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The science of synthetic fuel production began in the seventeenth century. However, large-scale production of synthetic fuels started in the early 1900's and, for several decades, gas manufactured from coal significantly contributed to the U.S. economy. The production of synthetic fuels declined due to increases in the price of coal and discoveries of predominantly methane natural gas. Today, an extensive network of pipelines is used to transmit and distribute natural gas for industrial and residential applications. The decline of natural gas reserves in the United States, in conjunction with the availability of very large coal reserves, has provided the incentive for development of coal gasification plants. Synthetic fuels are expected to contribute significantly to the supply of energy before the end of this century, and coal will be the primary source for production of these fuels. By many accounts, difficulties in raising the high amount of initial capital and future uncertainties with regard to fuel and operating costs have made development of synthetic fuels economically infeasible. However, as the prices of oil and natural gas increase, synthetic fuels production becomes a more attractive alternative. The purpose of this study is to evaluate the economics of synthetic natural gas with the current state of technology and to determine its future role as prices of oil and gas increase. In this report, a general methodology of production of synthetic natural gas is explained. For the economic analysis, the Lurgi Model was selected because it has been the most common model used for commercial production of high BTU gases. An extensive analytical model is described in which inflated capital, fuel, and operating and maintenance costs were accounted for and the equivalent annual cost of cash flows over the project life was calculated. The risk analysis was accomplished by applying Monte Carlo techniques through a simulation model which handles risks associated with various input parameters. SLAM, a FORTRAN-based language, was selected as the simulation language. Based on the results, all the cost elements were evaluated and the sensitivity of the total cost to each element was examined. This study was extended to the calculation of costs associated with he generation of electricity by burning synthetic natural gas. The results were then compared to the respective costs related to oil-burning power plants. The results show that high cost of synthetic high BTU gas makes it difficult to compete with natural gas at current prices. Coal feed stocks represent a major portion of the total cost of synthetic gases. The cost of capital, which is a critical factor at the developing stage, constitutes a relatively small portion of the total cost over the plant life. A similar observation was made for operating and maintenance costs. However, the future regulations regarding pollution control could have a strong impact on this portion of the cost. For power generations, oil was found to be far more economical than using synthetic natural gas. The computer simulation also revealed that the total cost of each alternative is very sensitive to this fuel cost. The conclusion of this study points to the fuel costs as the dominant factor in the choice of fuel alternatives in the future.

Submitted in fulfillment of the requirements for the Degree of Master of Technology: Chemical Engineering, Durban University of Technology, 2014. / Biodiesel is a renewable fuel that can be produced from animal fats, vegetable oils or recycled used cooking oil. From the 1970’s, biodiesel received increased focus as an alternative to crude oil and its component products. Among various processes used for biodiesel production, transesterification of glyceride and alcohol in the presence of a catalyst to produce ester (biodiesel) and glycerin remains the most common. In Africa, biodiesel is currently produced industrially in a number of ways via different methods. In South Africa, there are a number of biodiesel production plants that are continuous processes with feed samples from different sources. Reviewing the batch systems for developing economies, various observations were made. Some produced biodiesel using batch systems at room or day temperatures, another used different temperatures, some also used flat based buckets for their mixing and so on. This becomes difficult for local producers who desired to produce biodiesel on a very small scale for their farms or business. Hence, the study was aimed at evaluation batch biodiesel systems and to come up with a simplified approach for a producer in a developing economy or a local user. The objectives of this study were as follows; To evaluate biodiesel production options, and hence develop a simplified process that can be used to produce biodiesel in developing economies. The criteria for evaluation will include: ease of operation, non-specialist equipment, range of feedstock, product quality and product yield. To evaluate various factors that affect these criteria and make recommendations that will enable a local producer to remain within an optimum range Compare the produced biodiesel properties against general biodiesel and petroleum diesel ASTM standard range Recommend simplified equipment design for a local producer Perform economic evaluation to establish cost required both for equipment and raw materials for a local producer. After literature review on the existing processes, base catalyzed transesterification was selected. This is because of the simplicity as well as ease of operation. Experimental trials commenced using feeds from pure vegetable oil (PVO) and waste vegetable oil (WVO) to familiarize biodiesel production, as well as study the behavior of each having the research criteria in focus. Various variables that affect ease of operation, product quality, and yield were also investigated. These include temperature, type of catalyst (KOH or NaOH), type of alcohol (Methanol or Ethanol), concentration of catalyst, and purity of alcohol, and nature of feed (PVO or WVO). The effect of temperature was compared against product quality, yield, and ease of operation. Other variables were also compared against the same criteria. Treatment of WVO because of impurity and moisture contamination associated with such samples was also studied. The product was then tested using some ASTM procedures to compare biodiesel quality to acceptable standards. Efficient reaction time is paramount for a quality biodiesel. It was observed that biodiesel required between 25 and 30 minutes for a complete reaction. Lower temperatures clearly affected the quality of biodiesel produced. Best operating range was found to be between 55 oC – 75 oC is usually recommended for a transesterification reaction to obtain optimum yield and quality. The use of KOH compared to NaOH yields similar results even though NaOH is usually selected because of the reduced cost. The use of methanol compared to ethanol also yields similar results, even though methanol is usually preferred due to cost. Purity of available alcohol is vital as its reduction from 99.5 % to 75 % during experimental trials, yielded poor quality biodiesel. This is mainly due to moisture content that usually gives room for bacteria growth and corrosion of fuel lines in engines. As long as a titration test is carried out on the feed, the use of WVO is a good option. Varying catalyst concentrations from 0.5 % to 1.75 % were considered and the best regimes identified. This test will enable a producer from a growing economy to use the appropriate reagent, which will ensure the transesterification reaction is complete. After comparing appleseed and cone based design, the latter was selected as it will eliminate any difficulty that a local producer might encounter in making the biodiesel batch. In terms of costs, it was discovered that the major costs to a local producer will be the biodiesel mixer and fittings which will be fixed costs. Other variable costs are considered to be affordable, as the cost of waste vegetable oil is very low as well as other industrial reagent grade that will be required. In summary, batch biodiesel production for a local user or developing economy is a very feasible exercise. One needs to ensure that the recommendations regarding pre-treatment of feed oil, basic reaction criteria and other generic parameters are considered during production.

published_or_final_version / abstract / toc / Mechanical Engineering / Master / Master of Philosophy

This study presents an experimental investigation into the effects of running biodiesel fuel blends on conventional diesel engines. Bio fuels provide a way to produce fuels without redesigning any of the engine technology present today, yet allowing for green house emissions to decrease. Bio-diesel is one of these types of emerging bio-fuels, which has an immediate alternative fuel aspect to it, while providing a decrease in green house emissions, as well as a solution to recycling used Waste Vegetable Oils which are other wise disposed. This study shows how by blending bio-diesel with petroleum diesel at intervals of B5, B10, B15, and B20 decrease green house emissions can significantly while maintaining similar performance output and efficiency with respect to 100% petroleum diesel. / by Sergio Bastiani. / Thesis (M.S.C.S.)--Florida Atlantic University, 2008. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2008. Mode of access: World Wide Web.

Solar-thermochemische Redoxzyklen stellen eine vielversprechende Technologieoption zur Nutzung und Umwandlung von erneuerbaren Energiequellen dar. Durch Reduktion von Metalloxiden bei hoher Temperatur und/oder niedrigem Sauerstoffpartialdruck kann ein Material in einen Zustand überführt werden, der dazu geeignet ist, Sauerstoff aus einem Gasstrom zu entfernen oder Wasser bzw. Kohlenstoffdioxid zu spalten. Dadurch ist es möglich, Luft zu zerlegen oder Sauerstoff zu pumpen, sowie sogenannte solare Brennstoffe zu erzeugen. Eine besonders vielversprechende Materialklasse stellen dabei die Perowskite dar. Diese Materialien bilden stabile Phasen mit sehr unterschiedlichen Zusammensetzungen. In dieser Arbeit wird gezeigt, wie diese Perowskit-Oxide in thermochemischen Redoxzyklen verwendet werden können und die Mechanismen hinter diesen Redoxreaktionen werden mit in-situ-Röntgenuntersuchungen aufgeklärt. Es wird auch gezeigt, dass die kinetischen Parameter der Oxidationsreaktion sehr vielversprechend sind. Zudem wird demonstriert, wie feste Lösungen aus Perowskiten in einem weiten Bereich verschiedener Zusammensetzungen hergestellt werden können und wie die Zusammensetzung der Perowskite die Phasenbildung und Stabilität beinflusst. Mit diesem Wissen wird ein Schwerpunkt dieser Arbeit auf die thermodynamischen Eigenschaften dieser Perowskite gelegt. Eine neue Methode der gezielten Materialentwicklung wird demonstriert, welche darauf basiert, den Toleranzfaktor und die thermodynamischen Eigenschaften der Perowskite gezielt einzustellen. Sowohl experimentelle, als auch theoretische Untersuchungen werden durchgeführt, letzere basierend auf Dichtefunktionaltheorie (DFT) im Rahmen von „Materials Project“. Über 240 Perowskit-Brownmillerit-Paare wurden untersucht. Detaillierte Modelle wurden entwickelt, um die thermodynamischen Eigenschaften solcher fester Lösungen aus Perowskiten als eine Funktion der Temperatur, des Sauerstoffpartialdrucks, und der Sauerstoff-Fehlstellenkonzentration 𝛿 zu beschreiben. Mit Hilfe dieser Funktionen wurde ein interaktiver Beitrag im Rahmen von Materials Project entwickelt, mit dem Materialeigenschaften in einem weiten Bereich verschiedener Bedingungen untersucht werden können. Darin ist auch eine Perowskit-Suchmaschine enthalten. Diese verwendet ein vereinfachtes Prozessmodell, um den materialspezifischen Energiebedarf von Redoxzyklen auszuwerten und ermöglicht es so, das effizienteste Material basierend auf den Prozessbedingungen auszuwählen. Es konnten neue Redoxmaterialien zur Anwendung in thermochemischen Kreisprozessen identifiziert werden und es wurde festgestellt, dass Perowskite die Effizienz der solaren Brennstofferzeugung bei vergleichsweise niedrigen Reduktionstemperaturen von 1300-1400 °C erhöhen können. So soll eine höhere Reaktorlebensdauer erreicht werden. Es wird auch diskutiert, welche Faktoren die Prozesseffizienz beeinflussen und es werden Ideen präsentiert, welche Schritte nötig sind, um eine kommerzielle Nutzung zu ermöglichen. Der wichtigste Faktor ist dabei die Wärmerückgewinnungseffizienz zwischen Feststoffen. Durch die Veröffentlichung aller Daten im Rahmen von MPContribs/Materials Project durch das Erstellen von interaktiven Graphen wird eine wertvolle Ressource zur schnelleren und zielgerichteten Materialentwicklung bereitgestellt. / Solar-thermochemical redox cycles are a promising technological option in the framework of utilization and conversion of renewable energy. By reducing metal oxides at high temperature and/or low oxygen partial pressure, one can generate a material in a state which can be used to capture oxygen from a gas stream or split water or carbon dioxide. By this means, air can be separated, oxygen can be pumped, or so-called solar fuels can be generated. One especially attractive materials class for application in such redox cycles is constituted by perovskites. These materials form stable phases over a large compositional range. Within this work, we show how these perovskite oxides can be applied in thermochemical redox cycles and study the mechanisms behind these redox reactions using in-situ X-Ray techniques. We also show that the kinetic properties of the oxidation reaction are very appealing. It is furthermore presented how perovskite solid solutions can be formed over a large compositional range and how phase formation and stability are affected by the perovskite composition. Based on this knowledge, the focus of this work is set on the materials thermodynamics. A new method of rational perovskite materials design is developed by adjusting the tolerance factor of the perovskites and their thermodynamics. Both experimental and theoretical materials development are conducted, the latter based on density functional theory (DFT) within the framework of the online resource “Materials Project”. Over 240 perovsite-brownmillerite pairs are included in the search. Detailed models describing the thermodynamics of such perovskite solid solutions are established which allow describing the perovskite redox properties as a function of the temperature, oxygen partial pressure, and oxygen non-stoichiometry 𝛿. Using these functions, we developed an interactive tool within the framework of Materials Project, which can be used to model materials properties for a large range of conditions and also serves as a perovskite search engine. This search engine uses a simplified process model to evaluate the material-specific energy demand of a thermochemical redox process and allows finding the most efficient materials choice for a large range of different operational parameters. We could identify new redox materials for application in such processes and found that perovskites can lead to more efficient thermochemical fuels production than the state of the art, especially if the reduction temperature is lowered to 1300-1400 °C to reach higher reactor longevity. It is also discussed which factors affect the overall process efficiency to which extent, and suggestions are given which steps are necessary for a commercialization of such redox processes. The most important factor is the solid-solid heat recovery efficiency. By making all this data publicly available in the framework of MPContribs/Materials Project through providing user-controlled interactive graphs, we are providing a valuable resource for accelerating the discovery and use of new redox materials.

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. / text

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Gas cleaning is an essential step in many chemical processes. The reason for cleaning is to remove components that can damage equipment or inhibit further reactions. The treatment can include the removal of particulates, removal of one or more chemical species, or the conversion of one species to another. The gases include natural gases, combustion gases or synthesis gas (syngas). Of particular importance is the hot gas desulphurization (HGD) of syngas after gasification. This method of treatment offers potential energy and raw material savings to traditional ‘wet’ gas cleaning methods, such as physical or chemical absorption. Syngas is a valuable intermediate product because it can be processed into a number of different chemicals. These range from hydrocarbon chains (Fischer-Tropsch reactions), methanol, and ammonia (from hydrogen in the syngas). Methanol and ammonia are important raw materials to produce other chemicals. Syngas can be used for production of electricity via gas turbines in an Integrated Gasification Combined Cycle (IGCC) plant. In this study, a laboratory scale gasification and desulphurization unit was designed and constructed for removal of hydrogen sulphide (H2S) from syngas. The gasifier operates at moderately high temperature (700-900 °C) and low pressure (1-3 bar g) to produce syngas containing H2S (1-6 mol %) from a liquid hydrocarbon fuel mixture and oxygen. Desulphurization occurs in a fixed bed isothermal reactor (300-600 °C) whereby H2S is removed by chemical reaction with a sorbent. The fuel used was a mixture of methanol and ipropanethiol and the sorbent chosen was zinc oxide. The apparatus was tested to obtain a reliable experimental method. A series of experiments were conducted to determine two results: Firstly, to see the performance of the unit during repeated sorbent testing (i.e. a systematic experimental run programme). Secondly, to determine the effect of some process variables (temperature, flowrate and particle size) on the conversion of sorbent. GC analysis of the syngas showed consistent gas composition during the experiment, an important result which justifies this new method of syngas production from a liquid fuel. The final conversions from ZnO to ZnS ranged from 2-12 mole %. However, there was some variation under repeated conditions, which showed the need for additional method development. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.