Danish Engineers Turn AI Data Centre Waste Heat into District Heating

As AI data centres strain global energy systems, engineers in Denmark are capturing the waste heat these facilities normally vent into the outside air and feeding it into municipal heating networks.

The International Energy Agency reported that data centres used 485 terawatt hours of electricity in 2024 - about 1.5 percent of the world's total energy supply, equal to Germany's entire electricity generation. That share is expected to double to 3 percent by 2030, driven increasingly by AI. The United Nations Economic Commission for Europe has warned that the rapid expansion of hyperscalers and their data centres poses a growing threat to electricity systems worldwide.

At the University of Southern Denmark in Sonderborg, the Bitten supercomputer runs around the clock. Instead of letting its heat dissipate, liquid cooling technology from Danish engineering company Danfoss pumps coolant directly over the processing chips and channels the recovered heat into the town's district heating network, serving 75,000 residents.

Kristian Strand, president of Danfoss Climate Solutions, said the process effectively leaves a tap of hot water coming out of the data centre, usable for heating homes and in industrial processes. Danfoss has calculated that heat wasted across Europe in one year could power Paris for 48 years, and that roughly two-thirds of the world's energy is expelled as excess heat.

Scandinavia has led on recovery, according to Jan Rosenow, professor of energy and climate policy at the University of Oxford, who pointed to Meta's Odense data centre recovering around 100 GWh a year - enough for 6,900 homes - and Stockholm feeding data centre heat into its network since 2014. The United States hosts about 4,000 data centres, drawing 5 percent of the nation's electricity, but recovers very little heat. Rosenow argued data centres should be built where their heat can be used, not just where land is cheapest.

Danfoss also replaced two gas boilers at Sonderborg Hospital with a heat pump system capturing waste heat from MRI scanners and temperature regulation in operating theatres, wards and corridors. Lasse Bo Madsen, head of technical services at the hospital, said the project will pay for itself within two years, freeing money for patient care and new equipment.

Source: Al Jazeera