With Bionic Leaf, Sunlight Becomes Liquid Fuel

With a new design called the bionic leaf, scientists have successfully found a way to turn sunlight into liquid fuel, potentially changing the game of renewable energy, new research shows.

Nature has known how to harvest sunlight for energy for more than a billion years (via photosynthesis), and now a team at Harvard University has found out how to mimic this process as well. The new work utilizes an "artificial leaf," which uses a catalyst to make sunlight split water into hydrogen and oxygen. An engineered bacterium then converts carbon dioxide (CO2) plus hydrogen into the liquid fuel isopropanol.

The bacterium involved 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. The result: isopropanol.

"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," Pamela Silver, one of the researchers, said in a news release.

While this is certainly a breakthrough discovery, researchers still faces some challenges. Currently, the team's new system is at about only 1 percent efficiency - the same rate as photosynthesis - but researchers are shooting for 5 percent efficiency if the bionic leaf is to lead to a sustainable solar fuel industry.

Using hydrogen as a means of fuel is nothing new. However, the idea has failed to catch on as a practical fuel for cars or power plants due to the popularity of liquid, not gas, fuel. If successful, this bionic leaf system could give the people what they want, as well as help combat global warming, find an alternative to fossil fuels, and avoid the concerns of biofuels - which has been shown to generate more greenhouse gases than gasoline in some cases.

The new artificial leaf system is described in further detail in the journal Proceedings of the National Academy of Sciences.

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