Where the mail-order company Neckermann once revolutionized the world of shopping and travel, a piece of Frankfurt's economic history is now to be written again: the data center being built by the operator Interxion in the historic building could become the first in the city to emit its waste heat into the city-wide district heating network.

On Thursday, the Interxion parent company Digital Realty and the Frankfurt-based energy supplier Mainova formalized the planned cooperation with a declaration of intent.

Heating for 3600 households

Inga Janovic

Editor in the regional section of the Frankfurter Allgemeine Zeitung and responsible editor of the business magazine Metropol.

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It is therefore not yet certain whether it will come about, because in the next step, a feasibility study should be carried out to examine "whether the waste heat from one of the data centers can be fed into Mainova's district heating network in the future".

In theory, up to 20 megawatts of waste heat are available for district heating in the so-called Digitalpark Fechenheim, enough to heat around 3,600 households.

In addition, the heat from the servers and routers is enough to heat 18,000 square meters of office and storage space that the operator uses himself.

"The cooperation with our partner Digital Realty will enable us for the first time to integrate data center waste heat in our district heating system," says Martin Giehl, CTO of the energy supplier and praised the project as a further step for decarbonization and more climate protection.

The local heating network on the site will be much easier to set up than connecting to the district heating network.

Because the latter first has to lead to the former Neckermann site in the east of Frankfurt, as there are currently no hot water pipes along Hanauer Landstrasse.

However, Mainova has already completed the plans for expanding the network from the city center to the biogas plant in Fechenheim and has already started construction.

Heat pumps as an intermediate stage

The problem of large temperature differences remains: Data centers that have to cool their server rooms have a lot of waste heat to offer, but with temperatures of around 30 degrees Celsius, this is far too cold for the district heating supply, which is more like 80 degrees.

The rough plan therefore envisages Mainova installing several large industrial heat pumps in a listed boiler house that is still preserved on the site.

The temperature is then increased there with the help of electricity, only then can the heat be released into the grid.

The amount of investment required for this will be determined in the course of the feasibility study.

Digital Realty is investing around one billion euros in the location, eleven data centers with a total of 100,000 square meters of IT space are planned.

The first, which is located in a new building behind the listed mail-order company building, has just been completed. The 4,500 square meter area is now being occupied by customers who are setting up their servers there.

Meanwhile, the next two data centers are under construction, they should also be connected to the grid next winter, and in the summer the builders want to inaugurate the substation that is being built to supply the giant data center with a total output of 200 megawatts.

With the increasing number of data centers in Frankfurt and the Rhine-Main region, the discussion about their resource consumption has recently become louder and louder.

The buildings, which contain the digitization hardware, so to speak, for storing, processing and forwarding data, together replaced the airport as the largest consumer of electricity a few years ago.

Their consumption of space and the high cooling requirements, which produce the mostly unused waste heat, are also criticized.

The Neckermann project is the second in Frankfurt that wants to change something.

The cooperation between the operator Telehouse and the developer of a housing estate in the Gallus district is much closer to completion, where 1300 residential units are to be heated via a local heating network with the excess energy from data processing.

In purely mathematical terms, as scientists announced a few years ago, there are so many data centers in Frankfurt that all private households could be supplied with heat in this way.