Not only since the big bang caused by the water vapor explosion on Tuesday night, the Frankfurt power plant West has come into focus. Climate activists are calling for it to be shut down because hard coal is burned there. They want to demonstrate for this once again in a few days. With the accident, however, even less radical citizens were forced to ask themselves why such a large power plant had to run in the middle of the big city. To keep them warm, the operator's terse and clear answer could be Mainova.

Inga Janović

Editor in the regional section of the Frankfurter Allgemeine Zeitung and responsible editor of the business magazine Metropol.

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This is because the energy supplier, which resells electricity and gas to major customers and private households in Frankfurt and Rhine-Main, sees itself first and foremost as a district heating supplier in its role as an energy producer. The electricity generated in its seven combined heat and power plants in Frankfurt is a kind of by-product, because all plants operate on the principle of combined heat and power. This means that the water vapor heated to several hundred degrees by the combustion of coal, natural gas, crude oil or waste is first passed through turbines before it is used for heat supply. This increases the efficiency of the systems, and there is no need for large cooling towers.

Heat is a bigger task than electricity

"Combined heat and power generation is our genetics," says Winand Zeggel, adding that the company has always worked with both forms of energy. Since 2017, Zeggel has been Head of Generation Heat and Electricity at the utility and is thus responsible for the power plants as well as the 311-kilometre-long district heating network and Mainova's investments in plants for the generation of electricity from renewable sources. He has 270 employees to keep this system running, which has to react to particularly cold days, the rush of many trade fair guests or even summer heat with humming air conditioning systems throughout the year. The Kraftwerk West, which is located not far from the main train station directly on the banks of the Main, is the oldest and, from Frankfurt's point of view, also the largest site. In 1894, the "Elektrische Centralanstalt" had generated electricity there for the first time on Gutleutstraße: two megawatts.

Today, the power plant has an annual output of 430 megawatts of heat and 273 megawatts of electricity. This is only a small part of the city's total energy consumption, which was 2020.12 terawatt hours in 4, of which electrical energy accounted for 5.1 terawatt hours. The heating sector, as Mainova CEO Constantin Alsheimer never tires of emphasizing, is by far the greater task than electricity generation when it comes to phasing out the use of fossil fuels.

In his opinion, it cannot be solved with electrically operated heat pumps on every house. Instead, there is still a need for central locations for generation, including the West power plant, and an expansion of the district heating network. About a quarter of households are already supplied with this energy, a high proportion compared to other large cities. The expansion is underway, and the next step is to connect the biomass power plant in the Fechenheim district, whose twelve megawatts of energy yield mainly benefits the neighboring industrial park, to the pipeline system as a further heat source. In general, alternative sources are to be increasingly used to generate heat: waste, biomass, waste heat – especially from data centers.

Meanwhile, the age of hard coal continues at the West power plant, which is why the climate protectors are gathering there primarily to protest. The coal phase-out has already been decided. In addition to today's 40-metre-high boiler house, a new power plant with two gas turbines is to be built at a cost of 300 million euros. The building permit is expected in the next few days, and construction is scheduled to begin in the summer. Natural gas will be the energy source for commissioning in 2026, but the power plant's carbon dioxide emissions are expected to be reduced by 400,000 tonnes. At some point in the thirties, it is hoped, it will be possible to switch to sustainably produced hydrogen. Without gases, which are ultimately energy storage, the heat supply is hardly conceivable – after all, the sun shines in summer, and not in winter, when the heating is turned up in homes and offices.

There is already a gas turbine in the West power plant, it has to take over the work of unit two, which has been shut down since the explosion on Tuesday night. How long is still open, just as the question of the cause remains unresolved. This is likely to be the biggest concern for the employees at the site – there are twelve in each of the three shifts a day. The power plant crew is usually proud of the fact that they so reliably supply citizens with electricity and warm their homes. This was quite a challenge last winter, because as simple as the process of coal-fired power generation seems, the chemical processes are just as sensitive, as power plant manager Holger Knapp explained during a tour. For a long time, Russian coal in particular had come into the Frankfurt boilers, but after the import ban, Knapp had various coal mixtures supplied by the wholesalers until combustion was as clean as possible again.