Anybody who migrates to smart phones soon begins to question the smartness of it all. While batteries lasted a fortnight or so in vanilla mobile phones, a smartphone typically empties the battery in less than a day. Carrying those bulky rechargers is a remedy worse than malady. How do you power your smart phone for days when you are nowhere near a power source?
A promising innovation by researchers at IIT Bombay and their collaborators at Institute of Aeronautical Engineering Hyderabad and Far Eastern Federal University, Russia holds a ray of hope that it may be possible, sooner rather than later, to be able to find a more efficient source of mobile power than conventional batteries.
Electric batteries are inefficient in terms of energy carried for given weight. For instance, normal batteries can only carry around 1 Mega Joule per kilogram educates Professor Sudarshan Kumar, Department of Aerospace Engineering, IIT Bombay. Whereas hydrocarbon fuels–LPG, Methane, and Kerosene–can carry almost 40 - 50 times more fuel per kilogram.
Of course the solution is simple–convert thermal energy of hydrocarbons into electric energy. Alas, if only it were that simple. The first hurdle is in the fabrication and manufacture of microscopic devices of really small dimensions to convert chemical energy stored in these fuels to thermal energy and then followed to electric energy. Even if one somehow overcomes that hurdle, the real bad news is that at present level of technological development, the level of efficiency in converting thermal energy to electric energy only barely reaches 2.6%, making the entire effort pointless, considering the arithmetic of it all.
However, the latest innovation at IIT Bombay is really promising. The micro combustor based micro thermoelectric power generator design by Professor Sudarshan and other colleagues, leapfrogs the efficiency of energy conversion from 2.6% to a respectable 4.5%, with more improvements possible, thus making conversion of thermal energy to electric energy through a minute device, not only feasible technically but also commercially.
The design by Professor Sudarshan and others relies on Seebeck effect, which simply put means that when there is a circuit connecting two different metals and there is difference in temperature from one junction to another, electricity is generated.
The researchers have fabricated a micro thermoelectric power generator based on Bismuth-Telluride modules. The high temperature end (around 200 degrees Celsius) is created by burning a fuel – LPG in this instance. The low temperature end is normal room temperature. This combination of different metals being connected with a temperature difference generates electricity. Of course, if the room temperature is lower, say 5 degrees Celsius instead of 25 degree Celsius, more electricity would be generated. Apart from including the inner micro-combustor for burning the fuel, the design also includes heat sinks to take away the heat not converted to electric energy. The Micro Thermoelectric Power Generator may cost around Rs. 7000 and their bulk production will bring the costs down.
Going ahead, of course the levels of efficiencies of conversion of thermal energy to electric energy need to improve further, so that use of such Micro Thermoelectric Power Generators becomes a compelling case. Professor Sudarshan educates that efficiency levels have improved slowly from mere 0.1% to 1% and slowly to 2.6% and now to 4.5% in the present innovation. Hence, it would be realistic to hope for better efficiency.