Wednesday, February 18, 2015, 10:43 AM - Solar power is a great way to supply our energy needs, tapping into the vast resource that is the Sun. However, what do you do when night falls? Bottle the sunlight for later, of course.

This is what a team of Harvard researchers have now done, building upon the 'artificial leaf' invented by Harvard chemist Daniel Nocera, who worked at MIT at the time, to create a 'bionic leaf' - combining the artificial with the biological.

Nocera's breakthrough was a new catalyst that, when coating a silicon solar cell, could use sunlight to split water molecules into their component atoms, to produce oxygen and hydrogen gases.

According to MIT, the simulated sunlight falling on the solar cell produces an electric current, which the catalyst uses to split the water surrounding the cell into hydrogen and oxygen, which then bubble up to the surface. The oxygen is left alone, while the hydrogen could be harvested to use as a fuel.

However, while there are a few hydrogen-powered vehicles, this type of technology is unlikely to catch on.

As Elon Musk recently put it, "hydrogen is an energy storage mechanism. It's not a source of energy." He was speaking specifically about its use compared to directly charging an electric battery from a solar cell, but the point is clear, that he views hydrogen as simply a step along the path (and one which his Tesla Motors company simply skips over).

However, we can't dismiss hydrogen completely, as it does offer a way to store energy for later, and in a way that can be used by a much wider sample vehicles on the road.

That's where the 'bionic leaf' comes in.

The researchers have taken a common soil bacteria known as Ralstonia eutropha, which uses hydrogen and carbon dioxide to reproduce, and they've changed it so that it, instead, combines the two gases into a liquid fuel called isopropanol. Thus, combining this bacteria with Nocera's artificial leaf produces a bionic system that converts sunlight into 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 a liquid fuel," Pamela Silver, a co-author of the study from Harvard Medical School, said in a press release. "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."

We're not going to be seeing this revolutionize the fuel industry overnight, though. There is still one part to work out before we'll be filling our tanks with fuel made from bionic leaves.

"We’re almost at a 1 percent efficiency rate of converting sunlight into isopropanol," Nocera said in the Harvard press release. "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."

Sources: Harvard Medical School, MIT, Elon Musk.

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