‘World’s largest untapped energy source’: How waste heat could help Europe end its reliance on gas

“We are throwing away energy that we have already paid for." Capturing and reusing waste heat could be the next “breakthrough” in Europe’s energy security and competitiveness – helping sever its reliance on gas. A new report from Danish engineering firm Danfoss found that two-thirds of global energy was wasted as heat in 2024. As energy demand continues to increase, this is expected to hit 55 per cent by 2030. It’s why experts are now describing waste heat from facilities such as supermarkets, factories, wastewater treatment plants and data centres as the world’s “largest untapped” energy source. However, governments are lagging when it comes to unlocking its potential. How much heat does Europe waste and how can it be reused? Waste heat is the excess warmth given off by everyday processes, such as a supermarket running its refrigerators. Instead of letting this escape into the air, which risks contributing to the urban heat island effect, it can be captured. This is usually done using heat pumps that “upgrade” the temperature and then pipe the heat into the same building or a nearby district heating network that provides spaces with heating and hot water. One aluminium manufacturer in Denmark has stopped using gas on-site through this process, which is projected to save the annual heating and hot water gas use of 132 Danish homes. The analysis states that reusing waste heat could save Europe a staggering €140 billion a year, based on the 3,1000 TWh that was dumped in 2023. It means that Europe’s waste heat alone could power the entire city of Paris for 48 years. In Germany, existing industrial waste heat emitters could supply more than 30 per cent of the country’s district heating demand. This doesn’t include data centres, which experts say could push the coverage considerably higher – considering that the country has more than 3,000 servers already. Europe ‘cannot afford’ wasting heat “We’re throwing away energy we’ve already paid for,” says Kirstian Strand, President of Danfoss Climate Solutions. “Waste heat is one of the world’s biggest untapped energy sources and reusing it is one of the fastest ways to strengthen Europe’s competitiveness, energy security and resilience. We cannot afford to keep letting it go to waste.” Strand argues that to make the most out of waste heat, industry must make heat recovery “standard practice”. Energy operators also need to make connections easier while governments need to remove the barriers that make electricity more expensive than gas for these investments. “Get those pieces in place and waste heat stops being waste,” he adds. “It becomes a source of cheaper energy, greater resilience and stronger competitiveness.”