Body heat may soon recharge cell phones

Washington, Jan 12 (UNI) You can soon charge your cell phone and other electronic items by your own body heat, according to a new research.

Scientists have developed a technique to harness energy now lost as heat during the production of electricity through the use of synthesised silicon nanowires, the sudy said.

The far-ranging potential applications of this technology include a hydrogen fuel cell-powered 'Freedom Car', and personal power-jackets that could use heat from the human body to recharge cell phones and other electronic devices.

''This is the first demonstration of high performance thermoelectric capability in silicon, an abundant semiconductor for which there already exists a multibillion dollar infrastructure for low-cost and high-yield processing and packaging,'' said Arun Majumdar, a mechanical engineer and materials scientist with joint appointments at the US Department of Energy's (DOE) Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) at Berkeley, who was one of the principal investigators behind this research.

''We've shown that it's possible to achieve a large enhancement of thermoelectric energy efficiency at room temperature in rough silicon nanowires that have been processed by wafer-scale electrochemical synthesis,'' said chemist Peidong Yang, the other principal investigator behind this research, who also holds a joint Berkeley Lab and UC Berkeley appointment.

''Nearly all of the world's electrical power, approximately 10 trillion Watts, is generated by heat engines, giant gas or steam-powered turbines that convert heat to mechanical energy, which is then converted to electricity,'' Mr Majumdar said.

Much of this heat, however, is not converted but is instead released into the environment, approximately 15 trillion Watts. If even a small fraction of this lost heat could be converted to electricity, its impact on the energy situation would be enormous, he added.

''Thermoelectric materials, which have the ability to convert heat into electricity, potentially could be used to capture much of the low-grade waste heat now being lost and convert it into electricity,'' Science Daily quoted him as saying.

''This would result in massive savings on fuel and carbon dioxide emissions. The same devices can also be used as refrigerators and air conditioners, and because these devices can be miniaturised, it could make heating and cooling much more localised and efficient,'' he added.

''You can siphon electrical power from just about any situation in which heat is being given off, heat that is currently being wasted,'' said Mr Majumdar.

''For example, if it is cold outside and you are wearing a jacket made of material embedded with thermoelectric modules, you could recharge mobile electronic devices off the heat of your body. In fact, thermoelectric generators have already been used to convert body heat to power wrist watches,'' he concluded.

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