The chemistry of clean fuel
A new energy-efficient method developed by a team of WSU scientists to locally produce hydrogen gas from ethanol and water has the potential to make clean hydrogen fuel a more viable alternative to fossil fuels.
“Our technology produces pure hydrogen at high pressure with high efficiency and at a low energy cost while also capturing the carbon dioxide by-product,” said Louis Scudiero, professor of chemistry and co-author of a paper on the research published in the journal Applied Catalysis A.
Like electric battery-powered cars, hydrogen fuel-cell cars don’t emit harmful carbon dioxide during operation and, like traditional gasoline-powered cars, hydrogen-powered cars can be refilled in minutes.
Despite its potential, the technology’s market penetration is very low. Delivery of compressed hydrogen gas to consumers is a significant stumbling block. The economic and safety challenges involved in transporting and storing large volumes of high-pressure hydrogen gas means there is little appropriate infrastructure in the U.S.
A new way of thinking
The novel WSU conversion system uses an ethanol and water mixture stimulated by a small amount of electricity to safely produce small amounts of pure compressed hydrogen on-demand. Making the fuel on-site at consumer refueling stations would only require transportation of the ethanol solution, which could be handled by existing infrastructure.
In their work, the WSU researchers created a conversion system with an anode and a cathode. When they put a small amount of electricity into the ethanol and water mixture with a catalyst, they were able to electrochemically produce pure compressed hydrogen. Carbon dioxide from the reaction is captured in a liquid form.
Instead of having to transport hazardous hydrogen gas, the conversion method would mean that the existing infrastructure for transporting ethanol could be used and that the compressed hydrogen gas could be easily and safely created on-demand at gas stations.
“We’re already using ethanol-containing gasoline at every gas station,” said Ha. “You can imagine that an ethanol water mixture can be easily delivered to a local gas station using our existing infrastructure, and then using our technology, you can produce hydrogen that is ready to pump into a hydrogen fuel cell car. We don’t need to worry about hydrogen storage or transportation at all.”
The electrochemical system the team developed uses less than half the electricity of pure water splitting, another method that researchers have studied for de-carbonized hydrogen production. Instead of working hard to compress the hydrogen gas later in the process, the researchers used less energy by instead compressing the liquid ethanol mixture, thereby directly producing an already compressed hydrogen gas.
“The presence of the ethanol in water changes the chemistry,” said graduate student Wei-Jyun Wang, a co-lead author on the paper. “We can actually do our reaction at a much lower electrical voltage than is typically needed for pure water electrolysis.”
Their system also doesn’t require an expensive membrane that other water splitting methods do. The resulting hydrogen from the electrochemical reaction is then ready for use.
“A process that offers a low-electrical energy cost alternative to water electrolysis and can effectively capture carbon dioxide while producing compressed hydrogen could have a significant impact on the hydrogen economy,” said Jamie Kee, a postdoctoral researcher and co-author on the paper. “It’s really exciting because there are a whole lot of aspects that play into improving the production methods of hydrogen.”
Next steps include scaling up the technology for industrial and consumer markets and continuous operation, and working to make use of the captured carbon dioxide.
The research was funded by the Gas Technology Institute and the US Department of Energy’s RAPID Manufacturing Institute.
Top image: Professor Su Ha (left) and postdoctoral researcher Jamie Kee inspect the novel reactor they developed to produce pure compressed hydrogen.
Adapted from Voiland College of Engineering and Architecture by Tina Hilding for WSU Insider.