South SFV Today

Researchers at Stanford Engineering have designed and demonstrated a new type of thermochemical reactor capable of generating the immense amounts of heat required for many industrial processes using electricity instead of burning fossil fuels. The design, published on Aug. 19 in Joule, is also smaller, cheaper, and more efficient than existing fossil fuel technology.

“We have an electrified and scalable reactor infrastructure for thermochemical processes that features ideal heating and heat-transfer properties,” said Jonathan Fan, an associate professor of electrical engineering at Stanford and senior author on the paper. “Essentially, we’re pushing reactor performance to its physical limits, and we’re using green electricity to power it.”

Currently, industrial processes in the U.S. account for approximately a third of the country’s carbon dioxide emissions – more than the annual emissions from passenger vehicles, trucks, and airplanes combined. Decarbonizing this sector is a challenging but vital step in mitigating impacts on future climate.

Most standard thermochemical reactors work by burning fossil fuels to heat a fluid, which then flows into pipes in the reactor. This requires significant infrastructure with numerous opportunities for heat loss along the way.

The new electrified reactor uses magnetic induction to generate heat – similar to induction stoves. Instead of transporting heat through pipes, induction heating creates heat internally within the reactor by utilizing interactions between electric currents and magnetic fields.

Adapting induction heating for the chemicals industry involves creating even heat distribution in a three-dimensional space while being highly efficient. The researchers maximized efficiency by using high-frequency currents alongside materials that are poor conductors of electricity.

Juan Rivas-Davila, an associate professor of electrical engineering and co-author on the paper, developed new high-efficiency electronics to produce the necessary currents. These were used to inductively heat a three-dimensional lattice made of poorly conducting ceramic material at the core of their reactor. The lattice structure lowers electrical conductivity further and can be filled with catalysts needed to initiate chemical reactions.

“You’re heating a large surface area structure that is right next to the catalyst so the heat you’re generating gets to the catalyst very quickly to drive the chemical reactions,” Fan said. “Plus, it’s simplifying everything...you don’t have any pipes going in and out of the reactor – you can fully insulate it.”

The researchers powered a reverse water gas shift reaction using a sustainable catalyst developed by Matthew Kanan, a professor of chemistry at Stanford and co-author on the paper. The reaction can turn captured carbon dioxide into valuable gas for sustainable fuels production. In their proof-of-concept demonstration, the reactor was over 85% efficient.

“As we make these reactors even larger or operate them at even higher temperatures, they just get more efficient,” Fan stated.

Fan, Rivas-Davila, Kanan, and colleagues are working to scale up their technology and expand its applications including capturing carbon dioxide and manufacturing cement. They are collaborating with industrial partners in oil and gas sectors to understand adoption needs while conducting economic analyses for system-wide sustainable solutions.

“Electrification affords us the opportunity to reinvent infrastructure...and I think we’re just getting started,” Fan concluded.

Fan is affiliated with Stanford Bio-X and Wu Tsai Neurosciences Institute; Rivas with Stanford Cardiovascular Institute; Kanan with Stanford Bio-X; Maternal & Child Health Research Institute; other co-authors include Pinak Mohapatra; Chenghao Wan; Calvin H. Lin; Zhennan Ru; Connor Cremers; Dolly L. Mantle; Kesha Tamakuwala; Ariana Höfelmann funded by various institutions including Stanford Doerr School of Sustainability Accelerator.

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