Theses and Dissertations at Montana State University (MSU)
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Item Investigation of field relevant parameters for microbially enhanced coalbed methane scale up(Montana State University - Bozeman, College of Engineering, 2019) Platt, George Addison; Chairperson, Graduate Committee: Robin Gerlach; K. J. Davis, E. P. Barnhart, M. W. Fields and R. Gerlach were co-authors of the article, 'Optimization of 13C-algae amendment concentration for enhanced coal dependent methanogenesis' submitted to the journal 'International journal of coal geology' which is contained within this thesis.; K. J. Davis, H. D. Schweitzer, H. J. Smith, E. P. Barnhart, M. W. Fields, R. Gerlach were co-authors of the article, 'Algal amendment enhances biogenic methane production from coals of different thermal maturity' submitted to the journal 'International journal of coal geology' which is contained within this thesis.Energy production from coal is projected to decline significantly over the next 30 years, due to concerns over anthropogenic carbon emissions, climate change, and cost. As coal-based energy production decreases, the demand for natural gas is expected to increase. Coalbed methane (CBM), a biogenic natural gas resource found in subsurface coal beds, may aid in meeting the projected increase in demand. However, costs associated with traditional CBM extraction currently make utilizing this resource economically prohibitive due to slow coal-to-methane conversion rates and the necessity to treat co-produced water. Algae can be cultivated in co-produced formation water and the addition of very small amounts of this algal biomass can increase coal-to-methane conversion rates. The goal of this work was to determine the optimal algae amendment concentration for the enhancement of microbial coal-to-methane conversion to maximize return on investment. Concentrations of 13C-labeled algae amendment ranging from 0.01-0.50 g/L (equivalent to 0.0001-0.005 g per g of coal) were tested in coal-containing batch microcosms. Enhanced methane production was observed in all amended microcosms and maximum methane production occurred between 169-203 days earlier than in unamended microcosms. When as little as 0.01 g/L algae amendment was added, 13CH 4 and 12CH 4 tracking revealed that the improvement in coal-to-methane conversion kinetics was due to enhanced coal degradation. Increasing amendment concentrations to 0.05-0.50 g/L improved coal-to-methane conversion rates further, but improvements from amendment concentrations above 0.05 g/L were insignificant. The geologic scope of this CBM enhancement strategy was investigated by studying methane production from five coals ranging in thermal maturity. Biogenic methane was produced from all coals, with subbituminous coals generally producing more methane than thermally mature bituminous coals. The addition of algae amendment to thermally mature coal microcosms resulted in methane production that was comparable to production from unamended, thermally immature coals. This improvement was associated with an increased relative abundance of coal degrading microorganisms. Collectively, this work demonstrates that algae amendment concentrations can be reduced further (to 0.01-0.05 g/L) relative to the previously investigated concentrations (ranging from 0.1-0.5 g/L) and still improve coal-to-methane conversion rates for a range of coal sources.Item Organic amendments for enhancing microbial coalbed methane production(Montana State University - Bozeman, College of Engineering, 2017) Davis, Katherine Jean; Chairperson, Graduate Committee: Robin Gerlach; Robin Gerlach was a co-author of the article, 'Transition of biogenic coal-to-methane conversion from the laboratory to the field: a review of important parameters and studies' submitted to the journal 'International Journal of coal geology' which is contained within this thesis.; Shipeng Lu, Elliott P. Barnhart, Albert E. Parker, Matthew W. Fields and Robin Gerlach were co-authors of the article, 'Type and amount of organic amendments affect enhanced biogenic methane production from coal and microbial community structure' submitted to the journal 'Fuel' which is contained within this thesis.; Elliott P. Barnhart, Matthew W. Fields and Robin Gerlach were co-authors of the article, 'Fate of carbon during enhanced microbial methane production from coal with repeated organic amendment' submitted to the journal 'Energy & Fuels' which is contained within this thesis.; Matthew W. Fields and Robin Gerlach were co-authors of the article, '13C-labeled amendments for enhanced biogenic methane production in coal systems indicate increased coal-to-methane conversion' submitted to the journal 'Nature' which is contained within this thesis.; George A. Platt, Randy Hiebert, Robert Hyatt, Matthew W. Fields and Robin Gerlach were co-authors of the article, 'Development and pilot testing of column reactors for the study of anaerobic subsurface process' submitted to the journal 'International Journal of Coal Geology' which is contained within this thesis.Coalbed methane (CBM) is natural gas found in subsurface coal beds and supplies approximately 4-6% of the annual U.S. natural gas requirements. Many unmineable coal beds contain CBM produced by native microbial communities. Enhancing the microbial processes for coal-to-methane conversion can increase the rates of CBM production and the amount of extractable natural gas in these coal beds. Strategies for enhancing microbially-produced CBM must be logistically attainable and economically practical. The goal of this dissertation work was to determine a feasible methane enhancement strategy using organic amendments to increase microbial coal-to-methane conversion. Four organic amendments were tested in coal-containing batch microcosms. Increased coal-to-methane conversion was demonstrated with small amounts of amendment addition, and all four tested amendments increased methane production similarly. Subsequent amendment addition produced smaller amounts of additional methane which appeared to be primarily due to amendment-to-methane conversion. 13 C-labeled algal and yeast amendments were used in coal systems for tracking carbon for methane production. It was shown that <22% of the amendment carbon was converted to methane. By tracking amendment carbon, it became clear that carbon sources besides coal and amendment are utilized for methane production; these carbon sources potentially include organic and inorganic carbon in the formation water and inoculum. Amendment strategies tested in batch systems were scaled up and applied to column reactors. Methane production from coal increased with small amounts of 13 C-labeled algal amendment addition. However, unlike in batch experiments, methane production rates in the column flow reactors did not slow or cease after 60-90 days, and methane was still being produced after 176 days when the study was terminated.