Coal phaseout at Stuttgart-Münster

October 2024: The “hot startup” phase in Stuttgart-Münster begins. The construction process that started back in January 2023 reached the so-called “hot startup” phase for the first gas turbine this week. The former coal boiler and heating oil-driven turbines have been replaced by a highly efficient gas turbine system with an output of 124 megawatts. To check whether everything is working as intended, tests will now be carried out repeatedly over several days. This includes gradually increasing the output of the gas turbines to adjust and test them for optimum operation. It will be possible to see the flue gases generated during the combustion process as they are discharged from the newly constructed chimney, just like the flue gases from the chimney for the existing waste and coal boiler.

September 2024: An ABC of the pipelines. Different brightly colored pipelines can be seen running along the pipe bridges and through the highly efficient gas turbine plant. Installing these pipelines on the construction site takes a lot of time. But what is being transported by which pipeline?

Green:

• A cooling water pipeline providing water to cool the gas compressors with a total length of approx. 340 meters

Yellow:

• A high pressure natural gas pipeline running from the gas control pressure measurement station to the gas turbines via the compressors with a total length of approx. 290 meters
• A low pressure natural gas pipeline running to the hot water boilers, waste heat boiler and existing plant with a total length of approx. 450 meters

Grey/brown:

• A district heating pipeline in the M1 grid supplying downtown Stuttgart with a total length of approx. 130 meters
• A district heating pipeline in the M2 grid supplying North/West Stuttgart with a total length of approx. 1,300 meters

August 2024: Delivery and installation of the transformers. In August 2024, four transformers, two auxiliary power transformers and two generator transformers were delivered on heavy goods vehicles and installed. The generator transformers each weigh 106 metric tons and convert the generator voltage into the voltage used in the high-voltage public grid. This means that the electricity can be fed directly into the public grid. The auxiliary power transformer are lighter and each weigh 27 metric tons. They convert the generator voltage into the medium-voltage electricity required by the power plant itself to efficiently cover the plant’s electricity needs (such as for pumps, control systems and lighting) from own generation.

More insights can be found here.

June 2024: East pipe bridge lifted into position. The four sections of the east pipe bridge were lifted into place in June. The bridge connects the existing power plant with the gas turbine plant that is currently under construction. The pipe bridge is approx. 43 meters long and weighs a total of 110 metric tons. It carries, among other things, the pipes for ammonia water, fresh steam, heating oil and demineralized water.

April 2024: Delivery and assembly of the gas turbines. In April, the two SGT-800 gas turbines were delivered to the construction site and installed. A gas turbine is a heat engine that converts thermal energy into rotational energy. An electrical generator uses this rotational energy to generate electricity. Exhaust gases leave the gas turbine at a very high temperature and can be reused to generate heat, steam and even more electricity. The two gas turbines have a total electrical output of 124 MWel. You can find more insights here.

February 2024: Start of construction of the black- start battery system. A black-start battery system is being built at the Stuttgart-Münster site. Construction work began in February 2024. The power required to start up the power plant at the site can be covered by the black-start battery system in combination with the gas turbines. The CO₂-neutral black-start battery system is also able to provide primary and secondary control power at short notice and thus help to stabilize the grid.

January 2024: Delivery and installation of the hot water boilers and associated chimneys. The three hot water boilers were delivered and installed in January 2024. Immediately afterwards, the three approx. 60-meter-high chimneys were lifted into place in 3 segments each. You can find more insights here.

December 2023: Commissioning of the large-scale heat pump. Commissioning of the large-scale heat pump began in December 2023. The large-scale heat pump will utilize the waste heat from the cooling water discharged at the site to generate up to 24 MW of district heating. The climate-neutral district heating generated in this manner will cut carbon emissions by around 15,000 tonnes per year. The heat pump will thus not only make an important contribution to the decarbonization of EnBW's district heating generation, but also significantly help the City of Stuttgart to achieve its climate protection goals. You can find more insights here.

November 2023: Lifting of the northern pipe bridge. On 03.11.2023, the northern pipe bridge over Neckartalstraße was lifted into place in cooperation with SSB and the city of Stuttgart using a tandem lift with 2 cranes. The pipe bridge was installed on site before being lifted into place, including the district heating and natural gas pipes for supplying the city of Stuttgart. The natural gas pipelines are already 100% H2-ready.

October 2023: Delivery and assembly of the first waste heat boiler for the gas turbines.The components of the first waste heat boiler were delivered by heavy goods vehicle at the end of September. The individual components that ultimately make up the waste heat boiler are welded together piece by piece and assembled. The waste heat boiler utilises the heat recovered from the gas turbine to generate steam and hot water to drive the steam turbine. When fed into the respective grids, district heating and electricity are generated.

September 2023: Delivery and installation of the large heat pump.The components of the large heat pump were delivered and installed at the beginning of August 2023. Components such as the evaporator, intercooler and condenser were delivered and installed in various partial deliveries. The large heat pump can generate up to 24 MW of green district heating. This can save around 15,000 tonnes of CO₂ per year.

August 2023: Steelwork for the gas turbine building. Work on the steel structure for the gas turbine building began in mid-July 2023. The two gas turbines, each with a capacity of 24 MW, will be housed in the gas turbine building along with the waste heat boilers and two chimneys. The gas turbine building will be constructed as a steel skeleton frame using approx. 1,300 metric tons of steel girders and its dimensions will be approx. 65.20 x 45.15 x 34.00/17.80 meters (L x W x H). The main structure of the steel skeleton frame generally consists of a series of steel columns and horizontal beams connected by means of riveting, bolting or welding. This construction method enables rapid progress to be made, with completion already scheduled for mid-May 2024.

June 2023: Chimney foundations with integrated crane support. In keeping with the motto 2 in 1, the chimney foundations were used as a crane support. The crane was erected using a built-in part that serves as a rear anchor to stabilize the crane. The 60-meter-high crane has a working radius of up to around 60 meters and can thus cover almost the entire construction site. In 2024, the chimney will then be built using the slip form method. This approach guarantees a flexible, efficient and economical construction process.

May 2023: Concrete casting and reinforcement of the gas turbine building. Once the foundation work was completed, the reinforcement work started, along with the concrete casting in stages for the two gas turbine foundations. Approximately 600 m³ of concrete were needed for each of the foundations, which is the equivalent to around 3,000 bathtubs per foundation. It took 130 concrete mixers and two concrete pumps to complete the job. The concrete structural elements are reinforced using steel, increasing the load-bearing capacity of the building being constructed on them. The 124 MW gas turbines are housed in the gas turbine building.

April 2023: Installation of the driven piles. Work on installing the 202 driven piles began in April. Pile foundations are deep foundations where the loads of supporting structures are transferred to deeper soil layers with a higher load-bearing capacity. Soil layers with poor load-bearing capacity are thus bridged using piles. With so-called pile foundations, the piles are driven into the ground with a pile driver until a soil layer sufficiently capable of bearing the load has been reached. Concrete is then poured into them.

March 2023: Groundbreaking ceremony and official opening of the building site. The starting signal was given in Stuttgart-Münster for the construction of the new gas turbine plant and large-scale heat pump. Minister for the Environment, Climate Protection and Energy Sector for Baden-Württemberg Thekla Walker, Mayor Dr. Frank Nopper and the EnBW Board Member responsible for sustainable generation infrastructure Dr. Georg Stamatelopoulos performed the traditional groundbreaking ceremony on 31 March 2023.

February 2023: Start of foundation works. Foundation works create a stable and load-bearing basis for the buildings and machinery associated with the new plants. This covers groundwork such as the excavation of pits and the construction of the foundations, including pile foundations.