New Water-splitting System Could be 'Holy Grail' of Clean, Alternative Energy Revolution

Scientists at University of Colorado Boulder claim to have found the "Holy Grail" of alternative energy by successfully designing a system that uses sunlight to split water into its components of hydrogen and oxygen at a stable temperature. The development, the researchers contend, could "pave the way for the broad use of hydrogen as a clean, green fuel."

The system's design is similar to solar energy operations like the Ivanpah Solar Electric Generating System in California's Mojave Desert, which employs fields of sunlight-catching mirrors to direct concentrated solar beams to a single point atop a tower.

The UC-Boulder team's design would direct the sunlight to a tower hundreds of feet tall, gathering heat generated by the mirror system to about 2,500 degrees Fahrenheit (1,350 Celsius), and then delivering the energy to a reactor containing metal oxides.

As the metal oxide compound heats up it causes a chemical reaction which releases oxygen atoms, thus changing the chemical composition of the metal oxide and triggering another reaction in which the altered compound seeks out new oxygen atoms.

Alan Weimer, the research group leader, found that the addition of steam to the system -- which could be produced by boiling water in the reactor with the concentrated sunlight beamed to the tower -- would cause oxygen from the water molecules to adhere to the surface of the metal oxide, freeing up hydrogen molecules for collection as hydrogen gas.

"We have designed something here that is very different from other methods and frankly something that nobody thought was possible before," said Weimer, who works out of the UC-Boulder chemical and biological engineering department. "Splitting water with sunlight is the Holy Grail of a sustainable hydrogen economy."

Charles Musgrave, a co-author for the paper on the subject which was published Friday in the journal Science, said the key differences between their system and other methods developed to split water with sunlight is the ability to conduct two chemical reactions at the same temperature. The previous scientific consensus on using sunlight to produce hydrogen through metal oxides required extremely high temperatures to remove oxygen, then significantly lowering the temperature before steam is introduced and and hydrogen is released.

"The more conventional approaches require the control of both the switching of the temperature in the reactor from a hot to a cool state and the introduction of steam into the system," Musgrave said. "One of the big innovations in our system is that there is no swing in the temperature. The whole process is driven by either turning a steam valve on or off."

Despite the discovery, a commercial application of the design is still years away, Weimer said, in part because the energy market is not demanding a system such as theirs.

"With the price of natural gas so low, there is no incentive to burn clean energy," Weimer said.

"There would have to be a substantial monetary penalty for putting carbon into the atmosphere, or the price of fossil fuels would have to go way up."