Sustainable Energy

Technology could harness warmth from sewers to heat a city the size of Glasgow over winter, study says

Freer Law | iStock | Getty Images

Sewers in Scotland are home to enough discarded and natural heat to warm a city as big as Glasgow for over four months per year, according to new research.

In a news release on Thursday, Scottish Renewables said that 921 million litres of wastewater and sewage were flushed down toilets and plugholes in Scotland daily.

With water in U.K. sewers potentially as warm as 21 degrees Celsius, the environmental group said capturing its warmth could stop over 10,000 tonnes of CO2 entering the atmosphere.

Figures produced for Scottish Renewables by Scottish Water Horizons showed how the energy potential of sewers could be captured using technologies such as heat pumps and waste water recovery systems.

"These new figures show the enormous scale of the energy we are literally flushing away every day," Scottish Renewables' policy manager, Stephanie Clark, said in a statement.

"Water which is used in homes and businesses collects heat from the air around it, as in a toilet cistern, or is heated, as in dishwashers and showers," Clark added.

"That's in addition to the energy that it gains from the sun when stored in reservoirs. Technology now exists which allows us to capture that energy, and waste heat can play an important role in helping us reach our challenging climate change targets."

Scottish Water Horizons' business development manager, Donald MacBrayne, said that water flushed down the drain at homes and businesses represented a significant source of thermal energy.

"Usually, this heat is lost during the treatment process and when treated effluent is returned to the environment," he said. "By tapping into this resource using heat recovery technology we can provide a sustainable heating solution which brings both cost, carbon and wider environmental benefits."