Concerns about climate change and greenhouse gas emissions are instilling a new dynamism – and fueling something of a renaissance – in alternative energy research and development. It’s increasingly apparent even to lay observers like myself that there’s potential energy – in widely varying degrees and at widely varying scales – in natural processes all around us.
Researchers in Erlangen, Germany, for instance, are developing circuits and medical sensors that can generate electricity from body heat. Actually, scientists and engineers at the Fraunhofer Institute for Integrated Circuits – working with colleagues from the Institutes for Manufacturing and Applied Materials Research, and Physical Measurement Techniques – are using semiconductor elements to build thermoelectric generators that tap into small temperature differentials to produce low voltage electrical currents.
Temperature differences in the tens of degrees are typically required to generate enough electricity to power a cell phone or smaller piece of medical monitoring equipment, which require at least one or two volts.
Conventional TEGs (thermoelectric generators) are able to produce currents of roughly 200 millivolts but the researchers combined components in a new way to create circuits that can operate on 200 millivolts, according to Peter Spies, manager of the IIS sub-project. “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 in an interview.
The researchers are now looking to apply these TEGs in other ways. “Electricity can be generated from heat anyplace where a temperature difference occurs. That could be on the body, on radiators to meter the heating costs, when monitoring the cooling chain during the transport of refrigerated goods, or in air conditioning systems,” Spies said.