In Hamburg, a city district is nearly completely supplied with carbon-neutral exhaust heat
Energy efficiency

Energy efficiency

Steamy liaison

The metal company Aurubis and the energy supplier enercity are making industrial history in Hamburg. HafenCity Ost (”HarbourCity East“) is the first city district to be supplied almost completely with waste heat that is virtually carbon-free.

Excellent!

The fact that a municipal waste heat cooperation in northern Germany can become an energy-policy flagship project with radiance is proven by a price that Aurubis can put on its shelf. The German Energy Agency (dena), driver and pioneer of the energy turnaround, awarded the Hamburg metal processor the "Energy Efficiency Award". 104 energy efficiency projects applied in 2018, Aurubis won in the category "Energy Turnaround 2.0".

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It is Hamburg's pride and joy and Europe's largest urban development project in a city centre: HafenCity. A completely new city district is being built step by step in the former harbour area. One day, in around 2030, it is expected that 15,000 people will live here, more than 40,000 will work here and 80,000 tourists will visit here. KfW and the Federal Ministry for Economic Affairs and Energy (BMWi) are also involved in this groundbreaking project – with a spectacular energy project linking HafenCity with the metal company Aurubis.

The heat, vapours and smells given off by the factory on the other side of the Elbe River are a manifestation of the one million tonnes of copper that are produced here every year using enormous amounts of energy. Since spring 2018, an orange colossus weighing 250 tonnes, 18 metres high and six metres in diameter has been sitting in the middle of this complex made up of grey halls, boilers, pipes and conveyor belts – the intermediate absorber. It is the central element of the district heating system for Hamburg's HafenCity East.

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Infographic Aurubis
The site of the project

The eastern tip of Hamburg's HafenCity and the Aurubis site are only 2.5 kilometres apart. An ideal arrangement for transporting the waste heat from the copper smelter to the heating systems of HafenCity's buildings using the new heat transport pipeline from energy supplier enercity. The hot water is scheduled to start flowing into HafenCity from October 2018 onwards. (Infographic: Andrew Timmins)

In its boiler, which is lined from the inside with 50,000 acid- and heat-resistant ceramic bricks, sulphur dioxide – a by-product of copper purification – is converted to sulphuric acid, releasing heat that is virtually carbon-free. The people working at Aurubis have been familiar with this chemical process since the plant opened. What makes the brand-new technology of the intermediate absorber so innovative is that the hot air – which used to be cooled with lots of water from the Elbe River – can be discharged as hot water through a district heating pipe. But it doesn't go just anywhere: it is routed to the HafenCity neighbourhood 2.5 kilometres away, which made the sustainable district heating possible in the first place.

"The idea of using the resulting waste heat has been around for quite some time," says Christian Hein, head of the district heating project at Aurubis, "but it is only now possible to make practical use of the waste heat from the contact system at a suitable temperature level thanks to the potential heat consumer and the material properties of the required aggregates currently available on the market. Heat extraction until now hasn't been cost-effective as only 25 per cent of the waste heat could be used in the plant itself."

The project is enormous. In line with the district heating pipeline's capacity of 60 megawatts, 6,000 households will ultimately benefit from hot water transport. As will the atmosphere: more than 20,000 tonnes of carbon dioxide emissions can be prevented annually thanks to the Herculean project. About half of the reduction in emissions is the result of replacing natural gas used to produce steam on the Aurubis premises, while the other half is saved by supplying the waste heat to the energy supplier enercity AG (formerly Stadtwerke Hannover).

"The idea of using the resulting waste heat has been around for quite some time."

Christian Hein, head of the district heating project at Aurubis

Support from KfW

With the KfW Energy Efficiency Programme Waste Heat, KfW supports investments in updating, expanding or building new systems for preventing or using waste heat in Germany.

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Enercity won a Europe-wide public tender to supply heat to HafenCity East. During project development, enercity benefited from its many years of experience participating in contracting schemes. "The starting point for this project was when we were confronted with the decision to either build another heating plant to supply the growing HafenCity or to use waste heat," explains Dr Manfred Schüle, CEO of enercity Contracting GmbH. "After a preliminary exploratory phase, the project partners Aurubis and enercity decided to work together.”

However, the deal wasn't perfect until KfW and the Federal Ministry for Economic Affairs and Energy pledged their support. Everyone agrees that without the funding, the district heating project would not have been carried out. With repayment bonuses financed by the Federal Ministry for Economic Affairs and Energy from the "KfW Energy Efficiency Programme – Waste Heat", Aurubis was able to fund the necessary plant conversion, heat extraction and internal pipeline up to the site perimeter more cost-effectively. Funding was also provided for the heat transport pipeline of the project partner enercity. "We are pleased to have enabled implementation of this flagship project thanks to our waste heat programme," says Gerd-Henner Rupp, Team Head at KfW, Environmental Programme, "and hope to be able to support more challenging projects like this one in the future."

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In Hamburg, a city district is nearly completely supplied with carbon-neutral exhaust heat.

To German edition

Due to its particularly high potential for waste heat and its applicability to other companies in the energy-intensive metal industry, the Hamburg project was elevated to the status of a flagship project by the German Energy Agency (dena) already in 2017. And the total energy potential of Aurubis is far from exhausted with the project. If politicians play their part, the district heating project could be the first of several measures which could reduce carbon emissions by a total of 140,000 tonnes per year by utilising the other production lines. There is no shortage of opportunities for the industry as a whole. The Institute for Energy and Environmental Research in Heidelberg (ifeu) estimates the potential savings in energy costs from the use of industrial waste heat in Germany at around EUR 5 billion per year.

However, Hamburg's HafenCity East will not be able to do entirely without fossil fuels. To make the strongly fluctuating waste heat usable for supplying heat, it has to be constant and reliable. To this end, enercity set up an energy centre with a buffer storage system and boilers. They become operational during malfunctions or maintenance work at Aurubis – and are powered by gas and oil.

Published on KfW Stories: Tuesday, 4 December 2018