June 20th, 2020 by Steve Hanley
Fuel cell news usually get a frosty reception from CleanTechnica readers, most of whom prefer to think of fuel cells as a distraction from the main objective, which is to move the electrification of the transportation sector forward as fast as possible. It’s possible our attitudes about fuel cells have been forever poisoned by Elon Musk’s characterization of them as “fool cells.”
A lot of the negativity about fuel cells focuses on the difficulties involved with making hydrogen (a lot of which comes from reforming fracked natural gas), compressing it, transporting it, and building refueling stations that actually work. But did you know there are fuel cells that operate on liquid fuels like methanol and ethanol? Neither did I until I saw an article about new research at the school of engineering at Washington University in St. Louis in Science Daily.
Scientists Vijay Ramani, Shrihari Sankarasubramanian, and Zhongyang Wang have been studying fuel cells that operate on sodium borohydride, a liquid fuel that does not need to be pressurized the way hydrogen does, eliminating one of the most troublesome aspects of conventional fuel cells. The best part is the fuel cell they have developed produces twice the voltage — 1.4 volts — of hydrogen fuel cells. Current fuel cells, despite producing no waste products other than water and heat, are quite modest in their energy generation, which means they need a boost from a battery or super capacitor if they are being used in an automotive capacity.
Doubling the voltage allows for a smaller, lighter, more efficient fuel cell design, which translates to significant gravimetric and volumetric advantages when assembling multiple cells into a stack for commercial use. The researchers say their approach is broadly applicable to other classes of liquid fuel cells.
“The reactant-transport engineering approach provides an elegant and facile way to significantly boost the performance of these fuel cells while still using existing components,” Ramani said. “By following our guidelines, even current, commercially deployed liquid fuel cells can see gains in performance.” The research has been published recently in the journal Cell Reports Physical Science.
The key to improving any existing fuel cell technology is reducing or eliminating side reactions. The majority of efforts to achieve this goal involve developing new catalysts that face significant hurdles in terms of adoption and field deployment, says a Washington University press release.
“Fuel cell manufacturers are typically reluctant to spend significant capital or effort to adopt a new material,” says Shrihari Sankarasubramanian. “But achieving the same or better improvement with their existing hardware and components is a game changer.” Zhongyang Wang adds, “Hydrogen bubbles formed on the surface of the catalyst have long been a problem for direct sodium borohydride fuel cells, and it can be minimized by the rational design of the flow field. With the development of this reactant-transport approach, we are on the path to scale-up and deployment.”
Ramani says, “This promising technology has been developed with the continuous support of the Office of Naval Research, which I acknowledge with gratitude. We are at the stage of scaling up our cells into stacks for applications in both submersibles and drones.” No word yet on when or if the the liquid fuel cells might find their way into vehicles, but the relative ease of storing a liquid in a vehicle as opposed to a volatile and highly compressed gas like hydrogen suggests this technology could prove adaptable to cars and trucks eventually.