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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.
101

A COMPUTATIONAL STUDY OF LINKING SOLID OXIDE FUEL CELL MICROSTRUCTURE PARAMETERS TO CELL PERFORMANCE

Wang, Chao 08 November 2013 (has links)
No description available.
102

Experimental Demonstration of Photovoltaic Powered Solar Cooling With Ice Storage

January 2012 (has links)
abstract: The ability to shift the photovoltaic (PV) power curve and make the energy accessible during peak hours can be accomplished through pairing solar PV with energy storage technologies. A prototype hybrid air conditioning system (HACS), built under supervision of project head Patrick Phelan, consists of PV modules running a DC compressor that operates a conventional HVAC system paired with a second evaporator submerged within a thermal storage tank. The thermal storage is a 0.284m3 or 75 gallon freezer filled with Cryogel balls, submerged in a weak glycol solution. It is paired with its own separate air handler, circulating the glycol solution. The refrigerant flow is controlled by solenoid valves that are electrically connected to a high and low temperature thermostat. During daylight hours, the PV modules run the DC compressor. The refrigerant flow is directed to the conventional HVAC air handler when cooling is needed. Once the desired room temperature is met, refrigerant flow is diverted to the thermal storage, storing excess PV power. During peak energy demand hours, the system uses only small amounts of grid power to pump the glycol solution through the air handler (note the compressor is off), allowing for money and energy savings. The conventional HVAC unit can be scaled down, since during times of large cooling demands the glycol air handler can be operated in parallel with the conventional HVAC unit. Four major test scenarios were drawn up in order to fully comprehend the performance characteristics of the HACS. Upon initial running of the system, ice was produced and the thermal storage was charged. A simple test run consisting of discharging the thermal storage, initially ~¼ frozen, was performed. The glycol air handler ran for 6 hours and the initial cooling power was 4.5 kW. This initial test was significant, since greater than 3.5 kW of cooling power was produced for 3 hours, thus demonstrating the concept of energy storage and recovery. / Dissertation/Thesis / M.S. Mechanical Engineering 2012
103

Feasibility of Energy Harvesting Using a Piezoelectric Tire

January 2012 (has links)
abstract: While the piezoelectric effect has been around for some time, it has only recently caught interest as a potential sustainable energy harvesting device. Piezoelectric energy harvesting has been developed for shoes and panels, but has yet to be integrated into a marketable bicycle tire. For this thesis, the development and feasibility of a piezoelectric tire was done. This includes the development of a circuit that incorporates piezoceramic elements, energy harvesting circuitry, and an energy storage device. A single phase circuit was designed using an ac-dc diode rectifier. An electrolytic capacitor was used as the energy storage device. A financial feasibility was also done to determine targets for manufacturing cost and sales price. These models take into account market trends for high performance tires, economies of scale, and the possibility of government subsidies. This research will help understand the potential for the marketability of a piezoelectric energy harvesting tire that can create electricity for remote use. This study found that there are many obstacles that must be addressed before a piezoelectric tire can be marketed to the general public. The power output of this device is miniscule compared to an alkaline battery. In order for this device to approach the power output of an alkaline battery the weight of the device would also become an issue. Additionally this device is very costly compared to the average bicycle tire. Lastly, this device is extreme fragile and easily broken. In order for this device to become marketable the issues of power output, cost, weight, and durability must all be successfully overcome. / Dissertation/Thesis / M.S.Tech Educational Technology 2012
104

Alternatyvių energijos šaltinių panaudojimo skatinimo galimybės Lietuvoje / The opportunities to promote alternative energy sources in lithuania

Megelinskienė, Aistė 26 June 2014 (has links)
Vykstant intensyviai pasaulio ekonomikos plėtrai, nuolat auga ir energijos vartojimo mastai. Labiausiai naudojamų energijos šaltinių, ypač naftos bei dujų, atsargos yra ribotos ir nuolat senka. Ekonominė priklausomybė nuo energijos išteklių tiekėjų – energijos išteklių stokojančių šalių problema. Dar viena problema – neigiama organinio kuro deginimo įtaka klimato kaitai. Vienas iš ilgalaikių Lietuvos darnaus vystymosi strategijos uždavinių – skatinti, kad atsinaujinančiųjų energijos išteklių naudojimas energetikoje ir transporte nuolat didėtų ir iki 2020 metų sudarytų ne mažiau kaip 15 procentų bendro pirminės energijos balanso. Darbo tikslas – atskleisti alternatyvių energijos šaltinių panaudojimo skatinimo galimybes Lietuvoje. Uždaviniai: 1) išnagrinėti alternatyvių energijos šaltinių panaudojimo skatinimo teorinius aspektus; 2) išanalizuoti Lietuvoje bei užsienyje atliktus tyrimus bei empirinius duomenis atsinaujinančių energijos išteklių panaudojimo skatinimo srityje; 3) parengti empirinio tyrimo, įvertinančio alternatyvių energijos išteklių skatinimo priemonių efektyvumą Lietuvoje, metodologiją; 4) pritaikyti parengtą tyrimo metodologiją ir įvertinti alternatyvių energijos išteklių panaudojimo skatinimo priemonių efektyvumą; 5) pateikti alternatyvių energijos išteklių skatinimo Lietuvoje rekomendacijas. Buvo vykdoma ekspertų apklausa ir rezultatai parodė, kad atsinaujinančių energijos šaltinių skatinimas nėra pakankamas Lietuvoje. Supirkimo tarifai, ES struktūrinių fondų... [toliau žr. visą tekstą] / As world economy intensively develops, there is also seen a constant growth of energy consumption. Mostly used sources of energy, especially oil and gas resources are limited and constantly wasting. Economic dependence on energy suppliers is the problem of countries lacking in energy resources. Another problem is the negative impact of burning biogas on climate change. One of the long-term sustainable development strategies for Lithuania tasks is to promote the use of renewable energy resources in energetics and transport. The aim of work is to disclose the opportunities of alternative energy sources promotion for Lithuania. The objectives of work are: 1) to explore the theoretical aspects of alternative energy sources promotion; 2) to analyze Lithuanian and abroad studies and empirical data for renewable energy promotion; 3) to prepare the methodology of empirical study evaluating the efficiency of alternative energy resources promoting measures in Lithuania; 4) to adapt the methodology and assess the efficiency of alternative energy resources promoting measures; 5) to provide the recommendations how to promote alternative energy sources in Lithuania. It was conducted the survey of experts and the results showed that the promotion of renewables in Lithuania is not sufficient enough. Feed-in-tariffs, the promotion of the EU Structural Funds and tradable pollution permits can be identified as the best currently existing promotional measures. Currently operating tax incentives... [to full text]
105

Cost Benefit Analysis of Wind Power in Germany

Labunets, Nazariy January 2014 (has links)
The objective of this thesis is to perform a cost benefits analysis of the wind power sector in Germany, with the horizon of 2030. Various costs and benefits stemming from the expansion of wind power are inferred from literature review and studying the peculiarities of the German case. The magnitude of governmental support is calculated by applying the Weibull distribution of wind at different zones across Germany and power curves of 5 modern wind turbines, as specified by the law. A number of sensitivity analyses is performed on the main inputs for onshore installations. Under the baseline assumptions, the onshore sector is found as non-beneficial to the society, without a visible improving trend for the future. While the offshore sector does not reach a point where the benefits would start overweighing the cost until 2030, the overall trend look much more promising. Powered by TCPDF (www.tcpdf.org)
106

Annual cellulose crop options for ethanol and oil cropping intensification for biodiesel feedstocks

Ballard, Todd Curtis January 1900 (has links)
Doctor of Philosophy / Department of Agronomy / Scott Alan Staggenborg / Ethanol from cellulose and biodiesel are both advanced biofuels according to the renewable fuel standard version two (RFS2) as part of the Energy Independence and Security Act of 2007. Agricultural production of feedstocks for these fuels can occur as co-products from the primary use of the crops. Use of cellulosic material produced from annual grain and sugar crops does not displace land use from grain and sugar production. Production of corn (Zea mays L.), grain sorghum, dual purpose forage sorghum, sweet sorghum, and photoperiod sensitive sorghum (Sorghum bicolor (L.) Moench) are all primarily driven for products other than cellulosic ethanol. Corn production if driven by grain and silage markets with fodder occasionally used for forage. Grain sorghum production is driven by grain markets and grown primarily in semi arid regions. Dual purpose forage sorghum is used for forage both as baled hay and as silage. Sweet sorghum is produced for sugar and molasses production. Photoperiod sensitive sorghum is produced for baled hay. The current study tests the effect of seeding rate on cellulosic ethanol on each crop. Yellow grease is the most common source of oil for biodiesel production. Intensification of oil crop production may increase the feedstock availability for biodiesel. The current study uses double cropping of spring camelina (Camelina sativa (L.) Crantz), spring canola (Brassica napus L.), sesame (Sesamum indicum L.), safflower (Carthamus tinctorius Mohler, Roth, Schmidt and Bourdeux), soybean (Glycine max L.), and sunflower (Helianthus annuus L.) to search for cropping system options that will produce more oil on an annual basis than full season crops. The full season crop options used were maturity group IV soybean, maturity group V soybean, and full season sunflower. Fertility inputs are inherently less for the non legume crops due to the N fixation ability of symbiotic rhizobium. Canola and camelina are also more sensitive to sulfur deficiency than many crops. Long chain and polyunsaturated fatty acids have higher market values than biodiesel. Separation of these fatty acids from the lipid profile of oil seed crops provides additional demand for oil seed crops. Demand for the crops will drive commodity prices and move land use into oil crop production. The second year of oilseed production provided an opportunity to look at lipid profiles of successfully produced crops during a drought year. Three new discoveries were concluded. Grams cellulosic ethanol g[superscript]-1 stover is not affected by density within the densities considered. Among the double crop options tested only sesame after spring crops was viable in normal years and none were viable in an extreme drought year. Lipid profiles are provided for crops produced in concurrent field growing conditions.
107

Engineering Escherichia coli for the production of polyketide-based platform chemicals

January 2012 (has links)
The current chemical industry produces a diverse array of industrial chemicals from a handful of highly reduced byproducts (termed "platform chemicals") derived from oil refining. However, petroleum is a non-renewable resource, and increases in its cost have created pressure to convert the chemical industry into one that is renewable to ensure its long-term viability. To complete this objective, one approach is the conversion of biomass to platform chemicals through fermentation by Escherichia coli . One such platform chemical is methyl ketone, which can be readily converted to dienes that can directly replace existing platform chemicals such as ethylene. To bestow non-native methyl ketone production capability to E. coli from glucose, the polyketide biosynthesis pathway was exploited in conjunction with grafting in a heterologous methyl ketone synthesis pathway found in wild tomato species Solanum habrochaites to produce the methyl ketones. Cultivation under microaerobic conditions improved titers and yields, and further engineering to knock out the native competitive pathways that become activated under microaerobic conditions led to significantly improved strains. The final strain, ΔadheΔldhaΔptaΔpoxB [pTrcHis2A-shmks2-mks1], produced up to 450 mg/L of methyl ketones at 17 mg of methyl ketones produced per gram of glucose consumed under optimized operating conditions in minimal media supplemented with glucose.
108

Ligand Design for Novel Metal-Organic Polyhedra and Metal-Organic Frameworks for Alternative Energy Applications

Kuppler, Ryan John 2010 August 1900 (has links)
The primary goal of this research concerns the synthesis of organic ligands in an effort to create metal-organic porous materials for the storage of gas molecules for alternative energy applications as well as other applications such as catalysis, molecular sensing, selective gas adsorption and separation. Initially, the focus of this work was on the synthesis of metal-organic polyhedra, yet the research has to date not progressed past the synthesis of ligands and the theoretical polyhedron that may form. Further efforts to obtain polyhedra from these ligands need to be explored. Concurrently, the search for a metal-organic framework that hopefully breaks the record for methane adsorption at low pressure and standard temperature was undertaken. A framework, PCN-80, was synthesized based off a newly synthesized extended bianthracene derivative, yet was unstable to the atmosphere. Hydrogen and methane adsorption capacities have been evaluated by molecular simulations; these adsorption isotherms indicated a gravimetric hydrogen uptake of 9.59 weight percent and a volumetric uptake of methane of 78.47 g/L. Following the synthesis of PCN-80, a comparison study involving the effect of the stepwise growth of the number of aromatic rings in the ligand of a MOF was pursued; the number of aromatic rings in the ligand was varied from one to eight while still maintaining a linear, ditopic moiety. The synthesis of another bianthracene-based ligand was used to complete the series of ligands and PCN-81, a two-dimensional framework with no noticeable porosity as evident by the simulated hydrogen uptake of 0.68 weight percent, was synthesized. All of these MOFs were synthesized from zinc salts to reduce the number of variables. No clear relationship was established in terms of the number of aromatic rings present in the ligand and the hydrogen adsorption capacity. However, it was confirmed that the density and hydrogen uptake in weight percent are inversely proportional. Further work needs to be done to determine what advantages are offered by these novel frameworks containing extended bianthracene derivatives. For example, with the highly fluorescent nature of the ligands from which they are composed, both PCN-80 and PCN-81 should be studied for the potential use in the application of fluorescent materials.
109

the study on the decision-making of alternative energy technologies establishing within manufacturing firms.

Lu, Chieh-lien 15 June 2009 (has links)
Over the past two decades, quite a few scientists agree that global warming is real, it¡¦s already happening and that it is the result of our activities and not a natural occurrence. The evidence is overwhelming and undeniable. Carbon dioxide and other gases warm the surface of the planet naturally by trapping solar heat in the atmosphere. Recently, government, non-profit organizations and firms put great emphasis on environmental issues. They also encourage those firms to develop alternative energy technologies. For example, the American government wants to invest $150 billion over the next ten years to catalyze private efforts to build a clean energy future. A lot of excellent companies put great emphasis on green supply chain. Some firms try to do some research and development on alternative energy technologies. In this way, these companies can enhance business efficiency and competitiveness, providing better productivity and process. Many manufacturing firms have tried to introduce alternative energy technology to improve its operation performance and to keep its competitive advantages. Nevertheless, introducing and evaluating alternative energy technology are quite demanding, difficulties being both conceptual and operational. At the same time, firms need to adjust the internal processes. In this way, adopting alternative energy technologies become a very challenging task. In this thesis, the criterion was sifted by using an Analysis Hierarchy Process (AHP) to develop a general framework for evaluating and introducing alternative energy technology into a manufacturing firm is presented.
110

Switchgrass potential on reclaimed surface mines for biofuel production in West Virginia

Marra, Michael A. 03 May 2013 (has links)
<p> The high cost and environmental risks associated with non-renewable energy sources has caused an increased interest in, and development of renewable biofuels. Switchgrass (<i>Panicum virgatum</i> L.), a warm season perennial grass, has been investigated as a source of biofuel feedstock due to its high biomass production on marginal soils, its tolerance of harsh growing conditions, and its ability to provide habitat for wildlife and soil conservation cover. West Virginia contains vast expanses of reclaimed surface mine lands and could potentially benefit from the production of switchgrass as a biofuel feedstock. Furthermore, switchgrass production could satisfy Surface Mining Reclamation and Control Act of 1977 (SMCRA) requirements for reclamation bond release to mine operators. Three separate studies will be discussed in this thesis to determine if switchgrass grown on reclaimed surface mines can produce yields similar to yields from stands grown under normal agronomic conditions and what common surface mining reclamation practices may be most appropriate for growing switchgrass. The first study examined yield production of three commercially-available, upland switchgrass varieties grown on two reclaimed surface mines in production years two, three and four. The Hampshire Hill mine site, which was reclaimed in the late 1990s using top soil and treated municipal sludge, averaged 5,800 kg (ha-yr)<sup>-1</sup> of switchgrass compared to 803 kg (ha-yr)<sup>-1</sup> at the Hobet 21 site which was reclaimed with crushed, unweathered rock over compacted overburden. Site and variety interacted with Cave-in-Rock as the top performer at the more fertile Hampshire Hill site and Shawnee produced the highest yields at Hobet 21 (7,853 kg ha<sup>-1</sup> and 1,086 kg ha<sup>-1</sup> averaged across years, respectively). Switchgrass yields increased from 2009 to 2010, but declined from 2010 to 2011. Switchgrass yields from farmlands in this region averaged about 15000 kg (ha-yr)<sup>-1</sup> in the research literature, so switchgrass grown on reclaimed lands appears to be about 50% lower. A second study to determine optimal nitrogen and mulch rates for switchgrass establishment began in June 2011 on two newly-reclaimed surface mines. Both sites were seeded at a rate of 11.2 kg pure live seed (PLS) ha<sup>-1</sup> of Cave-in-Rock on replicated treatments of 0, 33.6 and 67.0 kg N ha<sup>-1</sup>, and high and low mulch rates of mulch applied as hydromulch. Switchgrass cover, frequency and yield improved with the addition of any amount of N fertilizer compared to no N application. There was no significant difference in yield associated with high and low levels of N. We also observed that yields were not affected by application of additional mulch. The final study compared a one- and two-harvest system in the fourth year of production at the Hampshire Hill and Hobet 21 sites. There was no increase in yield production utilizing a two-harvest system (2922 kg (ha-yr)<sup>-1</sup>, averaged across site) compared to a one-harvest system (3029 kg (ha-yr)<sup>-1</sup>). The data also showed that re-growth collected from July to October in the two-harvest system added negligible yield and that yield collected in July was comparable in one- and two-harvest systems.</p>

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