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Coal phaseout at Stuttgart-Münster

Climate-neutral by 2035 – based on this promise, EnBW is committed to playing its part in mitigating climate change in line with the 2015 Paris Agreement. For EnBW, this partly means continuing to systematically expand renewable energy capacity, while also pursuing its aim of phasing out the use of coal in the medium term and the use of fossil fuels as an energy source in the long term. EnBW is one step closer to achieving this aim with the construction of a new gas turbine plant for generating electricity and heat based on more climate-friendly natural gas at its Stuttgart-Münster site. The fuel switch to more climate-friendly natural gas is just a bridging technology on the way to energy generation using green gases such as hydrogen produced from renewable sources.

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District heating – from the combined heat and power plant directly to the customer

The district heating network for Stuttgart and the “Mittlere Neckar Line”.

In a combined heat and power plant, useful thermal energy is generated in addition to electrical energy in a cogeneration process. Since the heat usually needs to be fed into a district heating network, combined heat and power plants are often located in urban areas with high demand for it. The thermal energy is carried via district heating pipe networks directly to households and businesses, supplying them with environmentally friendly and reliable district heating.

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How the new combined heat and power plant works

A functional diagram of the new combined heat and power plant

Due to the existing power plant facilities, there is a so-called common steam range in Stuttgart-Münster. In simple terms, this is a large steam pipe into which all plants feed the steam they generate – i.e., the three waste incineration boilers as well as the three remaining coal boilers.

This common steam range then conveys the high-pressure steam to the three steam turbines (two condensing and one back-pressure turbine) that will produce electricity and district heating. Both the common steam range and the steam turbines will be retained so that the new gas turbine CHP plant can feed in the steam it generates and thus make use of the site’s existing infrastructure. Ultimately, the gas turbine CHP plant will be replacing the existing three coal boilers.

Various auxiliary facilities are still needed to operate the power plant. These include the cooling systems, feed water supply, condensate system, electrical and control systems, gas compression and control stations, fire protection systems and ventilation systems. They also use the existing infrastructure at the site, when returning condensate, for example, or supplying treated feed water for the heat recovery steam generators, supplying fully demineralized water or compressed air or channeling away wastewater.

Key data for Stuttgart-Münster power plant

Existing plants
New plants
First commissioned
Existing plants
1908
New plants
2025
Blocks
Existing plants
3 waste boilers, 1 hard coal block, 3 coal boilers, 3 turbine plants powered by heating oil
New plants
3 waste boilers, 3 hot water boilers, 2 gas-fired turbines
Gross electrical power
Existing plants
approx. 114 MW steam turbines / approx. 69 MWe turbines powered by heating oil
New plants
approx. 114 MW steam turbines and 124 MWe gas turbines
District heating power drawn off
Existing plants
approx. 450 MW
New plants
approx. 450 MW
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The most important benefits of the new construction project

  • Climate change mitigation: The new turbines emit around 60 percent less CO₂ than a coal-fired plant with a comparable output. Since the new plants are larger than the old ones, they will even replace coal capacity in the region beyond Münster.
  • Air pollution control: The chemical composition of natural gas has considerably fewer critical components than hard coal, which means that natural gas burns cleaner. In addition, plants with the latest firing technology are being built to replace the decades-old coal boilers, making it possible to cut particulate matter emissions by around 88% and those of sulfur oxides also by around 88%. The use of catalytic converters in the gas turbines’ flue gas system will reduce nitrogen oxides by more than 45%, while emissions of heavy metal compounds – and particularly mercury – will be completely eliminated. The conversion of the site is therefore also a sustainable project to control air pollution in the state capital.
  • Noise control: Once the new plant has been commissioned, the old plants – including the coal boilers, the coal storage facility and the flue gas cleaning system for the coal boilers – will be shut down. Besides the waste boilers and their auxiliary systems, these have been one of the sources of noise at the site until now. The new plant will be equipped with state-of-the-art sound absorbers, sound traps, etc. in order to stay within legal limits as specified in noise control guidelines (TA Lärm). In addition, there will no longer be any disposal of residues or delivery of additives associated with the coal boilers’ flue gas cleaning system, which will in turn reduce the volume of traffic and the resulting noise.
  • Water pollution control: The newly built power plant facilities do not require any additional withdrawal of cooling water from the Neckar. Instead, the gas turbine CHP plant is cooled by heat exchangers installed on the roof of the building in a separate water-glycol system. They permanently reduce the heat discharged into the Neckar via the cooling water. Particularly when temperatures are high in the summer and the demand for district heating is lower than the amount of heat produced in the continuous waste incineration operation, the water currently has to be discharged into the Neckar via the cooling water system. In the future, the heat discharged should be kept to a minimum by the new heat exchange system in order to counteract warming in the Neckar. Care is being taken to ensure that the units are both efficient and quiet.
  • District heating: In order to guarantee the future heating supply, part of the site’s existing systems supplying the Stuttgart Northwest and Cannstatt district heating networks will be replaced by new, more efficient plants. These will be installed in the new power plant’s buildings, replacing the existing stock that dates back to the 1980s.