each individual part,” explains Matthias Karasch, a civil engineer at Max Bögl Wind AG. A total of 262 containers loaded with approximately 3,500 tons of materials are to be shipped to Thailand by mid-November 2017. Once they arrive at the site, the individual parts will be assembled together to form a mobile manufacturing plant. Around 25 employees from Sengenthal will be on hand to run the plant, while the remaining workers will be hired locally.

 

The Max Bögl hybrid tower system

The Max Bögl hybrid tower system allows for the cost-effective realization of hub heights between 130 and 180 meters. This is possible thanks to a new technology that offers a unique combination of precast concrete parts and steel elements. The tower consists of a concrete foundation poured in place, with 60 to 100 meter concrete elements assembled on top using modular construction. The concrete elements can be combined to create towers of different heights and shapes according to a modular system. Individual tower types are designed to precisely match the static-dynamic and customer requirements of the systems.

 

A special segment geometry and cylindrical rings as spacers make these great heights possible, as well as the customization to suit project-specific conditions. During production, the concrete elements are machined to one tenth of a millimeter using a CNC milling machine. This makes it possible to then stack the rings precisely on top of each other – using dry joints, i.e. without mortar or other compensating layer. The tubular steel tower is finally added to the top reaching hub heights of 130 to 180 meters.

 

Using hybrid construction, it becomes possible to find the economic optimum for the required tower heights. The concrete component is completely maintenance-free and especially durable. In addition, with the strong concrete section and more flexible steel tip, the hybrid system ensures improved structural stability than pure concrete or steel towers. The modular design and the simple “stacking” of the rings allow fast construction in one week, and this under any weather conditions.

 

Picture caption: MB truck on its way to the freight depot in Nuremberg.

 

Photo credits: Max Bögl Wind AG, Reinhard Mederer