Festive warmth and flushed energy: turning body heat (and poo!) into power💩
From bustling crowds to sewage systems, the warmth and waste we generate are being transformed into sustainable energy sources — keeping up cosy for Christmas!
When it comes to warmth, few things are more reliable than gathering close to others – whether it’s huddling together around a cosy fire or snuggling up with a loved one.
Since ancient times, people have huddled together in the winter, not just for comfort, but to keep warm as temperatures drop. And yet, aside from warming our hands with a few breaths on a frosty day, there aren’t many ways we capture and use the heat we naturally generate. So, how close are we to harnessing our own body warmth for good?
The human battery: a timeless source of heat
No, not like the Matrix. We’re not advocating keeping thousands of humans captive to provide power. But, the average human body produces around 100 watts of heat when at rest, rising to 300-400 watts during physical activity – the equivalent of a holiday string of lights left glowing for a full day! Like festive lighting, up to 80% of that energy becomes heat, with most of it radiating into the surroundings.
Innovators are exploring ways to capture this warmth, with small but promising results.
In Stockholm’s Central Station, their heat exchangers (in the ventilation system) convert the warmth generated by its 250,000 daily commuters into hot water, piped to a nearby office building for heating. The festive spirit, quite literally, helps warm up the neighbourhood!
But large-scale projects like this aren’t feasible everywhere. Still, in cities with high foot traffic, heat exchangers might bring extra warmth without additional energy use – capturing a little human warmth along with the holiday spirit.
Body warmth is also finding new applications in personal tech. Thermoelectric materials can generate small amounts of electricity by capturing the temperature difference between body heat and the cooler winter air. Today’s ultra-low-power wearables, like fitness trackers, use this technology to stay powered, hinting at a future where body heat could even run our devices.
Harnessing heat where you least expect it… down the loo!
While body warmth is an age-old source of energy, another surprising contender is rising to prominence: sewage. Yes, poo-powered energy is becoming a reality, offering an innovative way to reduce waste and cut carbon emissions (hold your nose and stay with us!)
Our partnership with Severn Trent Water and Horiba MIRA is pioneering a groundbreaking system that captures waste heat from sewers to warm homes and businesses. Wastewater, with its constant temperature of up to 20°C, provides an untapped source of renewable energy.
Don’t worry though, the water in your house never touches the, ahem, source. It’s what’s called a ‘closed loop’ system where what’s in the two pipe networks never actually meet. Instead, a stainless-steel heat exchanger extracts heat from the wastewater, and a heat pump elevates it to a temperature suitable for heating buildings. Remarkably, the same system can reverse the process in summer, offering cooling instead.
The potential is enormous: UK water companies treat around 11 billion litres of wastewater daily, which could supply renewable heat to 33 million homes. And with the festive season in full swing, the thought of all that extra Christmas dinner contributing to energy generation is both impressive — and perhaps best left unexplored!
Power from the people – and festive spirit?
From the warmth of holiday shoppers to the heat hidden in our sewers, innovative energy solutions are exploring ways to turn the everyday into extraordinary opportunities for sustainability. So next time you feel the warmth of a crowd or flush the toilet, take a moment to think: could you be helping heat your city or even your own home?
Perhaps next winter we’ll not just be sharing festive cheer — we’ll be sharing energy too.