One of the UK’s largest low-carbon heating systems will soon begin warming homes and offices in London’s Square Mile by capturing heat from more than 650ft below the streets of the City. The £4m scheme, to be housed in the historic Port of London Authority building on Charterhouse Street next to Smithfield Market, will provide the same amount of heat as used by 2,300 average UK homes with 50% less carbon emissions. Built by the energy company E.ON UK, it will use a heat pump and three 650ft boreholes to tap the natural warmth of the Earth, and will also capture the heat created by a nearby gas plant that has helped to power London’s financial district since 1993. The new project will extend the existing Citigen plant, which uses a heat network connected to a small gas-fired power plant to generate enough electricity and heating for the equivalent of more than 11,000 homes for local offices. Heat networks, and heat pumps, are expected to become a major part of the government’s plan to reduce the UK’s reliance on fossil fuels for heating homes and businesses in order to cut carbon emissions to net zero by the middle of the century. Lord Callanan, the energy minister, said E.ON’s heat network was “a commercial vote of confidence” in low-carbon heating technologies, “meaning homes and businesses across the City of London will benefit from clean heat”. “Heating in buildings forms a significant part of the UK’s carbon footprint, so changing how we warm and cool our homes and workspaces is a vital part of eradicating our contribution to climate change by 2050,” he added. Michael Lewis, the chief executive of E.ON UK, said meeting the UK’s low-carbon heating challenge will mean “reimagining how energy is provided to homes, businesses and cities”. “In taking the next step and installing heat pump and geothermal technology at Citigen we’re making a powerful statement of what can be done to reduce carbon usage on a large scale,” he said.