TomKat Center’s new graduate fellows innovate to reduce industrial emissions and improve climate adaptation

Four Stanford doctoral students have won the opportunity to move their advances in decarbonized cement, thermal energy conversion, low-cost gas detection, and water management toward real-world implementation. 

Starting in the fall, the new fellows will dedicate the next two years to develop and test their prototypes, thanks to TomKat Center for Sustainable Energy’s Graduate Fellowships for Translational Research. The fellowship provides two years of fellows’ tuition and stipends, with an additional $5,000 of funding for research costs. The program also assists them in cultivating a network of peers and mentors with experience in creating new technologies.

“The fellowship is designed to give students the freedom to focus on research activities that are critical for translation,” said Matthew Kanan, associate professor of chemistry and the director of the TomKat Center. “Our goal is to increase the likelihood that their research will bridge the gap between the lab and products that impact energy and sustainability.” 

Each of the labs the students are working in are tackling complex challenges that underlie industrial emissions and resource management. Faculty advisors nominate a student for these fellowships because they have confidence the PhD candidates can advance the research toward impactful outcomes. Candidates for the program have demonstrated the creativity and leadership that will benefit from this student-centric opportunity. Unlike traditional funding, the fellowship is designed to support students to “immediately get off and running on high impact, high-risk research trajectories,” explained Jonathan Fan, associate professor of electrical engineering and advisor to one of the fellows.

“The fellowship will foster a profound sense of ownership and motivation that leads to more dedicated and enthusiastic researchers,” said Fang Liu, assistant professor of chemistry and advisor to one of the fellows. She is hopeful that the program’s mentorship will challenge fellows to become “a new generation of innovators who will drive the transition toward a more sustainable and equitable future.”

Established in 2020, the fellowship is available to Stanford doctoral students in their third year or beyond. The fellowship is also intended to prepare awardees for possible participation in the TomKat Center’s Innovation Transfer Program, which assists scholars in commercializing energy and sustainability technologies or innovative models. Since 2013, TomKat has awarded $6.1 million across 107 Innovation Transfer grants. Collectively, these ventures have grown to receive $1.7 billion in additional grants, investments, and acquisitions. The active ventures employ nearly 2,000 people.

Below are the descriptions of the four awarded projects:

Toward emissions-free cement

Cement production emits about 8 percent of global CO₂, the largest single industrial emitter of CO₂. Part of these CO₂ emissions come during the calcination process, where limestone is heated up in a funnel to create lime, the key ingredient for cement. Traditionally, factories must burn fossil fuels to exceed the required temperature of 900 degrees Celcius to heat up the center of the funnel, resulting in excessive emissions. 

This carbon-intensive supply chain has caught the attention of Dolly Mantle, a third-year PhD candidate in mechanical engineering and her advisor Jonathan Fan, moving them to leverage their background in electrical heating to reduce the impact of cement production.

“I think decarbonization is such an interdisciplinary problem,” said Mantle. “I wanted to work on a concrete solution for sustainable materials. For me, that just so happens to be concrete.”

Mantle is tackling this problem by inventing a reactor that relies on inductive heating via renewable electricity. By running alternating current through a metal coil outside of the reactor, Mantle generates currents in metal structures within the reactor that dissipate as heat. These metal structures within the reactor directly transfer heat to raw limestone, eliminating the need for excess heat generation. Mantle is also designing the reactor to increase CO₂ concentration in the furnace, making it more efficient to apply carbon-capture technology in cement production in the future.

Beyond working with electrical heating in her home department, Mantle will also collaborate with Tiziana Vanorio, associate professor of earth and planetary sciences who is working on material science of low-carbon cement.

Mantle received an NSF Graduate Research Fellowship in 2020. She is a member of the Department of Mechanical Engineering’s Diversity, Equity, & Inclusion Committee. 

Electricity from industrial waste heat

It is estimated that over half of global energy inputs are currently wasted as heat. Amalya Johnson, fourth-year Ph.D. in materials science & engineering, and her advisor Fang Liu, are refining an engineering technique that may convert that waste heat back into electricity, one ultra-thin sheet at a time. Through the fellowship, Johnson will embed nanoscale bubbles and nanoscale wrinkles into single atom-thick sheets of materials. 

By adding tiny bubbles and wrinkles into the sheets, Johnson can selectively tune how heat or electrons move in the material. By lowering the material’s thermal conductivity without compromising electronic conductivity, Johnson can create a temperature gradient that generates electricity within the sheet. This allows a direct conversion of temperature differences to electric voltage, making materials optimal for thermoelectric applications. 

“I used to be really focused on the fundamental physics of materials,” said Johnson. “But now I can see how I can leverage that understanding to change a material’s properties to be useful in solving real-world problems.

The technique has the potential to scale up to create thermoelectric devices that capture the waste heat from industrial processes and return it back into the system as useful electricity. Although she is working with semiconductor materials at the moment, Johnson’s approach has the potential to be applied to other films made from a wide array of materials in the future.

Johnson won the 2023 Graduate Student Research Program award from the Department of Energy’s Office of Science. She is the communications chair for the Stanford Black Graduate Student Association.

Affordable LEDs for gas sensors

Modern manufacturing and heavy industrial processes are big emitters of various harmful gases, from greenhouse gas to petrochemical mixtures to volatile organic compounds. New technologies are needed to reduce avoidable emissions, and the first step is to effectively monitor gas leaks and spills.

For optical gas sensing, mid infrared light sources are required. However, current mid infrared light emitters are either too expensive or too inefficient at room temperature, inhibiting widespread deployment for the oil and gas sector, environmental hazard management, and indoor air quality control.

Jarod Meyer, a fourth-year PhD candidate in material science and engineering, is instead developing an alternative optical chemical sensor of these gases using light-emitting-diodes. Meyer expects LED-based gas sensors to perform effectively at ambient temperatures, with lower costs and more compact sizes compared to traditional laser-based sensors.

“This fellowship is exciting because we have been working for a long time on understanding just the basic materials properties of these semiconductors,” expressed Meyer. “Now, we have an opportunity to take what we are doing in the lab and apply it to real world sustainability goals.”

Building on the work in his lab with Kunal Mukherjee, assistant professor of materials science & engineering, Meyer will synthesize tunable lead-tin-selenide mid-infrared LEDs and create calibration algorithms to detect different gases. LED gas sensors based on lead tin selenide could be manufactured even more cheaply than existing products, leveraging processes similar to silicon chip production while retaining a high room temperature efficiency. 

Meyer received an honorable mention from NSF’s Graduate Research Fellowship in 2022.

Water affordability in infrastructure decisions

Back in 2012, California was the first state in the US to recognize the human right to water. Over a decade later, water accessibility remains another unresolved environmental justice issue. Jennifer Skerker, a fourth-year PhD candidate in civil & environmental engineering, is developing a decision-support tool to help water utilities understand the affordability implications of their infrastructure investment, drought response, and rate structure decisions

“Our water infrastructure is coming to the end of its lifetime,” explained Skerker. “Utilities need new types of solutions to meet the current challenges from climate change.” 

Past drought responses included water curtailments paired with small surcharges to keep the utilities running when they were selling less water. For high-income households, using a little less water is fairly easy and the monthly water bill remains roughly the same, even after the surcharge. For low-income households that already use water carefully and cannot cut down on water consumption as much, the unit price of water becomes higher, imposing a barrier to water access. 

By modeling different climate scenarios, various uncertainties, and infrastructure options, Skerker’s model will optimize water supply to dynamic household water demands. In doing so, the decision-support tool could help utilities distribute water more equitably under different possible water-limited futures. During the fellowship, Skerker and her advisor, Sarah Fletcher, assistant professor of civil & environmental engineering, will be working with the City of Santa Cruz to run trials with the decision-support tool.

Skerker received the Woods Institute for the Environment’s Rising Environmental Leader award in 2023 and NSF Graduate Research Fellowship honorable mention in 2022.  Skerker currently serves as the co-lead of Stanford Engineering Students for Diversity, Equity, and Inclusion.