Excess heat produced across Europe could almost power the entire region but preventing this waste is largely being ignored as a solution to the energy crisis, say environmental experts.
“The global energy crisis is a wakeup call to stop wasting energy,” said Toby Morgan, senior manager for the built environment at Climate Group, an environmental not-for-profit. “Now, more than ever, we need to make better use of the energy we already produce, we simply can’t afford to let it literally escape out the window. Energy efficiency improvements, like capturing and recycling excess heat, are absolutely critical to lower fossil fuel demand and lower bills.”
A report published this week by the global engineering company Danfoss estimated that in the EU alone, excess heat was equal to 2,860 TWh a year, almost the same as the EU’s total energy demand for heat and hot water.
Surplus heat is released into the air from a wide range of sources, including supermarkets, transport networks, data centres and commercial buildings. Much of this can be captured and used via existing heat recovery technologies, such as heat pumps, plus more efficient air conditioners and manufacturing machinery according to the authors of the report. Other solutions include improved urban planning and district energy systems based on networks of renewable energy supplies for both heating and cooling.
Brian Vad Mathiesen, a professor in energy planning and renewable energy systems at Aalborg University, led the research cited in the report that builds on his team’s previous Heat Roadmap Europe projects. “The amount of cities, regions and countries in Europe which waste heat while spending billions on natural gas or electric heating is mind-blowing,” said Vad Mathiesen, warning that Europe’s energy security was at stake.
“Take the Netherlands – there is virtually no district heating even though there is almost twice the amount of waste heat compared to the heat demand. Denmark is the same size but has towards 60% percent district heating with only one third of the population. The use of waste heat is certainly not connected to technical differences. While the physical laws are the same, the political will and traditions are very different.”
There was “huge, unharnessed potential” to the excess heat produced by heavy industry, such as chemical manufacturing, steel and cement production. In the EU, that amounts to more than 267 TWh a year, more than the combined heat generation of Germany, Poland and Sweden in 2021.
Data centres are also major consumers of electricity. In 2020, European data centres consumed about 3.5% of the region’s electricity demand, according to ReUseHeat, an EU project that explored barriers to urban heat recovery. The report highlights that the UK has an abundance of excess energy, including from 456 data centres. “That’s third most in the world, just behind Germany and the US,” explains Kim Fausing, the president and chief executive of Danfoss, who believes recycling heat is a crucial step towards a green transition.
“If businesses were to harness all the excess heat from these centres, the emissions savings and revenue from selling this heat would be highly significant. In Greater London, we have identified at least 648 eligible excess heat sources, including data centres, underground stations, supermarkets, wastewater treatment plants, and food production facilities. Why aren’t businesses and local government organisations using these?” said Fausing, adding that London’s excess heat equated to 9.5 TWh a year, roughly the amount of heat required to heat 790,000 households. “Reusing excess heat offers incredible opportunities for businesses throughout the UK to reduce their emissions, save money and make money. What are we waiting for?”
To rapidly tackle the energy crisis, Vad Mathiesen proposes a heat planning directive that enables local authorities to plan according to local conditions. This would involve mapping existing waste heat sources in greater detail, then proposing thermal networks that distribute heat more effectively and initiatives that improve energy efficiency in buildings.
“Energy efficiency needs to be a top priority for any business or government, particularly during an energy crisis,” said Morgan, who advises every corporate net zero commitment to include a time-bound energy efficiency target, and for governments to incentivise the uptake of energy efficient technologies. “Energy efficiency improvements are climate critical. The time for action is now.”
