Copper Smelting Plant in Germany Also Heats Water for District Heating: An Exothermic Reaction Produces the Recoverable Heat Chemically

     German company Aurubis smelts recycled copper sustainably. Aurubis is a leading global provider of non-ferrous metals and one of the largest copper recyclers worldwide. They aim to be the most sustainable copper smelter in the world.

“Thanks to its many targeted measures, Aurubis has succeeded in reducing the carbon footprint of its copper cathodes, the standard product in the copper industry, by over 40 % in the past 11 years. This means they have less than 60 % of the global average CO2 footprint for copper cathodes.”

 

Carbon-Neutral Industrial Heat

     Industrial waste heat recovery comes in different forms. In this case, the heat recovered is chemical heat from an exothermic chemical reaction. The process utilizes a catalyst to cause sulfur in the copper ore to react with oxygen to generate the heat needed to transform the ore into metal. The process does not produce CO2. However, there is a natural gas boiler on-site that is used in the winter months when demand is higher than the process heat alone can supply.

“Using process heat from a subprocess of copper production, Aurubis delivers heat to up to 28,000 Hamburg households — saving up to 120,000 tons of CO2 emissions in the city of Hamburg annually.”

     The reactive heat is channeled through a pipeline network several kilometers long to the Hafencity district heating system. The total cost for the project was about €70 million ($78 million), about a third of some comparable fossil fuel-powered district heating projects.

     According to Aurubis:

“The accumulator already holds up to four million liters of hot water from Aurubis heat today. It works a bit like a thermos, and the heat is released into Hamburger Energiewerke’s over 860-kilometer-long city network when needed.”

     They also note that in the coming years, industrial waste heat recovery will grow, from data centers and electrolyzers used to make hydrogen, especially.

     Aurubis explains the project further:

“The heat is generated in Aurubis’ contact acid plant in Hamburg where sulfuric acid, a by-product of copper refining, is formed in multiple process steps. This process is an exothermic chemical reaction that generates CO2-free heat at a temperature suitable for carbon-neutral district heating. The technology has been successfully used at the Aurubis plant since 2018 to supply heat to enercity to cover HafenCity East and Rothenburgsort, and is now being significantly expanded. The Industrial Heat project highlights the multimetal company’s ambitious decarbonization targets and underscores Aurubis’ efforts to pioneer solutions for ecological and sustainable business activity.”

“Heat production at Aurubis and the heating needs of district heat customers often occur at different times. So the extracted industrial heat is temporarily stored as 105 degree Celsius water in the nearby Hamburger Energiewerke pressure heat accumulator. The heat can then be fed into the over 860-kilometer city network using a network pump system. To deliver the industrial heat to Hamburg households, Hamburger Energiewerke is using an existing enercity Contracting Nord GmbH pipeline to cover the first segment from the Aurubis plant to the Elbe River crossing. Starting at Billhorner Brueckenstrasse, a 2.8-kilometer HEnW district heating pipeline continues to the heat conversion plant at Spaldingstrasse. The heat conversion plant serves as an interface for integrating various heat sources into the district heating network. The final steps for integrating the industrial heat supply into the city network will be carried out before the actual launch.”

     Some specs for the project are given below:

  

 

References:

 

Waste from Copper Plant Is Heating a German Waterfront Without Emitting CO2. Andy Corbley, Good News Network. July 24, 2025. Waste from Copper Plant Is Heating a German Waterfront Without Emitting CO2

Aurubis demonstrates sustainable metal production with extensive the Copper Mark certification. Aurubis. Press Release. September 27, 2024. Aurubis demonstrates sustainable metal production with extensive the Copper Mark certification

Responsible metal production: Aurubis honored with the 17th German Sustainability Award. Aurubis. Press Release. November 4, 2024. Responsible metal production: Aurubis honored with the 17th German Sustainability Award

Symbolic start of industrial heat feed-in to Hamburg city network. Aurubis. Press Release. January 9, 2025. Symbolic start of industrial heat feed-in to Hamburg city network