- More than 750,000 homes could benefit from £90 million for new heat networks and repairs to inefficient existing systems.
- The £41 million London Strategic Heat Main is designed eventually to serve up to 650,000 homes, but remains subject to planning and substantial private investment.
- The package marks a shift towards city-scale heat infrastructure, although it remains modest beside the capital required for nationwide deployment.
A planned heat network running alongside and beneath the River Thames has secured £41 million of government support as part of a £90 million package intended to reduce gas use and improve heating systems serving more than 750,000 homes.
The London Strategic Heat Main would capture surplus heat from data centres, factories and energy-from-waste facilities before distributing it through a network of hot water pipes. The initial route would cross Bexley, Greenwich, Lewisham, Southwark, the City of London, Lambeth and Westminster.
The system could eventually serve 650,000 homes and more than one million residents, according to the Department for Energy Security and Net Zero. Extensions towards Barking and Dagenham, Tower Hamlets and Kensington and Chelsea are also under consideration, according to reports.
Ministers say the award could help unlock £5 billion of wider investment and support jobs in tunnelling, engineering and river transport. Those are prospective benefits, however: the network still requires planning permission, detailed engineering and substantially more capital.
Imaginative engineering concept
The project’s interim design is unusual: while a permanent heat transmission tunnel is developed, surplus heat would be transported along the Thames using electrically powered barges.
The government describes this as moving hot water approximately 25 km a day. According to project partner Sunamp, as much as 240 MWh of heat a day would be stored in shipping container sized thermal batteries and carried around 28 km from Cory’s Riverside energy-from-waste plant in Bexley to Pimlico.
Each barge could carry 40 thermal battery containers. The heat would be discharged through a connection to the Pimlico District Heating Undertaking, which already supplies more than 3,000 homes and 50 commercial and community buildings.
The funding package also includes £9.7 million to extend Bradford’s network to 255 homes, a hospital and seven schools and colleges; £11.5 million for a Bexley and Greenwich network that could serve 100,000 homes; £11.4 million for an aquifer-based Marble Arch system; and £3.9 million for an extension in Solihull.
A further £13.3 million will repair 76 existing networks in England and Wales, including replacement of leaking pipes, insulation and heat interface units. At one Brighton development, earlier improvements cut gas consumption by 50% and reduced annual household bills by £438.
“This funding is a clear signal that heat networks matter,” said Meghan Newman of ADE: Heat Networks.
Heat networks can capture energy that would otherwise be wasted and avoid the cost and disruption of fitting individual heat pumps in dense urban areas. They may also provide valuable flexibility by storing heat when electricity is plentiful.
But the economics remain challenging. Networks require high initial capital expenditure, predictable customer demand and strong consumer protection because connected households cannot easily change heating supplier. Poorly maintained legacy systems have also demonstrated how heat losses and weak controls can erase theoretical savings.
The Thames project could become a national model for reusing urban waste heat. Its real test will be whether the government can turn an imaginative engineering concept into a financeable utility that delivers demonstrably lower bills.
