'Bionic Leaf' Converts Sunlight into Liquid Fuel

'Bionic Leaf' Converts Sunlight into Liquid FuelPresented By: Asad Saeed, J.EThemeResearchers at Harvard University have designed a system that mimics the process of Photosynthesis, the process by which plants convert solar energy into chemical energy that is later used to fuel the plant. The idea is not new though. The innovation, nicknamed "Bionic leaf," which was considered too good to be true, has now become a reality.History. This topic builds on the work of Professor of Energy Daniel Nocera and his artificial leaf first demonstrated in 2011.

Professor Noceras leaf was made from a silicon strip coated with catalysts on each side.

That Leaf Produced oxygen and hydrogen from solar energy.

Artificial leaves harness solar energy and turn it into hydrogen for use in fuel cells.

But cars and other vehicles still predominantly rely on liquid fuels.Solar Energy into Liquid Fuels.(Harvard University) Researchers have designed a bionic leaf that not only uses solar energy to produce oxygen and hydrogen, it feeds this hydrogen to bacteria that is then engineered to make isopropanol.

The Harvard leaf produces oxygen and hydrogen in the same way as Professor Noceras, but the hydrogen is then channeled through a chamber filled with a bacterium called Ralstonia eutropha.

ContinueAn enzyme in this bacteria takes the hydrogen back to protons and electrons, and these are combined with carbon dioxide within the same chamber.The researchers then extract this bacteria, with the protons, electrons and carbon dioxide and metabolically engineers it to make iso-propanol.

Challenges...The Problem with Hydrogen"The problem with the artificial leaf," infrastructure to use hydrogen."

Why? Because hydrogen is extremely unstable. The smallest stable molecule, it tries to escape into the atmosphere. Hydrogen must be compressed first before it can be contained which may be way expensive. Gasoline and diesel have an advantage over hydrogen in that they are stable and the most convenient.

The artificial leaf addresses this problem with the specially engineered bacterium which converts hydrogen into a liquid fuel.

Death of bacteria: the eluding challengeKeeping the bacteria alive requires high-voltage current, which makes the process less efficient. During the initial stages, the bacteria died. Reactive oxygen was identified as the culprit. But more interesting is the source: the reactive oxygen was coming out of the hydrogen side, not the oxygen side.

"We were shocked," Nocera says. "That confused us for a while." Keeping the bacteria alive requires high-voltage current, making the process far less efficient. Nocera's team solved this problem and were able to produce fuel more efficiently.