Sustainable lattice towers for 380kV transmission lines

“Decarbonizing Supply Chain (DSC)” with the aim to reduce the CO2 emissions along supply chains, without reducing the quality of the final products. This purpose can be achieved either through reduction of steel weight per pole or by using green products like green steel.

Within this paper some approaches have been investigated to make the steel lattice tower more sustainable. These approaches are focused on three aspects:

 Substitute of standard steel through steel of higher quality S460

 Use of green steel

 Combination of both aspects

The usage of higher steel grade means the replacement of conventional S355 with S460 for the lattice towers. The use of S460 enables us to optimize the profile sections and thus to achieve a reduction of steel weight by providing the same bearing capacity. A similar topic was already investigated by Elia Group in 2024 for CIGRE Paris 2024. The actual paper serves as an extension of the previous investigation, which provides more details to this topic.

By using S460 steel for lattice towers, there is the possibility to reduce the steel weight of towers. Less weight means less raw materials, less transport load and reduced construction time.

This leads to a significant reduction of carbon footprint. This paper explains how the reduction of steel weight is connected to the reduction of CO2 emissions and in which cases the benefits are more evident. For a better overview of the benefits, two kinds of poles were chosen for the investigation: a heavy one and a light one. Both poles are produced with S355, and they are already installed in the German transition lines. The heavy tower is a 4-circuit 380 kV double barrel tower (Doppeltonne), called pole 19, in northern Germany, which weighs almost 600 tons. The light tower is a typical 380 kV Danube (Donau) tension tower of about 106 tons.

The investigation is carried out by means of software Turrix, in combination with manual calculations, and it meets the design standards.

The second approach is to design a sustainable tower with green steel. In this way the network operator has already gained experience, by implementing a pilot project of 4 lattice towers made of green steel in quality S355. This paper describes this pilot project, with the focus on the life cycle assessment A1-A3 of the steel material and the reduction of carbon footprint of towers.

It has been proven that the usage of green steel can reduce the CO2 emissions up to 70% compared to the steel, which is produced in conventional way.

At the end of the paper, an evaluation of results is presented concerning the two approaches as well as a discussion about the possibilities and difficulties for the implementation in practice.

The challenge of the future is the combination of S460 and green steel. This option is not yet mature for the market, mainly concerning the availability of products.