When we think of clean energy sources, we easily associate them with gushing rivers, gusty winds, novel biofuels and even nuclear power. One less-explored clean energy source you may have missed out on is temperature. Specifically, thermoelectric generators, which utilise the waste heat arising from the temperature difference between two surfaces to create electricity.
Thermoelectric generators are already a common feature on NASA spacecraft, but you’re less likely to find them in use on Earth. This is because making thermoelectric generators for such terrestrial applications isn’t easy, said Ady Suwardi, a Principal Investigator at A*STAR’s Institute of Materials Research and Engineering (IMRE).
“Some thermoelectric materials perform well at low temperatures, some perform well at higher temperatures,” Suwardi explained, adding that efficient generators require materials that pair well together—what's known as the compatibility factor.
Along with scientists from A*STAR’s Institute of High Performance Computing (IHPC); A*STAR’s Institute of Sustainability for Chemicals, Energy and Environment (ISCE2); Nanyang Technological University; National University of Singapore; and Tokyo Institute of Technology, Japan, Suwardi sought to find the perfect pair of materials to construct a thermoelectric generator for harvesting waste heat.
They first designed a generator with ‘segmented’ structures made of two compatible thermoelectric materials. They narrowed down compatible materials to GeTe and Bi0.5Sb1.5Te3 (BST), and also optimised the lengths of each leg to achieve the highest possible performance.
“By carefully designing the combination of materials to achieve optimal compatibility factor, we essentially achieved optimal electrical and heat conduction,” Suwardi said, adding that their design reached an extremely high efficiency of power conversion efficiency of 13.6 percent over a wider temperature range than its predecessors.
These exciting results are helping to break barriers to implementing thermoelectric technology towards a sustainable, circular economy, according to Suwardi. The team is optimistic that their thermoelectric generator design could be a robust clean energy solution as the devices require virtually no maintenance and last a long time.
Spurred on by their success, the team is working towards commercialising their technology with an ambitious goal of seeing their generators capture waste heat in real-world settings within the next 3 to 5 years. An example is garbage incinerators—heat from burning landfill waste can be transformed into electricity to power homes.
“This will bring about double benefits: reducing waste heat in the environment, and generating free electricity,” said Suwardi. “Both of these are good for the planet.”
The team is also working on developing a method for turning old solar panels into thermoelectric devices.
The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering (IMRE), the Institute of High Performance Computing (IHPC) and the Institute of Sustainability for Chemicals, Energy and Environment (ISCE2).