Physical Sciences

Paulding, Anna (Utah State University)
Faculty Advisor: Bradbury, Kelly (College of Science, Geosciences Department)

A dramatic increase in seismicity has occurred in the midcontinent region since 2009 (Rubinstein and Mahani, 2015), causing public concern for the stability of infrastructure and buildings. Several studies have directly linked this seismicity to the reactivation of buried fault systems near the Paleozoic sedimentary bedrock-Precambrian crystalline basement contact as a result of high volumes of injection of wastewater produced by the oil and gas industry (Ellsworth, 2013; Keranen et al., 2013).

The reactivation of fault zones due to fluid injection is not only influenced by injection rates but also by the ability of fluids to migrate along or across the contact, which is controlled by the rock properties and geologic setting. To better understand the rock property variations that may occur along the nonconformity interface, we use an outcrop analog site of an exhumed fault near Gunnison, Colorado. My undergraduate research focuses on using a portable handheld X-Ray Fluorescence Unit (pXRF) as a tool to measure compositional variations in outcrop. To directly compare data, a calibration using 16 USGS Concentration Standards as well as 12 analog samples will be used to create a calibration optimized for this specific suite of rocks which informs the accuracy of in-situ field data measurements against laboratory measurements of powdered samples, influencing how future pXRF measurements can be analyzed. Micro-scale variations of major and trace element concentrations reflect alteration and related fluid-rock interactions and may serve as a proxy for fluid migration along or across faulted sections of a nonconformity interface. I propose that calibrated pXRF data and whole rock XRF data is a useful tool for understanding the nature and degree of rock alteration in fault zones and across analog sites nonconformity interface. These data can aid in a more broad understanding of how pXRF data can be used in the field to characterize the nonconformity interface and fault zones.

Leininger, Sara; Minteer, Shelley; Rhodes, Zayn; Sigman, Matt; Pancoast, Adam (University of Utah)
Faculty Advisor: Minteer, Shelley (University of Utah College of Science, Chemisty)

In the effort to improve renewable energy as a response to the depletion of fossil fuels, one important aspect to consider is the availability of such sources. The supply of solar and wind power, for example, faces issues with intermittency. Therefore, it is crucial to develop reliable energy storage methods, with redox flow batteries (RFBs) being of particular interest given their potential low cost and high efficiency. RFBs operate similarly to conventional batteries, except the anode and cathode materials are dissolved in electrolyte solutions, and pumped into the electrochemical cell from external storage tanks. Within the cell, the anode and cathode species are separated by a membrane to prevent them from mixing, which would cause the battery to self-discharge. RFBs can utilize aqueous- or organic-based electrolyte solutions, with organic solvents being especially appealing, as the electrochemical potential window is larger than water. However, one major impediment of using organic solvent is the high chemical crossover rate of anode and cathode species through the membrane, causing rapid capacity fade of the battery. Several research studies have shown that the use of redox active polymers (RAPs) with high molecular weights, paired with a size-exclusion membrane effectively counteracts this problem. The resulting steric hindrance between the small pores of the membrane and these large molecules blocks any crossover from the active species. This study will include the construction of an RFB using two previously developed RAPs demonstrated to have high electrochemical cycling stability as electrolytes. By using RAPs as both anode and cathode materials, it is expected that chemical crossover will be minimized, and the lifetime of the battery will be elongated compared to an RFB with one or both species in monomeric form. This study will be significant in the advancement of RFBs, potentially leading to their widespread use for energy storage.