Stanford Energy Seminar - Four Speakers

Membrane-based lithium recovery: Composition and driving force effects in ion-selective separations

The rapid growth of the electric vehicle market is driving a substantial increase in lithium demand, and with it, efforts to selectively recover lithium from unconventional sources such as lithium-ion battery waste and oilfield brines. Ion-selective membranes are of particular interest in these lithium recovery applications due to the benefits of scalability, low energy consumption, and low chemical input. Unfortunately, current polymeric membranes are incapable of selective lithium recovery from these complex wastewaters. While investigations have been performed to relate membrane structural properties like water content and ion-coordinating ligand chemistries to ion-ion separation performance, few systematic studies investigate the effects of membrane composition beyond monomer chemical identity and the effects of driving force beyond diffusion. In this work, we synthesized a library of polymeric membranes with varying percentages of ion-coordinating ligand to investigate the influence of ligand content on separation performance. Given the recent interest in process electrification, we also compare trends in membrane performance under electrodialysis conditions to assess driving force effects on separation performance. We demonstrate that both ligand content and electric potential driving force can be used to enhance ion-specific membrane separations, exemplified with lithium/nickel separation in pyridine-functionalized membranes.

Speaker: Kristen Abels, Stanford University

Techno-economics of Enhanced Geothermal Systems across the Continental United States

Conventional geothermal systems are geographically limited because they require the natural co-occurrence of high temperatures, in-situ fluid for heat transport, and permeable or fractured rock for fluid flow. Recent technological advancements and field implementations have successfully demonstrated Enhanced Geothermal Systems (EGS), where heat transport and fluid flow are supplemented artificially by water injection and rock stimulation. EGS are applicable across diverse geographies, as naturally and sufficiently elevated subsurface temperatures are always present at certain depths. We conducted a comprehensive techno-economic analysis to evaluate EGS potential across the contiguous United States. Our approach involved developing a nationwide temperature-at-depth model for depths of 0-7 km with a spatial resolution of 18 km². We integrated accurate techno-economic data and models, including geothermal resource characteristics, capital and operational costs, weather patterns, and proximity to transmission lines, among other factors. The majority of EGS supply potential was found in the Western and Southwestern regions of the United States, with Texas, California, Oregon, and Nevada showing the greatest EGS capacity potential. We identified various EGS targets with a competitive levelized cost of electricity of less than $50/MWh.

Speaker: Mohammad Aljubran, Stanford University

Unveiling the stability of encapsulated Pt catalysts

Platinum exhibits desirable catalytic properties, but it is scarce and expensive. Optimizing its use in key applications like emission control catalysis is important to reduce our reliance on such a rare element. Supported Pt nanoparticles used in emission control systems deactivate over time because of particle growth in sintering processes. In this work, we shed light on the stability against sintering of Pt nanoparticles supported on and encapsulated in Al2O3 using a combination of nanocrystal catalysts and atomic layer deposition (ALD) techniques. We find that small amounts of alumina overlayers created by ALD on pre-formed Pt nanoparticles can stabilize supported Pt catalysts, significantly reducing deactivation caused by sintering, as previously observed by others. We correlate this behavior to the decreased propensity of oxidized Pt species to undergo Ostwald ripening phenomena because of the physical barrier imposed by the alumina overlayers. The enhanced stability significantly improves the Pt utilization efficiency after accelerated aging treatments, with encapsulated Pt catalysts reaching reaction rates more than two times greater than a control supported Pt catalyst.

Speaker: Gennaro Liccardo, Stanford University

Dual-function materials for integrated carbon capture and utilization

Carbon capture, utilization and sequestration consists of multiple challenging steps. From CO2 capture to compression and transportation, each step is energy and cost intensive. Dual function materials (DFMs) can reduce energy and cost demands by coupling CO2 adsorption and conversion processes into a single material with multiple functionalities, most commonly an adsorbent phase and a metal for CO2 conversion. For optimal DFMs, the interaction between the capturing and converting component is crucial and has relevance in engineering DFMs for better performance and stability. In this talk, I will share the results of our recent work on using colloidal catalysts to understand these adsorbent-catalytic phase interactions. By controlling these interactions at the molecular level, we demonstrate the critical role of each component, shedding light on the possible mechanism and paving the way to design DFMs with maximum CO2 capture and conversion efficiency.

Speaker: Shradha Sabru, Stanford University

Attend in person or watch online (see weblink)