According to a new report released by Scottish Renewables, a massive 921 million litres of water are flushed down drains and toilets in Scotland every single day. According to the new data, this sewer water contains sufficient heat to warm a city the size of Glasgow for more than four months per year.

Apparently the water in the UK sewers is around 21C, leading the group to claim that renewable energy technologies such as wastewater recovery systems and heat pumps could easily be utilised to harness the energy potential in the sewer water.

Scotland’s daily 921 million litres of wastewater and sewage are transported to more than 1,800 wastewater treatment facilities via more than 31,000 miles of sewers. If this warmth could be captured, it could prevent in excess of 10,000 tonnes of harmful CO2 entering the atmosphere every year, according to data produced by utility Scottish Water subsidiary Scottish Water Horizons.

The organisation is now using heat maps to explore other locations where heat recovery schemes could be developed, and 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,” she added.

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

“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 cost, carbon and wider environmental benefits.”

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