Browsing by Subject "Biodiesel"
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Item A Holistic Approach to Safety Assessment in the Life Cycle of Biodiesel Industry(2014-12-02) El-Said, Marwa HA number of goals have been set in several countries to rapidly increase biofuels production and focus more on sustainable energy resources because of limited fossil fuel reserves versus renewable biofuels, global warming and climate change. Biodiesel considers very attractive environmentally friendly fuel because it is compatible with the existing diesel engines with little or no modification needed. The majority of the studies performed to improve the biofuel industry was done from economic, environmental or social point of view but failed to include the safety aspects in the whole analysis. In this thesis, a holistic approach is presented to conduct a life-cycle assessment of the risks associated with the supply, transportation, processing, storage, and production of biomass to biodiesel by assessing technologies and supply chains. Total risk calculations were done quantitatively and semi-quantitatively utilizing the historical record of the reported accidents/incidents from 2006 to 2013 in the United States. Based on the work done in this thesis, several key results were obtained. It was found that fire in biodiesel plants accounts for the most likely scenario for an accident (around 85% of total accidents). It was also found that the process area contributed the highest percentage of accidents (43%) followed by storage (33%). In the transportation phase, the overwhelming majority of events (98%) occurred as a result of spillage. In general, the thesis results demonstrate that assessing the risk utilizing the real accident scenarios to know the safety trend involved can be utilized afterwards to anticipate the upcoming loss from the capacity increase. The results also provide further evidence on the effectiveness of the use of overall risk calculations to get better understanding of the incident situations, facilitate more organized and successful emergency response, highlight the areas that need more attention and improvement, and more importantly act towards a life-cycle approach that is aimed at keeping overall risk within acceptable limits. The thesis analyzes reported data and discusses root causes and potential mitigation strategies.Item A Process Integration Approach to the Strategic Design and Scheduling of Biorefineries(2011-02-22) Elms, Rene ?DavinaThis work focused upon design and operation of biodiesel production facilities in support of the broader goal of developing a strategic approach to the development of biorefineries. Biodiesel production provided an appropriate starting point for these efforts. The work was segregated into two stages. Various feedstocks may be utilized to produce biodiesel, to include virgin vegetable oils and waste cooking oil. With changing prices, supply, and demand of feedstocks, a need exists to consider various feedstock options. The objective of the first stage was to develop a systematic procedure for scheduling and operation of flexible biodiesel plants accommodating a variety of feedstocks. This work employed a holistic approach and combination of process simulation, synthesis, and integration techniques to provide: process simulation of a biodiesel plant for various feedstocks, integration of energy and mass resources, optimization of process design and scheduling, and techno-economic assessment and sensitivity analysis of proposed schemes. An optimization formulation was developed to determine scheduling and operation for various feedstocks and a case study solved to illustrate the merits of the devised procedure. With increasing attention to the environmental impact of discharging greenhouse gases (GHGs), there has been growing public pressure to reduce the carbon footprint associated with fossil fuel use. In this context, one key strategy is substitution of fossil fuels with biofuels such as biodiesel. Design of biodiesel plants has traditionally been conducted based on technical and economic criteria. GHG policies have the potential to significantly alter design of these facilities, selection of feedstocks, and scheduling of multiple feedstocks. The objective of the second stage was to develop a systematic approach to design and scheduling of biodiesel production processes while accounting for the effect of GHG policies. An optimization formulation was developed to maximize profit of the process subject to flowsheet synthesis and performance modeling equations. The carbon footprint is accounted for through a life cycle analysis (LCA). The objective function includes a term reflecting the impact of the LCA of a feedstock and its processing to biodiesel. A multiperiod approach was used and a case study solved with several scenarios of feedstocks and GHG policies.Item 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 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 COMPUTATIONAL STUDIES OF EXO-5,6-DIDEUTERIO-2,3-DIAZABICYCLO[2.2.1]HEPT-2-ENE AND OPTIMIZATION OF BIODIESEL SYNTHESIS FROM SAFFLOWER AND CASTOR OIL(2011-08) Tamas, George G.; Birney, David M.; Mayer, Michael F.; Niwayama, SatomiA computational study of the thermal deazetization of exo-5,6-dideuterio-2,3-diazabicyclo[2.2.1]hept-2-ene has been carried out, aiming to explain the formation of the products after the nitrogen loss. The transition state with the lowest energy suggests a concerted breaking of the C-N bonds leading over a flat diradical to the endo and exo products. Higher in energy by only 0.5 kcal/mol another transition state represents a possible exit channel, via a 1,2-hydrogen shift, to the observed syn-3,4-dideuteriocyclopentene. Only at increased temperature of reaction 1,5-dideuterio-1,4-pentadiene starts forming, a fact computationally justified by a transition state 7 kcal/mol more energetic than any of the other ones. The development of the second-generation renewable fuels from vegetable oils by chemical methods that minimize the use of toxic reagents and the formation of wasteful byproducts has been optimized. Castor and safflower oil were chosen because they are non-food crops and can be grown on marginal lands. Two possibilities were explored: base and acid-catalyzed transesterification of triglycerides. The base-catalyzed transesterification has been proven to be a remarkably efficient process. The acid-catalyzed transesterification converts the triglycerides into their esters and also converts free fatty acids pre-existing in oils, eliminating the formation of soap as by-product. Catalyzed transesterification of safflower and castor oil in the presence of guanidine and guanidine derivatives has been studied. High yields and a very good reaction timeframe have been observed for some of the guanidine catalysts. A computational investigation of the possible structures involved in the reaction’s mechanism identifies acylguanidine as a pivotal intermediate and, explains, in good correlation with the experimental results, the differences of reactivity for the catalysts used.Item An enviro-economic assessment of waste vegetable oil to biodiesel conversion : an analysis of cost and GHG emissions for the University of Texas at Austin(2014-08) Ernst, Kendall Robert; Blackhurst, Michael F.With its multiple dining halls, close proximity to restaurants, and diesel vehicle fleet, the University of Texas at Austin (UT) has both the supply of raw materials to implement a waste vegetable oil to biodiesel recycling program and the capacity to use it. At face value, implementing a large-scale recycling program provides a source of cheap, low emissions fuel. However, the feasibility of such a program is contingent on its economic cost and environmental impact relative to alternative fuel sources. Thus, this research estimated the greenhouse gas (GHG) inventories and the unit cost associated with 1 megajoule worth of recycled biodiesel derived from three production processes –Alkali Catalyzed, Acid Catalyzed, and Supercritical Methanol–using environmental life cycle assessment and life cycle costing. These GHG inventories and unit costs were then compared to the conventional diesel and oilseed biodiesel sources that make up UT’s current fuel portfolio. This analysis suggested that implementing a recycling program using a Supercritical Methanol biodiesel conversion process would have the lowest combined GHG impact and unit cost, although as an emerging technology, it poses a high investment risk. In general, these findings are encouraging to the success and impact of a large-scale recycling program.Item Evaluation of Flax and Other Cool-Season Oilseed Crops for Yield and Adaptation in Texas(2012-10-19) Darapuneni, MuraliFinding the alternate biofuel feedstock(s) in addition to and/or replacement of traditional soybean feedstock is necessary to meet the future demand of biofuels. Two field studies were conducted in diverse environments in Texas during 2007-2011 to evaluate the yield, adaptation, and oil content of 4 cool-season crop species (rapeseed, safflower, flax, and camelina). In addition to the evaluation of yield and adaptation in these cool-season crops, two more studies were conducted during 2009-2011 to study flax yield components (field study) and the effect of vernalization and photoperiod on flowering of flax (growth chamber study). Out of two field studies conducted in Texas, the evaluation of four cool-season crops was designed as a randomized complete block with fifty-one genotypes (four species) and three replications in nine locations across the Texas. In addition to the evaluation of cool-season crops, an exclusive replicated study was conducted in flax to evaluate 20 genotypes for the yield, adaptation, and association between yield and its components in three locations in South Texas. Additionally, a growth chamber study was setup as a split-split plot design with twenty genotypes, two vernalized treatments (vernalized and unvernalized), and two photoperiods (10 hours and 14 hours). Spring rapeseed (canola) and safflower were the highest yielding crops with a maximum yield of 1372 kg ha-1 and 1240 kg ha-1, respectively. In South and Central Texas, fall - seeded flax yield averaged 1075 kg ha^-1 with a mean oil content of 38.3%. The flax genotype evaluation in Southeast Texas suggested that all genotypes developed in Texas showed relative cold tolerance compared to genotypes developed in other locations. A cross between Caldwell / Dillman (Texas genotype) was highly adapted to the environments of southeast Texas. Nekoma and York (genotypes developed in North Dakota) yielded well in non-cold years (> -2 degrees C) in College Station. Overall, flax is well adapted to growth in the area surrounding College Station, TX. The results of association of yield and its components in flax suggest that tiller number was the most significant contributing factor (p<0.05) affecting yield of flax in all three locations. However, the effect of tiller number was almost negated by the effect of pods per tiller (compensatory) in two out of three locations. The effect of vernalization and photoperiod on flowering of 20 genotypes of flax suggested that Texas genotypes delayed anthesis for 7 days or more in non-vernalized seedlings. These genotypes also delayed anthesis for 12 days or more in vernalized and short day conditions compared to vernalized and long day conditions. In summary, the spring rapeseed in diverse environments of Texas and fall-planted flax in South Texas showed promising yield and adaptation. Selection for more productive tiller number and intrinsic earliness of flowering to reduce the time of maturation would benefit the flax yields in Southeast Texas. Safflower was widely adapted to Texas and with increased oil content could have potential to the biofuel industry in Texas.Item Formation Kinetics of Nitric Oxide of Biodiesel Relative to Petroleum Diesel under Comparable Oxygen Equivalence Ratio in a Homogeneous Reactor(2011-10-21) Rathore, Gurlovleen K.Interest in biodiesel has piqued with advent of stringent emissions regulations. Biodiesel is a viable substitute for petroleum diesel because biodiesel produces significantly lower particulate and soot emissions relative to petroleum diesel. Higher nitric oxide (NO) emissions for biodiesel, however, are of primary concern in biodiesel-fueled engines. Search for an in-cylinder technique to reduce NO emissions for biodiesel has motivated studies to gain an improved understanding of fundamental factors that drive increase in NO emissions with biodiesel. Potential factors include fuel-bound oxygen, fuel-bound nitrogen and post-flame gas temperature. The role of fuel-bound oxygen however is debated in the literature. The research objective of this study is to computationally determine if biodiesel and petroleum diesel yield equivalent concentrations of NO with the same oxygen equivalence ratio in a 0-D homogeneous reactor, to explain the role of fuel-bound oxygen in biodiesel on increases in NO emissions with biodiesel. The results from this study indicate that the biodiesel surrogate yields higher NO emissions than the n-heptane because of its lower oxygen consumption efficiency. The lower oxygen consumption efficiency for biodiesel is likely because of the slower decomposition of the individual components and the blending ratios of the biodiesel surrogate blend. The relative differences in combustion efficiency of individual components of the biodiesel blend suggest this conclusion. The more efficient burning of the methyl esters relative to the n-heptane in biodiesel surrogate perhaps indicates the favorable role of fuel-bound oxygen in the fuel?s combustion. The low utilization of oxygen by the biodiesel surrogate could not be explained in this study. The dominance of NO2 H ? NO OH and N NO ? N2 O mechanisms during biodiesel combustion however explain the high NO emissions for the biodiesel surrogate relative to the n-heptane. The biodiesel may yield lower NO emissions than the petroleum diesel if the blending ratios for the biodiesel are adjusted such that combustion efficiency of biodiesel and petroleum diesel is same or the NO2 H ? NO OH and N NO ? N2 O mechanisms are suppressed during biodiesel combustion.Item Harnessing Yarrowia lipolytica’s potential as a lipid and alkane production platform(2013-08) Blazeck, John James; Alper, Hal S.; Contreras, Lydia; Ellington, Andrew; Georgiou, George; Maynard, JenniferEngineering cellular phenotype can enable the in vivo synthesis of renewable fuels, industrial precursors, and pharmaceuticals. Achieving economic viability requires the use of a cellular platform that generates high titers independent of fermentation condition, through either native or imported biosynthetic metabolism. While lacking fully developed genetic tools, the oleaginous yeast Yarrowia lipolytica has the native capacity to produce large titers of lipids and citric acid cycle intermediates. However, unlocking this biosynthetic capacity requires complete rewiring of native metabolism. To this end, this work focuses on the development and engineering of the yeast Y. lipolytica to rewire native metabolism and enable the production of lipids, alkanes, and itaconic acid. Precise control of gene expression is a requisite to enable metabolic and pathway engineering applications for any host organism. However, Y. lipolytica lacks promoter elements strong enough to manipulate intracellular metabolism. Thus, we utilized a hybrid promoter engineering approach to produce libraries of high-expressing, tunable promoters, seven-fold stronger than promoters previously characterized in Y. lipolytica 1,2. We successfully applied this approach to Saccharomyces cerevisiae, expanding transcriptional capacity of the strongest constitutive to highlight our hybrid approach as a generalizable method to increase expression capacity in eukaryotic organisms 3. We utilized our novel Y. lipolytica hybrid promoters to drive intracellular metabolism towards lipid production and to overexpress heterologous enzymes that enable alkane and itaconic acid production. Specifically, we implemented a global rewiring of Y. lipolytica’s native metabolism to increase lipogenesis more than sixty fold to 25.3g/L (the highest lipid production ever reported) and generated cells nearly 90% lipid content. We further expressed a lipoxygenase enzyme to catalyze the novel microbial production of the short-chain n-alkane, pentane. Finally, we exploited Y. lipolytica’s capacity to accumulate citric acid cycle intermediates by expressing a heterologous cis-aconitic acid decarboxylase enzyme to produce itaconic acid. Increasing substrate availability through media optimization and genomic engineering increased pentane and itaconic acid production threefold and eightfold, respectively 4. Collectively, these studies have facilitated the utilization of Y. lipolytica as an industrially relevant microbial platform, and represent a generic approach towards enabling biosynthetic control in microbial hosts will ill-defined gene expression technology.Item Investigating the Use of Ion Exchange Resins for Processing Biodiesel Feedstocks(2012-11-27) Jamal, Yousuf 1973-Ion exchange resins, commonly used in water treatment, demonstrate promise for the production of biodiesel from biomass feedstocks. The goal of this presented PhD research is to investigate novel uses of ion exchange resins for processing biodiesel feedstocks. Specifically, this research explored using ion exchange resins to remove free fatty acids (FFA) from soybean and waste cooking oils, catalyze transesterification of soybean oil, and catalyze in-situ conversion of dried algal biomass to biodiesel and other recoverable organics. The effect of temperature, moisture content, mixing rate, and resin drying on deacidification of soybean oil with 5% oleic acid feedstock was explored using Dowex Monosphere MR-450 UPW within a batch reactor. The resins were observed to remove up to 83 +/- 1.3% of FFA from soybean oil with less than 5% moisture content while operated at a 20% resin loading at 50 degrees C while mixing at 550 rpm. Once operation characteristics impacting deacidification were evaluated, a series of experiments were carried out to demonstrate the use of mixed bed resin to remove FFA from waste cooking oils. An investigation of wash solutions capable of regenerating the resins was also carried out. Using methanol to regenerate the resins resulted in more than 40% FFA removal over three regeneration cycles, highlighting the utility of resin regeneration as a cost saving measure. Transesterification of soybean oil on Amberlyst A26-OH, a basic ion exchange resin, in the presence of excess methanol was carried out to determine the mechanism of the reaction occurring on the surface. A batch reactor approach was used and reactions were carried out with and without FFA present in the soybean oil feed stock at a 20% resin loading at 50 degrees C while mixing at 550 rpm. When FFA was present in the feedstock and methanol is present in excess, the rate constant for methanol consumption increased. Based upon model fitting, the rate constant of methanol consumption was determined to be 2.08 x 10^-7 /sec with FFA absent and 5.39 x 10^-4/sec when FFA is present when the Eley-Rideal model was used to fit the data. In-situ conversion of dried algal biomass to biodiesel and other recoverable organics was investigated using a batch reaction system with 1 gram of algae. The system was operated with 40:60 methanol:hexane as the solvent system operated at 50 degrees C while mixing at 550 rpm over a range of catalyst loadings. The highest observed ester yield, approximately 60% yield (37 mg_ester/g_algae), was observed when air dried algae was reacted with a 20% resin. An evaluation of the reaction products showed a mixture of esters, phytol, alcohols, and ketones; highlighting the complexity of the reactions occurring during in-situ biomass conversion.Item Market penetration of biodiesel and ethanol(Texas A&M University, 2007-09-17) Szulczyk, Kenneth RayThis dissertation examines the influence that economic and technological factors have on the penetration of biodiesel and ethanol into the transportation fuels market. This dissertation focuses on four aspects. The first involves the influence of fossil fuel prices, because biofuels are substitutes and have to compete in price. The second involves biofuel manufacturing technology, principally the feedstock-to-biofuel conversion rates, and the biofuel manufacturing costs. The third involves prices for greenhouse gas offsets. The fourth involves the agricultural commodity markets for feedstocks, and biofuel byproducts. This dissertation uses the Forest and Agricultural Sector Optimization Model-Greenhouse Gas (FASOM-GHG) to quantitatively examine these issues and calculates equilibrium prices and quantities, given market interactions, fossil fuel prices, carbon dioxide equivalent prices, government biofuel subsidies, technological improvement, and crop yield gains. The results indicate that for the ranges studied, gasoline prices have a major impact on aggregate ethanol production but only at low prices. At higher prices, one runs into a capacity constraint that limits expansion on the capacity of ethanol production. Aggregate biodiesel production is highly responsive to gasoline prices and increases over time. (Diesel fuel price is proportional to the gasoline price). Carbon dioxide equivalent prices expand the biodiesel industry, but have no impact on ethanol aggregate production when gasoline prices are high again because of refinery capacity expansion. Improvement of crop yields shows a similar pattern, expanding ethanol production when the gasoline price is low and expanding biodiesel. Technological improvement, where biorefinery production costs decrease over time, had minimal impact on aggregate ethanol and biodiesel production. Finally, U.S. government subsidies have a large expansionary impact on aggregate biodiesel production, but only expand the ethanol industry at low gasoline prices. All of these factors increase agricultural welfare with most expanding producer surplus and mixed effects on consumers.Item Performance Characterization of a Medium-Duty Diesel Engine with Bio-Diesel and Petroleum Diesel Fuels(2010-01-16) Esquivel, JasonIn the wake of global warming and fossil fuel depletion, renewed attention has been paid to shifting away from the use of petroleum based fuels. The world?s energy demand is commencing its dependency on alternative fuels. Such alternative fuels in use today consist of bio-alcohols (such as ethanol), hydrogen, biomass, and natural oil/fat derived fuels. However, in this study, the focus will be on the alternative fuel derived from natural oils and fats, namely biodiesel. The following study characterizes the performance of a medium-duty diesel engine fuelled with biodiesel and conventional diesel. The objective is accomplished by taking measurements of manifold pressure and temperature, fuel flow, air flow, and torque. The study first characterizes a John Deere 4.5 liter 4 cylinder direct injection engine with exhaust gas recirculation (EGR), common rail fuel injection, and variable turbo-charging with conventional petroleum diesel to set a reference for comparison. The study then proceeds to characterize the differences in engine performance as a result of using biodiesel relative to conventional diesel. The results show that torque decreases with the use of biodiesel by about 10%. The evaluation of engine performance parameters shows that torque is decreased because of the lower heating value of biodiesel compared to conventional diesel. The insignificant difference between the other performance parameters shows that the ECM demands the same performance of the engine regardless of the fuel being combusted by the engine.Item Polymer applications for improved biofuel production from algae(2011-12) Jones, Jessica Naomi; Poenie, Martin F.; Brand, Jerry; Brodbelt, Jennifer; Georgiou, George; Roy, Krishnendu; Seibert, FrankBiofuel is a renewable and sustainable energy source with near-neutral carbon footprint. Algae are an ideal feedstock for biofuel production because they reproduce quickly and have high oil. Algae can be cultivated in non-arable land, and would not impact the food supply. Unfortunately, processing algae into biofuel is more expensive than land crops due to the large volumes of dilute algal suspension that must be harvested and concentrated. In order to improve algae-based biofuel economics, resins were developed that reduce costs associated with water pumping and transport. Hydrophobic resins were developed for binding oil out of an algal suspension so that the residual biomass could be recovered without solvent contamination. Binding behavior displayed lipid species specificity, and binding capacity was improved by ethanol treatment of the biomass. Algae was harvested by binding to anion exchange resin and directly converted into biodiesel. One-step, room temperature in situ transesterification of algae yielded nearly as much biodiesel as two-step, heated transesterification of dried biomass. Elution with transesterification reagent also regenerated the resin for subsequent algal binding. Functionalized resins were developed with high algal binding capacity at neutral pH. Binding was easily reversed, as treatment with buffer with pH higher than pKa of the resin functional group removed the algae and regenerated the resin for subsequent use. The resin bound 10% of its weight in algae and released it as a 100-fold concentrated suspension. The polymers developed can be scaled up for commercial processes and reduce algal harvesting and concentration costs.Item Three Essays on Energy Economics and Forecasting(2012-02-14) Shin, Yoon SungThis dissertation contains three independent essays relating energy economics. The first essay investigates price asymmetry of diesel in South Korea by using the error correction model. Analyzing weekly market prices in the pass-through of crude oil, this model shows asymmetric price response does not exist at the upstream market but at the downstream market. Since time-variant residuals are found by the specified models for both weekly and daily retail prices at the downstream level, these models are implemented by a Generalized Autoregressive Conditional Heteroskedasticity (GARCH) process. The estimated results reveal that retail prices increase fast in the rise of crude oil prices but decrease slowly in the fall of those. Surprisingly, retail prices rarely respond to changes of crude oil prices for the first five days. Based on collusive behaviors of retailers, this price asymmetry in Korea diesel market is explained. The second essay aims to evaluate the new incentive system for biodiesel in South Korea, which keeps the blend mandate but abolishes tax credits for government revenues. To estimate changed welfare from the new policy, a multivariate stochastic simulation method is applied into time-series data for the last five years. From the simulation results, the new biodiesel policy will lead government revenues to increases with the abolishment of tax credit. However, increased prices of blended diesel will cause to decrease demands of both biodiesel and blended diesel, so consumer and producer surplus in the transport fuel market will decrease. In the third essay, the Regression - Seasonal Autoregressive Integrated Moving Average (REGSARIMA) model is employed to predict the impact of air temperature on daily peak load demand in Houston. Compared with ARIMA and Seasonal Model, a REGARIMA model provides the more accurate prediction for daily peak load demand for the short term. The estimated results reveal air temperature in the Houston areas causes an increase in electricity consumption for cooling but to save that for heating. Since the daily peak electricity consumption is significantly affected by hot air temperature, this study makes a conclusion that it is necessary to establish policies to reduce urban heat island phenomena in Houston.Item Use of an Engine Cycle Simulation to Study a Biodiesel Fueled Engine(2010-01-14) Zheng, JunnianBased on the GT-Power software, an engine cycle simulation for a biodiesel fueled direct injection compression ignition engine was developed and used to study its performance and emission characteristics. The major objectives were to establish the engine model for simulation and then apply the model to study the biodiesel fueled engine and compare it to a petroleum-fueled engine. The engine model was developed corresponding to a 4.5 liter, John Deere 4045 four-cylinder diesel engine. Submodels for flow in intake/exhaust system, fuel injection, fuel vaporization and combustion, cylinder heat transfer, and energy transfer in a turbocharging system were combined with a thermodynamic analysis of the engine to yield instantaneous in-cylinder parameters and overall engine performance and emission characteristics. At selected engine operating conditions, sensitivities of engine performance and emission on engine load/speed, injection timing, injection pressure, EGR level, and compression ratio were investigated. Variations in cylinder pressure, ignition delay, bsfc, and indicated specific nitrogen dioxide were determined for both a biodiesel fueled engine and a conventional diesel fueled engine. Cylinder pressure and indicated specific nitrogen dioxide for a diesel fueled engine were consistently higher than those for a biodiesel fueled engine, while ignition delay and bsfc had opposite trends. In addition, numerical study focusing on NOx emission were also investigated by using 5 different NO kinetics. Differences in NOx prediction between kinetics ranged from 10% to 65%.