Cheap catalyst and dirty water could turn sunlight into fuel, say scientists

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Solar panels coated with a newly-developed and inexpensive metal catalyst could become a cheap source of solar energy for the developing world, according to a study.

Two years ago, scientists achieved a major breakthrough, splitting water into hydrogen and oxygen using sunlight and a cobalt catalyst. They found a way to efficiently store the sun's energy as fuel.

Now, researchers have used a cheaper nickel-borate catalyst that could be used instead of cobalt to make inexpensive and efficient solar power storage — "the 'fast food' equivalent of energy systems", said the team which published its research last week (10 May) in the journal Proceedings of the National Academy of Sciences. 

Lead author Mircea Dincă, researcher at the US-based Massachusetts Institute of Technology told SciDev.Net: "One of the main problems with solar energy is using it at night".

"With our device you use the solar energy you get during the day to electrolyse water [break it down to oxygen and hydrogen], store the hydrogen, then consume it later."

Conventional photovoltaic and battery systems are already widely used in the developing world to store solar energy for night-time use but such systems have limited storage capacity (see Financing solar power for the poor). Hydrogen stores a thousand times more energy per unit of volume than do the best batteries, researchers said.

Another advantage, according to Dincă, is that the catalyst works with dirty water and could even purify it for drinking.

"In developing countries you don't normally have access to very pure water," he said. "Our catalysts work with water taken from rivers and this is something that hasn't been shown before."

Dincă added that the catalyst is now being tested for commercial value. The idea is to take it to the developing world, "the sooner, the better," he said.

Harish Hande, head of India's SELCO Solar — a social enterprise taking sustainable power to under-served households and businesses — said that cheaper and more flexible ways to store energy will also help develop new business opportunities.

"Now, because of expensive and heavy storage systems, there is much less opportunity to innovate, especially for the poor," said Hande.  "For example, women entrepreneurs cannot do rentals because the batteries are too heavy and the acid destroys their sari!"

But Frederik Krebs, researcher from the Solar Energy Programme, Technical University of Denmark, cautioned that this laboratory-based research is still far from being used in the developing world. "Putting science to work in society is pretty difficult," he said.

"It is not clear whether the new catalyst is any better than the [previously developed] cobalt catalyst," said Harry Gray, a chemist from the California Institute of Technology, United States. "More work will be needed before we will know whether it will perform as well in solar-driven water splitters," he added.

Link to paper abstract in Proceedings of the National Academy of Sciences

Link to full 2008 paper in Science