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Development of Carbon-Neutral Artificial Photosynthesis Technology

The Japanese Animation, Conan, the Boy in Future, which was broadcast in Korea in early 1980s, described the landscape of ‘Industria’ where humans baked bread from waste resources, such as plastics, as the world was covered with piles of garbage due to environmental disasters. The viewers at that time must have considered it as just an imagination, but it is likely entering into the real world in the 21st century.
The key word is ‘C1 gas,’ which includes carbon dioxide (CO2), carbon monoxide (CO) and methane (CH4). The utilization of the C1 gases, consisting of a single carbon atom and another element, is drawing keen interest, since carbon-neutrality has become an issue of the times. If six carbon atoms can make starch, can the chimneys of the factory, emitting the exhaust incessantly, be converted to huge storehouses of food in a sense?

|Development of C1 Gas Fixation Technology for Realizing Carbon-Neutrality|

Optical nanoparticles meet acetogen.
Professor Byung Kwan Cho, the Director of the KAIST Institute for the Bio-Century, and his colleagues are searching for the answer from ‘artificial photosynthesis’ technology for efficiently operating the C1 gas fixation cycle of the microorganism, called acetogen. The research group found a method for artificially maximizing the photosynthesis by microbial acetogen. There was an existing artificial photosynthesis technology for the microorganism, which obtains the reducing energy from hydrogen or sugars, not light energy as plants do. The reducing energy from hydrogen gas and so on supplies electrons to acetogen, which fix and reduce carbon dioxide to useful materials, including starch, acetic acid and ethanol.
However, the supply of electrons through hydrogen or sugars or the direct provision by using an electrode has limitations. The culture tank should be huge to supply hydrogen energy as much as it is desired, and the electrode also has problems. The research group tried to overcome the constrains in the efficiency and cost by using highly efficient optical nanoparticles. The chosen strategy is to dividing an electrode in nano-sized particles and attaching them to individual microorganisms to supply electrons.

Carbon Dioxide Recycling in Virtuous Cycle
The significance of the results of the study, published in PNAS USA in 2021 (February 23, online), is that they provide an alternative clue for making tremendous contributions to the reduction of greenhouse gas emission, which is considered as the biggest villain of climate change. The blueprint of ‘carbon-neutral artificial photosynthesis technology,’ drawn by Director Cho, is directed to a greater future.
“What is produced by acetogen through artificial photosynthesis is monomers of plastic. This means that plastics can be produced again by fixing carbon dioxide. It is a virtuous cycle in which plastics are burned to obtain fuels, and carbon dioxide generated from the burning process is returned to plastics. That is the ultimate goal of our research.”

Prof.Byung Kwan Cho
2021 Annual Report

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