Emissions from the past decade have made Europe's recent heat waves worse

Europe possesses the world’s largest untapped energy source – waste heat generated by everyday processes such as refrigeration in supermarkets and data centres. A new report from Danish engineering firm Danfoss highlights that two-thirds of global energy was wasted as heat in 2024, with this figure expected to reach 55 per cent by 2030 as energy demand continues to surge. Experts are now viewing this waste heat as a potential solution to Europe’s reliance on gas.

Waste heat refers to excess warmth generated by various processes. Rather than allowing this heat to dissipate into the atmosphere, it can be captured and utilized. This is typically achieved through heat pumps, which enhance the temperature before piping the heat back into the original building or a nearby district heating network that supplies heat and hot water to multiple spaces.

For instance, an aluminium manufacturer in Denmark has eliminated its on-site gas usage through this process, potentially saving the annual heating and hot water gas usage for 132 Danish homes.

According to the analysis, reusing waste heat could save Europe an estimated €140 billion annually, based on the 3,100 terawatt-hours (TWh) of heat that was discarded in 2023. This means that Europe’s waste heat alone could power the entire city of Paris for 48 years. In Germany specifically, industrial facilities with existing waste heat emitters could potentially supply more than 30 per cent of the country’s district heating demand.

This estimate does not account for the potential contributions of data centres, which experts believe could substantially increase these figures given Germany’s over 3,000 servers.

Kirstian Strand, President of Danfoss Climate Solutions, emphasizes that waste heat is the world’s biggest untapped energy source and reusing it is a swift means to enhance Europe’s competitiveness, energy security, and resilience. "We are throwing away energy we've already paid for," she asserts. Strand advocates for heat recovery to be standard practice in industry, while also encouraging energy operators to facilitate connections and governments to remove barriers that make electricity more expensive than gas for these investments.

Once these elements are in place, waste heat transitions from being waste to a source of cheaper energy, improved resilience, and increased competitiveness.