European priority project: the South-West Interconnector

The integration of renewable energy sources has already progressed well in the east of Germany. In this regard, generation and consumption will be located at an even greater geographic distance as is currently the case for coal-fired and nuclear power plants. Because of the cross-regional transport of these renewables, the South-West Interconnector makes a crucial contribution to climate protection.

At the same time, the South-West Interconnector fills an important gap between the grids of the old and new Bundesländer. Moreover, since theplanning for trans-European grids of 2006, it is part of the European priority project Halle-Schweinfurt. As a result of the Power Grid Expansion Act (EnLAG) of 2009, the South-West Interconnector is also one of the 24 national priority projects for the expansion of the extra high voltage grid. With the decision of 2011, it is a European priority project in the scope of the EU initiative “North-South Energy Interconnections”.

The first needs assessments were given in both Dena grid studies I and II of 2005 and 2010. As of 2012, the Grid Development Plans determined the need for expansion within the national transmission system (see also the information provided by the Federal Network Agency).

The South-West Interconnector is realised in three sections. Section 1 starts in Saxony-Anhalt, near Halle, and ends at the Vieselbach substation near Erfurt. The 2nd section connects Vieselbach and Altenfeld. From there on out, the 3rd section runs through the Thuringian Forest up to the state border with Bavaria.

The first section between Bad Lauchstädt and Vieselbach, which has been operational since December 2008, follows an existing 220 kV line and the ICE railway for most of its length, which totals 80 kilometres. The route leads from the area of Halle (Saale) in Saxony-Anhalt to Thuringia, in the vicinity of Erfurt.

The supreme state planning authority confirmed the route of the 57 km long second section from Vieselbach to Altenfeld in its state planning assessment of March 2007. In accordance with the bundling principle, it follows the infrastructure lines of the 380 kV line between Mecklar and Vieselbach, national highway A71 and the ICE railway up to Altenfeld. From Vieselbach, the overhead line route runs westward and northward, parallel to the existing overhead line Vieselbach-Eisenach/Mecklar, until it reaches national highway A71, where it heads south along the highway and the ICE railway between Nürnberg and Erfurt, up to Altenfeld. From Traßdorf on, the pylons for the new 380 kV line will also support the 110 kV line connecting Stadtilm and Altenfeld. It arrives there from the east, coming from the Stadtilm substation.

For the 3rd section between Altenfeld and the Thuringian state border, 50Hertz presented a detailed route planning in the first six months of 2013. The route's corridor was decided by the state planning assessment concluding the regional planning procedure. This assessment confirmed that the route would closely follow the ICE railway. With its total length of 25.7 km, it will run from the Altenfeld substation up to the northern entrance to the Singertal, running closely parallel to the existing 380 kV line, in the direction of Goldisthal. At the Bleßberg mountain, the corridor continues to Schalkau and the interconnection point at the state border with Bavaria. At this point, TenneT TSO GmbH, the transmission system operator responsible for Bavaria takes over the line circuits and extends them to Redwitz (to the website of the Bavarian part of the project).

Project status 1st section (Bad Lauchstädt - Vieselbach)

The first section was completed in 2008. Since then, the 380 kV overhead line between the substations of Bad Lauchstädt near Halle and Vieselbach near Erfurt has been in operation.

The overhead line is located on the territories of Saxony-Anhalt and Thuringia. As a result, the mandatory procedures are carried out by two Länder authorities. Within only two years, the spatial planning and plan approval had been concluded. Work commenced in February 2006, in Steigra (Saale district, Saxony-Anhalt).

The 380 kV route replaced a 220 kV line that had connected Bad Lauchstädt and the Vieselbach substation since the 1960s. The new EHV line therefore mostly follows the old route.

Project status 2nd section (Vieselbach - Altenfeld)

The second section between Vieselbach and Altenfeld is currently under construction. After the works were interrupted between February and August, 50Hertz recommenced construction of the second section in September 2012. In addition to the 380 kV line, 50Hertz is constructing a section of 110 kV line from the substation at Stadtilm to the 380 kV route for Thüringer Energienetze GmbH.

For the second section between Vieselbach and Altenfeld, the competent Thuringian Administrative Office in Weimar finalised the regional planning procedure on 30 March 2007 with its "state planning assessment". This was followed by the plan approval procedure. Approval for the plan was then granted on 31 January 2012.

Project status 3rd section (Altenfeld – Thuringian state border)

The plan approval procedure was officially initiated by the Thuringian Administrative Office on 19/09/2013. Between 7 October and 18 November 2013, the planning documents were available for consultation at the offices of the municipalities involved, namely: municipal association Großbreitenbach (Ilm-Kreis), municipal association Langer Berg (Ilm-Kreis), city of Langewiesen (Ilm-Kreis), municipal association Bergbahnregion/Schwarzatal (district Saalfeld-Rudolstadt), municipal association Lichtetal am Rennsteig (district Saalfeld-Rudolstadt), city of Bad Blankenburg (district Saalfeld-Rudolstadt), municipality of Masserberg (district Hildburghausen), city of Eisfeld (district Hildburghausen), city of Neuhaus am Rennweg (district Sonneberg), city of Schalkau (district Sonneberg), municipality of Frankenblick (district Sonneberg), municipality of Judenbach (district Sonneberg), municipal association Buttelstedt (Landkreis Weimarer Land).

50Hertz has now also published the planning documents online. They can be consulted here.

For the plan approval procedure, project developer 50Hertz drew up a detailed plan of the line route, containing the mast locations, a feasibility study for a possible partial underground cable solution in the Schalkau area and a landscape management plan, mentioning all effects on the environment and proposing compensation measures.

In the scope of the preparatory works, extensive discussions with the city and municipal administrations as well as the forestry authorities are necessary. 50Hertz takes account of the special topograhic conditions with wide span sections. These bridge valleys of up to 800 metres wide. The objective is to minimise the visibility of the pylons and the effects on the forest. To this end, technical calculations are currently being performed for the droop and for the construction of special pylons that can handle the enormous tractive forces.

The plan approval procedure was preceded by the regional planning procedure. To this end, the Thuringian Administrative Office in Weimar, which is responsible for the procedures, held a project conference in May 2006. Subsequently, an additional consulting round was held in February 2007. In January 2010, the regional planning procedure was formally initiated. During its course, alternative line routes were studied. The regional planning procedure was concluded with the state planning assessment on 30/03/2011.

TenneT TSO GmbH is the responsible transmission system operator for the construction work on the section from the Bavarian state border to Redwitz (to the project website).

Since 17 December 2015, the South-West Interconnector has been in trial operation.

1st line section (Lauchstädt - Vieselbach)

The first and longest section (78 kilometres and 197 towers) of the South-West Interconnector between the substations of Lauchstädt in Halle and Vieselbach near Erfurt has been operational since 2008.

2nd line section (Vieselbach - Altenfeld)

Construction on the second section (56 kilometres and 170 towers) between the substations Vieselbach and Altenfeld started in 2012. The section underwent trial operation from early July 2015 to mid-December 2015 and was released for permanent operation on 17 December 2015

3rd line section (Altenfeld - Thuringian state border)

Construction on the third and shortest section, from Altenfeld to the state border between Thuringia and Bavaria (26 kilometres and 78 towers), started in January 2018. Since 17 December 2015, the first electrical circuit of this section has been in trial operation. Since 14 September 2017, the second circuit of the South-West Interconnector has also been operational.