Scientists in Australia say they have have made a breakthrough in the efficiency of using sunlight to generate hydrogen from water. It may be a step toward an affordable source of clean energy.

A renewable source of energy to replace the world’s declining fossil fuel reserves is perhaps the scientific community’s holy grail. Hydrogen is all around us. It is seen by many as the cleanest and most efficient fuel for powering everything from vehicles to furnaces and air-conditioning—if only we can find an affordable way to harness it.

Now two researchers in Australia say they have made substantial progress.

Scientists have known for a long time how to split water into its two elements, oxygen and hydrogen. But the problem is that the process requires electricity—typically derived from fossil fuels—which makes the process counterproductive and expensive.

Janusz Nowotny and Charles Sorrell are researchers from the Centre for Materials Research in Energy Conversion at the University of New South Wales in Sydney, Australia. They have been looking for an economical way to use titanium dioxide to act as a catalyst to split water into oxygen and hydrogen—using solar energy.

The Stuff of Toothpaste

Titanium dioxide (TiO2) is widely used as a white pigment in paint, paper, cosmetics, sunscreens, and toothpastes. It is found in its purest form in rutile, a beach sand but is also extracted from certain ores. Rio Tinto, a mining company that produces titanium oxide, helps fund Nowotny’s and Sorrell’s research.

Nowotny and Sorrell announced their breakthrough today at the International Conference on Materials for Hydrogen Energy, hosted by the University of New South Wales in Sydney. They believe they have found a way to considerably improve the productivity of the solar hydrogen process (using sunlight to extract hydrogen from water) using a device made out of titanium dioxide.

“This is potentially huge, with a market the size of all the existing markets for coal, oil, and gas combined,” Nowotny said in a news statement released ahead of the conference. “Based on our research results, we know we are on the right track.”

Although Australia’s sunny climate makes it an ideal place to generate solar energy, Sorrell said the technology could be used anywhere in the world.

“It’s been the dream of many people for a long time to develop it, and it’s exciting to know it’s within such close reach,” Sorrell said.

Honda-Fujishima Effect

The Australians’ research has not been tested yet by other scientists, although the findings were applauded by the pioneers of the solar hydrogen process, Akira Fujishima and Kenichi Honda.

In 1967 the Japanese scientists discovered that titanium dioxide could be used to extract hydrogen from water in a process that has become known as the Honda-Fujishima effect. The finding was reported in the journal Nature and led to numerous awards, including the 2004 Japan Prize in the category Chemical Technology for the Environment.

Hydrogen is “very simple but very efficient,” said Fujishima, who is also in Sydney for today’s conference. “We must keep working hard on it.”

Since the 1967 discovery much research has focused on the materials that might be used to split water with sunlight.

Fujishima, chairman of the Kanagawa Academy of Science and Technology, says using titanium dioxide as a catalyst means energy production will result in “cleaner air, cleaner water, and a cleaner atmosphere.”

Many Years to Hydrogen Power

The world is still a long way off from large-scale conversion from fossil fuels to hydrogen for its energy needs. For one thing, the Honda-Fujishima effect, even if it is greatly enhanced by the research breakthrough announced today, still has to be adapted into devices that can be used on a commercially viable scale. Engineers will have to design fuel cells that collect sunlight from rooftops and elsewhere.

The world’s energy infrastructure is primarily based on fossil fuels and nuclear energy. Transitioning from gasoline-powered vehicles and gas stations to hydrogen-fuel replacements would require a huge investment and many years. Storage and safety issues still need to be resolved.

But the vision of a world powered by hydrogen is gaining momentum and science and technology is catching up.

T. Nejat Veziroglu is the director of the Clean Energy Research Institute at the University of Miami and the president of the International Association for Hydrogen Energy. He was called a “hydrogen romantic'” when he first started talking about a world powered by hydrogen in the 1960s.

Veziroglu recently appeared before a U.S. Congressional hearing. Afterward, he said, he was stopped by a committee member who told him hydrogen would never be as cheap as existing forms of energy. “I said, make the companies responsible for environmental damage and no one will use anything but hydrogen. That way the whole world will benefit.”