New research is paving the way to power our devices by powering up our fitness.
Thermal energy and solar energy are not new, but as researchers have learnt more about how to harvest that energy and convert it into power, they turned their attention to turning body heat into electricity.
This week at the 2017 Big Ideas Festival event, Professor Jun Chen of the University of Wollongong, spoke about his ongoing research into the area.
Eight years ago he, and an international team of researchers were tasked with exploring how to harness the unused heat from the pipelines at oil-based industry to create renewable power.
His team at the ARC Centre of Excellence for Electromaterials Science (ACES), then started thinking about other ways to capture the heat for power, including using our body's natural heat.
"Our body's temperature is different to the temperature in the environment," Chen explains. "Skin temperature is about 26 to 35 degrees ... and inside we always keep our body at 36-38 degrees – it's a very reliable temperature."
It is the difference between our body's temperature and the outside temperature that is the key and the technology works by using electrodes on either side of the fabric to convert this difference into an electric current that can charge small medical devices, fitness trackers or smart watch.
"Even when we are doing nothing as adults we are losing 50 to 100 volts per day, through the heat exchange with our environment," Chen says.
We don't need to convert all of the body's heat, just a small portion, he adds. A wristband or shirt, for instance, could be powerful enough to charge a small medical device, a Nintendo Wii (14 watts), mobile phone (about 1 watt) or a laptop (45 watts).
While the more we move, the more energy we can generate, our mood can also make a difference.
"If we are happy, your body temperature goes up by about 4 degrees," Chen says, suggesting we can "power" tech with happiness as well as fitness.
The challenge was that the heat-capturing technology was not user-friendly. "The device is rigid, it's not flexible or comfortable or wearable," Chen says.
So they began working with smart textile designers to create wearable technology that is flexible and can integrate into the clothes fibres to capture the heat and transform it into energy to power our electronic devices.
It's still early days. Chen hopes to eventually bring on industry partners to take the technology one step closer to market, which is at least five years away.
There are still issues of production scale cost and fabrication to resolve as well as continuing to refine the technology. In terms of the safety of such a product, he explains that because it's attached to the skin there are "biosafety issues".
"We tried to choose all the biomaterials that have passed all the medical tests already," he says.
Eventually, the fitness industry will be one of the "key markets".
"When we do activities our body temperature is going up – you are generating energy you can harvest," Chen says. "Also, while you are doing fitness, people can monitor your personal healthcare parameters. Especially in the sport's activities, this has a big potential market for us."