A Breakthrough in Artificial Photosynthesis

“We’re almost at a 1 percent efficiency rate of converting sunlight into isopropanol,” Nocera said. “There have been 2.6 billion years of evolution, and Pam and I working together a year and a half have already achieved the efficiency of photosynthesis.”

Harvesting sunlight is a trick plants mastered more than a billion years ago, using solar energy to feed themselves from the air and water around them in the process we know as photosynthesis.

Scientists have also figured out how to harness solar energy, using electricity from photovoltaic cells to yield hydrogen that can be later used in fuel cells. But hydrogen has failed to catch on as a practical fuel for cars or for power generation in a world designed around liquid fuels.

Now scientists from a team spanning Harvard University’s Faculty of Arts and Sciences, Harvard Medical School and the Wyss Institute for Biologically Inspired Engineering have created a system that uses bacteria to convert solar energy into a liquid fuel. Their work integrates an “artificial leaf,” which uses a catalyst to make sunlight split water into hydrogen and oxygen, with a bacterium engineered to convert carbon dioxide plus hydrogen into the liquid fuel isopropanol.

The findings are published Feb. 9 in PNAS. The co-first authors are Joseph Torella, a recent PhD graduate from the HMS Department of Systems Biology, and Christopher Gagliardi, a postdoctoral fellow in the Harvard Department of Chemistry and Chemical Biology.

Pamela Silver, the Elliott T. and Onie H. Adams Professor of Biochemistry and Systems Biology at HMS and an author of the paper, calls the system a bionic leaf, a nod to the artificial leaf invented by the paper’s senior author,Daniel Nocera, the Patterson Rockwood Professor of Energy at Harvard University.

“This is a proof of concept that you can have a way of harvesting solar energy and storing it in the form of a liquid fuel,” said Silver, who is a founding core faculty member of the Wyss. “Dan’s formidable discovery of the catalyst really set this off, and we had a mission of wanting to interface some kinds of organisms with the harvesting of solar energy. It was a perfect match.”

Read more: A Breakthrough in Artificial Photosynthesis

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Artificial photosynthesis with the help of an all-in-one catalytic system for the first time