Wastewater could heat cities the size of Glasgow, finds report

Sewers in Scotland contain enough heat to warm a city the size of Glasgow for more than four months a year, according to new data.

Jun 15th, 2017
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GLASGOW, Scotland – Sewers in Scotland contain enough heat to warm a city the size of Glasgow for more than four months a year, according to new data.

Figures released by Scottish Renewables found that 921 million litres are flushed down toilets and plugholes in Scotland daily.

With this water in UK sewers as warm as 21C, the group claimed that renewable energy technologies like heat pumps and wastewater recovery systems could be used to harness that energy potential.

Capturing such warmth could prevent more than 10,000 tonnes of harmful CO2 entering the atmosphere every year, new analysis has shown.

Scotland’s daily 921 million litres of wastewater and sewage are transmitted through more than 31,000 miles of sewers to over 1,800 wastewater treatment facilities.

The data was produced by utility Scottish Water subsidiary Scottish Water Horizons.

Heat maps are now being used by the organisation to explore locations where heat recovery schemes could be developed

The Scottish Government’s draft Energy Strategy contains an ambitious proposal that 50% of all energy (heat, electricity and transport) should come from renewable sources by 2030.

Stephanie Clark, policy manager at Scottish Renewables, said: “These new figures show the enormous scale of the energy we are literally flushing away every day.

“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. 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.”

Donald MacBrayne, business development manager with Scottish Water Horizons, added: “Water that is flushed down the drain from homes and businesses represents a significant source of thermal energy.

"Usually, this heat is lost during the treatment process and when treated effluent is returned to the environment. 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.”


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