Data center firm Digital Realty and German energy firm Mainova AG are partnering for a potential waste heat project in Frankfurt.

The two companies have signed a letter of intent for a joint project for the sustainable use of waste heat from an upcoming campus Digital Realty is developing in the German city.

Digital Realty is currently building a massive new campus in Digital Park Fechenheim, the former headquarters of the Neckermann mail-order company.

The companies said they are conducting a feasibility study examining whether the waste heat from one of the data centers can be fed into Mainova's district heating network in the future.

According to current plans, up to 20MW of waste heat should be provided for the district heating system, totaling the heating requirement of approximately 3,600 households. The system is also planned to supply heat to the 18,000 sqm (193,750 sq ft) on-site office and storage space at the park.

“The use of waste heat from data centers is an important factor in resource conservation, now and in the future. I am pleased to be initiating another lighthouse project for the industry together with our partner Mainova, which will also bring us closer to the international goal of operating data centers even more sustainably," said Volker Ludwig, managing director, Digital Realty Germany.

Mainova chief technology officer Martin Giehl added: “We are pushing ahead with the decarbonization of our heat supply in a technology-neutral and consistent manner. The cooperation with our partner Digital Realty will enable us for the first time to integrate data center waste heat into our district heating system. This is another important step for the energy transition and climate protection. Everyone involved in the project and the city of Frankfurt will benefit from this in achieving their climate protection goals.”

In August 2021, Digital Realty's now-rebranded Interxion unit laid the foundation stone for its new Digital Park Fechenheim data center campus in Frankfurt and began work on the first FRA17 data center at the site.

When fully built out – Digital Realty is suggesting as early as 2028 – the park will host 11 data centers and an IT area of ​​100,000 square meters (1 million sq ft) and 200MW of capacity. FRA17 was due to go live last year and is now listed on the company's website.

Based in the east of the city at the former headquarters of the German mail-order company Neckermann, the park includes the Egon-Eiermann building. Designed by German modernist architect Egon Eiermann and built around 1959 in 180 days, the seven-story concrete building is seen as one of the earliest examples of the modern industrial age. Neckermann went into bankruptcy in 2012; Interxion acquired the site in 2020.

FRA18 will see Digital Realty expand the Eiermann building itself; the front building and the facade with around 1,000 windows will be retained while the rest of the building will be converted to house a 45,000 sqm (484,000 sqft) data center. Work on FRA18 was due to begin in 2022.

Mainova also noted there is a listed boiler house in the Digital Park, in which the company intends to install several large industrial heat pumps that will raise the waste heat from the data center to the required temperature level for reuse. In order to connect the area to the grid, the regional energy supplier is also planning to build a new district heating line in the immediate vicinity of the park.

Mainova subsidiary Mainova WebHouse is developing a 30MW data center in Frankfurt.

The German city, traditionally one of the major European data center hubs, last year introduced new regulations designed to limit where such developments could be located, and require more efforts around district heating networks.