Cologne-Merkenich Combined Heat and Power Plant

The site has three chimneys, the tallest of which stands 250 metres and is now out of service. This makes it Cologne's second-tallest structure after the Colonius TV tower — considerably taller than Cologne Cathedral — and one of the 100 tallest structures in Germany. It was taken out of service in 2004 when Boiler 5 of the original plant was decommissioned.

The 75-kilometre "North Network" supplies the districts of Bocklemünd, Chorweiler, and Merkenich with heat. Alongside private households, industrial and commercial customers receive heat, process steam, and deionised water — including the Ford, Deutsche Infineum, and Vinnolit plants in Cologne-Niehl. The electricity generated through combined heat and power is fed into the grid.

Construction began in 1956, and the plant came online in 1958 with two boilers, initially supplying neighbouring industry with steam. In 1961, Cologne City Council resolved to provide district heating to the city's north from Merkenich, and the first households received heat from 1962.

Boiler 6, commissioned in 1990, burned Rhenish lignite in a circulating fluidised bed combustion system. Lignite firing was discontinued in 2025; heat and power supply will in future be handled by the existing combined-cycle gas turbine plant. A sewage sludge incineration facility is planned for the site by 2029, and the potential addition of a large-scale heat pump is under review. The plant operates almost exclusively in combined heat and power mode, achieving fuel utilisation rates of up to 80 percent.

The civic initiative "Tschö RheinEnergie" has criticised the burning of lignite for producing significantly higher emissions of pollutants and CO₂ than natural gas would.