Cologne municipal drainage company: On the way to zero emissions from fossil fuels

The theme of climate change is omnipresent at StEB Cologne (Stadtentwässerungsbetrieben Köln, AöR) (Cologne municipal drainage company) – after all, they deal with their city’s water management. Now the company is working on reducing its own impact on the climate as far as possible and is planning to meet its energy needs entirely from its own renewable energy plants in the future.

The tasks covered by Cologne municipal drainage company include sewage disposal, maintaining Cologne’s streams and the lakes in its parks, as well as flood prevention and corresponding precautions. Particularly in the area of flood prevention, there are issues regarding adaptation to climate change, which StEB Cologne is dealing with in its business activities. The company is also focusing more on eco-friendly technology in its daily business in order to limit its own impact on the climate.

Climate protection objective:

  • Reducing the overall power consumption in sewage treatment plants by 20 per cent by 2025
  • Increasing production of on-site electricity to cover 100 per cent of company needs by 2025
  • Construction of a screenings fermentation plant in 2018 to increase sewage gas production
  • Digitisation of the administrative side of the business to create a paperless office

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Photo: Peter Jost

At the sewage treatment plants operated by StEB Cologne, the sewage gas that accrues is transformed into electricity and heat in efficient combined heat and power units. The company uses the electricity that is generated itself, feeds heat into the Cologne district heating network and thus contributes to climate protection.

Use of sewage gas to produce energy

StEB Cologne operates a total of five sewage treatment plants in the city. In all these plants, gas is produced from the sewage sludge that accrues and is transformed into electricity and heat in on-site combined heat and power units (CHPUs). Since sewage gas is considered to be a renewable source of energy, no fossil fuel emissions occur. The company itself is already producing more than 38 gigawatt-hours of electricity per year. It can supply around 90 per cent of its own electricity requirements with its sewage gas-powered CHPUs and its own photovoltaic facilities. The remaining electricity is bought in as green electricity. The heat produced in the sewage gas-powered CHPUs which is not used on site is fed into the Cologne district heating network. StEB Cologne has managed to reduce its total CO2 emissions from fossil fuels by more than a half in comparison to the reference year 2012.

Various measures planned

StEB Cologne aims to cover its entire electricity needs itself by using sewage gas and solar energy, planning to achieve this by 2025. To this end, the company is replacing inefficient systems technology, including projects in the sewer network. The company is a partner in the “Celsius” project, which uses waste heat from the sewer network to supply heat to buildings. In the administration department they plan to create a paperless office and in the canteen more regional products are to be offered. What is more, in the area of corporate transport, StEB Cologne are already focusing increasingly on electric cars and pedelecs.

Photo: StEB Köln, Bettina Fürst-Fastré

StEB Cologne ensures that the city has clean water that citizens can experience in a tangible way. As a public service provider we feel that we are particularly committed to operating in a sustainable manner. Reducing CO2 emissions is a key aspect of climate protection. Our energy strategy reflects this and we are thus helping to ensure that Cologne is sustainable for the future.

Otto Schaaf, Management Board, Cologne municipal drainage company