Publications by Colleges and Departments (MSU - Bozeman)
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Item Molten salt biomass torrefaction - A sensitivity analysis of process conditions(Elsevier BV, 2024-07) Kohlin, Lee; Pritchard, Hayden; Gladen, Adam C.; Dehkordi, Behrooz; Bajwa, DilpreetBiomass is an abundant renewable resource that can be upgraded via torrefaction. Molten salts catalyze the torrefaction reaction, creating enhanced products for fuel and soil amendment purposes at lower temperatures than inert gas torrefaction. The objective of this study is to elucidate the main effects of molten salt torrefaction process conditions on ponderosa pine (Pinus ponderosa) and cave in rock switchgrass (Panicum virgatum) in a binary salt blend of lithium nitrate and potassium nitrate using a Plackett-Burman screening analysis. The investigated process conditions include sweep gas, temperature, salt to biomass ratio (S-B ratio), residence time, and lithium content. The metrics used to evaluate torrefaction severity include mass yields, chemical composition (lignin, cellulose, hemicellulose, extractives), higher heating value (HHV), carbon and nitrogen content, pH, and water sorption. The results show that switchgrass is more severely torrefied through molten salt torrefaction than pine at the same process conditions. For example, switchgrass mass yields are on average 23.3 % lower than pine mass yields across the test conditions. For both feedstocks, the most impactful process conditions are temperature, time, and lithium content in that order with some exceptions. For instance, the effect of temperature, time and lithium content on HHV are, respectively, 3.4×, 2.3×, and 1.7× larger than the next largest process condition for pine, whereas for switchgrass, these values are 3.6×, 2.7×, and 1×. Particle size, sweep gas, and S-B ratio have minor effects depending on the metric, but are overall not significant compared to temperature. The data suggests that an inert gaseous environment need not be maintained to facilitate molten salt torrefaction. Additionally, molten salt torrefaction can produce torrefied biomass with slightly different characteristics than inert gas torrefaction.Item Long‐term cover crop effects on biomass, soil nitrate, soil water, and wheat(Wiley, 2023-05) Miller, Perry R.; Jones, Clain A.; Zabinski, Catherine A.; Tallman, Susan M.; Housman, Megan L.; D'Agati, Kristen M.; Holmes, Jeffrey A.Cover crops during summer fallow have been rarely researched in the semiarid northern Great Plains. This study was conducted during 2012–2019 at four Montana locations and included four functional groups (Brassica family, fibrous-rooted crops, legumes, and tap-rooted crops). Eleven treatments included sole functional groups, a Full Mix, the Full Mix minus each functional group, pea, and chemical fallow. Wheat (Triticum aestivum L.) was grown after each cover crop year with three nitrogen (N) fertilizer rates. Cover crops were terminated with herbicide at first flower stage of pea (Pisum sativum L.) 57 to 66 days after planting. Shoot biomass averaged 2.0 Mg ha−1 over eight site-years representative of dryland farming in Montana. Using equal overall plant densities, treatments with six species averaged 13% greater biomass than two species. Measured at termination to a 0.9-m depth, Fallow held greater soil water than cover crop treatments, with Fallow averaging 57 mm greater than the Full Mix. Soil nitrate averaged 49 kg N ha−1 greater after Fallow than the Full Mix; the Legume treatment averaged 26 kg N ha−1 greater than the Minus Legume treatment. Wheat yield on Fallow averaged 0.85 Mg ha−1 greater than the Full Mix in 5 of 10 site-years, mainly at the driest site-years. The Legume treatment elevated wheat protein over the Minus Legume treatment by an average of 15 g kg−1. Cover crops grown during summer fallow reduced soil nitrate-N, soil water, and wheat yields compared with chemical fallow, especially in the major wheat growing region of north central Montana.Item Ground-based investigation of HO<sub><i>x</i></sub> and ozone chemistry in biomass burning plumes in rural Idaho(Copernicus GmbH, 2022-04) Lindsay, Andrew J.; Anderson, Daniel C.; Wernis, Rebecca A.; Liang, Yutong; Goldstein, Allen H.; Herndon, Scott C.; Roscioli, Joseph R.; Dyroff, Christoph; Fortner, Ed C.; Croteau, Philip L.; Majluf, Francesca; Krechmer, Jordan E.; Yacovitch, Tara I.; Knighton, Walter B.; Wood, Ezra C.Ozone (O3), a potent greenhouse gas that is detrimental to human health, is typically found in elevated concentrations within biomass burning (BB) smoke plumes. The radical species OH, HO2, and RO2 (known collectively as ROx) have central roles in the formation of secondary pollutants including O3 but are poorly characterized for BB plumes. We present measurements of total peroxy radical concentrations ([XO2] ≡ [HO2] + [RO2]) and additional trace-gas and particulate matter measurements from McCall, Idaho, during August 2018. There were five distinct periods in which BB smoke impacted this site. During BB events, O3 concentrations were enhanced, evident by ozone enhancement ratios (ΔO3/ΔCO) that ranged up to 0.06 ppbv ppbv−1. [XO2] was similarly elevated during some BB events. Overall, instantaneous ozone production rates (P(O3)) were minimally impacted by the presence of smoke as [NOx] enhancements were minimal. Measured XO2 concentrations were compared to zero-dimensional box modeling results to evaluate the Master Chemical Mechanism (MCM) and GEOS-Chem mechanisms overall and during periods of BB influence. The models consistently overestimated XO2 with the base MCM and GEOS-Chem XO2 predictions high by an average of 28 % and 20 %, respectively. One period of BB influence had distinct measured enhancements of 15 pptv XO2 that were not reflected in the model output, likely due to the presence of unmeasured HOx sources. To the best of our knowledge, this is the first BB study featuring peroxy radical measurements.