Building and operating a grid stabilization plant

Due to Germany’s phasing out of nuclear power and the increased use of renewable energy sources, it is necessary to expand the German electricity grid. Not least because the electricity generated mainly in the north from renewable sources must also be transported to southern Germany. This grid expansion is not progressing as quickly as planned. It is therefore conceivable that additional reserve capacity to support the stability of the grid will be required once the last nuclear power plants have been shut down in 2022.

The Federal Network Agency has therefore decided to have new generation plants built in southern Germany in addition to the current power plant stock. These grid stabilization plants are only used if one or more plants within the power grid have already failed and there is a specific threat to grid stability. In such cases, the grid stabilization plants serve to ease the load on the power grids – probably for a relatively short period of time.

The transmission system operators TransnetBW, Amprion and TenneT have defined the capacity they each require and issued invitations to tender for the construction of suitable power plants within their control zones to cover this capacity. TransnetBW GmbH has issued an invitation to tender for a capacity of 300 megawatts (MW) for Baden-Württemberg.

EnBW Energie Baden-Württemberg AG participated in this tendering process with its Marbach am Neckar power plant site. Having secured the contract in August 2019, a so-called open-cycle gas turbine will now be installed there. The advantage of such turbines is their ability to supply a high level of electrical power within a relatively short space of time. Having completed the approval process in line with the Federal Immission Control Act (BImSchG) in July 2020, the plant is currently under construction.

With a groundbreaking ceremony on 12 October 2020 in the presence of Environment Minister Franz Untersteller, the official starting signal was given for the start of construction work on the grid stabilization plant at the Marbach site. Bringing about the energy transition while ensuring security of supply had previously been the subject of a discussion forum organized by EnBW involving the minister alongside experts from the science community and the energy industry. The discussion and groundbreaking ceremony can be seen in this video (only available in German).

netzstabilitaetsanlage@enbw.com

No further events are currently planned.

In the course of the plant supplier’s detailed planning, it was ascertained that the low noise immission values can only be maintained by increasing the chimney diameter by approx. three meters to 10.5 meters. Both the flue gas volume and exhaust gas immissions remain unchanged. In this context, small structural alterations to auxiliary buildings were collated and included in the approval application. The main components, such as the gas turbine, have not changed. Alterations between the approval planning and detailed planning stages are not uncommon for such large-scale projects. Public participation in the process was not necessary because a preliminary assessment established that the alterations would not have any adverse environmental impact. However, the alterations were discussed in October by Marbach municipal council. Alteration approval was granted by the Stuttgart Regional Council on 8 December 2021.

EnBW’s power plant construction site in Marbach is bustling with activity. The buildings, plants and the chimney can already be clearly seen. However, the project has progressed more slowly than originally planned.

Global delivery problems, material supply bottlenecks, plant closures and staff shortages have led to delays in construction work. The buffer time built in as a precaution has now been used up. Despite efforts to speed up construction by recruiting additional personnel and undertaking parallel work, among other measures, it will not be possible to meet the set deadline. The project will be delayed by some months and will not be completed as planned in October 2022. However, EnBW is doing everything in its power to keep the delay as short as possible.

The commissioning delay has no impact on the security of supply assessment in the current situation on the energy market. That’s because the plant in Marbach was never intended to replace any potential loss in power plant output in the first place. It will only be used in situations where facilities such as transformers, substations or sections of the grid fail within the transmission grid, leaving the power grid in a critical condition. In such a scenario, the power plant can restore grid stability in the short term – hence the name “grid stabilization plant.” Its use is regulated by law. It may only be started up at the request of the transmission system operator TransnetBW GmbH.