Harnessing the power of poo… no really!

Imagine turning your waste into warmth. Well, that’s exactly what we’re doing. From sewer to superhero, we’ll be heating homes – and businesses - with waste as part of a groundbreaking project in partnership with Severn Trent Water and Horiba MIRA.

Having secured government funding from the Ofwat Innovation Fund, we’ll be developing a system alongside Horiba-MIRA to capture waste heat from sewers and use it to heat homes and businesses - supporting our customers in keeping their bills low, reducing carbon generation, and itching ever closer to achieving the UK’s net zero targets.

And the potential is huge… UK water companies treat approximately 11 billion litres of wastewater every day, which could offer around 400 TWh of renewable heat – that’s enough to heat 33 million homes in the future!

Warming up to the idea of sewer heat?

Using an in-sewer heat capture solution means the system can be set up close to where the heat is needed, unlike options that capture heat from a sewage treatment works. This means the system can be placed close to where the heat will be used, reducing the amount of additional infrastructure required – helping cut unnecessary costs.

The project includes installing the UK’s first in-sewer wastewater heat recovery system and an energy centre at Horiba MIRA’s technology park in Warwickshire, serving as a pivotal testbed for this innovative venture. Data and learnings from the project will be openly shared with other water companies across England and Wales, offering the potential to expand and grow these networks in the future.

The project will build on our extensive experience of delivering a similar system in Germany – where a former department store in Berlin was transformed into a modern office building, supplied with heating and cooling from wastewater via a 200-meter-long heat exchanger.

How does it work?

Wastewater has a year-round constant temperature of up to 20°C, and this heat would usually be released back (and unused) into the surrounding soil. If we take Berlin’s project as our example, here, a 100-year-old gravity sewer with a two-meter diameter enables a withdrawal power of more than 600 kilowatts (kW).

A stainless-steel heat exchanger then extracts the existing heat from the wastewater, after which a large heat pump increases the temperature of the heat generated to heat the building. In the summer, the principle is reversed, and the channel can be used as an efficient source of cooling. Smart, really.

So next time you flush – you may very well be helping heat up your own home – or your neighbours!