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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Development of Transition Metal Carbide and Nitride Electrocatalysts for Chemical Energy Storage and CO2 Conversion

Tackett, Brian M. January 2019 (has links)
The rapid influx of solar energy and the desire to utilize carbon dioxide (CO2) will require large-scale energy storage and CO2 conversion technologies. Electrocatalytic devices can substantially impact both challenges, but improvements to electrocatalyst cost, activity, and selectivity are needed. Transition metal carbides provide a unique framework to reduce the loading of expensive catalyst metals while tuning the electrocatalytic activity and selectivity. Transition metal nitrides have many similar properties as carbides, and their synthesis inherently avoids the unwanted carbonaceous overlayer associated with carbide synthesis. Here it is shown that carbides and nitrides enable lower platinum-group metal (PGM) loadings and improve the activity and selectivity of electrocatalysts for reactions of water electrolysis and electrochemical CO2 reduction. Atom-thick layers of Pt were deposited onto niobium carbide (NbC) thin films to assess hydrogen evolution reaction (HER) activity. The Pt/NbC thin film, with one monolayer of Pt on NbC, performed similarly to bulk Pt. This correlated well with density functional theory (DFT) calculations of the hydrogen binding energy on the Pt/NbC surface. Potential applications of transition metal nitrides as electrocatalyst support materials were explored by synthesizing thin film nitrides of niobium and tungsten. The stability of each nitride was evaluated across broad potential-pH regimes to create a pseudo-Pourbaix diagram for each one. The films were each modified with atom-thick layers of Pt and were evaluated for HER performance in acid and alkaline electrolyte. Thin layers of Pt on WN and NbN showed Pt-like HER performance in acid and are promising candidates for high-surface area catalysts. To address the issue of high iridium (Ir) loading for the oxygen evolution reaction (OER) at the water electrolyzer anode, core-shell Ir-metal nitride particles were synthesized that contained 50% of the Ir mass loading of benchmark IrO¬2 particles. Iridium-iron nitride (Ir/Fe4N) showed increased activity on a mass-Ir basis and on a per-site basis, compared to IrO2. The core-shell morphology and stability under reaction conditions were confirmed with electron microscopy and in-situ X-ray absorption spectroscopy. Electrochemical reduction of CO2 to a mixture of CO and H¬2 (synthesis gas) was achieved on the palladium hydride (PdH) electrocatalyst. The product mixture can then be used as feedstock for the Fischer–Tropsch process and methanol synthesis. The syngas production performance was optimized by evaluating shape controlled PdH particles, bimetallic PdH, and PdH supported on transition metal carbides. At each step, the phase transition from Pd to PdH was monitored under reaction conditions with synchrotron-based X-ray absorption spectroscopy and X-ray diffraction. We also performed an overall carbon balance for catalytic transformation of CO2 to methanol via four reaction schemes, including one relying on electrocatalytic syngas production. The analysis revealed that hybrid electrocatalytic/thermocatalytic processes are most promising for resulting in overall CO2 reduction, but current densities of recently reported electrocatalysts need to increase to make the process economically feasible.
32

Reaction of sulfur dioxide (SO2) with reversible ionic liquids (RevILs) for carbon dioxide (CO2) capture

Momin, Farhana 02 February 2012 (has links)
Silylated amines, also known as reversible ionic liquids (RevILs), have been designed and structurally modified by our group for potential use as solvents for CO₂ capture from flue gas. An ideal CO₂ capture ionic liquid should be able to selectively and reversibly capture CO₂ and have tolerance for other components in flue gas, including SO₂, NO₂, and O₂. In this project, we study the reactivity, selectivity, uptake capacity, and reversibility of RevILs in the presence of pure SO₂ and mixed gas streams tosimulate flue gas compositions. Tripropylsilylamine (TPSA), a candidate CO₂ capture RevIL, reacts with pure SO₂ to form an ionic liquid consisting of an ammonium group and a salfamate group, supported by IR and NMR results. The resulting IL with pure SO₂ partially reverses when heated to temperatures of upto 500 C in the TGA. TGA analysis of the ionic liquid formed from a 4 vol% SO₂ in CO₂ mixture indicates a possible reversal temperature in the 86-163 C range.
33

On institutions, economic growth and the environment /

Lundström, Susanna. January 2003 (has links)
Thesis (doctoral)--Göteborgs universitet, 2003. / Extra t.p. with thesis statement inserted. Includes bibliographical references.
34

Potential of zero carbon buildings in Hong Kong

Wong, Man-chi, Man Joao., 黃文志. January 2012 (has links)
It is doubtless that global warming is enhanced by human activities, and being accelerated in recent years. The building sector is one of the main contributors in carbon emissions over the world, which contributed to over 20%. Hong Kong is a typical metropolis located in the sub-tropical region, whereas financing and servicing are the major industries supporting the development of the city. With these industries, it implies the major carbon emission is from buildings of commercial and residential sectors. A wide range of policies and researches on high efficient / green building design were conducted in the Western countries since the 90s, and there are more in the Asia Pacific since 2000. Among different countries there are many methods in calculating carbon emissions, which are similar in principle and different in the details. It is important to agree a consistenct framework on the calculation of carbon emission and study the performance of different carbon reduction strategies, hence to serve a reference for designers. This study conducted a critical review on the calculation of carbon emission, hence definition of carbon emissions. The review classified different calculation methods by 7 factors, which are the major governors on the results. All methods reviewed in the section were either current standards or methods suggested by scholars. With the critical review, a potential calculation methodology is suggested and will used for the calculation in the later part. A case study was carried out for the identification of the strategies used on two zero carbon buildings and one zero energy building. The study shows these buildings used similar strategies on the emission reduction, including photovoltaics, well insulated fabric, natural lighting, natural ventilation, high efficient lighting system and solar hot water system. A computer simulation was used to analyze the performance of different strategies that could be used on buildings in Hong Kong climate. Commercial buildings and residential buildings are selected as sample buildings for the analysis. A baseline building is setup with typical design. The computer simulation studied the strategies used by other buildings from case study and compares their effect with baseline building. The simulation shows that a zero carbon residential building is possible with sufficient offsetting on the building surface. However, office building cannot be zero carbon by applying the analyzed strategies. The study shows solar hot water is the most effective strategy for residential buildings and day lighting is the most effective strategy for office buildings. / published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management
35

The informational efficiency of the European carbon market

Viteva, Svetlana January 2012 (has links)
This thesis examines the informational efficiency of the European carbon market based on the European Union Emissions Trading Scheme (EU ETS). The issue is approached from three different perspectives. I explore whether the volatility embedded in carbon options is a rational forecast of subsequently realized volatility. Then, I investigate if, and to what extent, new information about the structural and institutional set-up of the market impacts the carbon price dynamics. Lastly, I examine whether the European carbon market is relevant for the firm valuations of covered companies. First, perhaps because the market is new and derivatives’ trading on emission allowances has only started recently, carbon options have not yet been extensively studied. By using data on options traded on the European Climate Exchange, this thesis examines an aspect of market efficiency which has been previously overlooked. Market efficiency suggests that, conditional upon the accuracy of the option pricing model, implied volatility should be an unbiased and efficient forecast of future realized volatility (Campbell et al., 1997). Black (1976) implied volatility and implied volatility estimates directly surveyed from market participants are used in this thesis to study the information content of carbon options. Implied volatility is found to be highly informative and directionally accurate in forecasting future volatility. There is no evidence, however, that volatility embedded in carbon options is an unbiased and efficient forecast of future realized volatility. Instead, historical volatility-based forecasts are shown to contain incremental information to implied volatility, particularly for short-term forecasts. In addition, this thesis finds no evidence that directly surveyed implied volatility estimates perform better as a forecast of future volatility relative to Black’s (1976) estimates. Second, the market sensitivity to announcements about the organizational and institutional set-up of the EU ETS is re-examined. Despite their importance for the carbon price formation, demand-side announcements and announcements about the post-2012 framework have not yet been researched. By examining a very comprehensive and updated dataset of announcements, this thesis adds to the earlier works of Miclaus et al. (2008), Mansanet-Bataller and Pardo (2009) and Lepone et al. (2011). Market participants are found to rationally incorporate new information about the institutional and regulatory framework of the emissions trading scheme into the carbon price dynamics. However, they seem to be unable to accurately assess the implications of inter-temporal banking and borrowing on pricing futures contracts with different maturities. The impact of macroeconomic conditions on the market responsiveness is investigated by splitting the dataset into subsamples according to two alternative methods: 1) a simple split into pre-crisis and full-crisis time periods, and 2) according to a Bai-Perron structural break test. Evidence is found that in the context of economic slowdown and known allowances oversupply, the relationship between the carbon price and its fundamentals (institutional announcements, energy prices and extreme weather) breaks down. These findings are consistent with the arguments in Hintermann (2010), Keppler and Mansanet-Bataller (2010) and Koop and Tole (2011) that carbon price drivers change in response to the differing context of the individual trading periods. Third, the role of carbon performance in firm valuation is understudied. Since companies were not obliged to disclose their carbon emissions prior to the launch of the EU ETS, there exists little empirical evidence of the effect of carbon performance on market value. Earlier studies of the European carbon market have only focused on the impact of ETS compliance on the profitability and competitiveness of covered companies (e.g. Anger and Oberndorfer, 2008). There is also little research on how the newly available emissions data has altered the carbon performance of companies. This thesis addresses these gaps in the literature by examining the stock price reactions of British and German firms on the day of verified emissions release under the EU ETS over the period 2006 – 2011. An event study is conducted using a Seemingly Unrelated Regressions model to deal with the event clustering present in the dataset. Limited evidence is found that investors use information about the carbon performance of companies in their valuations. The information contained in the carbon emissions reports is shown to be somewhat more important for companies with high carbon-intensive operations. This thesis finds no conclusive evidence that the cap-and-trade programme has been able to provide regulated companies with enough incentives to de-carbonize their operations. The market does not punish companies which continue to emit carbon at increasing rates or reward companies which improve their carbon performance. In brief, the results of the thesis suggest that the market is not fully efficient yet. Inefficiently priced carbon options may allow for arbitrage trades in the market. The inability of investors to incorporate rules on inter-temporal banking and borrowing of allowances across the different trading periods leads to significant price reactions when there should be none. A recessionary economic environment and a known oversupply of emission allowances have led to a disconnect between the carbon price and its fundamental drivers. And, lastly, the signal embedded in the carbon price is not strong enough to invoke investor action and turn carbon performance into a standard component of investment analysis.
36

Reducing CO₂ emissions associated with fast moving consumer goods : development and testing of tools and frameworks

Bocken, Nancy Maria Petronella January 2012 (has links)
No description available.
37

Carbon storage of Panamanian harvest-age teak (Tectona grandis) plantations

Kraenzel, Margaret. January 2000 (has links)
Reforestation is being considered as a mitigation option to help combat the climate change predicted to result from atmospheric carbon dioxide pollution. Forestry-based carbon storage projects are being introduced in many tropical countries, and assessment of species-specific carbon storage potentials is made difficult by a lack of species-level information. This study focuses on teak (Tectona grandis), to measure many of the characteristics affecting the carbon storage potential both of the trees themselves and of the plantations they are in. Root-to-shoot ratio, above- and belowground biomass, as well as tissue carbon content were measured in 20-year-old teak trees in Panamanian plantations. A regression relating diameter at breast height (DBH) to total tree carbon storage for trees of various sizes was developed. To scale up to the plantation level, this regression was used to estimate the carbon storage of the trees of four plantations. Litter, undergrowth, and soil were studied to estimate carbon storage in these compartments. These estimates were collated to form a global estimate of carbon storage in Panamanian harvest age teak plantations. Various methods of calculation of carbon storage in short-rotation plantations are discussed. This work will allow greater precision in the assessment of carbon storage in individual plantations.
38

EVALUATION OF HEAT SHOCK PROTEIN 70A (HSP70A) IN <i>CHLAMYDOMONAS REINHARDTII</i>

Short, Sarah Nicole 01 January 2012 (has links)
Algae are being considered as a possible tool for carbon dioxide mitigation because they uptake carbon dioxide during photosynthesis. Using flue gas from a coal-fired power plant as a carbon source would allow the algae to remove CO2 from the flue gas before it is emitted into the atmosphere. Because algae do not grow well at the high temperature, low pH conditions presented by flue gas, the traditional approach has been to alter the flue gas to suit the needs of the algae; however, this work aimed to genetically modify the algae Chlamydomonas reinhardtii to grow better at less than optimal conditions. Heat shock proteins are important in the stress responses of many organisms; therefore, this work modified C. reinhardtii to overexpress HSP70A in order to increase the tolerance of C. reinhardtii to higher temperature and lower pH. Experiments yielded mixed results, but there were several instances in which the modified algae appeared to have gained an increased tolerance to decreased pH based on the chlorophyll concentration of the algae.
39

Climate changers : an interdisciplinary exploration of reducing personal carbon emissions /

Johnson, Carly A. January 1900 (has links)
Thesis (M.A.I.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 74-79). Also available on the World Wide Web.
40

On institutions, economic growth and the environment

Lundström, Susanna. January 2003 (has links)
Thesis (doctoral)--Göteborgs universitet, 2003. / Extra t.p. with thesis statement inserted. Includes bibliographical references.

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