Feb 12, 2004

Plants May Be the Next Answer to the Current Energy CrisisSource: Imperial College of Science, Technology and Medicine

A highly energy-efficient way to form cheap supplies of hydrogen fuel may be possible in the future, thanks to new findings from Imperial College London.

Through photosynthesis, plants use sunlight to split water naturally, producing oxygen. By mimicking the method plants use to split water into hydrogen and oxygen atoms, researchers believe it may be possible to recreate the process on an industrial scale, allowing hydrogen to be produced as a fuel.

Researchers at Imperial have used high-resolution X-ray crystallography to make an image of a tiny water splitter, separating the two hydrogen atoms from an oxygen atom in a photosynthetic bacteria called Thermosynechoccus elongatus. The team of researchers say this is the best picture yet of the water-splitting structure plants have used for 2.5 billion years.

Scientists have known that plants split water in a “catalytic center” containing four atoms of maganese. Now, researchers have taken it one step further. According to So Iwata, professor at Imperial’s Department of Biological Sciences, they can now show that “three of the maganese atoms, a calcium atom and four oxygen atoms, form a cubelike structure, which brings stability to the catalytic center. The fourth and most reactive manganese atom is attached to one of the oxygen atoms of the cube. Together, this arrangement gives strong hints about the water-splitting chemistry.”

While scientists have used electrolysis to separate water’s two hydrogen atoms from its oxygen atom, it currently costs 10 times as much as natural gas and is three times as expensive as gasoline. Hydrogen contained in water could be one of the most promising energy sources for the future. It is highly efficient, low polluting and mobile, so it can be used in remote regions where it is normally difficult to access electricity.

According to Jim Barber, professor at Imperial’s Department of Biological Sciences, manufacturing hydrogen from water using the photosynthetic method would be far more efficient than using electrolysis. “If we can learn how to use even a fraction of the 326 million cubic miles of water on the planet, we can begin to address the world’s pressing need for new and environmentally friendly energy sources.”