The University of Colorado Boulder’s Weimer Lab has introduced an efficient and economical method to use renewable energy to produce fuel, opening doors to clean and sustainable energy sources for a wide array of industries, including transportation, steelmaking and ammonia production.

The groundbreaking study, detailed in the high-impact journal Joule, outlines a thermochemical process using solar energy to derive either hydrogen gas from water or carbon-neutral fuels from water and carbon dioxide. The new paper marks the first exploration of running this process at elevated pressure, said Kent Warren, one of the paper’s lead authors and a research associate in the Department of Chemical and Biological Engineering. 

Their findings indicated that for specific materials, elevating the pressure not only accelerated the reaction rate but also significantly increased the amount of fuel produced.

“This work is, thus far, the most significant accomplishment of my professional career,” he said.

All of the paper’s authors are affiliated with CU Boulder. Professor Al Weimer is the principal investigator, and Warren and PhD student Justin Tran are the first authors. Other authors include Dragan Mejic, instrument shop supervisor; Robert L. Anderson, senior professional research associate; Lucas Jones; Dana S. Hauschulz, fabrication advisor; and Carter Wilson, an undergraduate research assistant. 

In contrast to electrolysis, an alternative method attracting commercial attention for the production of green hydrogen, the researchers used heat – not electricity – to split water. Warren said the thermochemical process has the potential to be more economically viable. The method eliminates the need for scarce, rare-earth-element-containing materials and, unlike electrolysis, can rely on well-established engineering principles to be easily scaled.

The researchers demonstrated that, by simply elevating pressure, low-cost CU Boulder-developed iron-aluminate materials can more than double hydrogen production, a notable feat considering such yields are nearly 1,000 percent greater than what the current benchmark thermochemical approach can achieve.

The same process can also be used to split carbon dioxide into carbon monoxide. It’s significant because hydrogen and carbon monoxide combined form syngas, the building block for gasoline, diesel and other liquid hydrocarbon fuels. Since carbon dioxide is sourced from the atmosphere or industrial emitters, the resulting fuel – when used – is carbon neutral, contributing only as much emissions to the atmosphere as required for its production.

“The way I like to think about it is some day when you go to the pump you’ll have, for example, unleaded, super unleaded and ethanol options, and then an additional option being solar fuel, where the fuel is derived from sunlight, water and carbon dioxide,” Warren said. “Our hope is that it will be cost-competitive to the fuels sourced from the ground.”

This research was supported by Shell Oil and the National Science Foundation.

Photo caption: From left to right, Justin Tran, Professor Al Weimer and Kent Warren stand in the Weimer Lab.