small scale, big impact

Rice scientists develop simple but game-changing carbon capture device

Peng Zhu (left) and Haotian Wang developed a carbon-capture device prototype. Photos courtesy Jeff Fitlow/Rice University

A Rice University lab has developed an efficient, scalable way to capture carbon dioxide — and it just needs to be plugged into a power outlet to work.

The new technology developed in the lab of chemical and biomolecular engineer Haotian Wang, the William Marsh Rice Trustee Chair and an associate professor at Rice, uses electricity to remove carbon dioxide from air capture to induce a water-and-oxygen-based electrochemical reaction. The findings were shared in a study published in Nature last month.

Traditionally, carbon capture requires very energy intensive processes that need high temperatures and for the carbon that's been captured to be regenerated. The process also often requires large-scale infrastructure.

In the Wang lab's method, the small reactor can continuously remove carbon dioxide from a simulated flue gas with nearly 100 percent efficiency, generating between 10 to 25 liters of high-purity carbon using only the power of a standard lightbulb, according to a statement from Rice.

It does not create or consume chemicals, nor does it need to be heated up or pressurized, according to Wang. And it only requires a simple power source.

"The technology can be scaled up to industrial settings—power plants, chemical plants—but the great thing about it is that it allows for small-scale use as well: I can even use it in my office,” Wang says in the statement. “We could, for example, pull carbon dioxide from the atmosphere and continuously inject that concentrated gas into a greenhouse to stimulate plant growth. We’ve heard from space technology companies interested in using the device on space stations to remove the carbon dioxide astronauts exhale.”

Wang and lab member Peng Zhu, a chemical and biomolecular engineering graduate student at Rice and lead author on the study, initially made the discovery when working on an earlier version of the reactor intended for carbon dioxide utilization.

During this process Zhu noticed that gas bubbles flowed out of the reactor’s middle chamber when producing liquid products like acetic acid and formic acid, and that the number of bubbles would increase when more current was applied to the reactor.

This led the scientists to realize that the reactor was creating carbonate ions that were converted into a continuous flow of high-purity carbon dioxide after passing through the reactor's solid-electrolyte layer.

“Scientific discovery often requires this patient, continuous observation and the curiosity to learn what’s really going on, the choice not to neglect those phenomena that don’t necessarily fit in the experimental frame," Wang said in a statement.

A number of players in the Houston area have been making headway in carbon capture space in recent weeks.

Earlier this summer, the U.S. Department of Energy granted more than $45 million in federal funding to four Houston companies to promote the capture, transportation, use, and storage of tons of carbon dioxide emissions.

The Rice Alliance also recently named 15 startups to its Clean Energy Accelerator. A number of the fledgling companies are focused on carbon management and capture.

Video by Brandon Martin/Rice University

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A View From HETI

Chevron operates nine biodiesel plants around the world. Photo via Unsplash.

As Chevron Chairman and CEO Mike Wirth surveys the renewable energy landscape, he sees the most potential in biofuels.

At a recent WSJ CEO Council event, Wirth put a particular emphasis on biofuels—the most established form of renewable energy—among the mix of low-carbon energy sources. According to Biofuels International, Chevron operates nine biorefineries around the world.

Biofuels are made from fats and oils, such as canola oil, soybean oil and used cooking oil.

At Chevron’s renewable diesel plant in Geismar, Louisiana, a recent expansion boosted annual production by 278 percent — from 90 million gallons to 340 million gallons. To drive innovation in the low-carbon-fuels sector, Chevron opened a technology center this summer at its renewable energy campus in Ames, Iowa.

Across the board, Chevron has earmarked $8 billion to advance its low-carbon business by 2028.

In addition to biofuels, Chevron’s low-carbon strategy includes hydrogen, although Wirth said hydrogen “is proving to be very difficult” because “you’re fighting the laws of thermodynamics.”

Nonetheless, Chevron is heavily invested in the hydrogen market:

As for geothermal energy, Wirth said it shows “some real promise.” Chevron’s plans for this segment of the renewable energy industry include a 20-megawatt geothermal pilot project in Northern California, according to the California Community Choice Association. The project is part of an initiative that aims to eventually produce 600 megawatts of geothermal energy.

What about solar and wind power?

“We start with things where we have some reason to believe we can create shareholder value, where we’ve got skills and competency, so we didn’t go into wind or solar because we’re not a turbine manufacturer installing wind and solar,” he said in remarks reported by The Wall Street Journal.

In a September interview with The New York Times, Wirth touched on Chevron’s green energy capabilities.

“We are investing in new technologies, like hydrogen, carbon capture and storage, lithium and renewable fuels,” Wirth said. “They are growing fast but off a very small base. We need to do things that meet demand as it exists and then evolve as demand evolves.”

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