UPI.com, March 9, 2010
A team of Massachusetts Institute of Technology scientists say they’ve discovered a phenomenon that might lead to a new way of producing electricity.
The researchers, led by Associate Professor Michael Strano, said their discovery of the phenomenon that causes waves of energy to shoot through carbon nanotubes — described as thermopower waves — is similar to flotsam being propelled along the ocean’s surface by waves.
The scientists said a thermal wave — a moving pulse of heat — traveling along a submicroscopic nanotube can drive electrons along with it, creating an electrical current.
Because it is such a new discovery, Strano said it’s difficult to predict what the practical applications will be. But he suggests it might enable new kinds of ultra-small electronic devices — for example, devices the size of grains of rice, or perhaps a sensor or treatment device that could be injected into the body.
In theory, he said, such devices could maintain their power indefinitely until used, unlike batteries nicwhose charge gradually diminishes as they remain unused.
The research that included doctoral student Wonjoon Choi is reported in the journal Nature Materials.
From the peswiki @ MIT, here’s how they describe it works:
Rechargable and disposable batteries use a chemical reaction to produce energy. The problem is that after many charges and discharges the battery loses capacity to the point where the user has to discard it.
However, capacitors contain energy as an electric field of charged particles created by two metal electrodes. Capacitors charge faster and last longer than normal batteries.
The problem is that storage capacity is proportional to the surface area of the battery’s electrodes, so even today’s most powerful capacitors hold 25 times less energy than similarly sized standard chemical batteries.
MIT researchers have solved this by covering the electrodes with millions of nanotubes, which are essentially tiny filaments. The nanotube filaments increase the surface area of the electrodes and allow the capacitor to store more energy.
The MIT capacitor thus combines the strength of today’s batteries with the longevity and speed of capacitors.