Now you can potentially charge your cellphone battery just by walking with a new charger which can be fitted with the sole of your shoes and produce power when you walk.
Mobile phone company European Telco Orange has developed a charging prototype - a set of thermoelectric gumboots or Wellington boots with a 'power generating sole' that converts heat from the wearer's feet into electrical power.
The boot was designed by Dave Pain, managing director at GotWind, an energy firm.
Pain said the boot uses the Seebeck effect, named after physicist Thomas Johann Seebeck, in which a circuit made of two dissimilar metals conducts electricity if the two places where they connect are held at different temperatures, reported TVNZ.
"In the sole of the Wellington boot there's a thermocouple and if you apply heat to one side of the thermocouple and cold to the other side it generates an electrical charge," Pain said.
"That electrical charge we then pass through to a battery which you'll find in the heel of the boot for storage of the electrical power for later use to charge your mobile phone."
These thermocouples are connected electrically, forming an array of multiple thermocouples. They are then sandwiched between two thin ceramic wafers.
When the heat from the foot is applied on the top side of the ceramic wafer and cold is applied on the opposite side, from the cold of the ground, electricity is generated.
But the power boots have one drawback. You need to walk for 12 hours to generate one hour's worth of charge.
Pain, however, said his company was working on improving the technology, which could then also be used in other forms of clothing.
"The technology's not just limited to footwear, or indeed boots, but you could for example make clothing out of it, you know, a headband, for example," he said.