The UK government has committed £90 million ($119 million) to expand heat networks that capture waste heat from datacenters and factories to warm homes. The Department for Energy Security and Net Zero says more than 750,000 homes could benefit. The flagship "mega heat project" would push hot water through a tunnel under the River Thames, with £41 million ($54 million) earmarked for the scheme, which the department claims could supply 650,000 London homes with "clean heat." Similar district heating has operated for decades in Copenhagen, Amsterdam, Vienna, and Berlin.
Delivery is far from certain. The government says hot water will initially be carried 25 kilometers along the Thames each day by electric barges from a waste plant near Bexley, with service expected from 2028; the tunnels are hoped to follow in the 2030s. The Register notes that the recently completed Thames "super sewer" took nine years and cost about £5 billion, raising doubts about the tunnel's timeline and final price. The £41 million covers only the barge phase, and no cost estimate has been given for the tunnels.
Efficiency is also in question. The Uptime Institute has noted that datacenter waste heat is often not hot enough for domestic heating, requiring heat pumps that consume additional energy. A 2024 TechUK report found that most UK heat networks are older third-generation systems with lower efficiency, though fifth-generation designs can work with lower-temperature heat. Omdia analyst Alan Howard called the plan "a concept" rather than a project, citing likely engineering challenges and potential cost overruns. Still, a survey by EnergiRaven found about 60% of Britons think datacenter planning permission should depend on supplying excess heat, and 62% would be more supportive of a local project that did so.