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Kappanna, Hemanth K. "Reduction of toxic air contaminants (TACs) and particulate matter emissions from heavy-duty natural gas engines." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4553.
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Thesis (M.S.)--West Virginia University, 2006.Title from document title page. Document formatted into pages; contains xiii, 182 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 135-142).
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Thiruvengadam, Padmavathy Arvind. "Evaluation of exhaust after-treatment device effectiveness in reducing regulated and unregulated emissions from natural gas fueled heavy duty transit bus." Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5744.
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Thesis (M.S.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains xi, 146 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 115-121).
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Burlingame, Timothy S. "Reduction of natural gas engine emissions using a novel aftertreatment system." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3481.
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Thesis (M.S.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains v, 131 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 128-131).
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Santos, Roberto Amaral de Castro Prado. "Natural gas vehicles in Brazil: consequences to fuel markets." reponame:Repositório Institucional do FGV, 2018. http://hdl.handle.net/10438/24016.
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This Master Thesis consists of one empirical article on the field of Microeconomy. Natural Gas Vehicles (NGVs) are very popular in many countries around the world, including Brazil. The Brazilian State of Rio de Janeiro has the largest NGV fleet of the country. Using a panel database extending for 15 years, we evaluate the impact of the NGV fleet penetration growth in Rio de Janeiro on the retailers’s prices and margins of gasoline and sugarcane ethanol. By correcting for endogeneity, we are able to identify a negative impact of the former variables on the last ones. The result is generally robust to different specifications of our model and instrument, as well as to data adjustment. We also calculate that the NGV fleet growth has benefited the environment through lower pollutant emissions. Hence, the increase in the NGV fleet is benefitial to society not only through less polution, but also by lowering the prices of gasoline and ethanol, therefore benefiting its consumers.
Esta dissertação de mestrado consiste em um artigo empírico no campo da Microeconomia. Veículos movido a gás natural são populares em diversos países do mundo, incluindo o Brasil. O estado brasileiro do Rio de Janeiro tem a maior frota desse tipo de veículos no Brasil. Usando 15 anos de dados em painel, nós avaliamos o impacto do crescimento da penetração dos veículos movidos a gás natural no Rio de Janeiro sobre os preços e margens da gasolina e do etanol de cana-de-açúcar nos postos de gasolina fluminenses. Ao corrigir pela endogeneidade, identificamos um impacto negativo da primeira variável nas posteriores. Tal resultado é geralmente robusto a diferentes especificações do nosso modelo e instrumento, além de a ajustes nos dados. Além disso, calculamos que o crescimento da frota de veículos movidos a gás natural foi benéfico para o meio-ambiente por meio de menores emissões de poluentes. Assim, um aumento da frota de veículos movidos a gás natural beneficiou a sociedade não apenas através de uma menor poluição, mas também por diminuir o preço da gasolina e etanol, beneficiando, consequentemente, seus consumidores.
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Ramli, Anita. "Removal of nitric oxide from natural gas vehicle exhausts." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318618.
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Wu, Dien-yeh. "Evaluation of light duty vehicle conversions to natural gas and liquefied petroleum gas : speciated and off-cycle emissions /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Chen, Shr-Hung. "Novel design and optimization of vehicle's natural gas fuel tank." Ohio : Ohio University, 1997. http://www.ohiolink.edu/etd/view.cgi?ohiou1177607369.
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Udell, Thomas Gregory. "Reducing emissions of older vehicles through fuel system conversion to natural gas." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/19896.
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Crittle, David John. "An investigation into the catalytic combustion of methane for natural gas vehicles." Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298481.
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Thomas, Alister Julian. "Modelling of an automotive natural gas engine for A/F control investigations." Thesis, University of Warwick, 1995. http://wrap.warwick.ac.uk/109067/.
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In this thesis, the problem of A/F ratio control in a natural gas, internal combustion engine is addressed, with the global objective of reducing exhaust emission pollutants. A review of some mechanical approaches to exhaust pollutant reduction are assessed. It is found that many techniques aid the reduction of exhaust pollutants, but the most effective is the 3-way catalytic converter. To maintain conversion efficiency, the A/F ratio must be strictly controlled within the catalyst window limits around the stoichiometric operating point. In order to investigate possible control techniques, a mathematical model is developed to simulate the physical behaviour of the engine processes. This approach allows a quick turn-around in terms of cost and time, for control investigations. The model demonstrates close trend-wise approximation of the engine states with previous modelling studies, however, a full validation study was not possible. The model is then used to conduct investigations into A/F ratio control through the process of simulation. Conventional Pl-closed-loop control is assessed for steady-state and transient engine conditions, and for varying microprocessor sampling rates. It is found that Pi-control effectively removes state estimation errors, but is unable to remove A/F ratio excursions under transient operation. An open-loop compensation control structure is then developed as an extension to the IM-controller action. Simulation results show this approach to drastically reduce A/F ratio excursions for a number of typical driving scenarios. Potential problems that could well be encountered in the “real” engine environment are then investigated, and the practicality of the new controller assessed. A new approach to control is simulated that affords the most appropriate state estimation for the modelled system. This is shown to improve A/F ratio control upon that of the conventional approach but cannot match the compensation controller ability.
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Nobre, Mendes Acacio Miguel. "Development of an innovative system for pollution abatement in the new natural gas vehicles." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066599/document.
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Ce travail traite de la réduction catalytique sélective des oxydes d’azote en utilisant du méthane comme agent réducteur sur catalyseurs bimétalliques Pd/Ce/zéolithes. Dans un premier temps, la méthode d’introduction du palladium, la teneur en palladium et cérium ainsi que l’ordre d’introduction des métaux ont été optimisés pour une formulation considérant une zéolithe MOR comme support catalytique. Puis, l'effet des différentes conditions opératoires ont été évalués. L’effet du support catalytique a été également étudié en comparant un catalyseur PdCe-BEA au catalyseur PdCe-MOR résultant de l’optimisation effectuée. Il a été montré que les deux catalyseurs possèdent différentes espèces métalliques conduisant ainsi à différentes performances catalytiques. Des Relations structure/réactivité ont été établies par différentes techniques de caractérisation et des résultats des tests catalytiques. Il a été mis en évidence un effet synergique résultant de la combinaison de ces deux catalyseurs dans le même pot catalytique (configurations lit mélangé et lit double). Un traitement thermique innovant appliqué au catalyseur PdCe-MOR, pendant sa préparation a été développé et optimisé. Dans certaines conditions, ce traitement conduit à l’amélioration de la performance catalytique, notamment, à une conversion de NOx à N2 et à une sélectivité de CH4 pour la réaction NOx RCS plus élevée. Enfin, des catalyseurs structurés ont été préparés par "washcoating" de PdCe-MOR sur des monolithes de cordiérite possédant des géométries différentes. Les paramètres de préparation ont été ainsi évalués par des techniques de caractérisations et par des tests en banc de gazThe selective catalytic reduction of nitrogen oxides, in lean-conditions, using methane as reductant (NOx CH4-SCR) over PdCe/zeolite-based catalysts was considered in this work. Preparation method for palladium introduction, palladium/cerium loadings and metal introduction order were optimised for a formulation considering MOR zeolite as the catalytic support. The effect of different test conditions, namely [CH4]/[NO] ratio and water presence in the reaction mixture was assessed. The effect of the zeolite support in the stabilisation of Pd/Ce species was also evaluated by preparing a similar PdCe-BEA catalyst to the optimised PdCe-MOR catalyst, considering the same metal loadings and preparation methods. Both catalysts exhibited different metal species and different catalytic performances. Structure-reactivity relationships were drawn from the comparison of several characterisation techniques and catalytic test results for both catalysts. A synergic effect resulting from the use of both catalysts in a single bed application (mixed-bed and dual-bed configuration) is reported. An innovative thermal treatment applied to PdCe-MOR catalyst during its preparation is reported. Under certain conditions, this treatment results in the enhancement of the catalytic performance, namely, in higher NOx conversion into N2 and CH4 selectivity towards NOx SCR. Structured catalysts were prepared by washcoating of PdCe-MOR onto cordierite monoliths with different geometry (cpsi). Preparation parameters were evaluated through characterisation techniques and the catalytic performance was assessed in a synthetic gas bench plant
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McCollum, Jerl Levi. "Gracias a La Nacionalización De Los Hidrocarburos: a Critical Analysis of Bolivia’s Transition to Compressed Natural Gas." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc801935/.
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This paper critically analyzes the implementation of compressed natural gas and the ways in which it creates discourse in urban Bolivia. The rapidly developing nation is keen on making ubiquitous use of compressed natural gas a reality by issuing subsidies, citing increased mobility, savings, and environmental stewardship as the primary motives. Currently, eight out of every 10 public vehicles in Bolivia are powered by compressed natural gas. Through semi-structured interviews, questionnaires and secondary data collection, this paper elucidates the transitional process of building a natural gas-based transport network through discursive governance. This work draws on the critical discourse analysis literature to dissect disaggregated modal preference data, government documents, and news articles collected in Santa Cruz, Latin America's second fastest growing city. Moreover, this paper identifies and examines the ways in which the counter-discourse impacts the transformation of the country’s energy matrix. Results show that Bolivian automobile owners are reluctant to convert their automobiles, despite reduced transportation costs, stating that minimal compressed natural gas infrastructure exists outside of urban areas, and the conversion damages their vehicles’ motor. Additionally, the research reveals that automobile owners are currently the main beneficiaries, though respondents who do not posses an automobile speak more favorably of natural gas. Finally, this research illustrates that the compressed natural gas-oriented policies encourage personal automobile use that continues to drive socio-spatial segregation of Santa Cruz’s residents. Thus, the compressed natural gas discourse helps shape the urban landscape by persuading the public to consume domestically extracted and manufactured natural gas.
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Nigge, K. M. "Life cycle assessment of natural gas vehicles : development and application of site-dependent impact indicators /." Berlin : Springer, 2000. http://opac.nebis.ch/cgi-bin/showAbstract.pl?u20=3540672737.
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Klingstedt, Fredrik. "Development of catalysts for exhaust after-treatment of natural gas powered vehicles and biofuel combustion /." Åbo : Åbo akademi university, 2002. http://catalogue.bnf.fr/ark:/12148/cb40124623b.
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Yip, Arthur Hong Chun. "Modelling the global prospects and impacts of heavy duty liquefied natural gas vehicles in computable general equilibrium." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/95587.
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Thesis: S.M. in Technology and Policy, Massachusetts Institute of Technology, Engineering Systems Division, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 69-71).
Natural gas vehicles have the prospects of making substantial contributions to transportation needs. The adoption of natural gas vehicles could lead to impacts on energy and environmental systems. An analysis of the main factors and trends that affect adoption of natural gas vehicles such as vehicle costs, infrastructure costs, and fuel economics was performed. The fuel cost analysis showed that assuming production and distribution at scale, liquefied natural gas (LNG) can be competitive as a diesel fuel substitute for heavy duty vehicles in the US, and also in EU and China. A methodology of incorporating heavy duty natural gas vehicles into a computable general equilibrium (CGE) economic modelling was developed to investigate the potential adoption and impacts. Modelling variables such as vehicle and infrastructure costs were tested and several scenarios were applied to examine the general equilibrium impacts on natural gas vehicle adoption and the general equilibrium impacts of resulting natural gas vehicle adoption. Climate policy scenarios were also developed and tested. In the base case scenario, results showed significant adoption of LNG trucks (Class 8) in the US, with 10% penetration of heavy duty trucks by 2020 and up to 100% by 2040. In China and the EU, adoption was projected to be slower due to higher natural gas prices. In the US, introduction of LNG trucks resulted in moderately higher natural gas prices, slightly lower oil prices, and a small reduction in total GHG emissions, relative to scenarios without LNG truck availability. The development of natural gas fuelled transportation is still in its infancy and CGE modelling offers a tool that can be applied to test a wide range of assumptions of cost development and relative prices.
by Arthur Hong Chun Yip.
S.M. in Technology and Policy
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Nigge, Karl-Michael. "Life cycle assessment of natural gas vehicles : development and application of site-dependent impact indicators ; with 44 tables /." Berlin ; Heidelberg [u.a.] : Springer, 2000. http://swbplus.bsz-bw.de/bsz086457136inh.htm.
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Tong, Fan. "The Good, the Bad, and the Ugly: Economic and Environmental Implications of Using Natural Gas to Power On-Road Vehicles in the United States." Research Showcase @ CMU, 2016. http://repository.cmu.edu/dissertations/717.
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Currently, in the United States, on-road vehicles are primarily powered by petroleum fuels (gasoline and diesel). These vehicles have caused serious climate change effects from emissions of greenhouse gas (GHG) and health and environmental impacts from criteria air pollutant (CAP). The recent success of shale gas development has brought industry interest in using natural gas to power on-road vehicles. In addition to low costs and wide availability of this national fuel source, natural gas is a common feedstock to produce alternative fuels. The question arises of whether using natural gas for transportation could help or hinder the environment. In this dissertation, I study the economic and environmental effects of a wide range of natural gas fuel pathways for a selection of light duty (LDV) and medium and heavy duty (MHDV) vehicle types. I choose to focus on two environmental metrics: GHGs and CAPs emitted over the life cycle of each potential pathway for natural gas use. First in Chapters 2 and 3, I use life-cycle analysis to understand the emissions of GHGs from different natural gas pathway for LDVs and MHDVs. Then in Chapter 4 I focus on the CAP emissions from these vehicles. Overall, I find that none of the natural gas pathways eliminate life cycle air emissions. In fact, only a few pathways reduce life cycle GHG emissions and/or life cycle air pollution damages compared to baseline petroleum fuels (gasoline for light-duty vehicles (LDVs) and diesel for heavy-duty vehicles (HDVs)). For the cases of light duty vehicles (LDVs) and transit buses, battery electric vehicles (BEVs) powered by natural gas-based electricity provide significant reduction in life cycle GHG emissions and life cycle air pollution damages (for almost all counties) compared to the baseline petroleum fuels. However, the actual electricity that charges BEVs may not be natural gas-based electricity in most parts of the U.S. When powered by U.S. grid electricity (using average emission factors for 2010 and 2014), BEVs reduce life cycle GHG emissions to a lesser extent but increase life cycle air pollution damages significantly. Compressed natural gas (CNG), while reducing GHG emissions and CAP emissions (except CO) at tailpipe, are more likely to increase life cycle GHG emissions and increase life cycle air pollution damages in the majority of U.S. counties. For heavy-duty trucks, CNG sparking-ignition (SI) trucks and liquefied natural gas (LNG) high-pressure direct ignition (HPDI) trucks have mixed environmental impacts. While they are unlikely to reduce life cycle GHG emissions compared to diesel, they reduce life cycle air pollution damages in 76-99% of U.S. counties for local-haul tractor-trailers and in 32-71% of U.S. counties for long-haul tractor-trailers. In Chapters 5 and 6, I examine the economic impacts of natural gas fuel pathways for two vehicle types, tractor-trailers and transit buses. I study the economic feasibility of a national natural gas refueling infrastructure for long-haul trucks in U.S., which is a prerequisite for natural gas tractor-trailers. I find that a transition to natural gas fuels in long-haul trucks is more expensive when the shares of natural gas trucks are below 5% because of low refueling demands and over-capacity of the refueling infrastructure to ensure network coverage. At higher shares of natural gas trucks, both the total refueling capacity and the net economic benefits of the national refueling infrastructure increase almost linearly as adoption increases. Finally, in Chapter 6, I provide an economic-technology assessment for transit buses by considering both life cycle ownership costs and life cycle social costs due to GHG emissions and CAP emissions. Transit buses are early adopters of alternative fuel technologies because of funding supports and operation characteristics (such as high fuel consumption and private refueling infrastructure). I find that the availability of external funding is crucial for transit agencies to adopt any alternative fuel option. Without external funding, only rapid-charging battery electric buses (BEBs) have lower ownership & social costs than conventional diesel buses. When external funding is available to reduce bus purchase costs by 80%, BEBs become much more cost-effective. In this case, life cycle ownership and social costs of BEBs are 37-43% lower than conventional diesel buses. Including life cycle social costs does not change the ranking of alternative fuel options. The findings in this dissertation suggest different strategies of using natural gas for different vehicle markets. Natural gas is best used in electric power generation than to produce gaseous or liquid fuels for powering on-road LDVs. The use of CNG and LNG for heavy-duty trucks may continue as there are less alternative fuel options but issues such as methane leakage should be addressed to avoid important climate change effect. Finally, natural gas-based transportation fuels can at best partially mitigate climate change or air pollution damages, so other mitigation strategies in the transportation sector are ultimately needed to achieve sustainable transportation.
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Kärkkäinen, M. L. (Marja-Liisa). "Deactivation of oxidation catalysts by sulphur and phosphorus in diesel and gas driven vehicles." Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526217239.
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Abstract The combustion of fuels in motor vehicles is one of the most significant causes of air emissions. The use of oxidation catalysts in exhaust gas emission treatment can reduce hydrocarbons (HCs) and carbon monoxide (CO) emissions by more than 90%. Fuels and engine lubricants contain impurities like sulphur (S) and phosphorus (P), which can have a significant effect on the activity and durability of oxidation catalysts. This thesis aims at increasing the current knowledge of the deactivation phenomena caused by sulphur and phosphorus in diesel and natural/bio gas oxidation catalysts. Accelerated laboratory scale sulphur, phosphorus and thermal treatments in gas-phase conditions were carried out for alumina (Al2O3) based platinum (Pt) and platinum-palladium (PtPd) metallic monolith diesel and natural gas oxidation catalysts. In addition, a vehicle-aged natural gas oxidation catalyst and an engine-bench-aged diesel oxidation catalyst were studied and used as a reference for the laboratory-scale-aged catalysts. BET-BJH, FESEM, TEM, XPS and DRIFT were used as characterization techniques to determine changes on the catalysts. The effect of accelerated deactivation treatments on the catalyst activity was determined using laboratory scale measurements in CO, HC and nitric oxide (NO) oxidation. Sulphur and phosphorus were found to cause morphological and chemical changes on the studied catalysts. Sulphur was found to be adsorbed vertically throughout the entire catalyst support from the catalyst surface to the metallic monolith, while phosphorus accumulated on the surface region of the precious metal containing catalysts. Both, sulphur and phosphorus, slightly increased the average size of the precious metal particles size and are adsorbed onto the alumina by chemical bonds. In addition, a partial transformation from PdO to Pd and a change in the shape of the precious metal particles due to phosphorus were detected. Due to the detected structural and chemical changes on the catalysts, sulphur and phosphorus treatments reduced the catalytic activity of the studied diesel and natural-gas-oxidation catalysts. Correspondence between real and simulated ageing was found and thus the used accelerated laboratory scale aging method can be stated to be a good tool to simulate sulphur and phosphorus exposureTiivistelmä Moottoriajoneuvot ovat merkittäviä ilmapäästöjen aiheuttajia. Hapetuskatalyyttejä käyttämällä hiilimonoksidi- ja hiilivetypäästöistä pystytään poistamaan yli 90 %. Polttoaineet ja voiteluaineet sisältävät epäpuhtauksia kuten rikkiä ja fosforia, jotka voivat merkittävästi heikentää hapetuskatalyyttien aktiivisuutta ja kestävyyttä. Väitöskirjan tavoitteena on tuottaa uutta tietoa rikin ja fosforin aiheuttamasta diesel- ja maakaasukatalyyttien deaktivoitumisesta. Metalliseen monoliittiin tuettuja alumiinioksidipohjaisia platina- ja palladiumkatalyytteja ikäytetiin tekemällä niille rikki-, fosfori- ja lämpökäsittelyjä. Maantieikäytettyä maakaasuhapetuskatalyyttiä ja moottoripenkki-ikäytettyä dieselhapetuskatalyyttiä käytettiin laboratorioikäytettyjen katalyyttien referensseinä. Ikäytyskäsittelyjen aiheuttamat muutokset analysoitiin BET-BJH-, FESEM-, TEM-, XPS- ja DRIFT-menetelmillä. Käsittelyjen vaikutus katalyyttien hiilimonoksidin, hiilivetyjen ja typenoksidien hapetusaktiivisuuteen tutkittiin laboratoriomittakaavan aktiivisuuslaitteella. Rikki ja fosfori aiheuttivat rakenteellisia ja kemiallisia muutoksia tutkittuihin katalyytteihin. Rikki adsorboitui koko tukiaineeseen (tukiaineen pinnalta pohjalle), kun taas fosfori adsorboitui vain pinnan alueelle. Sekä rikki että fosfori kasvattivat jalometallipartikkeleiden kokoa sekä muodostivat alumiinioksidin kanssa yhdisteitä. Lisäksi fosforikäsittelyjen havaittiin osittain pelkistävän PdO:n Pd:ksi ja muuttavan jalometallipartikkelien muotoa. Havaitut rikin ja fosforin aiheuttamat rakenteelliset sekä kemialliset muutokset laskivat diesel- ja maakaasukatalyyttien hapetusaktiivisuutta. Laboratorioikäytyksillä havaittiin olevan hyvä korrelaatio todellisissa olosuhteissa tehtyjen ikäytysten kanssa ja tästä syystä työssä käytetyn laboratoriomittakaavan ikäytysmenetelmän voidaan todeta olevan hyvä työkalu simuloimaan rikin ja fosforin aiheuttamaa deaktivoitumista
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Törnmarck, Karl. "The Directive on the Deployment of Alternative Fuels Infrastructure : An analysis of its effects on the market uptake of natural gas vehicles." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-230168.
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The EU transport sector is currently extremely dependent on foreign oil and the import bill for this fuel was in 2011 approximately € 210 billion. The European Commission (EC) claims that this dependency will eventually affect the member states’ economic security and mobility as oil is a finite resource. At the same time, the transport sector needs to reduce its CO2 emissions with 60% until 2050. Therefore in 2013, the EC proposed the “Directive on the Deployment of Alternative Fuels Infrastructure”, which purpose is to create road fuel infrastructure for the alternative fuels electricity, hydrogen and, the main focus of this report, natural gas. The EC believes that infrastructure acts as a major barrier for the adoption of natural gas vehicles (NGV), which in the EU has been extremely limited. The scientific community agrees that infrastructure is an important barrier, but not the sole decider for the market penetration of NGV’s. Empirical evidence claims that in order for large-scale adoption to occur, natural gas needs to be priced at least 40% lower than conventional fuels (gasoline, diesel) and the payback period (the added investment cost of an NGV) must be lower than four years. Historical data shows that if these criteria are not met this will lead to market failure, even if the adequate infrastructure is in place. The two criteria are examined in this report in the four of the largest EU countries: Germany, UK, France and Spain whom together account for a majority of all vehicles registered in 2012. Italy was excluded as it has already has a well-developed NGV fleet. Two car models from different price ranges in NGV, gasoline and diesel versions were studied: the Fiat Punto and the Audi A3 Sportback. Payback periods where calculated based on yearly average annual distances travelled per country, fuel prices, vehicle fuel efficiency and the added investment cost for an NGV compared to gasoline and diesel vehicles. In order to compare fuel prices default energy content values were used to convert CNG into gasoline and diesel equivalents. As the price of CNG is heavily dependent on favorable taxation one needs to question the economic sustainability, and therefore this study also analyses the future price difference between gas and the conventional fuels using a supply and demand model with oligopoly conditions. This model was complemented with the 4 A’s method, which are Availability, Accessibility, Affordability and Acceptability. Results show that the conditions for NGV’s compared to diesel vehicles are optimal in Germany, UK and Spain, as they all have fuel price difference of minimum 40% and payback periods significantly below 4 years. As a majority of all new vehicles registered in the EU are diesel models this will have a strong positive impact on the NGV market. The conditions for the gasoline comparisons are suboptimal, or slightly inconclusive as the payback periods in a few cases are above, or just below four years. As default values have been used during calculations the numbers are sensitive to change and simply too uncertain to draw any solid conclusions. The price differences between CNG and gasoline are within the criteria level of 40%. The price difference analysis between oil and natural gas shows great uncertainty, as there are many factors involved, such as environmental and geopolitical. A potential factor that could decouple prices is “fracking” of domestic EU shale gas resources, but this seems unlikely to happen due to environmental, social and economical reasons. Imported US LNG could have a similar effect but it might be exported east in order to meet the increasing demand from countries in Asia pacific. In conclusion, if the Directive on the Deployment of Alternative Fuels Infrastructure was implemented we would likely see a moderate to high market penetration of NGV’s, mostly due to their comparative advantage towards diesel vehicles. As gasoline meets the fuel price difference criteria this will also have a positive effect on the NGV market albeit limited by questionable payback periods.
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Oscherov, Valeria. "Three Essays in Empirical Economics." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/51828.
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This dissertation consists of three essays. The first essay estimates a demand function for compressed natural gas as a fuel substitute to diesel fuel for firms with hybrid fleets. The data is from the Energy Information Administration, for the years 1989 to 2009, for 47 states. Results show that an increase of $0.10 in the price of diesel fuel will increase compressed natural gas demand by 5.59%.
The second essay focuses on regional trade agreements (RTAs). A number of studies have found that RTAs significantly increase members' trade flows. While recent studies have begun to explore the reasons for this, none have examined whether the RTA trade effect varies systematically with the number and type of policy areas covered by the agreement. While the empirical trade literature has shed considerable light on the trade-creating ability of RTAs (Grant and Lambert, 2008), much less is known about why these agreements are so successful. In this study, we draw on a new database from the World Trade Organization of trade policy areas covered by RTAs to examine whether the degree of trade liberalization is an important determinant of the RTA trade effect. An augmented, theoretically consistent gravity equation is developed to explore the effects of RTAs on trade, conditional on the policy areas they include. In particular, we investigate two policy areas that are particularly important for agricultural trade, sanitary and phytosanitary measures (SPS) and technical barriers to trade (TBT). The results suggest that harmonization of non-tariff measures inside RTAs matters: Agreements that liberalize these policies increase members' agricultural trade by an additional 62 percent compared to agreements that do not. We conclude that studying the components of RTAs -- in particular, the policy areas covered by these agreements -- is important when analyzing the determinants of RTA trade effects.
The third essay uses Bayesian Model Averaging (BMA) to study the effect of membership in the General Agreement on Tariffs and Trade (GATT), the predecessor to the World Trade Organization (WTO), and the WTO on trade flows. Existing GATT/WTO literature is not univocal as to whether membership in the GATT/WTO increases trade flows. In this study, Bayesian model averaging (BMA) is used in the presence of theoretical uncertainty to address whether membership in the GATT/WTO plays a role in the gravity model. Several datasets are examined: a dataset from a previous study; and two datasets compiled for this study, world trade and agricultural trade. Results show, for all three sets of data, that membership in the GATT/WTO does belong in the gravity equation and increases trade flows.Ph. D.
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Lomax, Franklin D. "Investigation of steam reformation of natural gas for the very small scale production of hydrogen fuel for light duty vehicles in appliance-type refueling systems." Master's thesis, This resource online, 1997. http://scholar.lib.vt.edu/theses/available/etd-09052009-040323/.
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Bartejsová, Vladimíra. "Analýza nákupu CNG vozidel skupinou RWE v České republice." Master's thesis, Vysoká škola ekonomická v Praze, 2009. http://www.nusl.cz/ntk/nusl-76564.
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This paper analyses the purchase and operation of vehicles on compressed natural gas. It contains a definition of Compressed Natural Gas (CNG) and discusses the various phases of its use in transport. It indicates the differences of this alternative fuel compared to traditional fuel such as gasoline or diesel. Then it focuses on the main reasons to support the use of compressed natural gas transport and talks about the legislation which has a major role in the development of alternative fuels. Then it specifies the disadvantages which can be associated with its use in transport. The last section includes an analysis on the specific example of the RWE CZ Group, which compares the different costs for compressed natural gas vehicles and vehicles which run on conventional fuel. Specifically the cost per kilometer of vehicle, CO2 emission and purchase price are given for comparison.
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Brito, Thiago Luis Felipe. "Modelagem ambiental e análise qualitativa comparativa de políticas de implantação de gás natural veicular em ônibus." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/106/106131/tde-13052015-122717/.
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Esta dissertação desenvolveu duas análises de natureza diferente, mas complementares, uma vez que são unidas por uma mesma questão. Esta questão diz respeito à utilização do gás natural veicular em substituição ao óleo diesel em ônibus urbanos. O autor argumenta que, devido a suas características técnicas, o gás natural pode contribuir para a promoção de um transporte mais sustentável, mesmo que o gás natural seja um combustível igualmente não renovável, como o óleo diesel. Na primeira análise desenvolvida, utiliza-se uma metodologia bottom-up para demonstrar os ganhos ambientais que podem ser alcançados ao se substituir o óleo diesel por gás natural em ônibus urbanos. Adota-se a cidade de São Paulo como estudo de caso. Esses ganhos ambientais manifestam-se tanto na redução das emissões de poluentes locais, como material particulado, monóxido de carbono e óxidos de enxofre, conduzindo a melhoras importantes na qualidade de vida das pessoas que sofrem os efeitos nocivos dessas emissões (usuários ou não do transporte público urbano), como, também, no declínio das emissões de gases de efeito estufa, especialmente o dióxido de carbono, levando a benefícios ambientais globais. Os resultados amparam o uso do gás natural em ônibus como uma estratégia de maior sustentabilidade no plano ambiental. Já, na segunda análise desenvolvida, a pesquisa levanta as questões seguintes: Quais outros parâmetros influenciam a decisão de se promover a substituição de combustíveis em ônibus urbanos? Quais critérios explicam as escolhas por distintos combustíveis substitutos? As respostas a essas questões são obtidas através de uma Análise Qualitativa Comparativa (AQC). A pesquisa comparou 39 cidades em todo o mundo, que adotaram combustíveis substitutos ao óleo diesel em ônibus urbanos, incluindo o gás natural, biocombustíveis, eletricidade e hidrogênio. Os resultados atestam que as cidades de fato utilizam-se da substituição de combustíveis para tornar o transporte mais sustentável. Observa-se que a opção pelo gás natural é acolhida na maioria dos casos analisados como uma opção com vantagens ambientais e economicamente mais atrativa. A principal razão para sua eventual não adoção identifica-se com a insegurança energética. Algumas cidades receiam depender de um combustível que, assim como o petróleo (do qual o óleo diesel é um derivado), também está afeito a importantes suscetibilidades geopolíticas. A conclusão do trabalho reforça a importância do gás natural como um combustível ambientalmente mais amigável, e que pode contribuir na busca das cidades por sistemas de transporte público mais sustentáveis, especialmente em grandes áreas metropolitanas. Olhando, especificamente, o caso da cidade de São Paulo, com desdobramentos para o Brasil como um todo, a pesquisa enfatiza a necessidade de se superar barreiras regulatórias, e de se comprovar vantagens econômicas e de segurança de suprimento energético, para que o gás natural possa confirmar-se atrativo e mais sustentável aos olhares dos gestores dos sistemas de transporte público urbanos. Esses temas não podem ser deslembrados ao se propor uma política mais racional de combustíveis para o transporte público das grandes cidades brasileiras.This work has developed two analyzes of different kinds, but complementary, since they are united by the same issue. This issue relates to the use of compressed natural gas to replace diesel fuel in city buses. The author argues that, due to its technical characteristics, natural gas can contribute to the promotion of more sustainable transport, even though the gas is a non-renewable fuel, such as diesel oil. In the first in-depth analysis, a bottom-up methodology is used in order to demonstrate the environmental benefits that can be achieved by replacing the diesel oil with natural gas in urban buses. The city of São Paulo is adopted as a case study. These environmental gains are manifested both in reducing emissions of local pollutants such as particulate matter, carbon monoxide and sulfur oxides, leading to significant improvements in quality of life of people suffering the harmful effects of the emissions (both public urban transport users and non-users), and also in the decline of emissions of greenhouse gases, especially carbon dioxide, leading to global environmental benefits. The results bolster the use of natural gas buses as a more sustainable strategy in environmental terms. In the second developed analysis, the research raises the following questions: What other parameters influence the decision to encourage the substitution of urban buses in fuels? What criteria explain the choices for different substitute fuels? The answers to these questions are obtained from a Qualitative Comparative Analysis (QCA). The study compared 39 cities across the world that have adopted fuel substitutes to diesel fuel in urban buses, including natural gas, biofuels, electricity and hydrogen. The results show that in fact, cities are use fuel shifting as a way to turn its transport system more sustainable. It is observed that the option for natural gas is considered, in most analyzed cases, as an option with environmental advantages and economically more attractive. The main reason for natural gas non-adoption was identified as energy insecurity. Some cities fear depending on a fuel that, like petroleum (of which diesel oil is a derivative), is also sensitive to relevant geopolitical issues. The conclusion of the work reinforces the importance of natural gas as a more environmentally friendly fuel, and can contribute to the promotion more sustainable public transport systems in cities, especially in large metropolitan areas. Looking specifically at the case of the city of São Paulo, as well as considering Brazil as a whole, the research emphasizes the need to overcome regulatory barriers, and to prove economic benefits and energy supply security, so that the natural gas can confirm is attractive and more sustainable to the eyes of managers of urban public transport systems. These issues cannot be forgotten in order to propose a more rational policy of fuel for public transport in large Brazilian cities.
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Valiante, Daniel. "Análise de viabilidade técnica, econômica, ambiental e mercadológica da instalação original de fábrica de sistema de conversão para uso de gás natural em veículos leves movidos a gasolina e/ou álcool." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/3/3149/tde-26122014-174836/.
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É cada vez maior a busca por fontes de energia alternativas com vistas à substituição dos derivados do Petróleo, em especial após a crise da década de 70. A indústria automotiva segue a mesma tendência, buscando alternativas viáveis frente à incerteza do tempo e quantidade que ainda resta de estoque de combustíveis fósseis líquidos. Além do Álcool como meio de substituição ao Diesel e a Gasolina, a utilização de GNV - Gás Natural Veicular - está entre as tecnologias atualmente consideradas viáveis e eficientes. Segundo a ANP - Agência Nacional do Petróleo, Gás Natural e Biocombustíveis (2006), o Brasil possui reservas comprovadas de 306,4 x 109 m3 de Gás Natural, quantidade estimada para abastecer o mercado nacional, no cenário mais pessimista, pelos próximos cinqüenta anos. A associação desses fatores resulta na busca do consumidor brasileiro pela redução dos gastos cada vez maiores com combustível e no aumento da demanda por veículos movidos a Gás Natural. Apesar da notória demanda de mercado, atualmente existem no Brasil poucas opções de veículos leves com Sistemas de Conversão originalmente instalados pelas montadoras e com manutenção da garantia de fábrica. A falta de opções de oferta abre espaço para o grande aumento do número de oficinas de conversão, freqüentemente ignorando aspectos técnicos e de legislação de conversão, na intenção de apenas obterem lucros com o aumento de demanda. Mais do que pretensiosas conclusões definitivas, o presente trabalho tem como objetivo oferecer uma pequena contribuição à indústria e à sociedade, através da análise da viabilidade técnica, econômica, ambiental e mercadológica da instalação original de fábrica de Sistema de Conversão para uso de Gás Natural em veículos leves movidos a Gasolina e / ou Álcool, frente ao atual mercado de veículos convertidos e ao aumento da demanda por fontes de energia alternativa.The search for alternative energy sources aiming the substitution of derivate Oil products is each time higher, especially after the 70s Petroleum crisis. The automotive industry follows this trend too, looking for possible alternatives in face of the uncertainness of time and quantity available stocks of liquid fossil fuels. Besides the Ethanol as a way of Gasohol and Diesel substitution, the CNG - Compressed Natural Gas - use is nowadays considered one of the most possible and efficient technologies. According to the ANP - National Petroleum, Natural Gas and Biofuel Agency (2006), Brazil owns 306,4 x 109 m3 of Compressed Natural Gas proved reserves, which are considered enough to supply the national market, in the worst case, for the next fifty years. The conjunction of these issues results in the Brazilian customers search for the each higher fuel expenses reduction and the raise of Compressed Natural Gas impelled vehicles demand. Despite the notorious market demand, there are nowadays on Brazil only a few options of light vehicles with Conversion System originally installed by automotive assemblers and warrantys maintenance. This lack of supply options creates a large field to the raise in the quantity of conversion workshops, frequently ignoring the technical aspects and the conversion legislation only with intent of achieving profit with the demand raise. More than pretentious definitive conclusions, the present work aims to offer a small contribution to the industry and society through the technical, economical, environmental and merchandizing practicability analysis of original assemblers installation of Conversion System to the use of Compressed Natural Gas in Gasohol and / or Ethanol impelled light vehicles, in face of the actual converted vehicles market and the demand raise for alternative energy sources.
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Araújo, Bárbara Susana Barbosa de. "Consciência ambiental: um estudo exploratório sobre sua influência na utilização do gás natural pelos motoristas de táxi do município de São Paulo." Universidade Presbiteriana Mackenzie, 2015. http://tede.mackenzie.br/jspui/handle/tede/651.
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The starting point for the construction of this study was the perception that the current societal behavior and business management models do not provide the balance needed for the continuation of environmental resources essential to human survival. The challenges to achieve the widespread sustainable development are immense and, for many, utopian. This research was conducted after admitting that the production of knowledge is one of the guiding pillars of the advancement of the discussions which enable a boost in understanding and engagement within society in favor of a less unsustainable future. This study sought to understand to what extent there is a relationship between the environmental awareness of taxi drivers in São Paulo and the use of natural gas for their vehicles, compared to the survey of the factors that stimulate and discourage the use of this fuel considered less pollutant. The choice of researching on the use of Natural Gas Vehicles (NGV) as an energy source was due to the fact that in Brazil the use of other clean energy sources in the transport sector is extremely incipient. We sought to identify which in practice, are perceived as attributes that encourage and / or inhibit drivers to use NGV. In addition, we sought to understand whether taxi drivers, apart from the technical and economic developments, were also motivated by an environmental concern to collaborate or reinforce the choice of a less polluting fuel than traditional ethanol and gasoline. The results obtained by our descriptive quantitative research, with 73 taxi drivers in São Paulo, preceded by a qualitative exploratory study. Factors related to the financial benefits of the use of CNG were confirmed as the main attractions for using this type of fuel; whereas the necessary investment to adapt the vehicle to the supply of natural gas was appointed as the main to its use. When analyzing the results, it can be concluded that, because there is no evidence that environmental awareness is an important attribute in the decision of taxi drivers to use cleaner fuel, it is necessary to have a greater incentive to use this power source, or any other offering less potential offensive worsening of urban pollution and consequent respiratory diseases, to which the population is subject to. The stimuli may be a result of, among others, tax exemptions, already practiced in some Brazilian municipalities.
A percepção de que os modelos atuais de comportamento da sociedade e de gestão de negócios não proporcionam o equilíbrio necessário para continuidade dos recursos ambientais essenciais à sobrevivência humana foi o ponto de partida para construção deste estudo. Os desafios para se atingir o tão difundido desenvolvimento sustentável, são imensos e, para muitos, utópicos. Essa pesquisa foi concebida por admitir-se que a produção do conhecimento é um dos pilares norteadores para o avanço dos debates capazes de impulsionar a compreensão e o engajamento da sociedade em prol de um futuro menos insustentável. Objetivou-se compreender em que medida existe relação entre a consciência ambiental dos taxistas do município de São Paulo e a utilização do gás natural em seus veículos, face ao levantamento dos fatores que estimulam e dos que desestimulam a utilização desse combustível tido como menos poluente. A escolha pela utilização do gás natural veicular (GNV) como fonte de energia pesquisada se deu pelo fato de que no Brasil a utilização de outras fontes de energia limpa no setor de transporte é extremamente incipiente. Buscou-se identificar o que na prática é percebido como atributos que incentivam e/ou inibem os motoristas a usarem o GNV. Além disso, buscou-se entender se, afora as motivações de cunho técnico-econômico havia, entre os taxistas, preocupação ambientais que colaborassem ou reforçassem a escolha por um combustível menos poluente do que os tradicionais etanol e gasolina. Os resultados foram fruto de uma pesquisa quantitativa descritiva realizada com 73 motorista de táxis do município de São Paulo, precedida de um estudo qualitativo exploratório. Os fatores relacionados às vantagens financeiras decorrentes do uso do GNV foram confirmados como os maiores atrativos para uso desse tipo de combustível; ao passo que, o investimento para a adaptação dos veículos ao abastecimento do GNV, foi apontado como o principal obstáculo a sua utilização. Através da análise dos resultados, pode-se concluir que, por não haver evidências de que a consciência ambiental é um atributo relevante na decisão dos taxistas pela utilização de um combustível menos poluente, faz-se necessário que haja maior estímulo ao uso dessa fonte de energia, ou de qualquer outra que ofereça menor potencial ofensivo ao agravamento da poluição urbana e das consequentes doenças respiratórias, as quais a população está sujeita. Os estímulos podem ser fruto, entre outros, da isenção de impostos, já praticada em alguns municípios brasileiros.
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Murphy, Paul Jarod. "The role of natural gas as a vehicle transportation fuel." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59773.
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Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 69-72).
This thesis analyzes pathways to directly use natural gas, as compressed natural gas (CNG) or liquefied natural gas (LNG), in the transportation sector. The thesis focuses on identifying opportunities to reduce market barriers in order to make the US natural gas vehicle market more efficient. We also identify vehicle market segments where NGV technology is mature and does not require sustained public subsidy to economically compete with comparable gasoline or diesel vehicles. This thesis finds that natural gas can play a useful but modest role as a vehicle fuel in the US, predominantly as CNG in high-mileage, light-duty fleet vehicles and in heavy-duty, short-haul fleet vehicles. For light-duty applications, there is a need to address an existing market barrier in the US by reducing the incremental cost and improving the vehicle performance of CNG vehicles to levels found in Europe. This incremental cost reduction is critical to foster market penetration in high-mileage fleet vehicles and to create a potential opportunity for market penetration beyond high-mileage fleet vehicles to average-mileage individual drivers. Increased use of CNG in light duty vehicles would displace petroleum, reduce greenhouse gas emissions in the transportation sector, and hedge consumers from volatile world oil prices (if CNG is used in a bi-fuel - gasoline and CNG- vehicle). In the heavy-duty, short-haul sector, CNG provides an additional benefit of reduced nitrogen oxide emissions compared to diesel trucks. With respect to long-haul LNG trucks, this thesis finds that while there is a large potential market for natural gas in the long-haul truck market, the present prospects for the use of LNGpowered long haul trucks appears quite limited. This is due to high incremental costs, unresolved operational issues, fueling infrastructure requirements, and reluctance of the trucking industry.
by Paul Jarod Murphy.
S.M.in Technology and Policy
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Wang, Chin-Cheng E. "Design and analysis of the natural gas storage tank for automobiles." Ohio : Ohio University, 1998. http://www.ohiolink.edu/etd/view.cgi?ohiou1176236134.
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Nikopoulos, Achilles. "Design and energy analysis of a hybrid electric natural gas vehicle." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ40218.pdf.
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Kragha, Oghenerume Christopher. "Economic implications of natural gas vehicle technology in U.S. private automobile transportation." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59686.
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Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 70-75).
Transportation represents almost 28 percent of the United States' energy demand. Approximately 95 percent of U.S. transportation utilizes petroleum, the majority of which is imported. With significant domestic conventional gas resources, optimistic projections of unconventional natural gas resources, and the growing international liquefied natural gas (LNG) market, gas prices are expected to remain lower than oil. While natural gas currently provides approximately 24 percent of the United States' energy consumption, there has been no significant growth in the natural gas vehicle market in the past fifteen years. Natural gas has comparative environmental advantages to gasoline and diesel, with lower CO2 emissions per mega joule of fuel consumption. A natural gas powered vehicle fleet could reduce the country's fuel costs, dependence on imported fuel, and greenhouse gas emissions. To fully comprehend the future role of natural gas vehicles in the United States, all the major technological and market forces affecting the successful deployment of this vehicle technology must be analyzed interdependently under market and energy policy-regulated scenarios. I investigate the potential role of natural gas in transportation using a computable general equilibrium (CGE) model of the global economy that is resolved for the US and other major countries and regions. To do so, I add a dedicated compressed natural gas (CNG) vehicle option to the Emissions Prediction and Policy Analysis (EPPA) Model as an option to the conventional internal combustion engine (ICE) vehicle. The model projects changing prices of fuel and other goods over time, given specification of resource availabilities. With the CNG vehicle specification I am able to evaluate the effect of the CNG option on transportation emissions, oil imports, natural gas use, and other economic indicators. I consider different policy scenarios for the future, including the adoption of a targeted emissions cap policy to see how that affects the competitiveness of CNG vehicles. Several conclusions about the potential role of nature gas vehicles in the United States are drawn from this analysis. First, NG vehicles will reduce household transportation emissions in proportion to their share of the vehicle fleet. Second, stringent emissions policies will stimulate the penetration of natural gas vehicles, but high vehicle costs and infrastructure may hinder their deployment. There is a correlation between increased NG vehicle use and the reduction of oil imports. In the long term, development of cleaner alternative fuels with similar infrastructure to gasoline may hamper CNG vehicle growth.
by Oghenerume Christopher Kragha.
S.M.in Technology and Policy
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Karlgren, Johansson Mikael, and Kevin Leong. "Auxiliary Heater for Natural Gas Trucks." Thesis, Linköpings universitet, Maskinkonstruktion, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-139687.
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As alternative fuels are becoming more common, technologies need to adjust to them. Natural gas is one of the alternative fuels that has grown during the latest years in the transport sector. Natural gas consists of around 97 % methane and is the cleanest fossil fuel. The use of natural gas can make it easier to transition to biogas as it has equivalent properties. Today Scania CV AB's trucks fuelled by natural gas are using auxiliary cabin heaters driven by diesel. This means that the natural gas trucks have two fuels on-board the truck. The goal of this project is to find a concept to eliminate the diesel fuel and replace it with an auxiliary cabin heater driven by another energy source. It will improve the heating solution and make it superior from an environmental perspective. The result of the project lead to a short-term solution with an auxiliary heater fuelled by natural gas. A long-term solution is to have a cooperation with a manufacturer to develop a better natural gas auxiliary heater that fulfils more of the requirements in the technical specification. An experiment plan is devised to test parameters out of reach of the project.
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Chao, Alice K. "Investigating the strategic impacts of natural gas on transportation fuel diversity and vehicle flexibility." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/81116.
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Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 97-100).
The near-total dependence of the U.S. transportation system on oil has been attributed to exposing consumers to price volatility, increasing the trade imbalance, weakening U.S. foreign policy options, and raising climate change concerns. As a matter of policy to mitigate these issues, the U.S. has promoted fuel diversification and vehicle fuel flexibility in the transportation sector as complementary strategies. However, the search for a fuel that replicates the features of oil has proven elusive to policy makers. With the technological innovation of horizontal hydraulic fracturing that has enabled low cost shale gas production, natural gas has a unique opportunity in potentially breaking the stalemate. This thesis uses an exploratory approach to first identify the underlying factors that create challenges for scaling up alternative fuel and vehicle development. Second, it examines how consumers and policymakers, as two opposing sources of demand, influence and shape their development as well as directions for technological progress. Third, it develops a visual representation using natural gas as a case study to explore some of these issues and how they affect the potential pathways for using natural gas in light duty vehicle applications. This thesis concludes that while there are no clear pathways forward for natural gas in light duty vehicle applications, the transportation sector's sensitivity to changes in fuel feedstock composition enables a number of opportunities for development rather than suppresses it. This thesis also finds that rather than searching for a single fungible alternative fuel, there may be more opportunities for accommodating new energy sources. However, how the transportation system responds and can adapt to them still remains an area for more research.
by Alice K. Chao.
S.M.in Technology and Policy
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Molinski, David W. "The feasibility of adopting natural gas as a vehicle fuel for Manitoba school bus fleets." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq23424.pdf.
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Li, Xiang. "Characterization of Air Pollutant and Greenhouse Gas Emissions from Energy Use and Energy Production Processes in United States." Research Showcase @ CMU, 2017. http://repository.cmu.edu/dissertations/1082.
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Air pollutants and greenhouse gases are two groups of important trace components in the earth’s atmosphere that can affect local air quality, be detrimental to the human health and ecosystem, and cause climate change. Human activities, especially the energy use and energy production processes, are responsible for a significant share of air pollutants and greenhouse gases in the atmosphere. In this work, I specifically focused on characterizing air pollutants and greenhouse gas emissions from the on-road gasoline and diesel vehicles, which is an important energy use process that largely contributes to the urban air pollutions, and from the natural gas production systems, which is a major energy production process that has increased dramatically in recent years and is expected to have a long-lasting impact in the future. We conducted multi-seasonal measurements in the Fort Pitt Tunnel in Pittsburgh, PA to update the on-road vehicle emission factors, to measure the size distribution of vehicle emitted particulate matter (PM), and to quantify the volatility distributions of the vehicle emitter primary organic aerosol (POA). We also conducted mobile measurements in the Denver-Julesburg Basin, the Uintah Basin, and the Marcellus Shale to quantify facility-level VOC emission from natural gas production facilities, and I constructed a gridded (0.1° × 0.1°) methane emission inventory of natural gas production and distribution over the contiguous US. I found that the stricter emission standards were effective on regulating NOx and PM emissions of diesel vehicles and the NOx, CO and organic carbon (OC) emissions of gasoline vehicles, while the elemental carbon (EC) emissions of gasoline vehicles did not change too much over the past three decades. Vehicle-emitted particles may be largely externally mixed, and a large fraction of vehicle-emitted particles may be purely composed of volatile component. Vehicle-emitted smaller particles (10– 60 nm) are dominantly (over 75%) composed of volatile component. The size-resolved particles and particles emission factors for both gasoline and diesel vehicles are also reported in this work. I also found that the POA volatility distribution measured in the dynamometer studies can be applied to describe gas-particle partitioning of ambient POA emissions. The POA volatility distribution measured in the tunnel does not have significant diurnal or seasonal variations, which indicate that a single volatility distribution is adequate to describe the gas-particle partitioning of vehicle emitted POA in the urban environment. The facility-level VOC emission rates measured at gas production facilities in all three gas production fields are highly variable and cross a range of ~2-3 order of magnitudes. It suggests that a single VOC emission profile may not be able to characterize VOC emissions from all natural gas production facilities. My gridded methane emission inventory over the contiguous US show higher methane emissions over major natural gas production fields compared with the Environmental Protection Agency Inventory of US Greenhouse Gas Emission and Sinks (EPA GHGI) and the Emission Database for Global Atmospheric Research, version 4.2 (Edgar v4.2). The total methane emissions of the natural gas production and distribution sector estimated by my inventory are 74% and 20% higher than the Edgar v4.2 and EPA GHGI, respectively. I also run the GEOS-Chem methane simulation with my inventory and EPA GHGI and compare with the GOSAT satellite data, and results show that my inventory can improve the model and satellite comparison, but the improvement is very limited. The size-resolved emission factors of vehicle emitted particles and POA volatility distribution reported in this work can be applied by the chemical transport models to better quantify the contribution of vehicle emissions to the PM in the atmosphere. Since our measurement of VOC emissions of natural gas production facilities were conducted before EPA started to regulate VOC emissions from the O&NG production facilities in 2016, the facility-level VOC emission rates reported in this work can serve as the basis for future studies to test the effectiveness of the regulatory policies. The spatially resolved methane emission inventory of natural gas production and distribution constructed in this work can be applied to update the current default methane emission inventory of GEOS-Chem, and the updated methane emission inventory can be used as a better a priori emission field for top-down studies that inversely estimate methane emissions from atmospheric methane observation.
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Kelly, Kenneth John. "The effects of fuels and test cycles on light-duty vehicle exhaust emissions." Ohio : Ohio University, 1998. http://www.ohiolink.edu/etd/view.cgi?ohiou1176490219.
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Vilhena, John Edward Neira. "Simula??o de reservat?rios n?o convencionais para armazenamento de g?s natural veicular." Universidade Federal do Rio Grande do Norte, 2004. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15546.
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Previous issue date: 2004-06-04Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
The investigation of viability to use containers for Natural Gas Vehicle (NGV) storage, with different geometries of commercial standards, come from necessity to join the ambient, financial and technological benefits offered by the gas combustion, to the convenience of not modify the original proposal of the automobile. The use of these current cylindrical models for storage in the converted vehicles is justified by the excellent behavior that this geometry presents about the imposed tensions for the high pressure that the related reservoirs are submitted. However, recent research directed toward application of adsorbent materials in the natural gas reservoirs had proven a substantial redusction of pressure and, consequently, a relief of the tensions in the reservoirs. However, this study considers alternative geometries for NGV reservoirs, searching the minimization of dimensions and weight, remaining capacity to resist the tensions imposed by the new pressure situation. The proposed reservoirs parameters are calculated through a mathematical study of the internal pressure according to Brazilian standards (NBR) for pressure vessels. Finally simulations of the new geometries behavior are carried through using a commercially avaible Finite Element Method (FEM) software package ALGOR? to verify of the reservoirs efficincy under the gas pressure load
A investiga??o da viabilidade de se utilizar recipientes para armazenamento de g?s natural veicular (GNV), com geometrias diferentes dos padr?es comerciais, parte da necessidade de se aliar os benef?cios ambientais, financeiros e tecnol?gicos oferecidos pela combust?o do g?s, ? conveni?ncia de n?o se alterar a proposta original do autom?vel. O uso dos atuais modelos cil?ndricos para estocagem nos ve?culos convertidos justifica-se pelo excelente comportamento que essa geometria apresenta diante das tens?es provocadas pela alta press?o a que os referidos reservat?rios est?o submetidos. Entretanto, recentes pesquisas, voltadas para aplica??o de materiais adsorventes nos reservat?rios de g?s natural, comprovaram uma substancial redu??o de press?o e, consequentemente, um al?vio das tens?es nos reservat?rios. Diante desse contexto, este estudo prop?e geometrias alternativas para os reservat?rios de GNV buscando a minimiza??o das dimens?es e do peso, mantendo-se, por?m, a capacidade de resistir ?s tens?es impostas pela nova situa??o de press?o. Todos os par?metros geom?tricos dos reservat?rios propostos s?o calculados realizando o estudo matem?tico das tens?es internas de trabalho tomando como base ? norma brasileira (NBR). Por ?ltimo s?o realizadas simula??es do comportamento das novas geometrias fazendo uso do software comercial ALGOR? o qual se baseia no M?todo dos Elementos Finitos (MEF), para realizar a comprova??o da efici?ncia dos reservat?rios sob a press?o imposta pelo g?s
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Duarte, Herbert de Melo. "Um estudo algor?tmico de problemas log?sticos na ind?stria de petr?leo e g?s natural." Universidade Federal do Rio Grande do Norte, 2006. http://repositorio.ufrn.br:8080/jspui/handle/123456789/18092.
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Previous issue date: 2006-11-16This work consists on the study of two important problems arising from the operations of petroleum and natural gas industries. The first problem the pipe dimensioning problem on constrained gas distribution networks consists in finding the least cost combination of diameters from a discrete set of commercially available ones for the pipes of a given gas network, such that it respects minimum pressure requirements at each demand node and upstream pipe conditions. On its turn, the second problem the piston pump unit routing problem comes from the need of defining the piston pump unit routes for visiting a number of non-emergent wells in on-shore fields, i.e., wells which don t have enough pressure to make the oil emerge to surface. The periodic version of this problem takes into account the wells re-filling equation to provide a more accurate planning in the long term. Besides the mathematical formulation of both problems, an exact algorithm and a taboo search were developed for the solution of the first problem and a theoretical limit and a ProtoGene transgenetic algorithm were developed for the solution of the second problem. The main concepts of the metaheuristics are presented along with the details of their application to the cited problems. The obtained results for both applications are promising when compared to theoretical limits and alternate solutions, either relative to the quality of the solutions or to associated running time
Este trabalho consiste do estudo de dois importantes problemas oriundos das opera??es das ind?strias de petr?leo e g?s natural. O primeiro problema do dimensionamento de dutos em uma rede urbana de distribui??o de g?s natural consiste em encontrar a combina??o de di?metros de menor custo, a partir de um conjunto de op??es comercialmente dispon?veis, para os dutos de uma dada rede de distribui??o de g?s, de forma a respeitar requisitos de press?o m?nima em cada n? de demanda e condi??es de upstream. Por sua vez, o segundo problema do roteamento da unidade m?vel do pistoneio decorre da necessidade de se definir as rotas de visita??o da dita unidade m?vel do pistoneio aos diversos po?os n?o surgentes do campo de explora??o, ou seja, po?os que n?o possuem press?o suficiente para fazer o ?leo emergir ? superf?cie. A vers?o peri?dica do problema leva em considera??o a equa??o de re-enchimento dos po?os, de forma a possibilitar um planejamento mais acurado num horizonte de tempo maior. Al?m da formula??o matem?tica dos dois problemas, para a solu??o do primeiro foram desenvolvidos um algoritmo exato e uma busca tabu e para o segundo, um limite superior e um algoritmo transgen?tico ProtoGene. Os principais conceitos das metaheur?sticas s?o apresentados, juntamente com os detalhes da aplica??o destas aos problemas citados. Os resultados obtidos para ambas as aplica??es s?o promissores quando comparados com limites te?ricos e solu??es alternativas, tanto relativamente ? qualidade das solu??es como ao tempo computacional envolvido
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Iuzzolino, Gregory. "Design of a vehicular liquefied natural gas fuel storage vessel." 2005. http://hdl.handle.net/1828/838.
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Hazlett, Ryan. "Examining the market potential for natural-gas-powered trucks : barriers and opportunities for promoting environmental sustainability and economic prosperity." 2013. http://hdl.handle.net/2152/22638.
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Over the past decade, public concerns have grown over America's energy use and production. Pushes towards more environmentally friendly and sustainable sources of energy have moved out of fringe politics and into mainstream political discourse. Advances in drilling technology and increased exploration of shale gas plays have made natural gas more available and accessible. The abundance of natural gas has led to its growing role in the U.S. electric production and has provided the United States with an opportunity to become a net exporter of energy in the near future.
The availability of natural gas, coupled with uncertainty in the liquid petroleum market, has prompted stakeholders to search out additional uses for this low-cost energy source. The result has been a large-scale effort to encourage the use of natural gas-based fuel within the trucking industry. Commercial long-haul trucks and truck fleets are a
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prime target of these efforts. The number of natural gas fueling stations around the country is increasing, and there are growing investments in new technologies and government incentives to retrofit and upgrade the nation's trucking fleet, making the logistics of a large-scale switch from a liquid petroleum-based fuel to natural gas much less complicated.
Through a detailed analysis of natural gas trucks, fueling infrastructure, and case studies this report seeks to reach conclusions over the role natural gas vehicles (NGVs) should play in the future U.S. transportation system. Chapter 1 provides a brief introduction to natural gas. Chapter 2 discusses the current state of natural gas in the United States. Chapter 3 provides an overview of natural gas vehicle and infrastructure technology. Chapter 4 discusses marketplace NGV adoption factors. Chapter 5 deals with benefits of adoption and policy options for expansion of NGVs. Chapter 6 provides an overview of current federal, state and local policies and incentives. Chapter 7 discusses barriers and opportunities for NGV adoption. The report synthesizes and concludes that natural gas trucking offers the U.S. a cheaper alternative to liquid petroleum while promoting environmental sustainability and economic prosperity.text
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Kennedy, Castlen Moore. "Assessing the viability of compressed natural gas as a transportation fuel for light-duty vehicles in the United States." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-08-4260.
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Recent optimistic revisions to projections for recoverable natural gas resources in the United States have generated renewed interest in the possibility of greater utilization of natural gas as a transportation fuel. Against a backdrop of significant policy challenges for the United States, including air quality concerns in urban areas, slow economic growth and high unemployment, and a rising unease with regard to an increasing dependence on foreign oil; natural gas offers the nation’s transportation sector an opportunity to reduce mobile emissions, lower fuel costs, create jobs and reduce dependence on imported oil.
While the current focus for expanded use of natural gas in the transportation sector emphasizes heavy duty and fleet vehicles, there may also be potential for increased use for passenger vehicles. Inconvenience, with regard to refueling, and high incremental vehicle costs, however, are seen as major obstacles to greater adaptation.
This analysis examines the benefits and drawbacks of natural gas vehicles from the passenger vehicle perspective and includes data from a cross-country road trip. The report includes a review of market trends and possible development scenarios and concludes with recommendations to minimize the potential challenges of greater adaptation of natural gas vehicles in the passenger vehicle market.text
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Li, Hai. "A heat transfer model applicable to the refuelling process for natural gas vehicles." Thesis, 1993. https://vuir.vu.edu.au/15630/.
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This research presents a study of transient heat transfer
phenomena taking place between a storage cylinder and the incoming gas during the cylinder charging process. A theoretical model of convective heat transfer between the gas and the cylinder is described. Experiments with the high pressure gas (AP=14.5-16.5MPa) charging process to a vehicle supply tank were carried out. For reasons of safety and comparison with other work, air was used instead of Natural Gas. The whole charging process can be divided
into three phases: forced convection, free convection and
conduction. The experimental results were used to develop empirical equations for convection between the gas and the tank for both the forced and free convection phases. In addition, a simulation method was developed to predict the heat transfer parameters appropriate to the charging process and the predictions correspond well with the
experimental results.
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Zheng, Qinghe. "Catalytic Abatement of Environmental Pollutants and Greenhouse Gases in Automotive, Natural Gas Vehicles, and Stationary Power Plant Applications." Thesis, 2016. https://doi.org/10.7916/D89K4B5K.
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The present dissertation covers three research topics on catalytic environmental emissions control, including (1) aging and regeneration mechanisms of Rh- and Pd- model three-way catalysts (TWC) for gasoline automotive emission control, (2) catalytic methane emissions abatement from natural gas vehicles, and (3) scale-up of CO₂ capture and methanation using dual functional catalytic materials. The study resulted in two peer-reviewed publications, two future papers and one patent application which is currently under review.
Modern TWC use supported two separate catalyst layers on a monolith containing one Pd and the other Rh for the emissions control of CO, HC and NOₓ. The rhodium (Rh) metallic component (active for NOₓ reduction) experiences the most severe oxidative thermal deactivation (forming inactive Rh³⁺) during fuel cutoff, an engine mode (e.g., at downhill coasting) used for enhancing fuel economy. In a subsequent switch to a slightly fuel rich condition, in situ catalyst regeneration is accomplished by the reduction of the Rh³⁺ with H₂ generated through steam reforming catalyzed by residual Rh⁰ sites. The present thesis reports the effects of the deactivation and regeneration processes on the activity, stability and structural properties of 0.5% Rh/Al₂O₃ and 0.5% Rh/Ce_xO_y-ZrO₂ (CZO) as model catalysts. Both materials are used to varying extents in modern TWC. A very brief introduction of three-way catalysis and system considerations will be presented.
During simulated fuel cutoff, catalyst deactivation is accelerated with increasing aging temperature from 800 °C to 1050 °C. Rh on a CZO support experiences less deactivation and faster regeneration than Rh on Al₂O₃. Catalyst characterization techniques including BET surface area, CO chemisorption, temperature programmed reduction, and x-ray photoelectron spectroscopy, transmission electron microscopy, scanning-electron microscopy, and x-ray diffraction measurements were applied to examine the role of metal-support interactions in each catalyst system. For Rh/Al₂O₃, strong metal-support interactions leading to the formation of a stable rhodium aluminate (Rh(AlO₂)_y) complex dominates during fuel cutoff, resulting in more difficult catalyst regeneration (reduction). For Rh/CZO, Rh sites were partially oxidized to Rh₂O₃ and were relatively easy to be reduced to active Rh⁰ during regeneration.
Moderate Pd and support sintering of Pd-Ce_xO_y is experienced upon aging, but with a minimal effect on the catalyst activity. Cooling in air, following aging, was not able to reverse the metallic Pd sintering by re-dispersing to PdO. Unlike the aged Rh-TWCs, reduction via in situ steam reforming (SR) of exhaust HCs was not effective in reversing the deactivation of aged Pd/Al₂O₃, but did show a slight recovery of the Pd activity when CZO was the carrier. The Pd⁺/Pd⁰ and Ce³⁺/Ce⁴⁺ couples in Pd/CZO are reported to promote the catalytic SR by improving the redox efficiency during the regeneration, while no such promoting effect was observed for Pd/Al₂O₃. A suggestion is made for improving the catalyst performance.
The use of natural gas for vehicle applications is growing in popularity due to advanced fracking technology. Exhaust methane has been excluded from regulations since it does not participate in photochemical reactions. New vehicle environmental regulations are expected for controlling methane emissions given their contribution to the greenhouse gas effects. Methane is extremely resistant to oxidation when the natural gas-fueled engine operates in the stoichiometric mode with a supported Rh-Pd three-way catalyst (TWC). Furthermore, vehicles will still operate with fuel cutoff (for enhanced fuel economy), resulting in thermal oxidative deactivation (1050 °C) of the Rh metal in TWC to inactive Rh³⁺, resulting in a loss of both NOₓ and methane abatement activity. When the engine returns to the slightly rich mode, H₂ generated by methane steam reforming does not readily occur to reduce and regenerate the Rh. We report a solution to methane emissions abatement by catalytic reforming of an injected aqueous solution of ethanol into the simulated exhaust stream in TWC mode, which generates sufficient H₂ to regenerate especially Rh by reducing Rh³⁺ to its metallic active state.
Conventional CO₂ capture and sequestration (CCS) in aqueous alkaline solutions is a very energy-intensive process with relative unstable performance and low efficiency especially for power plant effluents, and therefore there is a need for new approaches to control green house gas emissions of CO₂. Here we report on progress with an advanced technology involving CO₂ adsorption from flue gas and synthetic natural gas production, via methanation, both performed at the same temperature with the addition of renewable H₂ and by using a dual functional material (DFM). The stored H₂ used is produced by water electrolysis during those times when solar, wind, and other alternative energies generate excess power out of phase with the direct use of the electricity. The DFM is composed of nano-dispersed CaO (or Na₂CO₃) and Ru metal supported on γAl₂O₃ carrier, respectively functioning as the CO₂ adsorbent and methanation catalyst. The present paper focuses on a laboratory scale-up study by using a simulated flue gas and 5%Ru,10%CaO/Al₂O₃ and 5% Ru,10%Na₂CO₃/Al₂O₃ DFM samples. The effects of DFM preparation methods, Al₂O₃ carrier materials (with different shapes and properties), and adsorption and methanation conditions (feed compositions, flow rates, reaction temperatures) on the DFM performance were examined. Samples were prepared using chloride precursor salts and showed stable performance under pseudo scale-up conditions, with SASOL TH100 Al₂O₃ (with the highest BET surface area and pore volume/radius among the support materials) exhibiting the best performance. Compared to Ru-CaO, Ru-Na₂CO₃ based DFM materials showed improved CO₂ utilization and methanation production. Reaction conditions were explored to find optimized CO₂ adsorption and methanation.
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"The Transition to Alternative Fuel Vehicles (AFVs): an Analysis of Early Adopters of Natural Gas Vehicles and Implications for Refueling Infrastructure Location Methods." Doctoral diss., 2015. http://hdl.handle.net/2286/R.I.34802.
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abstract: Alternative fuel vehicles (AFVs) have seen increased attention as a way to reduce reliance on petroleum for transportation, but adoption rates lag behind conventional vehicles. One crucial barrier to their proliferation is the lack of a convenient refueling infrastructure, and there is not a consensus on how to locate initial stations. Some approaches recommend placing stations near where early adopters live. An alternate group of methods places stations along busy travel routes that drivers from across the metropolitan area traverse each day. To assess which theoretical approach is most appropriate, drivers of compressed natural gas (CNG) vehicles in Southern California were surveyed at stations while they refueled. Through GIS analysis, results demonstrate that respondents refueled on the way between their origins and destinations ten times more often than they refueled near their home, when no station satisfied both criteria. Freeway interchanges, which carry high daily passing traffic volumes in metropolitan areas, can be appropriate locations for initial stations based on these results. Stations cannot actually be built directly at these interchange sites, so suitable locations on nearby street networks must be chosen. A network GIS method is developed to assess street network locations' ability to capture all traffic passing through 72 interchanges in greater Los Angeles, using deviation from a driver's shortest path as the metric to assess a candidate site's suitability. There is variation in the ability of these locations to capture passing traffic both within and across interchanges, but only 7% of sites near interchanges can conveniently capture all travel directions passing through the interchange, indicating that an ad hoc station location strategy is unlikely to succeed. Surveys were then conducted at CNG stations near freeway interchanges to assess how drivers perceive and access refueling stations in these environments. Through comparative analysis of drivers' perceptions of stations, consideration of their choice sets, and the observed frequency of the use of a freeway to both access and leave these stations, results indicate that initial AFV stations near freeway interchanges can play an important role in regional AFV infrastructure.Dissertation/Thesis
Doctoral Dissertation Geography 2015
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(11208897), Shubham Pradeep Agnihotri. "EFFICIENCY IMPROVEMENT ANALYSIS FOR COMMERCIAL VEHICLES BY (I) POWERTRAIN HYBRIDIZATION AND (II) CYLINDER DEACTIVATION FOR NATURAL GAS ENGINES." Thesis, 2021.
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The commercial vehicle sector is an important enabler of the economy and is heavily dependent on fossil fuels. In the fight against climate change, reduction of emissions by improving fuel economy is a key step for the commercial vehicle sector. Improving fuel economy deals with reducing energy losses from fuel to the wheels. This study aims to analyze efficiency improvements for two systems that are important in reducing CO2 emissions - hybrid powertrains and natural gas engines. At first, a prototype series hybrid powertrain was analyzed based on on-highway data collected from its powertrain components. Work done per mile by the electrical components of the powertrain showed inefficient battery operation. The net energy delivery of the battery was close to zero at the end of the runs. This indicated battery was majorly used as an energy storage device. Roughly 15% of losses were observed in the power electronics to supply power from battery and generator to the motor. Ability of the hybrid system to capture regenerative energy and utilize it to propel the vehicle is a primary cause for fuel savings. The ability of this system to capture the regenerative energy was studied by modeling the system. The vehicle model demonstrated that the system was capturing most of the theoretically available regenerative energy. The thesis also demonstrates the possibility of reduction of vehicular level losses for the prototype truck. Drag and rolling resistance coefficients were estimated based on two coast down tests conducted. The ratio of captured regenerative to the drive energy energy for estimated drag and rolling resistant coefficients showed that the current system utilizes 4%-9% of its drive energy from the captured regenerative energy. Whereas a low mileage Peterbilt 579 truck could increase the energy capture ratio to 8%-18% for the same drive profile and route. Decrease in the truck’s aerodynamic drag and rolling resistance can potentially improve the fuel benefits.
The second study aimed to reduce the engine level pumping losses for a natural gas spark ignition engine by cylinder deactivation (CDA). Spark ignited stoichiometric engines with an intake throttle valve encounter pumping/throttling losses at low speed, low loads due to the restriction of intake air by the throttle body. A simulation study for CDA on a six cylinder natural gas engine model was performed in GT- Power. The simulations were ran for steady state operating points with a torque range 25-560 ftlbs and 1600 rpm. Two , three and four cylinders were deactivated in the simulation study. CDA showed significant fuel benefits with increase in brake thermal efficiency and reduction in brake specific fuel consumption depending on the number of deactivated cylinders. The fuel benefits tend to decrease with increase in torque. Engine cycle efficiencies were analyzed to investigate the efficiency improvements. The open cycle efficiency is the main contributor to the overall increase in the brake thermal efficiency. The work done by the engine to overcome the gas exchange during the intake and exhaust stroke is referred to the pumping losses. The reduction in pumping losses cause an improvement in the open cycle efficiency. By deactivating cylinders, the engine meets its low torque requirements by increase in the intake manifold pressure. Increased intake manifold pressure also resulted in reduction of the pumping loop indicating reduced pumping losses. A major limitation of the CDA strategy was ability to meet EGR fraction requirements. The increase in intake manifold pressure also caused a reduction in the delta pressure across the EGR valve. At higher torques with high EGR requirements CDA strategy was unable to meet the required EGR fraction targets. This limited the benefits of CDA to a specific torque range based on the number of deactivated cylinders. Some variable valve actuation strategies were suggested to overcome this challenge and extend the benefits of CDA for a greater torque range.
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Clark, Jamie Michael. "The effects of hydrogen addition on a spark-ignited compressed natural gas vehicle." 2008. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-2665/index.html.
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Ribarits, S. G. "Assessment of inspection criteria and techniques for recertification of natural gas vehicle (NGV) storage cylinders." Thesis, 1992. http://hdl.handle.net/2429/1785.
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In-service natural gas vehicle (NGV) storage cylinders are subject to various forms of damage which can degrade structural integrity. In recognition of this, the Canadian Transport Commission (CTC) requires that cylinders be recertified for service every five years.
Current standards for NGV cylinder recertification are based on cylinder behaviour during a hydrostatic test (pressurization to 1.67 x service pressure) and specify that a cylinder should be removed from service if either the measured plastic expansion exceeds 10 % of the total cylinder expansion or the cylinder ruptures. These criteria have been established, for the most part, to ensure a minimum cylinder wall thickness during service.
A serious deficiency of the current assessment criteria is that they do not specifically address the possibility of sub-critical crack growth that may occur between inspections due to the combined effects of aggressive environmental conditions and cyclic loading. Evidence of sub-critical crack growth in sectioned in-service NGV cylinders however, has raised concerns over the effectiveness of the current recertification criteria and points to the need to determine whether these criteria are adequate to ensure against in-service failure.
The objective of this research is to evaluate the current standards for NGV cylinder recertification.
In this investigation, various fracture mechanics based methodologies are investigated in view of their applicability to predicting cylinder rupture. Elastic-plastic finite element models of untracked and cracked NGV cylinders are utilized to predict cylinder behaviour (volumetric expansion/crack opening displacement) during a hydrostatic test. These analyses, in conjunction with small scale critical crack tip opening displacement (CTOD) test results and full scale burst test results indicate that a critical CTOD approach, modified by a plastic collapse analysis for small defects can be used to accurately predict cylinder rupture.
Analysis of full scale numerical and experimental results indicates that there exists a range of defect sizes which, if present in a cylinder, would not violate the current hydrostatic test acceptance criteria (i.e., volumetric expansion/rupture). This finding, in conjunction with available fatigue crack growth estimates indicates that it is possible for cylinders containing this range of defect sizes to fail in service during the subsequent five year inspection interval. This result indicates that current hydrostatic test criteria are non-conservative.
In view of the inability of current retest procedures to reject cylinders containing defects which may lead to in-service failure, the feasibility of utilizing acoustic emission (AE) techniques for NGV cylinder inspection is also investigated. Full scale cylinder AE tests indicate that it is possible for cylinders with similar defect sizes to exhibit markedly different AE characteristics (i.e., hit rate, amplitude distribution, etc.) due to other AE sources such as corrosion. However, the potential for using AE techniques for inspection of cylinders is discussed.
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Mathew, Brenda A. "The Link Between Smart Growth in Urban Development and Climate Change." Thesis, 2013. http://hdl.handle.net/1805/3206.
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