Heatwaves have pushed Australia's electricity system to the point of failure, but new technology could use this heat to generate clean energy.
New research has found ways to supercharge thermoelectric devices and make them up to three times more effective than standard thermoelectric semiconductors.
Thermoelectric devices – which are built from materials that convert temperature differences into electricity – have existed for some time, but new research is taking them to the next level.
When these semiconductor devices – which contain no moving parts – are exposed to temperature differences, where one end of the material is hot and the other less so, electrons within the material begin to flow from the hot end to the cooler end, creating an electric current.
The higher the difference in temperature the greater the level of current produced and the more power is created, but the level of energy generated is dependant on how well the materials allow the current to flow unimpeded.
To date, these devices have only been used for low energy operations where they can take advantage of waste heat, such as backing up batteries or in space probes, however, recent advancements may raise their potential for larger applications.
Researchers at the Massachusetts Institute of Technology have uncovered a method to triple the efficiency of these devices utilising ‘topological’ materials.
In a paper published earlier this month in the US journal Proceedings of the National Academy of Sciences, the researchers discovered properties which can make different topological materials more effective thermoelectrically compared to other materials.
Using tin telluride and nanostructuring techniques, the researchers were able to improve the thermoelectric materials conductivity by altering their ‘mean free path’, which is the distance electrons of certain energies can easily move before being affected by defects or hitting resistance within the materials themselves.
They found by shrinking the size of the tin telluride material’s nanostructure grain borders – which resemble tiny crystals – they were able to increase the level of electricity conducted by up to three times.
By reducing these grain sizes to around 10 nanometres, or approximately 10 millionths of a millimetre, and shrinking the distance between these borders' boundaries a larger voltage difference could be created.
This process was previously overlooked as it was believed that shrinking the size of the borders would also reduce conductivity.
“We’ve found we can push the boundaries of this nanostructured material in a way that makes topological materials a good thermoelectric material, more so than conventional semiconductors like silicon,” Te-Huan Liu, a researcher from MIT’s Department of Mechanical Engineering, told MIT News.
“In the end, this could be a clean-energy way to help us use a heat source to generate electricity, which will lessen our release of carbon dioxide.”
In Australia, thermoelectric materials are currently being studied for use in concentrated solar thermal systems to make the most out of the heat the process generates.