The 2021 United Nations Climate Change Conference (COP26), hosted in Glasgow, the UK this November, drew much speculation as all eyes watched to see if viable solutions would be rolled out to respond to the challenge of climate change. While such solutions are mainly driven by policies and strategies, science and technology is growing equally prominent in attaining the goal of carbon neutrality and energy transition.

As of now, the world’s primary power source is derived from fossil fuels. While nuclear energy and renewable energy – photovoltaics and wind power – are also used, fossil fuels, which generate carbon emissions, make up a disproportionate share of the total. Furthermore, more than 40% of the energy produced in this manner ends up being wasted as heat energy. If we could somehow harness this heat energy and convert it into useful energy, our efforts would surely contribute to creating a more carbon-neutral society.

The Thermal and Energy Lab or TE Lab directed by Professor Hyungyu Jin at the Department of Mechanical Engineering, POSTECH, explores ways to harness the thermal energy discarded in the power generation process. The Lab is primarily engaged in probing into new thermoelectric devices and materials that directly convert thermal energy into electricity, as well as methodologies that convert or store thermal energy into new energy sources and chemicals such as hydrogen and carbon monoxide.

The thermoelectric devices and materials that the TE Lab studies are different from conventional ones as they leverage spin currents generated within magnetic materials. While existing thermoelectric devices are structurally complicated and their manufacturing process is laborious, thermoelectric devices that leverage spin currents are gaining attention as next-generation devices for their simplified structure and their straightforward principle for generating greater electric energy in proportion to size increases.

Research on thermoelectric devices that harness magnetic substances is still in its nascent phase but is making rapid progress. This is attributable to the application of material design technology powered by machine learning that is deployed for artificial intelligence to eventually improve the accuracy of research and experimentation.

Thermochemical water splitting technology uses thermal energy, that would be otherwise wasted, to produce hydrogen. This is similar to water electrolysis that decomposes water mainly through the use of electricity, but is distinct in that it uses thermal energy in lieu of electric energy. This generates fewer carbon emissions than hydrogen reforming and is economically viable since it uses thermal energy that would be otherwise discarded.

One caveat to thermochemical water splitting is that it requires thermal energy to be very hot – at temperatures no lower than 2,000 degrees. Even with catalysts, temperatures should be above 1,300 degrees with the current level of technology. At the TE Lab, researchers are exploring novel catalysts and reaction mechanisms that enable the decomposition of water through thermal energy at temperatures below 1,000 degrees.

The TE Lab, led by Professor Hyungyu Jin, deals with two kinds of heat: extremely ‘cold heat’, which is approximately 271 degrees below zero and very ‘hot heat’ which can reach as high as 1,500 degrees. Earlier this year, the Lab gained acclaim as the very first lab to be published in Energy and Environmental Science, the most prestigious journal in the energy research sector, wherein it outlined a process to fabricate high-performance thermoelectric devices through the application of magnetic materials. Professor Jin notes “We have clearly set our goal of mitigating environmental and energy crises and this will drive our efforts to produce excellent academic outcomes and commercialize technology”.