Modernizing a Technology From the Vacuum Tube Era to Generate Cheap Power

Estimated reading time: 4 minutes

When scientists Daniel Riley and Jared Schwede left Stanford University last year to join Cyclotron Road, a Lawrence Berkeley National Laboratory (Berkeley Lab) program for entrepreneurial researchers, their vision was to take thermionics, an all-but-forgotten technology, and develop it into a clean, compact, and efficient source of power.

Little did they know that soon after arriving, a collaboration with a Berkeley Lab scientist would allow their research to take a big shortcut, providing them with unprecedented insight into the inner workings of thermionic devices.

“It turns out, by almost fortuitous coincidence, that a microscope we have is supremely sensitive to a material property these guys were after,” said Andreas Schmid, a scientist with Berkeley Lab’s Materials Sciences Division. “Once we had that conversation, it dawned on us, this is a match made in heaven.”

Riley and Schwede’s thermionics collaboration was recently awarded $3.8 million from the Department of Energy’s Advance Research Projects Agency­–Energy (ARPA-E), which they will share with Schmid at Berkeley Lab, as well as with collaborators from Stanford, UC Berkeley, and the University of Pennsylvania. Their goal is to develop an entirely new type of generator that can produce clean power from any fuel source at high efficiency, all in a quiet and scalable package.

“It’s very difficult to produce electricity in the same place you’re consuming it,” Riley said. “This is a huge problem in countries where they don’t have an electric grid in place. Our long-term vision is to give people an opportunity to generate power in places where they don’t have a massive infrastructure.”

Thermionics is a method for converting heat to electricity that was developed in the 1960s and 1970s, primarily for use in the space-nuclear program. In a thermionic device, electrons evaporate from a hot cathode into a vacuum and are collected by a cooler anode, generating current.

“Thermionics got a lot of interest as part of the space program because of its high efficiency and power density,” Schwede said. “But the program was shut down in 1973, and thermionics never really found its feet. It’s either been forgotten or has had a reputation of an old technology that’s been tried before.”

Now the idea is to revitalize the technology by applying tools of modern-day science, including twenty-first-century materials and microfabrication methods. This is where Schmid and his spin-polarized low-energy electron microscope (SPLEEM) come in. SPLEEM is housed at the National Center for Electron Microscopy, part of Berkeley Lab’s Molecular Foundry, a Department of Energy Office of Science User Facility.

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