Solving large-scale energy problems

John Vohs

The hydrogen side of a fuel cell. John Vohs calls fuel cells the “bridging technology” between solar and wind and fossil fuels.

When it comes to solving the global problem of the shrinking supply of fossil fuels, there is no silver bullet solution.

There is a push to move the U.S. energy supply toward renewable, non-polluting sources, such as wind and solar, says Professor John Vohs, but these options will take a while to come to fruition. Rapidly developing countries, such as China and India, will not be content to wait; their governments are intent on using fossil fuels to meet their massive populations’ growing energy needs until a switch to renewables is feasible.

“That’s a worthy goal and we might ultimately get there, but it’s going to take a long time,” says Vohs, the Carl V. S. Patterson Professor in the Department of Chemical and Biomolecular Engineering in the School of Engineering and Applied Science (SEAS). “My research is really interested in how we use our current natural resources in the most efficient way possible.”

Vohs, who has been at Penn since 1989, focuses his attention on the fundamental end of these large-scale energy problems. He is currently working in an area known as catalysis, in which he is examining how surfaces made of different materials can make energy-releasing chemical reactions more efficient or less polluting.

For his impact as a researcher, Vohs has received the 2014 Heilmeier Research Award, the highest honor of its kind in SEAS, which recognizes scientifically meritorious work that also has significant technological impact and visibility. He will be delivering a talk on Feb. 26 about his work.

Vohs notes that the production of many everyday items begins with crude oil or natural gas, including gasoline, plastics, and clothing. Producing these fuels from biomass sources is preferable since they release less carbon dioxide into the atmosphere. The challenge, however, lies in actually converting biomass into a useable material. After biomass is de-polymerized (when it is broken down into its constituent molecules), Vohs says the material that remains is a sugar, which is not an ideal form to use for other products since it contains too much oxygen.

“You have to figure out ways to selectively remove the oxygen while not rearranging the rest of the molecule,” Vohs explains. “We’re doing catalytic approaches, using a surface that has very specific properties that allows us to break specific bonds of these molecules, carbon-oxygen bonds, while not breaking all the carbon-carbon bonds.”

In much of catalysis research, he says that researchers tend to test and measure reactions on many different surfaces. While that’s useful, his team instead focuses its efforts on understanding the specific reactions that take place, the bond energies of the molecules with the surface, and the transition states from one molecule to another.

“If we understand all that fundamental information, then we can use it to design a surface that has specific properties,” he says.

Vohs has also collaborated with Raymond Gorte, the Russell Pearce and Elizabeth Crimian Heuer Professor in Chemical and Biomolecular Engineering, on research projects related to fuel cells. In this area, Vohs focuses on designing efficient electrodes on either side of the fuel cell that allow electricity-generating chemical reactions to occur. Vohs says solid oxide fuel cells run at high temperatures, which creates an unstable environment. The challenge in this line of research is to create a stable surface that is hospitable to the kind of chemistry Vohs finds integral to his work.

“Fuel cells I see as a bridging technology between [wind and solar and fossil fuels],” he says. “You’re still using fossil fuels in one way shape or form, you’re still emitting greenhouse gases, but you’re doing it in a much more efficient way than we currently are.”

Despite big changes to energy sources lying well in the future, Vohs emphasizes that things can be implemented now that could greatly impact greenhouse gas emissions.

“The U.S. probably wastes 20 or 30 percent of the energy it consumes just on lighting hallways at night, inefficient automobiles,” Vohs says. “At the same time, we should be developing the advanced technologies that are going to completely solve the problems, as well—but we need both approaches.”

In addition to his research, Vohs is co-director of the Vagelos Integrated Program in Energy Research (VIPER), in which undergraduates double major in basic science and engineering degrees and get involved in energy-related research starting in their first year.

“Undergrads tend to think of research, ‘I want to make solar panels to collect solar energy,’ but the real research is not the solar panels—it’s the properties of the silicon or the gallium arsenide or whatever materials are being used in the solar cells,” Vohs says. “It’s really getting them to get excited about the basic science and engineering that goes into these much more complicated applications.”

Originally published on December 12, 2013