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Waste not Want not

Recycled Heat from Data Centres is Warming Homes


Every time we upload a selfie, chat online or stream a video we are transmitting data to and from a Server. We virtually store all these files in the Cloud and they have a physical backbone keeping it all running smoother: a data centre.

Denmark is one of the cooler Nordic countries and there, how the internet is being used is actually helping to warm people’s homes. Odense Data Centre is providing 24/7 services for Meta applications Facebook, Instagram, WhatsApp, Messenger – pictures, videos stories – and this requires huge amounts of energy. This produces a lot of heat – it can feel like being in a sauna – in many data centres, the heat given off is lost or wasted. In Odense DC, the hot air is trapped behind the servers and then put to use.

What happens to the heat coming off the servers here?

The heat goes up to the roof to where there are cooling units and when it reaches the rooftop, the hot air flows through almost 200 heat exchanges. Cold water from a district heating system in the city is swapped for warm water, a heat exchange with warm elements exchanged for cold.

Residual cool air is left over from this process and that’s used to help cool all the hot servers.

Across from the data centre, a pump station is filled with different coloured pipes carrying water: red for hot, blue for cold. When the station receives the heat, it is elevated from 27 degrees celsius to 70 to be able to put it in the district heating grid. District heating is a community-wide heating system that’s common in Scandanavia.

Odense is the 3rd largest city in Denmark, with almost 200,000 residents and approximately 100,000 households and this plant is providing heat for more than 10% of these. There’s no need for a boiler because the heat is coming from the pipes and payment is based on usage. Seems like a sensible way for households to avail of heat.

In Finland, Microsoft and energy firm Fortum are planning the world’s biggest project to heat homes, services and businesses with sustainable waste heat from data centres.