Thermoelectric materials: efficiencies found in nanocomposites

Thermoelectricity is the conversion between heat and electricity. All materials exhibit thermoelectric effects but the name 'thermoelectric materials' is used to describe the materials that are good at converting heat to electricity. 

Uses for thermoelectric materials 

Thermoelectric materials are used in niche cooling applications, for example to maintain very stable temperatures in lasers and optical detectors, and they are often found in office water coolers. They are also used in space exploration to convert heat from a radioactive material into electricity. 

The current focus on energy sustainability and stricter legislation on the emissions of CO₂ imposed on automobile manufacturers has sparked a great deal of interest in these fascinating materials. 

Only about a third of the fuel energy is converted into mechanical energy in an internal combustion engine with the remainder lost as heat. A thermoelectric generator harvests waste heat from the exhaust gases, which are at a temperature of 300-500ºC, and turns this into electricity. State of the art modules generate about 1 kW, which can be used to power the electrical equipment in the car. This allows for a smaller alternator, which reduces the roll friction, leading to an increase in fuel efficiency and reduced CO₂ emissions.