Gas travels thousands of kilometres in international and national pipelines before reaching consumers. Thanks to compressor stations, gas is compressed and its pressure increased. This means that more gas can be transported through the pipeline. The shipping capacity of the pipeline increases – and therefore also the security of supply.
Our new gas compressor station on the Nordschwarzwald pipeline is being built in Rheinstetten in the Hardtwald south of the radio mast between the L566, the B3 and the A5. Construction began in the autumn of 2021. Commissioning is planned for 2023/2024.
Construction works for the new gas compressor station in Rheinstetten are progressing. Recently, setting up of the construction site was completed. This means all storage, handling and traffic areas are prepared. Equipment, machines and containers for the workers as well as for weather-sensitive building materials are also ready. terranets bw´s technical project manager, Nils Höger, who is regularly on site, also has a permanent working place on the construction site. In these weeks, foundations for the planned buildings such as the machine hall, the energy centre and the administration building are being prepared.
For this purpose, the previously braided rebars are filled with concrete. The surrounding formwork ensures that the concrete can harden without any negative external impact.
In the next step, the ground slabs are also made of reinforced concrete and will later support the prefabricated walls. And what is indispensable in all this: both 25-metre-high construction cranes used for construction site logistics.
The groundbreaking ceremony on 27 October 2021 signalled commencement of construction works for the gas compressor station in Rheinstetten. The event was opened by Katrin Flinspach, Managing Director of terranets bw GmbH. Subsequently, Sebastian Schrempp, Lord Mayor of Rheinstetten and Dirk Güsewell, Chairman of the Supervisory Board of terranets bw and member of the Executive Board of Energie Baden-Württemberg AG (EnBW) addressed the guests.
While preparing for the construction works, measures were implemented to protect nature around the site and to work on compensation for the impact. Since the commencement of construction, interested parties have been able to discover more about the project, the single project steps and the measures implemented to protect the environment during construction and operation of the gas compressor station.
In a gas compressor station, gas is compressed and its pressure increased. This means more gas can be transported through the pipeline. The shipping capacity of the pipeline increases – and therefore also security of supply for consumers. In Germany, there are about 70 gas compressor stations that are operated in particular in the case of increased capacity demand – which is primarily in winter time.
Travelling through underground pipelines, gas reaches the compressor station with a pressure of 40 bar. Firstly, dust and moisture are filtered out. And then the gas is passed into the compressor and there brought to the required pressure. A turbine or electric engine supplies the energy needed for the compression process.
During compression, the gas heats up to 70 °C and is therefore fed through gas coolers that cool it back down to operating temperature. The gas is then fed through a measuring section before being injected back into the transmission system of terranets bw with a pressure of 80 bar.
Regional grid operators connected to terranets bw´s transmission system (e. g. utilities) have been reporting constantly increasing demand for gas shipping capacity for years. By 2030, the demand in Baden-Württemberg will rise by about 30 % compared to 2020. For the entire terranets bw network, a demand increase of 24 percent is expected. The reason for this trend is the fuel switch from coal and oil to gas, the related rising demand from gas-fired power stations and in the heating market as well as new connections and developments.
The Federal Network Agency has confirmed the need for building the gas compressor station to secure supply in Baden-Württemberg by confirming the Gas Network Development Plan 2020-2030 in May 2021. All Network Development Plans are published on the website of the association of transmission system operators at www.fnb-gas.de.
Site selection was preceded by detailed studies, in which terranets bw took into account legal stipulations and technical requirements as well as a wide range of influencing factors. These include protected areas, distances to residential buildings, land use plans and information provided by the communities. After intensive assessment and in close exchange with local authorities and associations, a location was selected for the new compressor station. Special consideration was also given to maintaining a low visibility of the system. During the approval process, the Freiburg Regional Council, as competent approval authority, decided that the station could be built and operated at the proposed site.
A photomontage shows what the gas compressor station at the Rheinstetten site could look like. Here you can see the machine hall, which will house four machine units consisiting of a compressor and an engine. Next to it, there will be an administration building. (cf. How does a compressor station work?)
Construction and operation of gas compressor station requires public-law permission according to the Federal Immission Control Act (German: BImSchG). The competent approval authority is the Freiburg Regional Council. In order to achieve broad consensus with all stakeholders, terranets bw involved the affected communities and other stakeholders at an early stage.
Transmission system operators in Germany are obliged to guarantee a future-proof supply of gas by developing their network. As an independent transmission system operator for gas in Baden-Württemberg, terranets bw is responsible for building the gas compressor station.
When operational, the planned gas compressor station needs an area of approx. 2.4 ha (24,000 m²). This is roughly equivalent to the size of three football fields. During construction, additional land is temporarily needed for setting up the construction site and for the storage of building equipment and material.
For construction, additional areas are temporarily occupied for setting up the construction site and for the storage of building equipment and materials.
An increased volume of traffic can be expected because of deliveries along the access roads. As soon as the building works have been completed, the areas that were temporarily occupied (for setting up construction site and storing building equipment and material as well as the access roads) will be restored to their original state and can be used for their original purpose once again. Damage to land and vegetation caused by this temporary use will be compensated at the fixed rates.
When operating a gas compressor station, the noise pollution at the fence of the system corresponds to about 60 dB(A). This is comparable to a television set at room volume. The noise pollution at a distance of 350 m is then about 35 dB(A). This complies with statutory limits for a quiet residential area. The distance between the planned gas compressor station and the nearest residential area will be more than 350 m. Generally, the local noise situation is largely influenced by the neighbouring roads (A5, L566, K3581).
During the planning process, expert opinions are prepared regarding the noise emissions that can be expected. The results of these expert opinions serve to determine and dimension the noise protection measures required to comply with the statutory noise protection limits.
Operation and maintenance are carried out by qualified specialists employed by terranets bw. The gas compressor station is monitored and controlled, as is the whole transmission system of terranets bw, by a dispatching centre that is manned 24/7.
Compliance with legal and technical regulations is monitored by the state energy supervisory authority. Modifications must be inspected and signed-off by state certified experts. The supervisory authority for terranets bw is the State Mining Directorate (German: Landesbergdirektion) of the Freiburg Regional Council.
Constructing and commissioning a gas compressor station normally take about two years. This period includes land development, erecting the buildings, installing the compression equipment as well as restoring open spaces on the station site.
Construction began in the autumn of 2021 after receiving approval. Commissioning is planned for 2023/2024.
Throughout the whole planning and construction process, terranets bw takes numerous precautions to minimise the impact on nature and on the environment. At the start of the planning phase, terranets bw takes a detailed inventory of the landscape and surrounding nature and assesses the impact on plants, animals, ground, water, climate/air, landscape and people as well as on cultural assets.
Measures were derived from the study results to avoid and reduce the impact on the environment, which meant that the compressor station location, access and gas connection pipeline were adapted to avoid disruption of the forest edge as far as possible. The edge of the forest serves as a guiding structure for bats and additionally acts as a natural screen for the gas compressor station. Permanent lighting at the gas compressor station will also be avoided and insect-friendly lighting will be used. Measures to protect reptiles and amphibians will be implemented during the construction phase.
Unavoidable, permanent impairments will be compensated by corresponding measures (compensation measures). In addition to planting new trees, nesting boxes and hatching aids for birds and bats are planned for example, as well as upgrading a humid biotope in Rheinstetten.
Derived from empirical values for operating times at the terranets bw compressor stations, weather conditions over the last few years and the planned control of the network after commissioning the new compressor station, terranets bw currently estimates 500 to 2,000 operating hours per year. This assumption includes the sum of operating hours for all machine units (three gas turbines, one electric engine). The local CO2 emissions of one machine unit operated with a gas turbine amount to about 4,000 kg per operating hour. By using the electrically-powered machine unit, the local CO2 emissions are reduced. The level of CO2 emissions depends on the respective distribution of electricity generation. Using only machine units that are powered by a gas turbine produces 2,000 t to 8.000 t of local CO2 emissions per year.
terranets bw also uses a recompressor system at the gas compressor station in Rheinstetten. This is an additional measure taken by terranets bw to avoid methane emissions when operating the system.
Small amounts of methane escape at the drive shafts of the compressor units, which cannot be avoided completely. However, this methane is collected in a collection system and injected back into the transmission system with the recompression system. All other components of the compression system are technically sealed so that no methane emissions can escape.