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.

With its focus on recycling waste, Stuttgart-Münster combined heat and power plant is special within EnBW’s power plant portfolio. In order to make optimal use of the fuel, both district heating and electricity are generated simultaneously in line with the combined heat and power (CHP) principle. The existing combined heat and power plant consists of a hard coal power plant with three coal boilers, a waste incineration plant with three waste boilers, three steam turbines and a turbine plant powered by heating oil. This mix enables the heat and power plant to meet both base and peak load supply needs.

As a waste-to-energy combined heat and power plant, the site plays an important role in the reliable, environmentally friendly and efficient disposal of residual waste in Baden-Württemberg. It also forms part of the Mittlerer Neckar district heating group together with the combined heat and power plants in Stuttgart-Gaisburg and Altbach/Deizisau, supplying heat to more than 25,000 homes, 1,300 businesses and 300 public institutions in Stuttgart and the wider region.

The construction of a new gas turbine CHP plant is designed to ensure that the Münster site can continue to reliably perform these two main roles while becoming even more environmentally friendly. Following the successful commissioning of the combined heat and power plant in Stuttgart-Gaisburg back in 2018, which has also been converted from coal to run on natural gas, the construction of a new gas turbine CHP plant at the Münster site represents the next step in making the switch to a more climate-friendly district heating supply in the region.

Like all coal power plants in Germany, the blocks in Stuttgart-Münster are set to be shut down in the medium term. According to the Coal Phaseout Act of 2020, this process is due to be completed by no later than 2038. The coal blocks in Stuttgart-Münster must be decommissioned by no later than 2030. With the planned commissioning of the new plants at the Münster site in 2025, the last coal-fired power generation plants in Stuttgart would cease operations – meaning the coal phaseout for the metropolitan area would be completed many years ahead of the legally set deadline. In order to pave the way for climate neutrality from 2035, bridging technologies are needed to guarantee the year-round supply of district heating. That’s because the energy generated from waste incineration is no longer sufficient to cover district heating needs, particularly in the colder months. By using highly flexible gas turbine plants, a targeted approach can be taken to meeting the demand for district heating. In addition, they can react more flexibly to any fluctuations in the power grid attributable to the feed-in of renewable electricity generated by the wind and sun.

A new combined heat and power plant (CHP plant) with a maximum of three gas-fired turbines is therefore set to replace the coal boilers in the future. The new plant thus retains the advantages of combined heat and power generation – for example, a much higher fuel utilization efficiency rate compared to other types of power plants. The switch from coal to gas also significantly reduces the emission of carbon dioxide and other pollutants such as dust (PM 15) or sulfur dioxide (SOx) and entirely eliminates the emission of heavy metals (such as mercury). The use of SCR technology – which involves using catalytic converters in the flue gas system of gas turbines – also reduces emissions of nitrogen oxides (NOx) to a greater extent than required by the already strict legal requirements for gas turbine plants.

Another advantage of natural gas-fired plants is that they can eventually also be powered by “green gases” such as hydrogen produced from renewable energy sources. As soon as such “green gases” are available in sufficient quantities and the necessary supply infrastructure has been built to accommodate them, the Münster power plant site can be converted – and will then produce completely carbon- free electricity and district heating. The entire plant will be able to burn a certain percentage of hydrogen mixed into the natural gas from the moment it is commissioned. In order to enable a complete switch to hydrogen combustion, the gas turbine needs to be converted, which can be done at any time during one of the routine major overhauls as soon as hydrogen is available in sufficient quantities.

stuttgart-muenster@enbw.com

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