The thermoelectric process is the direct conversion of heat into electricity and back again in the heating or cooling of an object. Thermoelectric materials can be used to measure temperature changes, change the actual temperature of a object, and generate an electrical charge, which can be used to generate power. In 2011, thermoelectric materials too inefficient to be useful, but automotive engineers are attempting to use them to glean wasted heat energy from a vehicle and turn it into usable electricity. Researchers are attempting to increase the efficiency of thermoelectric materials to make them more economical so they can be used to create low cost and more efficient refrigerators, air conditioners, and other devices that require cooling.
Thermoelectric processes occur because of the Peltier effect, which is the cooling and heating of opposite junctions in electrical circuits containing dissimilar semiconductors. Thermoelectric materials may be used to create cooling devices or to provide refrigeration. One of the common thermoelectric materials used today is bismuth telluride, an expensive compound that can cost as much as $1,000 US dollars (USD)/lb ($2,000 USD/kg). When properly prepared, this thermoelectric material produces reliable temperature changes anywhere between 14 to 266 degrees F (-10 to 130 degrees C). Thermoelectric systems perform reliably and precisely without the noise of conventional heating, cooling, and refrigeration systems and without environmentally harmful chlorofluorocarbons (CFCs).
For several years, the National Aeronautics and Space Administration (NASA) has harnessed the power of thermoelectric materials to power space probes in the deepest reaches of space, so far from the sun that solar panels are useless. The process involves imbedding nuclear material in a radioisotope thermal generator, in which the radiological decay produces heat energy that is then converted into electricity to power the probe. This is the same process that automotive engineers are trying to harness from the exhaust heat of car engines — heat which can be converted into electricity to power the car.
Research and development in thermoelectric materials is being conducted by the Energy Frontier Research Center at the Massachusetts Institute of Technology (MIT). There, researchers and scientists have made some rather significant discoveries, such as the coupling of thermal disorder and electronic structures at a finite temperature. The current challenges in this field are identifying or synthesizing new, as yet undiscovered, materials with more efficient thermoelectric capabilities. Advancements in this field may enable the development of materials that generate electricity from waste heat, providing a sustainable global energy solution.