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The idea behind the project is to harness thermal energy from the waste gases produced by cooling them in a process that heats up cold water.

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The City of Hamburg has pledged to phase-out coal completely by 2030. But a large proportion of its district heating is still supplied by the Tiefstack plant, which burns coal to power steam turbines. A new initiative from Hamburg’s Ministry for Environment, Climate Protection, Energy and Agriculture (BUKEA) called Extended Heat Utilisation aims to save 104,000 tonnes of CO2 per year by recovering heat from a large waste incineration plant in Borsigstrasse.

Currently, over 320,000 tonnes of rubbish are burned annually at the plant, which is operated by Stadtreinigung Hamburg (SRH). The idea is to harness thermal energy from waste gase by cooling them in a process that heats up cold water. The utilities provider Wärme Hamburg GmbH will supply the heat pump to feed the hot water directly into its heating network.

"With this [project], we are not only advancing the phase-out of coal at the Tiefstack CHP plant but also taking a big step on our way to finally phasing out coal," says BUKEA’s senator Jens Kerstan in an article in FINK.HAMBURG. The project costs the city 55 million euros, but the ministry is already looking at converting another waste recycling plant at Rugenberger Damm.

Construction began at the waste plant in May 2021 and two large boilers will be ready for connection to the heating network later this year. A biomass power plant will be added to the mix next year, and by the end of 2023, the projected output of the plant will be 350,000 MW hours a year – enough to supply 35,000 Hamburg households with heating.

Commenting on the project, the not-for-profit group Greenpeace has pointed out that in principle "burning waste is neither climate-neutral nor renewable.” However, it acknowledges that waste incineration plants have a role to play in supplying heat where energy needs can’t otherwise be met by renewable sources.