Bionic Leaf and Bacteria Convert Sunlight to Liquid Fuel

Harvesting sunlight is a trick that plants have mastered. Now, scientists have created a system that also uses sunlight. The technique has the ability to use bacterial to convert solar energy to liquid fuel.

"This is a proof of concept that you can have a way of harvesting solar energy and storing it in the form of liquid fuel," said Pamela Silver, one of the researchers, in a news release.

The new work utilizes an "artificial leaf," which uses a catalyst to make sunlight split water into hydrogen and oxygen. An engineered bacterium then coverts carbon dioxide plus hydrogen into the liquid fuel isopropanol.

The bacterium itself is called Ralstonia eutropha. Once the hydrogen is fed to this bacterium, an enzyme takes the hydrogen back to protons and electrons, and then combines them with carbon dioxide to replicate, making more cells. Then new pathways in the bacterium are metabolically engineered to create isopropanol.

"The advantage of interfacing the inorganic catalyst with biology is you have an unprecedented platform for chemical synthesis that you don't have with inorganic catalysts alone," said Brendan Colon, one of the researchers. "Solar-to-chemical production is the heart of this paper, and so far we've been using plants for that, but we are using the unprecedented ability of biology to make lots of compounds."

The findings could be huge in terms of fuel conversion. That said, they're currently at a one percent efficiency rate of converting sunlight into isopropanol. What's interesting is that this same general method could be used to produce drugs such as vitamins in small amounts.

Currently, the scientists plan to improve the efficiency of conversion in order to potentially make it more useful for the future.

The findings are published in the journal Proceedings of the National Academy of Sciences.

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