Browsing by Subject "Biofuels"
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Item Algae biofuels in Texas(2009-08) Salpekar, Ashwini; Sylvie, George; Malcolm Brown Jr., RobertTexas – the energy center of the world – is emerging as a pioneer in algae biodiesel research and production. There are a number of reasons for this. Texas is the largest emitter of CO₂ in the country, and efforts are being made to reduce the state's dependence on fossil fuels. Also, algae – robust and promising organisms – need non-arable land, lots of sunlight and brackish/waste water, along with CO₂. Texas has all of these in abundance, plus universities and algae start-ups that are doing crucial RItem Algal Harvesting for Biodiesel Production: Comparing Centrifugation and Electrocoagulation(2013-08-09) Kovalcik, Derek JohnElectrocoagulation was compared to centrifugation at pilot scale for harvesting Nannochloris oculata and Nannochloropsis salina for biodiesel production. The pilot scale testing is a proof of concept and no optimization was conducted. Testing used the KASELCO commercial electrocoagulation system. The KASELCO electrocoagulation system successfully coagulated microalgae in laboratory testing. Aluminum and stainless steel electrodes successfully recovered algae in laboratory testing. Electricity consumed was lowest using aluminum electrodes in laboratory testing, but inconsistently coagulated microalgae at the pilot scale. Stainless steel electrodes consistently recovered algae and were selected as the primary electrode to treat microalgae at the pilot scale. Scaling power settings to pilot testing using laboratory data was successful following KASELCO?s proprietary guidelines. The KASELCO electrocoagulation system showed an electrical reduction in pilot scale operational cost for harvesting. Economic analysis using the Algae Income Simulation Model concluded that the KASELCO electrocoagulation system increase net present value of a commercial algae farm by $56,139,609 using a discount factor of 0.04. The KASELCO electrocoagulation system was calculated to use 26 kWh/ton at a commercial algae farm. However, cultivation and extraction processes are energy intensive, resulting in minimal electrical savings for the algae farm. The increase in net present value reduced production costs at the algae farm by 1%. The probability of success for the microalgae farm was zero for all scenarios analyzed. While a reduction in capital and operational costs were observed, several improvements, including harvesting using electrocoagulation, in cultivation, extraction, and conversion are necessary for economic success for biodiesel production using algae farms.Item Applications of Highly Cross Linked Mixed Bed Ion Exchange Resins in Biodiesel Processing(2010-10-12) Jamal, YousufBiofuels are a promising solution to society's quest for sustainable energy. In the transportation sector, biodiesel is the leading alternative diesel fuel currently in use today. However, the current global and domestic production of biodiesel is far below the petro-diesel consumption and demand. To increase the availability of biodiesel in the market, new methods of biodiesel production must be developed to take advantage of the plentiful low quality waste derived feed stocks that currently present problems to biodiesel production using conventional methods. This research presents one new approach based upon using heterogeneous highly cross linked mixed bed solid phase catalysts to facilitate the production of biodiesel from feed stocks with high concentrations of free fatty acids (FFA). The performance of the heterogeneous mixed bed catalysts method developed in this research was evaluated and optimized for catalyst concentration and reaction duration while the mixing rate, reaction temperature, initial FFA composition of the feed stock and the alcohol-to-oil molar ratio were kept constant. The presented method reduces the FFA content of the starting feed stock while limiting the release of water into the reaction. Through experimentation, it was found that FFA removal with the mixed bed resin is due to ion exchange with the quaternary ammonium functional group and not catalysis to form esters. A model describing the heterogeneous processing method is presented. The outcome of this research is the development of a new processing method that can be used to create biodiesel from poor quality raw feed stock materials.Item Assessing the Potential of Natural Microbial Communities to Improve a Second-Generation Biofuels Platform(2012-10-19) Hammett, Amy Jo MacbeyNaturally occurring microbial communities from high-salt and/or high-temperature environments were collected from sites across the United States and Puerto Rico and screened for their efficacy in the MixAlco biofuel production platform. The MixAlco process, based on the carboxylate platform, is a sustainable and economically viable platform for converting lignocellulosic biomass to biofuels. Using a mixed culture of anaerobic organisms, lignocellulosic biomass is fermented into carboxylic acids, which are neutralized to their corresponding carboxylate salts. These salts can then be converted into a wide variety of chemical products and fuels (alcohols, gasoline, diesel, jet fuel). The central hypothesis is that microbial communities from relatively extreme environments, having evolved to withstand selection pressures similar to the conditions in the carboxylate platform, will exhibit high rates of biomass conversion. A total of 559 soil communities was screened as inocula in established laboratory-scale fermentations. We used pyrotag sequencing of 16S rRNA genes to characterize the bacterial components of the best-performing microbial communities. The best performing communities converted up to 3 times more biomass to acids than a standard marine community inoculum. The community analyses have allowed us to determine the extent to which the same functional types are favored during fermentation, at both laboratory and demonstration plant scales. In all cases, we observed a shift from the more diverse sediment community to post-fermentation communities with relatively low diversity dominated by organisms in the phylum Firmicutes, specifically Bacilli and Clostridia classes. Despite the fact that the inoculum sources were both geographically and ecologically diverse, all of the post-fermentation communities were more similar to each other in community structure than to the corresponding original inoculum community. In addition, studies of the sediments used as inocula revealed that environmental parameters, such as pH and water content, were significantly correlated with bacterial community composition. The wealth of data provided by current sequencing technologies allowed us to question whether communities with high process performances tend to achieve that performance with similar community structures.Item Assessing the sustainability of transportation fuels : the air quality impacts of petroleum, bio and electrically powered vehicles(2010-05) Alhajeri, Nawaf Salem; Allen, David T.; McDonald-Buller, ElenaTransportation fleet emissions have a dominant role in air quality because of their significant contribution to ozone precursor and greenhouse gas emissions. Regulatory policies have emphasized improvements in vehicle fuel economy, alternative fuel use, and engine and vehicle technologies as approaches for obtaining transportation systems that support sustainable development. This study examined the air quality impacts of the partial electrification of the transportation fleet and the use of biofuels for the Austin Metropolitan Statistical Area under a 2030 vision of regional population growth and urban development using the Comprehensive Air Quality Model with extensions (CAMx). Different strategies were considered including the use of Plug-in Hybrid Electric Vehicles (PHEVs) with nighttime charging using excess capacity from electricity generation units and the replacement of conventional petroleum fuels with different percentages of the biofuels E85 and B100 along or in combination. Comparisons between a 2030 regional vision of growth assuming a continuation of current development trends (denoted as Envision Central Texas A or ECT A) in the Austin MSA and the electrification and biofuels scenarios were evaluated using different metrics, including changes in daily maximum 1-hour and 8-hour ozone concentrations, total area, time integrated area and total daily population exposure exceeding different 1-hour ozone concentration thresholds. Changes in ozone precursor emissions and predicted carbon monoxide and aldehyde concentrations were also determined for each scenario. Maximum changes in hourly ozone concentration from the use of PHEVs ranged from -8.5 to 2.2 ppb relative to ECT A. Replacement of petroleum based fuels with E85 had a lesser effect than PHEVs on maximum daily ozone concentrations. The maximum reduction due to replacement of 100% of gasoline fuel in light and heavy duty gasoline vehicles by E85 ranged from -2.1 to 2.8 ppb. The magnitude of the effect was sensitive to the biofuel penetration level. Unlike E85, B100 negatively impacted hourly ozone concentrations relative to the 2030 ECT A case. As the replacement level of petroleum-diesel fuel with B100 in diesel vehicles increased, hourly ozone concentrations increased as well. However, changes due to the penetration of B100 were relatively smaller than those due to E85 since the gasoline fraction of the fleet is larger than the diesel fraction. Because of the reductions in NOx emissions associated with E85, the results for the biofuels combination scenario were similar to those for the E85 scenario. Also, the results showed that as the threshold ozone concentration increased, so too did the percentage reductions in total daily population exposure for the PHEV, E85, and biofuel combination scenarios relative to ECT A. The greatest reductions in population exposure under higher threshold ozone concentrations were achieved with the E85 100% and 17% PHEV with EGU controls scenarios, while the B100 scenarios resulted in greater population exposure under higher threshold ozone concentrations.Item Barriers to a biofuels transition in the U.S. liquid fuels sector(2009-12) O'Donnell, Michael Joseph; Webber, Michael E., 1971-; Allen, David T.Demand for liquid fuels (i.e., petroleum products) has burdened the U.S. with major challenges, including national security and economic concerns stemming from rising petroleum imports; impacts of global climate change from rising emissions of CO2; and continued public health concerns from criteria and hazardous (i.e., toxic) air pollutants. Over the last decade or so, biofuels have been touted as a supply-side solution to several of these problems. Biofuels can be produced from domestic biomass feedstocks (e.g., corn, soybeans), they have the potential to reduce GHG emissions when compared to petroleum products on a lifecycle basis, and some biofuels have been shown to reduce criteria air pollutants. Today, there are numerous policy incentives—existing and proposed—aimed at supporting the biofuels industry in the U.S. However, the Renewable Fuel Standard (RFS) Program stands as perhaps the most significant mandate imposed to date to promote the use of biofuels. Overall, the RFS stands as the key driver in a transition to biofuels in the near term. By mandating annual consumption of biofuels, increasing to 36 bgy by 2022, the program has the potential to significantly alter the state of the U.S. liquid fuels sector. Fuel transitions in the transportation sector are the focus of this thesis. More specifically, the increasing consumption of biofuels in the transportation sector, as mandated by the RFS, is examined. With a well-developed, efficient, and expensive, petroleum-based infrastructure in place, many barriers must be overcome for biofuels to play a significant role in the transportation sector. Identifying and understanding the barriers to a biofuels transition is the objective of this thesis. Although fuel transitions may seem daunting and unfamiliar, the U.S. transportation sector has undergone numerous transitions in the past. Chapter 2 reviews major fuel transitions that have occurred in the U.S. liquid fuels sector over the last half century, including the phasing out of lead additives in gasoline, the transition from MTBE to ethanol as the predominant oxygenate additive in gasoline, and the recent introduction of ULSD. These historical transitions represent the uncertainty and diversity of fuel transition pathways, and illustrate the range of impacts that can occur across the fuel supply chain infrastructure. Many pertinent lessons can be derived from these historical transitions and used to identify and assess barriers facing the adoption of alternative fuels (i.e., biofuels) and to understand how such a transition might unfold. Computer models can also help to explore the implications of fuel transitions. In order to better understand the barriers associated with fuel transitions, and to identify options for overcoming these barriers, many recent research efforts have used sophisticated modeling techniques to analyze energy transitions. Chapter 3 reviews a number of these recent modeling efforts with a focus on understanding how these methodologies have been applied, or may be adapted, to analyzing a transition to biofuels. Four general categories of models are reviewed: system dynamics, complex adaptive systems, infrastructure optimization, and economic models. In chapter 4, scenarios created from a high-level model of the liquid fuels sector (the Liquid Fuels Transition model) are presented to explore potential pathways and barriers to a biofuels transition. The scenarios illustrate different pathways to meeting the requirements of the RFS mandate, and differ based on the overall demand of liquid fuels, how the biofuels mandate is met (i.e., the mix of biofuels), and the status of the ethanol blend limit in the motor gasoline sector. The scenarios are used to evaluate the infrastructure implications associated with a biofuels transition, and illustrate the uncertainty that exists in assessing such a transition.Item Characterization of Extremophilic Bacteria for Potential in the Biofuel and Bioprocess Industries(2014-04-18) Haynes, Abria RIndustrial bioprocesses are constrained by the availability of microbes that are optimized for harsh bioprocess conditions. Over 500 soil and sediment samples collected from 77 saline and/or thermal sites in the continental United States, Hawaii, and Puerto Rico were used to inoculate fermentations in an effort to optimize the microbial communities for a biofuel process developed at Texas A&M (MixAlco?). A diverse bacterial isolate library (N= 1,866 isolates) was constructed by employing a variety of culturing techniques across thirty-four of the fermentation communities selected based on superior performance in the biofuel platform. Phylogenetic analysis of partial 16S rDNA sequences placed 1,200 of these isolates in the genus Bacillus. Other genera include, but are not limited to: Ureibacillus, Bacillus, Geobacillus, and Caldalkalibacillus. The central hypothesis of this dissertation was that selection due to the original site conditions of the natural inocula, and also, survival during fermentation likely favored isolates in the library that possess biofuel/bioenergy relevant traits (e.g. hydrolysis of lignocellulosic biomass, utilization of hydrolysis products, and tolerance to inhibitory compounds released during hydrolysis). The phylogeny for this library was used to identify and prioritize a diverse subsample of the library (n=207) for high-throughput screens of extracellular cellulase activity, n-butanol tolerance, vanillin utilization, and lignin degradation, as indicated by decolorization of the surrogate Congo red. Many isolates exhibited the capacities screened, including several isolates that were positive for more than one of these traits. Subsequently, a subset of the 207 screened isolates were studied further for tolerance and/or utilization of bioprocess byproducts (e.g. lignocellulosic hydrolysate, bio-oil) that are known to harbor both compounds with inhibitory effects on growth and pentose sugars released after hydrolysis. Polyhydroxyalkanoates (PHA) are bio-plastics produced by some bacteria. There is interest in industry in the identification of bacteria that can utilize wastes from some bioprocesses while creating bio-plastics, thus, a subset of the library (n=43 isolates) was screened for PHA accumulation associated with growth with the bio-diesel byproduct glycerol as the carbon source. Several isolates from the library are PHA producers with glycerol based on a fluorescence screen conducted. Microfluidic microbial fuel cells (MFCs) take advantage of microbial metabolism to convert organic matter to electricity. Microbial communities collected directly from soils were screened in a MFC array developed at Texas A&M. The screening of natural microbial communities identified electricigens with enhanced power generation abilities. The variation identified in these industrially relevant traits across isolates provides a proof of concept for both the existence of this variation in nature and the efficacy of employing fermentation and culturing approaches to enrich for these phenotypes. Also, it became clear this library could serve as a resource for bioprocess isolates for industry, either directly or as a starting point to advance the bioprocess optimization prior to some form of genetic engineering targeting a particular function.Item Conceptual Design of Biorefineries Through the Synthesis of Optimal Chemical-reaction Pathways(2011-10-21) Pennaz, Eric JamesDecreasing fossil fuel reserves and environmental concerns necessitate a shift toward biofuels. However, the chemistry of many biomass to fuel conversion pathways remains to be thoroughly studied. The future of biorefineries thus depends on developing new pathways while optimizing existing ones. Here, potential chemicals are added to create a superstructure, then an algorithm is run to enumerate every feasible reaction stoichiometry through a mixed integer linear program (MILP). An optimal chemical reaction pathway, taking into account thermodynamic, safety, and economic constraints is then found through reaction network flux analysis (RNFA). The RNFA is first formulated as a linear programming problem (LP) and later recast as an MILP in order to solve multiple alternate optima through integer cuts. A graphical method is also developed in order to show a shortcut method based on thermodynamics as opposed to the reaction stoichiometry enumeration and RNFA methods. A hypothetical case study, based on the conversion of woody biomass to liquid fuels, is presented at the end of the work along with a more detailed look at the glucose and xylose to 2-mthyltetrahydrofuran (MTHF) biofuel production pathway.Item Developing Optimal Growth Parameters for the Green Microalgae Nannochloris oculata and the Diatom Nitzschia sp. for Large scale Raceway Production(2011-10-21) Luedecke, Phillip RyanMicroalgae produce large quantities of lipids that can be used for biofuel feedstock. The goal of this project was to determine the effect of several engineering and management parameters on the productivity of microalgae cultivated in large, outdoor facilities. The specific objectives were focused on the effects of inoculation ratios; the effects of light, temperature, and culture depth on growth; and the minimum circulation velocity necessary to maintain growth and minimize settling in open ponds. Microalgae must first be cultured in smaller quantities before the raceway is inoculated for optimized growth. Concentration ratios are defined as the ratio of the volume of microalgae inoculum to the volume of new growth media. The microalgae species used was Nannochloris oculata (UTEX #LB 1998). Inoculation ratios studied varied from 1:1 to 1:32 and were grown in 500 mL Erlenmeyer flasks. The study found that 1:16 and 1:32 were too dilute, while the 1:8 concentration had the largest growth rate. Determination of the effects of temperature, light intensity, and cultivation depth is critical to maintaining healthy cultures. Excess light intensity can result in photoinhibition and temperatures above the maximum growing tolerance can have detrimental effects. These factors can affect growth and evidence suggests an interaction that exacerbates these effects. In an outdoor culture there are few practical control variables other than pond depth. As cultivation depth increases, the algae undergo "selfshading" and the increased cultivation volume hinders temperature changes. Scaled raceway ponds were maintained at 10.16 cm (4 inch) and 13.97 cm (5.5 inch) depths. The species used was Nannochloris oculata and it was found to grow best at 785 micromol m?? s??m^-2 s^-1, 20?C, and 10.16 cm. Diatoms are attractive because of high growth rates, faster lipid production, and greater cell density. The latter promotes rapid settling once mixing has stopped. Because of the silica cell wall composition, diatoms are believed to be more susceptible to shear forces which can result in lysis. Determining the natural settling rate to the minimum channel velocity relationship in cultivation ponds was the objective. No flocculants/coagulants were added which created a case of "natural" settling. Four pennate Nitzschia sp. and one centric diatom were tested in a jar tester. There was no significant difference in settling times between the species. The mean settling time was 4.55 cm min?? and the minimum channel velocity was determined to be 10.12 cm min??.Item Economic Policy and Resource Implications of Biofuel Feedstock Production(2012-10-19) Adusumilli, NaveenDramatically higher fuel prices and massive petroleum imports from politically unstable countries have contributed to a major national initiative to generate renewable fuels in the United States. Often, such policies are enacted and implemented with huge taxpayer expenditures without due diligence to the consequences. The evaluation of the water quality impacts of converting pastureland to intensive biomass production for fuel in a southern Texas watershed suggest significant increases erosion and nutrient loadings to water bodies. The Best Management Practices (BMPs), cover crop and filter strips when implemented individually failed to produce status-quo reduction levels. Combined BMPs implementation produced improved mitigation, at substantially higher costs, highlighting the issue of sustainability related to the economics of renewable fuels. The estimation of the net energy of biomass ethanol accounting for the production input data indicate a greater than one energy return for biomass crops. However, the policy results indicate that only 70 percent in net contribution to the energy supply is achieved due to relatively lower energy returns compared to conventional fossil fuels. In addition, because the ethanol produced has to have the energy used deleted from the total, the cost of producing a gallon of biomass ethanol is substantially higher than that of gasoline. The impacts of an exogenously-specified biofuel mandate fulfilled by the production of a dedicated biomass crop and its consequent effects on commodity prices and overall welfare are estimated. Net farm income increased due to an increase in crop prices; however, both consumer surplus and total surplus decreased. The analysis is extended to estimate the sensitivity of Conservation Reserve Program (CRP) acres returning to crop production and the potential of higher biomass yields. The results indicate that net farm income decreased and consumer surplus increased due to a decrease in crop prices, resulting in an increase in overall welfare. This current research evaluates the unintended consequences of the U.S. energy policy and provides interesting insights of the potential economic and environmental impacts. These results suggest policy makers should be cautious before enacting energy policy and consider multiple alternative energy sources in an economic and financial context to achieve a sustainable energy goal.Item Effect of Bioreactor Mode of Operation on Mixed-Acid Fermentations(2012-10-19) Golub, KristinaUsing mixed-culture fermentation, the carboxylate platform produces carboxylic acids, which are chemically converted into chemicals and fuels. To optimize the mixed-acid fermentation, different bioreactor configurations and operating modes were investigated. Intermittent air exposure did not affect fermentation performance and bacterial profiles, but reduced the high-molecular-weight carboxylic acids. The microbial flora contained strict and facultative microbes, suggesting the presence of a facultative anaerobic community existing in a biofilm. Compared to countercurrent trains, propagated fixed-bed fermentations have similar selectivity and acid distribution, but lower yield, conversion, productivity, and acid concentration. One- to six-stage countercurrent fermentations were operated with similar conditions. Fewer stages increased conversion, whereas more stages increased acid concentration and selectivity. One to four stages achieved similar yield, and four to six stages achieved similar maximum acid concentration. Maximum conversion was achieved with a single stage. Recycling residual biomass retained microorganisms and nutrients and increased yield and productivity. Relative to lower biomass reflux, higher reflux increased conversion, decreased selectivity, and did not affect yield. The recommended carbon-nitrogen ratio is ~24 g carbon/g nitrogen. In four-stage fermentations, recycle to the second fermentor and in parallel to the first three fermentors was optimal. Fermentations with excess or insufficient nitrogen had higher selectivity, but decreased yield and conversion. The glucose-utilization assay is a rapid and repeatable method for determining the amount of microbial activity in a sample. This method determined ~25% efficiency of a new cell separation method. In continuous fermentation, compared to no cell recycle, recycling cellular biomass increased selectivity and yield, but decreased conversion. Compared to lower cell reflux, higher reflux increased productivity, yield, and conversion, but decreased selectivity. Compared to residual biomass recycle, cell recycle had increased selectivity and yield, but decreased conversion. A new method to screen and rank inoculum sources from natural environments was successfully developed and tested.Item Energy analysis of sweet sorghum ethanol using a bottom-up energy return ratio matrix approach(2015-12) Veracruz, John A.; King, Carey Wayne, 1974-; O'Rear, Jerry; Bermann, CelioBetween 2012 and 2013 the world increased biofuel consumption by 6.1% and if forecasts hold, according to the International Energy Agency, by 2050 27% of the world’s transport energy will come from biofuels. Rather than succumb to a shortage of corn, alternative feedstocks must gain the same traction corn has gained within the ethanol production industry. When considering an alternative feedstock what must also be considered it is that energy output from ethanol production exceeds the energy needed to produce one liter of alcohol. With origins traced back to Africa, sweet sorghum, or Sorghum bicolor(L) Moench, has gained traction as a viable ethanol feedstock due to the plant’s ability to reach a harvest maturity in as little as four months. With similarities to that of sugarcane, sweet sorghum’s stalk contains a relatively balanced amount of both insoluble and soluble carbohydrates. Although sweet sorghum will flourish with the appropriate amount of water, its drought resistance provides versatility other ethanol feedstocks do not possess. However, lower inputs, drought resistance, and the ability to grow on fallow land are all meaningless if growers miss a relatively short harvesting window, or even worse, allow fermentable sugars to decay by not expediting fermentation. If sweet sorghum ethanol is to displace any amount of corn and prove its feedstock viability, its energy balance must show more energy is output than is input. By using a bottom-up matrix based approach using energy return ratios (ERRs), a product’s system may be evaluated to determine its usefulness to society. The Brandt et al. framework requires the creation of two matrices; a technology matrix, A, and an intervention matrix, B. Devising information from these matrices requires the use of three main vectors which serve as the foundation for calculating the desired ERR. Using this method in conjunction with four ERRs allows the study of energy processes used to create inputs for sweet sorghum pathways and possibly allude to how this energy is used to eliminate waste or improve efficiency through cleaner energy sources.Item The energy-water nexus : an examination of the water quality impacts of biofuels(2010-05) Twomey, Kelly Marie; Webber, Michael E., 1971-; Lawler, Desmond F.Water and energy share an important relationship since it takes water to produce energy, and likewise, energy to pump, treat, and distribute water. This thesis explores the energy-water nexus in regards to electricity and transportation fuel production, as well as water treatment. It investigates how the Energy Independence and Security Act of 2007 might affect this interrelationship in the future since increases in corn cultivation for biofuels production are likely to lead to higher nitrate concentrations in US water reservoirs, which could trigger the requirement for additional energy consumption for drinking water treatment. The analysis indicates that advanced drinking water treatment might require an additional 2360 million kWh annually to treat drinking water currently exceeding the Environmental Protection Agency’s maximum contaminant level (MCL) limit of 10 mg per liter of nitrate-nitrogen. This is a 2100% increase in energy consumption for advanced water treatment to meet this MCL in comparison with surface water treatment alone. Although results indicate that most large surface and groundwater drinking water resources are not likely to exceed safe drinking water standards due to the expansion of corn-starch based ethanol production, smaller water reservoirs in agricultural regions are susceptible to nitrate contamination in the future. Consequently, these sources might require energy-intensive drinking water treatment to reduce nitrate levels below 10 mg per liter of nitrate-nitrogen. Based on these results, I conclude that projected increases in nitrate contamination in water may impact the energy consumed in the water treatment sector, because of the convergence of several related trends: (1) increasing cornstarch-based ethanol production, (2) increasing nutrient loading in surface water and groundwater resources as a consequence of increased corn-based ethanol production, (3) additional drinking water sources that exceed the MCL for nitrate, and (4) potentially more stringent drinking water standards for nitrate.Item Essays on the Effect of Biofuels on Agricultural Markets(2014-04-23) Maisashvili, AleksandreCorn and soybean meals are major feed ingredients for livestock producers. The first part of the research studies the effects of renewable fuel standard mandate on the U.S. beef and dairy sectors. A dynamic and recursive partial equilibrium model was developed to study the effect of renewable fuel standards on beef and dairy sectors. The study finds that feed cost shocks have significant impact at feedlot level and relatively less effect for cow-calf and milk producers. No major changes were found at the retail level. Given the projected corn prices are expected to be lower in the coming decade than the record high price observed in 2011, the results also suggest that the higher returns provide economic incentives for expansion of the beef and dairy sectors in the future. The second part of the research employs an application of hedonic pricing model for whole algae and post-extracted algae residue meal for aquaculture. Prices and nutritional characteristics of commonly applied aquaculture feed ingredients are used to determine the value of whole algae and post extracted algae residue based on its dietary composition. The research finds that whole algae will have value higher than that of soybean meal and lower than that of menhaden fishmeal. The results also indicate that post extracted algae residue will have value lower than that of soybean meal and menhaden fishmeal. The third part of this research estimates the economic feasibility of biofuel production and high value squalene from a tobacco biomass. Pro-forma stochastic financial statements were constructed and the feasibility of multi-year financial projects were evaluated. The results suggest the commercialization of biofuel production from tobacco is unrealistic. The results also indicate the economic feasibility of high value squalene is realistic under the certain conditions.Item Genetic Analysis of Stem Composition Variation in Sorghum Bicolor(2012-10-19) Evans, JosephSorghum (Sorghum bicolor [L.] Moench) is the world's fifth most economically important cereal crop, grown worldwide as a source of food for both humans and livestock. Sorghum is a C4 grass that is well adapted to hot and arid climes and is popular for cultivation on lands of marginal quality. Recent interest in development of biofuels from lignocellulosic biomass has drawn attention to sorghum, which can be cultivated in areas not suitable for more traditional crops, and is capable of generating plant biomass in excess of 40 tons per acre. While the quantity of biomass and low water consumption make sorghum a viable candidate for biofuels growth, the biomass composition is enriched in lignin, which is problematic for enzymatic and chemical conversion techniques. The genetic basis for stem composition was analyzed in sorghum populations using a combination of genetic, genomic, and bioinformatics techniques. Utilizing acetyl bromide extraction, the variation in stem lignin content was quantified across several sorghum cultivars, confirming that lignin content varied considerably among sorghum cultivars. Previous work identifying sorghum reduced-lignin lines has involved the monolignol biosynthetic pathway; all steps in the pathway were putatively identified in the sorghum genome using sequence analysis. A bioinformatics toolkit was constructed to allow for the development of genetic markers in sorghum populations, and a database and web portal were generated to allow users to access previously developed genetic markers. Recombinant inbred lines were analyzed for stem composition using near infrared reflectance spectroscopy (NIR) and genetic maps constructed using restriction site-linked polymorphisms, revealing 34 quantitative trail loci (QTL) for stem composition variation in a BTx642 x RTx7000 population, and six QTL for stem composition variation in an SC56 x RTx7000 population. Sequencing the genome of BTx642 and RTx7000 to a depth of ~11x using Illumina sequencing revealed approximately 1.4 million single nucleotide polymorphisms (SNPs) and 1 million SNPs, respectively. These polymorphisms can be used to identify putative amino acid changes in genes within these genotypes, and can also be used for fine mapping. Plotting the density of these SNPs revealed patterns of genetic inheritance from shared ancestral lines both between the newly sequenced genotypes and relative to the reference genotype BTx623.Item Hydrologic impacts of biofuel expansion in the Ivinhema basin, Brazil(2015-05) Libra, Jesse Madden; King, Carey Wayne, 1974-; McKinney, DaeneBrazil produces approximately a quarter of the world's yearly ethanol demand, making it a global leader in biofuel production. The repercussions for local water resources in areas of intensive biofuel expansion, however, remain uncertain. The purpose of this study is to assess the effects of various land-use scenarios on water sustainability in Brazil, specifically the Ivinhema basin. This basin, located in Southern Mato Grosso do Sul, has experienced extensive sugarcane expansion since the mid-1990s – a trend that is expected to continue in the short to medium term. To achieve the goals of the study, I used the Stockholm Environment Institutes' Water Evaluation and Planning software (WEAP), specifically, the Soil Moisture Method, to model hydrologic processes in the Ivinhema basin from 1990-2013. The study has two parts. The first part focuses on model calibration in a data poor environment. To circumvent poor data quality, I examined the effects on model accuracy of a number data processing methods for land-use, precipitation, and ethanol production data. A total of 8 different calibration scenarios were run using these different data inputs, which I evaluated for accuracy using Nash-Sutcliffe Model Efficiency coefficients. Those producing the best results were used as a baseline for part two. The second part of the study uses the baseline model developed in part one to investigate the crop yield and stream flow effects under three different irrigation and ethanol production scenarios. Water consumption for the ethanol production process has little impact on stream flows, with daily demand peaking at 0.7 percent of baseline flows. Irrigation, however, massively reduces flows -- when irrigation is limited to only sugarcane, flow reductions of over 60 percent only occurs on 1.98 percent of days, while reductions of up to 100 percent during the dry season. Despite these large flow reductions, sugarcane yield increase from irrigation was only 7-14 percent over the study period.Item Impacts of Biofuel Production and Navigation Impediments on Agricultural Transportation and Markets(2013-08-22) Ahmedov, ZafarbekThis study investigated the impacts of U.S. biofuel production and barge navigation impediments on agricultural transportation and markets. Both past and future impacts of U.S. biofuel production levels mandated by the Renewable Fuel Standards of the Energy Policy Act of 2005 (RFS1) and the Energy Independence and Security Act of 2007 (RFS2) were examined. Examination of barge navigations impediments included analysis of the impact of lock failure and low water levels on rivers due to drought, on agricultural transportation, and on consumer welfare. All scenarios were simulated using the International Grain Transportation Model, a price endogenous mathematical programming model. The results showed that RFS-associated (RFS1 and RFS2) U.S. corn ethanol production increased the total corn supply and diverted corn from non-ethanol consumption, reduced regional grain transportation volumes, and contributed to a rise in corn prices. The results of the forward-looking scenarios indicated that grain exports and transport volumes were increased. Exports from Gulf ports increased by 41%, while grain movements by rail increased by 60%. Additional investments in the expansion of the grain handling capacities of Gulf ports and the railroad industry are needed in the near future unless a large increase in biofuel production occurs. The results of navigation impediment scenarios indicated that both lock failures and low water levels on rivers adversely affect U.S. grain exports. The Gulf ports were most negatively impacted, relative to Pacific Northwest and Atlantic ports. Truck and barge freight volume declined while rail freight volume increased. Because trucks deliver grain from grain elevators to barge locations, truck volume also decreased in response to the decline in barge volume. The scenarios imposed welfare losses on society with most accruing to consumers, while the barge industry lost $10-154 million in revenue. The low water levels were more expensive than the lock failures. Major rehabilitation of the locks is needed to avoid lock failures and more dredging of the shallow parts of the river system is required because of frequent droughts.Item An integrated resource and biological growth model for estimating algal biomass production with geographic resolution(2010-12) Wogan, David Michael; Da Silva, Alexandre K., 1975-; Webber, Michael E., 1971-This thesis describes a geographically- and temporally-resolved, integrated biological and engineering model that estimates algal biomass and lipid production under resource-limited conditions with hourly and county resolution. Four primary resources are considered in this model: sunlight, carbon dioxide, water, and land. The variation in quantity and distribution of these resources affects algae growth, and is integrated into the analysis using a Monod model of algae growth, solar insolation data, and published values for water, carbon dioxide, and land availability. Finally, lipid production is calculated by assuming oil content based on dry weight of the biomass. The model accommodates a range of growth and production scenarios, including water recycling, co-location with wastewater treatment plants and coal-fired generators, and photobioreactor type (open pond or tubular), among others. Results for every county in Texas indicate that between 86 million and 2.2 billion gallons of lipids per year can be produced statewide for the various growth scenarios. The analysis suggests that algal biomass and lipid production does indeed vary geographically and temporally across Texas. Overall, most counties are water-limited for algae production, not sunlight or carbon dioxide-limited. However, there are many nuances in biomass and lipid production by county. Counties in west Texas are typically not solar- or land-limited, but are constrained by either water or carbon dioxide resources. Consequently, counties in east Texas are limited by either water, or land (depending on the fraction of water recycling). Varying carbon dioxide concentration results in higher growth rates, but not always increased biomass and lipid production because of limitations of other resources in each county.Item Mitigation of municipal biosolids via conversion to biocrude oil using hydrothermal liquefaction : a techno-economic analysis(2015-05) Bond, Cody Ray; Berberoglu, Halil; Greene, DavidIn this techno-economic analysis, we have shown that hydrothermal liquefaction (HTL) technology can be integrated with existing biosolids management facilities that utilize anaerobic digestion and biogas capture. The overall process converts raw sewage sludge to refinery-ready biocrude oil. The Hornsby Bend Biosolids Management Plant (HBBMP) in Austin, TX is used as a case study. First, the operation of the plant without any modification was modeled and validated with field data. A standalone HTL processing unit was then considered as an add-on to the existing infrastructure. Technical and economic parameters were obtained from literature and experimental data. The results showed that savings of about $32 M over current operation with a payback period of 4.35 years were achievable at HBBMP. A nation-wide implementation could result in production of almost 4.5 million barrels of upgraded biocrude oil per year while offsetting about 330,000 metric tons of CO2 equivalent greenhouse gas emissions annually.Item Pretreatment and Fermentation of Sugarcane Trash to Carboxylic Acids(2010-01-14) Nachiappan, BalasubramanThe rising price of oil is hurting consumers all over the world. There is growing interest in producing biofuels from non-food crops, such as sugarcane trash. Lignocellulosic biomass (e.g., sugarcane trash) is an abundant, inexpensive, and renewable resource. The patented MixAlco process is a cost-effective solution, which does not require sterility or the addition of expensive enzymes to convert lignocellulosic biomass to transportation fuels and valuable chemicals. In this study, the MixAlco process was used to convert sugarcane trash to carboxylic acids under thermophilic conditions. Lime-treated sugarcane trash (80%) and chicken manure (20%) was used as the feedstock in rotary 1-L fermentors. Ammonium bicarbonate buffer was used to mitigate the effects of product (carboxylic acid) inhibition. Marine inoculum was used because of the high adaptability of the mixed culture of microorganisms present. Iodoform solution was added to inhibit methanogenesis. Preliminary batch studies over a 20-day period produced 19.7 g/L of carboxylic acids. Sugarcane trash had the highest average yield (0.31 g total acid/g VS fed) and highest average conversion (0.70 g VS digested/g VS fed) among the three substrates compared. Countercurrent fermentations were performed at various volatile solid loading rates (VSLR) and liquid residence times (LRT). The highest acid productivity of 1.40 g/(L?d) was at a total acid concentration of 29.9 g/L. The highest conversion and yield were 0.64 g VS digested/g VS fed and 0.36 g total acid/g VS fed, respectively. The continuum particle distribution model (CPDM) was used to predict acid concentration at various VSLR and LRT. The average error in between the predicted and experimental acid concentration and conversion were 4.62% and 1.42%, respectively. The effectiveness of several pretreatment methods was evaluated using the CPDM method. The best-performing method was short-term, no-wash, oxidative lime pretreatment with ball milling. At an industrial-scale solids loading of 300 g VS/L liquid, the CPDM ?map? predicts a total acid concentration of 64.0 g/L at LRT of 30 days, VSLR of 7 g/(L?d), and conversion of 57%. Also high conversion of 76% and high acid concentration of 52 g/L are achieved at a VSLR of 4 g/(L?d) and LRT of 30 days.