towers and masts

For a couple of years our company is engaged with the use of timber in outdoor areas. Thus, for some years we work with our own pressure impregnation machine. We provide this performance as a service, of course. Talk to Bernd Schröder, who is your contact partner concerning these services. Apart from that your contact partners for masts & towers are available for your questions.

Further on we deal with various projects concerning towers and masts, and indeed we want to expand this subject as a focus. Have a look at our references. Beside this the principal themes are the two following topics:

Timber tower
transmission tower

Timber tower

TimberTower – the first wooden tower with a megawatt wind turbine, Vensys 1.5 megawatts, has a hub heigth of 100 m.

Since 20 December 2012 for the first time a megawatt wind turbine generates electricity on a wooden tower. The Hanoverian developers office TimberTower started the 100 meter high prototype tower with a 1.5 megawatt (MW) “Vensys” wind turbine on top, after four years of development and a long approval phase. In the future TimberTower wants to reduce the costs of wind based energy by constructing much larger towers – and open up places for small wind farms, which were not lucrative so far.

2.5 million EUR venture capital and 600,000 EUR sponsoring by the provincial government compared to total costs of 5 million EUR for research and development, a weight of 200 tons, 400 cubic meters of timber (spruce from Scandinavian trees), prefabricated to special parts in Austria. These are the bare data of the wind turbine tower on a university-owned ground in the north west of Hanover.

stable prices for timber

The tower is made of board plywood, flat wooden board wall components, which are three meters wide and 15 meters long. They consist of planks glued in several successive layers, which are perpendicular to each other. The effect, as with any plywood: The 30 cm thick tower walls can not deform under humidity or dryness and remain stable.

Obviously TimberTower has several selling points: The price of timber is stable for years, which is not true for standard material of common wind turbine towers: steel. In the medium term, the company wants to reduce the costs of producing wind based energy by providing wind turbine towers to more favorable prices. However, “the first models will initially cost as much as the comparable towers of Max Bögl or others” says TimberTower-boss Prass. The wooden towers are cheaper mainly because the project developers haven’t to put aside any capital for dismantling, that’s the hope at TimberTower. That’s because the timber can be sold even after up to 20 years of operation of a wind turbine, which is not true for steel, that will cost six-figure sums for its disposal. This explains investor Edwin Kohl, who took over the company (with now a dozen employees) to 80 percent a year ago.

Simple logistics

The most important marketing strategy of TimberTower, however, is expected t obe the fact, that the logistics of the timber components is simple: Available in simple containers, to mount with a simple connection system, the towers can be installed even at very narrow places, where the large tower bases (with much more than four meters in diameter) couldn’t be brought to the construction site without removing smaller buildings or trees, says Prass. However, meanwhile other tower building techniques circumvent the the problem of large tower bases of today’s wind turbine towers with a hub height of 140 m or more. The construction time of a TimberTower should be approx. four weeks, which is similar to the construction of other large modern towers.

Later this year TimberTower wants to make a start on a prototype with a hub height of 140 meters. It should carry a three MW strong engine, which could be supplied by South Tyrolean company Leitwind, a producer of gearless wind turbines. Probably from 2014 there could be a prototype with 165 m hub height. Generally speaking the maximum height, which is possible, is about 200 meter hub height, so explains the Carpentry Cordes from Lower Saxony, which mounted the construction of the first prototype in Hanover.

transmission tower

development of a wooden electricity pylon for high voltage transmission lines (> 50 kV)

sponsored by:
Investment and Development Bank – NBank
Guenther-Wagner-Allee 12-16
D-30177 Hanover

In 2010 – 2013 Cordes initiated a sponsoring project which had the aim to erect wooden electricity pylons. Approx. 30m high the prototype corresponds to an electricity pylon for a 110KV line imaging a “Donaumast” (see the book: “Freileitungen – Overhead lines” – Kiessling/Nefzger/Kaintzyk).

The complex supporting framework is made of common construction timber (KVH®). KVH® is an approved building material with assured technical characteristics. The connections are designed and optimized according to the static computation and the joining concept. For those connections, that are to be joined at the building site, the focus is on a simple and secure assembly with very few connectors. Generally speaking, we work with nails, screws and glue connections as well as with special steel parts. Thanks to the modular prefabrication the electricity pylon can be delivered in transportable segments to the building site, so no expensive special transports are necessary. A container transport is possible, too.

In order to protect the electricity pylon against weather effects the surface is protected with a durable wooden facade. Thanks to this weather protection complex constructions concerning the joints are expendable and the supporting framework is safely isolated from the weatherproof construction. The facade and the flats for the inner ladder mounts are already integrated in the workshop, so that you just have to assemble the different sections and the traverses of the pylon at the building site.

Typical pylons in serial fabrication or special ones such as fixing-, end- or corner-pylons can be made in the same style.

As a renewable raw material with the ability to store CO² timber is the perfect building material – seen in technical terms and as well concerning the availability and workability. In particular the acceptance and popularity of this material in the population is another important argument. Wooden products are produced regionally and are characterized by low primary energy demand.

Wood can be recycled very easily after the using period or it can be used for power generation purposes (thermal recycling).
The facade gives the pylon a modern look and also makes it resistant to damage during transportation, installation and usage time. The question of the maintenance of a wooden power pylon must be asked and answered, of course. In this regard the Cordes-pylon with its outer weather-resistant facade gives surprising answers. Thus it is prognosticated, that the maintenance intervals are rather larger compared to a conventional steel pylon, which is due to the advantages of a construction closed at the outside compared to an open supporting framework.

In addition to the protection of the supporting structure, the wooden exterior offers the big plus of the optics. If you look at the pylon, you can see, what it is: a wooden construction. The inner values are also visible at the outside. To many residents of a planned power line it may be easier to accept a wooden pylon than a cold, gray steel pylon.