Hamburg made a historical announcement that’s going to change the face of the energy efficiency landscape in Germany. The collaboration between metal company Aurubis and energy supplier Enercity is setting new standards by supplying HafenCity Ost (HarbourCity East) with waste heat that is virtually carbon-free, marking a significant step towards sustainable urban development. HafenCity is Europe’s largest urban development project within a city center. Expected to be completed by 2030, this former harbor area will transform into a vibrant district where 15,000 residents will live, 40,000 people will work, and 80,000 tourists will visit annually. Central to this transformation is an ambitious energy project that connects HafenCity with Aurubis, a leading copper producer. Located just 3.7 kilometers apart, the proximity of HafenCity East and the Aurubis site provides an ideal setup for the innovative use of waste heat. Enercity, the energy supplier, has laid a new heat transport pipeline that will channel waste heat from Aurubis's copper smelter directly to HafenCity’s heating systems. This initiative, which began delivering hot water in October 2018, exemplifies a sustainable approach to urban heating. At the heart of this project is a sophisticated process at the Aurubis plant. The plant's boiler, lined with 50,000 acid- and heat-resistant ceramic bricks, converts sulfur dioxide, a by-product of copper purification, into sulfuric acid, releasing substantial amounts of heat. This process is well-established at Aurubis, but the innovation lies in the new intermediate absorber technology. This technology allows the hot air, previously cooled with river water, to be transformed into hot water and transported via district heating pipes to HafenCity. The scale of this project is monumental. With a district heating pipeline capacity of 60 megawatts, approximately 6,000 households in HafenCity will benefit from this sustainable heating solution and the project will over 20,000 tonnes of carbon dioxide emissions annually.