Body heat touted as power source
Getting a little hot under the collar?
By Tom Jowitt | Techworld | Published: 14:50, 28 August 2007
German scientists claimed to have a developed a procedure that harnesses body heat in order to generate power, which in the future may be used to power mobile devices.
The Fraunhofer Institute for Integrated Circuits have said that they can use the difference between the body’s surface temperature and that of the surroundings to produce energy which could be used to power medical equipment, such as sensors attached to a body of a patient in an intensive care ward.
Essentially, the system works on the principle of thermoelectric generators (TEG) - semiconductor elements which extract electrical energy from the temperature difference between a hot and cold environment.
Peter Spies, project leader at the institute and his team have apparently improved these thermoelectric generators. Traditionally a temperature difference of several tens of degrees (Celsius) is needed in order to generate enough power. At most, the difference between human bodies and the surrounding environment is only a few degrees.
“Only low voltages can be produced from differences like these,” explains Spies. Traditional TEG produces roughly 200 millivolts, while electronic devices require at least one or two volts.
However, the German engineers have resolved this by combining “a number of components in a completely new way to create circuits that can operate on 200 millivolts.”
“This has enabled us to build entire electronic systems that do not require an internal battery, but draw their energy from body heat alone,” he said.
“We have a working device in our labs” confirmed Spies, who has demonstrated the device at various trade shows. When a hand is placed on a specifically designed pad, “it powers a wireless transceiver and a temperature sensor.”
However Spies admits that the technology is not currently a viable option to power mobile devices, although it does have some battery charging capabilities.
“The problem is the human body is not sufficient to power mobile phones at present,” said Spies. “Perhaps in the future this might be a feasible vision.”
He points out that at a recent trade show in California, aircraft maker Boeing said it was looking to use thermoelectric generator technology to power the switches located in airplane seats.
Spies believes that when further improvements have been made to the switching systems, a temperature difference of only 0.5 degrees will be sufficient to generate electricity.
