Browsing by Author "Platt, George"

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Attempting to identify the sources of microbial methane production from coal
(Montana State University, 2017-04) Platt, George
As the world begins to transition away from high-emissions fossil fuels, natural gas has become increasingly relevant. One natural gas reserve is found in subsurface coal seams, known as coalbed methane (CBM). Biogenic methane production occurs in anoxic environments where microorganisms catalyze the conversion of coal to methane through fermentation and methanogenesis. This study focuses on the upstream biogeochemical processes that promote the degradation of the coal matrix into bioavailable organic intermediates. A series of solid-liquid extractions were performed with coal from the Powder River Basin (PRB) using methanol, dichloromethane, and water in various treatments and sequences. The residual coal from the extractions was used in anaerobic bioreactors inoculated with a native microbial consortium from the PRB to assess and quantify the variation in methane production via Gas Chromatography (GC). Additionally, the liquid fraction of the extracts were analyzed using Gas Chromatography–Mass Spectrometry (GC-MS) and the bioreactor contents were analyzed using Fluorescence Excitation-Emission Matrix Spectroscopy (EEMS) to assess their chemical composition and fluorescent signatures. While the bioreactors produced limited amounts of methane compared to previous CBM studies, the EEMS analysis showed that the bioreactor contents experienced a shift in fluorescent signatures indicating potential biotic and abiotic chemical conversion of the coal. Dissolved inorganic and organic carbon measurements showed significant differences between treatments, indicating that the coal pre-treatment affected the biogeochemical processes necessary for coal conversion. Ultimately, this study provided insight into the organic intermediates that are bioavailable for coal conversion.
In Situ Enhancement and Isotopic Labeling of Biogenic Coalbed Methane
(American Chemical Society, 2022-02) Barnhart, Elliott P.; Ruppert, Leslie; Hiebert, Randy; Smith, Heidi J.; Schweitzer, Hannah D.; Clark, Arthur C.; Weeks, Edwin P.; Orem, William H.; Varonka, Matthew S.; Platt, George; Shelton, Jenna L.; Davis, Katherine J.; Hyatt, Robert J.; McIntosh, Jennifer C.; Ashley, Kilian; Ono, Shuhei; Martini, Anna M.; Hackley, Keith C.; Gerlach, Robin; Spangler, Lee; Phillips, Adrienne J.; Barry, Mark; Cunningham, Alfred B.; Fields, Matthew W.
Subsurface microbial (biogenic) methane production is an important part of the global carbon cycle that has resulted in natural gas accumulations in many coal beds worldwide. Laboratory studies suggest that complex carbon-containing nutrients (e.g., yeast or algae extract) can stimulate methane production, yet the effectiveness of these nutrients within coal beds is unknown. Here, we use downhole monitoring methods in combination with deuterated water (D2O) and a 200-liter injection of 0.1% yeast extract (YE) to stimulate and isotopically label newly generated methane. A total dissolved gas pressure sensor enabled real time gas measurements (641 days preinjection and for 478 days postinjection). Downhole samples, collected with subsurface environmental samplers, indicate that methane increased 132% above preinjection levels based on isotopic labeling from D2O, 108% based on pressure readings, and 183% based on methane measurements 266 days postinjection. Demonstrating that YE enhances biogenic coalbed methane production in situ using multiple novel measurement methods has immediate implications for other field-scale biogenic methane investigations, including in situ methods to detect and track microbial activities related to the methanogenic turnover of recalcitrant carbon in the subsurface.