British trade association Scottish Renewables and utility Scottish Water Ltd. claim that capturing heat from Britain’s age-old sewers system could provide carbon-free heat for more than one-third of London residents, according to a Bloomberg News report. Britain’s sewage pipes trap heat from household appliances, reaching as high as 70 degrees Fahrenheit. If brought back into homes, this heat recycling could provide heat for millions of residents without burning fossil fuels.
According to a 2013 report issued by the United Kingdom Secretary of State for Energy and Climate Change, 70% of the energy used by U.K. industries is for heat generation alone. Amid climate change concerns, the U.K. has sought to lower its carbon footprint while still meeting the heat demand. However, the sewer heat project is not the U.K.’s first go at capturing and repurposing heat from existing processes. In late 2013, London started a project to utilize heat from their subway, also known as "the Tube" as a way of heating 500 homes. By mid-2016, other projects were also under consideration, including geothermal heat and excess heat from industrial machinery.
London's Tube, a source of winter heat
Scottish Water already tested a similar technology at a Scottish university, where it currently supplies 95% of their heat. Further, the U.K. is not the first nation to consider such a project. The European Union’s “Celsius City” project contemplated a similar system in Cologne, Germany in 2013, for heating 70 homes. In the United States, a similar technology was deployed in a building in Philadelphia, Pennsylvania, which cut the building’s heating costs in half. Yet both of these systems were on a much smaller scale than what the U.K. is planning, making Britain’s project the first of its kind to serve such a large population.
Following cuts to government-sponsored programs, these installations have been delayed. The U.K.’s “Community Energy Savings Programme [CESP] Order 2009” created the CSEP program which, until 2012, instilled carbon reduction programs in public utilities, incentivizing them to offer efficiency installations to consumers. However, in 2012 when the CESP program was replaced by the U.K.’s Energy Company Obligation (ECO) program, efficiency installations plummeted by more than 75%. Additional budget cuts in 2013 only exacerbated this.
This is troubling given that the homes in the U.K. are among the most expensive to heat in Europe, making heating a significant concern for many of its 65 million residents. A 2011 report noted that approximately 30,000 “excess deaths” occur each year during the winter, with literature noting “a strong correlation between outside temperature and  mortality rate.” The report showed that for many low-income households, cold temperatures often correlated with income shock, resulting in “heat or eat” trade-offs for those who could not afford to do both.
Given the need for heat and underfunded government programs to help with improving home insulation, recapturing heat from Britain’s sewers may be an optimal solution for some.