Japanese researchers are producing hydrogen fuel on a small scale using mostly sunlight and water, according to published lab reports.
But the Shinshu University team is facing familiar foes as it works to scale the tech: efficiency, cost, and safety, per the Tech Xplore and Frontiers summaries.
Hydrogen is being studied by the U.S. government and labs around the world in large part because it's a cleaner fuel than gas and diesel. When used in a fuel cell, it emits only water. But when combusted to power a turbine, for example, it also produces harmful nitrogen oxides. That point and the fact that most hydrogen gas in the U.S. is produced using fossil fuels are among the barbs cited by environmental watchdog the Sierra Club in criticism of the alternative energy source.
That's why Shinshu's work holds great promise, as it leverages abundant sunlight and water to make the gas. It works by using photocatalysts that promote chemical reactions with sunlight to split hydrogen from water.
It "is an ideal technology for solar-to-chemical energy conversion and storage, and recent developments in photocatalytic materials and systems raise hopes for its realization," professor Kazunari Domen said, per Tech Xplore.
One-step excitation splits water into hydrogen and oxygen, which the experts said is inefficient. Two-step excitation, using two photocatalysts, is more exciting. One "evolves" hydrogen from water. The other focuses on oxygen, per Tech Xplore's report.
But efficiency under simulated sunlight is 1%. Natural sunlight works better but still falls short of the 5% rate needed to move forward, the experts said.
Greater efficiency will lower the cost as well. The dirtier natural gas production method remains cheaper. As a result, the scientists are looking for better photocatalysts, the summary continued.
The most explosive problem is the production of oxyhydrogen during the cycle. Producing the gases separately mitigates the risk. The experts also said, per Tech Xplore, that explosions can be negated by igniting oxyhydrogen in a small container.
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"Many challenges remain," Domen said about the process, per Tech Xplore.
Hydrogen-fueled machines, including aircraft, ships, and cranes, are well under development. The Shinshu experts also noted, per Tech Xplore, that the gas is an effective way to convert and store solar energy as a chemical power source for later use.
The gas could help limit the production of heat-trapping air pollution from burning fossil fuels. Air pollution is a planetwide health problem, as the World Health Organization reported that 99% of the Earth's population breathes air that doesn't meet its standards.
Fortunately, taking part in the solution is fairly easy. Unplugging unused chargers and devices can save you $165 a year while preventing energy waste, for example.
In Japan, the experts are continuing to search for photocatalysts that are efficient and can survive daily startups and shutdowns to utilize periodic sunshine.
If successful, the team expects big energy changes to follow. A prototype has already successfully operated for three years, according to the lab report.
"This will also change the way many people, including policymakers, think about solar energy conversion, and accelerate the development of infrastructure, laws, and regulations related to solar fuels," Domen said, per Tech Xplore.
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