Paving the Way for More Green Electricity

The energy transition is increasing electricity consumption – along with the need for high-performance grids at the high and extra-high voltage level. To enable more wind power to reach consumers in southwestern Germany from the North Sea, for example, the transmission system operator TransnetBW is strengthening the “Badische Rheinschiene” transmission line, replacing the existing 220 kV line with a 380 kV system that has greater transmission capacity. Fichtner is supporting TransnetBW in the technical planning and project control, while also helping to minimize the impact on nature and agriculture. It is a project with many facets.

With its “Badische Rheinschiene Grid Reinforcement” (NBR) project, the transmission system operator TransnetBW will enable more electricity to be transmitted with fewer transmission towers. A 120 km-long overhead line is being built between Daxlanden near Karlsruhe and Eichstetten am Kaiserstuhl, which will offer significantly more transmission capacity than the current line. This is made possible by changing the voltage level from 220 to 380 kilovolts (kV).

In parallel to modernization of the overhead line, the Daxlanden, Kuppenheim, Bühl, Weier and Eichstetten substations located along the route are being adapted to the new conditions, with two of them being upgraded and three being replaced by new ones. In addition, a new substation will be built in Kehl-Kork.

Routing Along the Old Overhead Line

To make sure that the increase in transmission capacity does not come at the expense of agriculture or flora and fauna, i.e. to ensure that it takes up as little space as possible, the project is not an additional new-build but rather a grid reinforcement according to the principle of grid optimization before expansion specified by the regulatory authority. The route of the new line is based on the existing line, and the old 220 kV overhead line will be dismantled. The new route deviates from the old one only in a few sections, for example to connect the new substations. This avoids unnecessary soil sealing and minimizes the impact on the environment. It is not only in this respect that many requirements and issues have to be taken into account for such an extensive project, such as the German Pollution Control Act, nature conservation, the interests of property owners, etc.

But that’s not the only thing that makes the NBR project an exciting challenge. Its construction also entails many different tasks that Fichtner is helping the transmission system operator to handle by providing consulting and engineering services. Fichtner supports the project from start to finish, from initial planning to supervision of the final construction works.

A Major Project with Many Challenges

From planning and implementation of the various nature and animal conservation measures through to supervision of the construction works, the Fichtner team offers everything from a single source. The tasks are more varied than they might at first appear. Construction of the overhead lines over the entire 120 km does repeatedly involve the erection of transmission towers and the suspension of conductors. But how the towers can be fixed into the ground, what temporary access routes are available during the construction phase or what safety measures are required on site can vary from one tower to the next. This often results in new challenges every few hundred meters. On top of this, there are special requirements resulting from the proximity to the Rhine river, the Karlsruhe-Basel highway, or the railway tracks.

Examples of such local challenges were already provided by the first of the four sections: the 47 km stretch between Daxlanden and Achern (the only section under the responsibility of the Karlsruhe regional authority). Construction work began there in November 2022, and several kilometers of overhead line are already operational. Some of the transmission towers there had to be erected on nutrient-poor and species-rich grassland. By using as little land as possible and relocating wild animals, the impact on nature in biologically valuable landscapes is kept to a minimum. What is unusual is that the geology, soil and previous use of the land in the immediate vicinity of the nutrient-poor grassland have given the site a varied structure, so that groundwater is high in some areas. During the foundation works, numerous pumps had to be used to keep the construction pits dry.

In many places, animals are collected and relocated or scared away before construction work begins. The nearby surroundings will later be renaturalized. (Pictures: TransnetBW GmbH)

Working at Railway Tracks with a “Safety Net”

Fichtner’s input, however, was not solely about technology. Loch Kemp and Loch Ness are located in a nature reserve, which is also attractive to tourists (not least because of “Nessie”, the monster that is said to live in Loch Ness). Nature and landscape conservation therefore play a major role in the Loch Kemp project during planning and construction of the plant. It is important to minimize the impact on nature caused by the construction work, such as the power plant building and the dams, by planning meticulously down to the square meter. Likewise, the operation of the pumped storage power plant should have as little impact as possible on the surrounding fauna and flora.

Win-Win Project: More Space for Greenery, More Capacity for Green Electricity

Our colleagues will also support and supervise the future works and are already proud of what is taking shape because, thanks to its transmission capacity, the new 380 kV line is not only necessary for the energy transition, it also has a positive impact on the environment. The new transmission towers are higher, and the conductors sag less when heated than conventional conductors. What’s more, the distance between the towers of the new line is greater than on the existing line, which reduces the amount of space required. This paves a way for the energy transition that is “green” in more sense than one, since in the medium term there will be more capacity for green electricity from coastal wind farms and there will be more greenery along the “Badische Rheinschiene” line.

July 2024

Featured image: TransnetBW GmbH

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