Browsing by Subject "Biomass energy"
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Item A discretized approach for solving for the optimal capacity and profit maximization level for a biomass refinery given supplemental sources of fuel(2012-05) Walker, Michael L.; Farmer, Michael; Knight, Thomas; Benson, Aaron G.; Burns, James R.The feasibility of a cotton gin that produces bio-fuels is explored. By utilizing cotton gin trash and supplemental feedstock such as rangeland grass, enough megawatt hours of energy can be produced to satisfy peak and sub-peak energy for power plan requirements. Furthermore, findings have confirmed that the amount of carbon displaced by a power plant relying on biomass energy as source of electricity rather than traditional coal is an additional offset that makes the business model even more appealing. For reasons stemming mainly from the availability of cotton gin trash in the Lubbock area, it has been confirmed that use of biomass already on site at agri-forestry processing centers to manufacture bio-products will also minimize transportation and handling costs. Therefore, at the core of this study is the determination of whether an operator of a power plant chooses to import supplemental biomass in the form of rangeland grass for the production of electricity when there is insufficient cotton gin waste due to a bad season. The decision is based on whether the profits derived from the additional megawatt hours from additional biomass are enough to offset the transportation and harvest costs associated with the imported biomass. A profit maximization model simulating the production and sale of biomass electricity suggests that while lowering the transportation and harvest costs through subsidies does influence an operator’s decision to import, it has a negligible effect on the plant capacity and efficiency. Furthermore, findings in this study suggest that a subsidy applied to the peak and sub-peak prices of megawatt hour prices do in fact have a substantial affect on the capacity and profitability of a plant producing electricity from biomass.Item A macro-particle, moving-boundary pyrolysis model(Texas Tech University, 1983-08) Lin, Ruey-jiaNot availableItem Analysis of biomass gasification products(Texas Tech University, 1981-05) Ruggieri, Russell JNot availableItem Biomass gasification feed system design and evaluation(Texas Tech University, 2001-05) Nevill, Joe DonOver the last 100 years, the ability to reliably extract energy through biomass gassification has proven to be quite elusive. Environmental issues, energy shortages, and the lack of coherent energy development policies in third world countries have kindled a renewed interest in biomass gassifîcation technology. Recent innovations in pressurized fluidized bed gassification technology have raised expectations for the development of highly efficient biomass gassifîcation power systems. The use of pressurized gassification systems has introduced a supposedly insurmountable problem regarding the transport of biomass across a pressure differential. The Mechanical Engineering Department of Texas Tech University has recently created the Institute for Design and Advanced Technology (IDEATE). The objective of IDEATE is to afford mechanical engineering graduate students the opportunity to gain real world experience through research and development in the corporate setting. In this instance, graduate student research assistant sponsorship was obtained through the Texas Tech University IDEATE program and Cratech, Incorporated. Cratech has developed a completely automated, highly reliable, and uniquely iimovative means of transporting biomass across a pressure differential. This study encompasses the development of the Cratech biomass feed system, weigh belt assembly modeling, and subsequent automated cascade loop PID control development.Item Constraints on algal biofuel production(2011-05) Beal, Colin McCartney; Ruoff, Rodney S.; Webber, Michael E., 1971-; Hebner, R. E. (Robert E.); Berberoglu, Halil; Seibert, A F.; King, Carey W.The aspiration for producing algal biofuel is motivated by the desire to replace conventional petroleum fuels, produce fuels domestically, and reduce greenhouse gas emissions. Although, in theory, algae have the potential to produce a large amount of petroleum fuel substitutes and capture carbon emissions, in practice, profitable algal biofuel production has proven quite challenging. This dissertation characterizes the production pathways for producing petroleum fuel substitutes from algae and evaluates constraints on algal biofuel production. Chapter 8 provides a summary of the entire dissertation. The first chapter provides a framework for reporting the production of renewable diesel from algae in a consistent way by using data that are specific and by presenting information with relevant metrics. The second chapter presents a review of analytical tools (i.e., microscopy, spectroscopy, and chromatography) that can be used to analyze the structure and composition of intermediate products in an algal biofuel production pathway. In chapters 3 through 6, the energy return on investment, water intensity, and financial return on investment are presented for three cases: 1) an Experimental Case in which data were measured during five batches of algal biocrude production with a combined processed volume of about 7600 L, 2) a hypothetical Reduced Case that assumes the same energy output as the Experimental Case, with reduced energy and material inputs, and 3) a Highly Productive Case that assumes higher energy outputs than the Experimental Case, with reduced energy and material inputs, similar to the Reduced Case. For all three cases, the second-order energy return on investment was determined to be significantly less than 1, which means that all three cases are energy negative. The water intensity (consumption and withdrawal) for all cases was determined to be much greater than that of conventional petroleum fuels and biofuels produced from non-irrigated crops. The financial return on investment was also found to be significantly less than 1 for all cases, indicating production would be unprofitable. Additionally, it was determined that large-scale algal biofuel production would be constrained by the availability of critical energy and material inputs (e.g., nitrogen and carbon dioxide). The final part of this dissertation presents a first-principles thermodynamic analysis that represents an initial attempt at characterizing the thermodynamic limits for algal biofuel production. In that analysis, the energy, entropy, and exergy is calculated for each intermediate product in the algal biofuel production pathway considered here. Based on the results presented in this body of work, game-changing technology and biotechnology developments are needed for sustainable and profitable algal biofuel production.Item Cotton gin trash gasification to power internal combustion engines(Texas Tech University, 1979-12) Holmes, Lyndell HartNot availableItem Enzymatic hydrolysis of cellulosic biomass by using immobilized cellulase(Texas Tech University, 1982-08) Oh, SanghaNot availableItem Evaluating the uncertainty of life cycle assessments : estimating the greenhouse gas emissions for Fischer-Tropsch fuels(2011-05) Denton, Rachel Marie; Allen, David T.; McDonald-Buller, ElenaEnvironmental regulations have historically been focused on individual emission points, facilities, or industrial sectors. However, recent and emerging regulations for greenhouse gas (GHG) emissions such as those contained in the Energy Independence and Security Act (EISA) of 2007 have introduced the concept of product life cycle limits on the emissions of transportation fuels. Thus, a complete life cycle assessment (LCA) of the transportation fuel must be completed where all emissions from field to the vehicle’s fuel tank and from tank to the vehicle’s exhaust must be assessed. However, although there have been extensive analysis of the GHG emissions associated with transportation fuels, there are substantial uncertainties associated with these estimates that can be attributed to poor data quality, inconsistent methodological choices, and model uncertainties, among others. This thesis evaluates the uncertainties present in LCA through the case study of fuel production using Fischer-Tropsch (F-T) synthesis of fuels derived from coal and biomass. Specifically, GHG emission estimates for F-T synthesis process scenarios are presented and the uncertainties in the estimates are discussed. Overall uncertainties in GHG emissions due to changes in the details of the process configurations in the F-T process can be up to 11%. This finding suggests that the details of fuel refining conditions will need to be specified in determining whether fuels meet GHG emission requirements, complicating the implementation of life cycle GHG regulations.Item Extraction of waste water from biomass gasification(Texas Tech University, 1980-08) Kao, Chih-hengA waste water mixture from the pyrolysis of cattle manure, wood residues and corn stover was examined. Some methods of waste water treatment were screened. Activated carbon adsorption and solvent (carbontetrachloride, methylene chloride, n-butyl alcohol and methyl ethyl ketone) extraction were the methods chosen to treat the waste water. The results showed that dual solvent extraction using methyl ethyl ketone as a polar solvent to extract the valuable pollutants from the waste water and nhexane as a volatile solvent to recover the dissolved, polar solvent from the extracted water is an effective method to treat the waste water. A computer program has been developed to aid in the design of a solvent extraction column.Item Fluidized bed gasification of agricultural residues(Texas Tech University, 1979-12) Hightower, James AlanNot availableItem Gin trash to gaseous fuel: demonstration and economics(Texas Tech University, 1985-05) Srikanth, T. SrinivasanNot availableItem Modeling of an experimental updraft countercurrent moving bed biomass gasifier(Texas Tech University, 1987-12) O'Hara, Michael LeeA steady-state model of a countercurrent, updraft, biomass gasifier was developed and verified against pilot-plant data. The gasifier was modeled in two parts: a combustion-fasification (CG) and a pyroiysis model. Development of the CG model demonstrated that the combustion reaction was mass transfer controlled, and the water-gas shift reaction was approximately at equilibrium. The CG model was studied for sensitivity to the particle diameter, air-to-steam ration, oxygen mass transfer coefficient, and the chemical reaction activation energies. THe pyroiysis model was based on the assumption that the pyroiysis process was heat transfer limited. The linearized results for a moving-boundary, phase-change model were used to develop the rate of the pyroiysis process.Item Process synthesis in manufacture of ethanol from cellulose(Texas Tech University, 1983-05) Deo, Avinash GajananNot availableItem Production and soil effects of sorghum biofuel cropping systems in semiarid marginal regions(2012-05) Cotton, Jon; Moore-Kucera, Jennifer; Acosta-Martinez, Veronica; Burow, Gloria B.; Wester, David B.In order to meet the growing demands for food, fiber, and biofuels, land management decisions will require identification of lands most suitable for each crop. Biofuel production that occurs on lands otherwise constrained for other intensive agricultural production by soil or water limitations (i.e., marginal lands) may not only meet some of these demands but, if managed properly, may also help improve soil function. For large-scale application to be sustainable, identification of crop type most efficient for feedstock production as well as impacts on soil and water resources are necessary. In this study, forage sorghum (Sorghum bicolor L. Moench) cropping systems were initiated in the semiarid Southern High Plains (SHP) of the U.S. to evaluate potential biofuel production and potential benefits on soils that are depleted of organic matter (< 0.7%) due to previous cropping history. Systems consisted of two sorghum cultivars (Sorghum Partners 1990 = SP 1990 and PaceSetter bmr = PS bmr) differing in lignin content due to brown midrib trait (bmr-12) that were tested under two different water levels (non-irrigated or deficit irrigation of 2.88 mm day-1), and biomass removal rate treatments of 50% and 100%. Forage sorghum SP1990 (non bmr) produced significantly higher weight and volumes of biomass than PS bmr under both deficit irrigation and no irrigation in the two years of study. However, PS bmr biomass was converted into ethanol (EtOH) 54% more efficiently during both years. When below average precipitation occurred during the first year of the study, both cultivars produced similar amounts of EtOH at each irrigation level (1,600 to 3,380 L ha-1). When higher than average precipitation occurred during the second year, higher biomass production of SP 1990 resulted in more EtOH production than PS bmr (3,380 vs. 2,640 L ha-1). Irrigation resulted in 26-49% more biomass and 28-72% more EtOH production during both growing seasons, indicating that non-irrigated production resulted in deficit water conditions regardless of precipitation. Overall EtOH production ranged from 1,600 to 3,380 L ha-1 during both years of the study. Changes in soil microbial properties (0-10 cm), known to be sensitive econsensors, were measured during the two year transition from previous long-term cotton cropping systems to the sorghum biofuel cropping systems. Increases in microbial biomass C (MBC) and N (MBN) (16-17%) and differences in fatty acid methyl ester (FAME) profiles were observed after one growing season. Additionally, soil enzyme activities (EAs) targeting C, N, P, and S increased 15-75% after two growing seasons. Increases in EAs 16-19%) and differences in FAME profiles were seen due to the irrigation treatment, which may be due to the increase in belowground biomass production even under deficit irrigation. When biomass was not fully removed (50% removal treatment), increases in MBC and MBN (11-15%), b-glucosidase (C cycling) and alkaline phosphatase (P cycling) (12-22%) occurred, which is likely attributed to the protection of the soil surface from aeolian erosion provided by the surface residue. The cultivars tested, which produced biomass with different chemical composition, had little effect on the soil microbial properties measured during the time frame of this study. This study indicates that chemical modifications and biomass yield potential are critical factors when selecting sorghum characteristics for use as biofuel feedstocks under marginal water-deficit conditions. These cropping systems also have the potential to improve sandy, low organic matter soils in this semiarid region, as was shown by increases in microbial biomass and soil functionality indicated by EAs after only two growing seasons. Early results from this study suggest sorghum biofuel cropping systems can be a sustainable practice for marginal lands in the SHP; however, tracking of long-term changes are necessary to fully evaluate effects. It is hypothesized that soil properties will continue to improve, especially in the lower biomass removal level as more above-ground biomass will be incorporated and decomposed. It is unclear how the chemical composition of biomass from different sorghum cultivars will impact soil properties but differences in organic matter accumulation and enhanced biochemical cycling are possible. Finally, additional research on incorporating biofuel production into traditional cotton production, along with the evaluation of novel sorghum cultivars specifically bred for use as feedstock, are important focuses for the application of biofuel production in the semiarid SHP.Item Reactor internal gas composition profiles during gasification of cattle manure(Texas Tech University, 1982-05) Landeene, Brian CharlesNot availableItem The effect of solid residence time on biomass gasification yields(Texas Tech University, 1981-08) Wang, Rong-chiNot available