An artist’s conception of a commercial hydrogen production plant (Credit: University of Colorado Boulder)
A laboratory model of a multi-tube solar reactor (Credit: University of Colorado Boulder)
Researchers from the University of Colorado Boulder developed a radically new technique which can fuel a sustainable green economy with nothing more than sunlight and water by producing clean hydrogen gas. The University of Colorado team new technique uses sunlight to split water into its components: hydrogen and oxygen. This might sound easy but this is something scientists and engineers have been trying to do cost effectively for years.
Using a vast array of mirrors, the Colorado team concentrated sunlight onto a single point atop a central tower several hundred feet tall. The heat from the mirrors reached roughly 2,500 degrees Fahrenheit (or 1,350 Celsius) at the main point of the tower. However having this super hot point is not enough. Splitting oxygen and hydrogen from water using heat alone requires more than twice this temperature which is hard to produce and maintain, can create thermal expansion and contraction, potentially causing damage to both the reactors. The Colorado team used a different method altogether. They used the concentrated solar energy to heat a reactor containing chemical compounds known as metal oxides.
When metal oxide compound heats up, it releases oxygen atoms, changing its composition and causing the newly formed compound to seek out oxygen atoms. By adding steam to the system the team discovered they can cause oxygen from the water molecules to adhere to the surface of the metal oxide, freeing up hydrogen molecules which can be collected.
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According to Professor Alan Weimer the research group leader: “We have designed something here that is very different from other methods and frankly something that nobody thought was possible before. Splitting water with sunlight is the Holy Grail of a sustainable hydrogen economy”.
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According to the researchers one of the key differences between their method and other methods developed to split water is the ability to conduct 2 chemical reactions at the same temperature. Typically you need to bring the reactor to a high temperature to remove oxygen, then cool it to a low temperature before introducing steam to re-oxidize the compound in order to release the hydrogen gas so it could be gathered. In the newly developed method there is no swing in the temperature. The whole process is driven by simply turning a steam valve on or off.
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According to Professor Weimer “the new design began percolating within the team about two years ago. When we saw that we could use this simpler, more effective method, it required a change in our thinking. We had to develop a theory to explain it and make it believable and understandable to other scientists and engineers.”
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As promising as all of this might sound, commercialization is probably still years away. According to Professor Weimer: “With the price of natural gas so low, there is no incentive to burn clean energy. 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.”
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You can find out more on the University of Colorado Boulder
website.
