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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.
441

The process of technology commercialization : A case study of project CHRISGAS

Holmgren, Annie, Karlsson, Simon January 2007 (has links)
<p>This thesis investigates, describes and understands the extensive process of technology commercialization. What stages there are, important aspects and implications. It is structured as a case analysis of project CHRISGAS development. CHRISGAS is a Swedish project, based in Värnamo, developing the technique of direct gasification of biomass to fuels.</p><p>The work has its origin in the debate of the imminent climate changes, where society needs to reduce its reliance on fossil fuels. The automotive sector (particularly transport) is significantly reliant. However, current attempts to transition to biofuels have not completely succeeded. New, efficient technologies must be commercialized, and the technology of wood gasification is said to be particularly promising for launching the next generation of biofuels.</p>
442

Hydrodynamics of a Cold Model of a Dual Fluidized Bed Gasification Plant

Lim, Mook Tzeng January 2012 (has links)
Biomass energy is increasingly used to reduce the dependence on fossil fuels and reduce the impact of greenhouse gas emissions on global warming. Fluidized bed gasification converts solid biomass into gaseous fuels that can be used for combustion or liquid fuels synthesis. The efficiency of biomass gasification is directly affected by the fluidized bed hydrodynamics. For example, the solids recirculation rate through the system is an important parameter that affects the heat and mass transfer rates. In this study, a cold model of a dual fluidized bed (DFB) biomass gasification plant was designed using scaling laws, and was constructed to investigate the hydrodynamics of industrial DFBs. A DFB consists of a bubbling fluidized bed (BFB), where biomass is gasified to produce syngas, and a circulating fluidized bed (CFB) where the residues of gasification are combusted. The investigation was divided into Phase I and II. In Phase I, an operational map was developed for the CFB to define operational boundaries for steady state operation of the plant. An empirical model was developed to predict the solids mass flow rate out of the CFB riser, which is an empirical function of the exit opening width, the CFB diameter, and a newly introduced aerodynamic factor. The correlation coefficient, R2 for the empirical function was 0.8327. The aerodynamic factor accounts for the particle inertia and clustering effects at the exit of the CFB riser. Results from Phase I also showed that increasing the fluidizing velocities increased the solids circulation rate and affected the pressure drop over various points in the CFB plant due to redistribution of solids with the system. A critical assessment was performed on published correlations found in the literature to determine how accurately they predicted the hydrodynamics in the CFB riser. By comparing predicted and experimental results, the correlations were found to be inaccurate for the conditions and configuration of the CFB tested in this study. For example, the solids velocity was not accurately predicted by published correlations due to unaccounted particle clustering effects. The main issue with the published correlations was a lack of generality, so that the correlations only applied for predicting fluidizing behaviour in the equipment they were developed in. In Phase II, an operational map was developed for the DFB, which incorporated both the CFB and the BFB. Experiments with a binary mixture representing sand and char in an industrial gasifier showed a blocking effect in the connecting chute between the CFB and BFB by the material representing char, which was larger and less dense than the material representing sand. A computational fluid dynamics (CFD) based design tool for modelling the cold model CFB cyclone was developed and validated by comparing the predicted and experimental cyclone pressure drop. The correlation coefficient for the CFD pressure drop prediction was 0.7755. The design tool contained information about the grid resolution and the time step required for modelling the cyclone accurately.
443

Energy Constraint and Adaptability: Focus on Renewable Energy on Small Islands

Mohamed, Muaviyath January 2012 (has links)
Renewable energy integration into diesel generation systems for remote island communities is a rapidly growing energy engineering field. Fuel supply issues are becoming more common and the disruption, instability and panic caused by fuel shortages results in inefficient and unreliable power supplies for remote island communities. This thesis develops an energy engineering approach for meeting renewable energy development, supply security, cost and sustainability objectives. The approach involves adapting proven energy engineering techniques including energy auditing, energy system modelling with basic cost analysis and demand side management. The novel aspect of this research is the development of critical load engineering in the system design, and informing this with an assessment of essentiality of energy services during the audit phase. This approach was prompted by experiences with previous fuel shortages and long term sustainability policy drivers. The methodology uses the most essential electric loads as the requirement for sizing the renewable energy capacity in the hybrid system. This approach is revolutionary because communication with the customers about availability and the need to shed non-essential loads helps to both meet cost and security requirements and to reduce levels of panic and uncertainty when fuel supply issues arise. A sustainable power generation system is a system that provides continuity of supply for electrical appliances that are considered by the residents to be essential and for which adaptability and resilience of behaviour were key design priorities over growth. The sustainable electrical energy supply should match the critical (essential) load and should have the ability to continue without major disruptions to the daily lives of the people in these communities. Essential energy end uses were identified through energy audits and surveys. The electric power system is designed so that renewable energy sources alone can meet that “essential” demand with a plant that is both economically and technically feasible. Diesel generators were supplemented to meet the short fall in meeting the unconstrained electric demand. This is to design a system that is generally competitive with the present conventional power generation. This method should be particularly suitable for handling the complexities of a modern-day energy system in terms of planning a sizable sustainable energy and electricity system, either based on wholly sustainable sources or integrating sustainable sources of energy into a conventional generation system. The final hybrid system chosen after numerous simulations for the case study (Fenfushi island in the Maldives) community has the minimum renewable energy sources to meet the essential load but uses diesel to supplement the present load. A variety of design parameters such as PV size, wind turbine sizes and numbers and battery capacity have been considered. The minimum renewable energy sources to supply the essential loads of the community were simulated with diesel generators to find the optimal supply mix for the present load (typical unconstrained demand). The final outcome has the following characteristics: NPC and COE were $1,532,340 and $0.37/kWh respectively, lower than any diesel-only systems that could supply the demand. The total annual electricity production is 386,444 units (kWh), of which 9.61% is excess electricity and the annual operating cost is $68,688. Compared to the diesel-only systems there is a fuel savings of 77,021 litres of diesel per year, which is a 66.5 % reduction. An annual carbon dioxide emission reduction of 202,824 kg was achieved, which is a reduction of 66.5%. An annual renewable energy contribution of 70% would be achieved, 34% of which would be from PV arrays and 36% from wind turbines. The selected system shows that even with 30 percent power supply from diesel generators, still the highest NPC is on diesel generation for a life of over 25 years.
444

A technical and economic feasibility study for the integration of GSHP technology in the Christchurch rebuild

Bustard, Samuel Kent January 2014 (has links)
Mr Wayne Tobeck, Director of Southrim Group (SRG), sponsored this 2013 MEM Project titled; A Technical and Economic Feasibility Study for the Integration of GSHP Technology in the Christchurch Rebuild. Following the recent Christchurch earthquakes, a significant amount of land has become too unstable to support traditional building foundations. This creates an opportunity to implement new and unique foundation designs previously unconsidered due to high costs compared to traditional methods. One such design proposes that an Injection Micro-Piling technique could be used. This can also be coupled with HVAC technology to create a Ground Source Heat Pump (GSHP) arrangement in both new buildings and as retrofits for building requiring foundation repair. The purpose of this study was to complete a feasibility study on the merits of SRG pursuing this proposed product. A significant market for such a product was found to exist, while the product was also found to be technically and legally feasible. However, the proposed product was found to not be economically feasible with respect to Air Source Heat Pumps due to the significantly higher capital and installation costs required. Further analysis suggests GSHPs may become more economically attractive in operating temperatures lower than -9oC, though the existence of markets with this climate in NZ has not been studied. It is therefore suggested that SRG do not proceed with plans to develop a GSHP coupled foundation solution for the Christchurch rebuild.
445

Geographies of biomass and solar energy: Spatial decision support for regional energy sustainability

Calvert, KIRBY 03 July 2013 (has links)
This thesis applies concepts and techniques in geography in order to contribute to our understanding of the opportunities and challenges associated with the transition toward renewable energy. The work is best understood as the sum of two parts. In the first part, the methodological and philosophical underpinnings of the field of energy geography are explored in order to situate the research in the broader constellation of geographical practices surrounding energy. I make the case that energy transitions are not merely shifts in energy supply but are also simultaneously fundamental shifts in prevailing spatial relations, so that energy transition management is best conceived as a spatial strategy with emphasis on regional level land-energy planning. In the second part of the thesis, I aim to provide decision support in favour of this spatial strategy. This begins in Chapter 4 with a comprehensive critical review of how GIScience and remote sensing has been applied in RE assessments and spatial planning. The next three chapters engage key gaps in this literature and are the analytical contributions of the thesis. The focus of the research is on biomass and solar energy in (eastern) Ontario. In Chapter 5 I develop geographically explicit supply-cost curves for forestry and agricultural biomass and assess the relative merits of a mixed biomass feedstock stream. In Chapter 6 I recognize and address the issue that developers of dedicated bioenergy crops and ground-mount solar PV systems prefer the same type of land. Land-energy trade-offs are modeled and their implications in the context of incentivizing RE development are discussed. In Chapter 7 I explore ways in which targeted facility siting can capture ancillary benefits related to RE production. I argue that focusing on the benefits as well as the costs of system siting is critical to linking developer and public interests. Ontario’s feed-in tariff program is evaluated in the light of this claim. Chapter 8 concludes with a summary of key findings and describes the ways in which this thesis can be used as a platform upon which a broader research program can be raised. / Thesis (Ph.D, Geography) -- Queen's University, 2013-07-03 00:36:53.142
446

Valuing the social cost of air-pollution in Bophelong township / Ismael Maloma

Maloma, Ismael January 2013 (has links)
The aim of this study is to quantify the social cost of air pollution in Bophelong Township. Bophelong is a dominantly Black low-income settlement located on the South-western part of the Emfuleni Local Municipality in the Vaal Triangle. In 2006 the Vaal Triangle was the first region in the country to be declared an Airshed Priority Area in terms of the National Environmental Management Act (39/2004). Economic literature reveals that there is a strong positive correlation between poverty and pollution. It is on this basis that the study provides a theoretical background to poverty and pollution. The study makes use of a Contingent valuation method to elicit respondents‘ maximum willingness to pay for the reduction of air-pollution in the area. The survey questionnaire covers three broad socio-economic categories namely, the demographic profile, labour force profile and the residents‘ attitudes towards environmental issues. The valuation part of the questionnaire makes use of an open-ended questionnaire to elicit the respondents‘ maximum willingness to pay for the reduction of air pollution in Bophelong. The mean willingness to pay for the reduction of air-pollution in Bophelong is estimated at R132 per annum. The annual social cost of air-pollution in Bophelong is calculated by multiplying the mean willingness to pay with the estimated total population. Bophelong‘s total population was estimated at 49 408. The annual social cost of pollution is thus estimated at R6 521 856. The regression analysis shows that several factors positively influence respondents‘ willingness to pay. The analysis shows that education, employment and level of income are positively correlated with the respondents‘ willingness to pay. This study indicates that there is a positive correlation between poverty and pollution. Most of the air pollution that affects the population of Bophelong is generated from domestic sources such as the burning of coal and biomass fuels for VALUING THE SOCIAL COST OF AIR-POLLUTION IN BOPHELONG TOWNSHIP heating and cooking purposes. In order to eliminate the negative impacts of air pollution on the residents of Bophelong the study recommends that authorities must begin by ameliorating the poverty situation in the area. On the main authorities must introduce measures that target domestic sources of pollution. Some of the measures that could be undertaken to reduce the impact of pollution could include: (a) encouraging residents to adopt the more cleaner top-down coal ignition method known as Basa-njengo-Magogo, (b) providing free basic electricity to poor households in the area and (c) ensuring that houses are constructed with thermal comfort in mind, as this will minimise the need for space heating particularly during winter months. / PhD (Economics), North-West University, Vaal Triangle Campus, 2013
447

An econometric analysis of energy poverty and sustainable development in Blantyre (Malawi) / Betchani Henry Mbuyampungatete Tchereni

Tchereni, Betchani Henry Mbuyampungatete January 2013 (has links)
Energy is the driver of activity in every economy and, therefore, its importance cannot be overemphasised. However, Sub-Saharan Africa (SSA) faces general problems of access to modern energy. Most households and industry in SSA use traditional and unclean energy resources for activities such as cooking, lighting and drying of farm produce. Many households in less developed countries have very limited choices with regard to alternatives to traditional energy supplies. Energy poverty is overt in many poor countries, particularly in the Sub-Saharan region where 700 million people are deprived of access to modern energy facilities. In Malawi, less than 6 percent of the population have access to electricity. There are, therefore, many questions regarding the state of energy poverty still to be answered, not only in Malawi, but also the entirety of the SSA region. Questions such as what is the level of energy poverty in these regions? What determines this level of poverty? Why are people not adopting renewable energy facilities for their household needs? Are some energy facilities inferior to others? Such questions were the centre of the present study. These questions are important because, with energy poverty, nearly all the Millennium Development Goals are unachievable and sustainable development could not be a success story where the dominant source of energy for both households and industry is biomass. This study was based on a survey conducted in South Lunzu Township (SLT), which is a low income area to the east of Ndirande Mountain in the city of Blantyre, Malawi. The survey administered a standard questionnaire through face-to-face interviews with heads of households. Data was collected from 319 respondents who were selected through random sampling techniques. The descriptive statistics suggest that the average household size for South Lunzu Township is 5 people. The average age of the sampled respondents was about 38. Energy Poverty and Sustainable Development The findings of the thesis suggest that over 90 percent of the households sampled were energy poor with energy expenditure exceeding 10 percent of total household expenditure. In terms of energy resources used in SLT, 2.9 percent used electricity for cooking meals. Only 2 households, representing 0.63 percent, use liquefied petroleum Gas (LPG) and just 1 household, representing 0.31 percent, depended mostly on solar power. On the other hand, energy facilities that are considered dirty, inefficient and a danger to the heath of people seem to be popular. For instance charcoal and firewood were used by 25 percent and 4.7 percent of the total sample respectively. Most households use a combination of energy facilities; however, those that are considered inferior are preferred. Of the sample, 42 percent use both charcoal and firewood to cook their meals. Further, the results of the Engel functions suggest that charcoal and wood were not regarded as inferior products for the cooking needs of households despite improvements in income. Electricity, which was also regarded as a normal energy resource, had positive income elasticity. To improve access to modern energy facilities at the household level, the thesis recommends that a flexible trade and tax regime, one that will improve the availability and affordability of renewable energy to the majority, should be adopted. The Logit model of energy poverty reveals that household expenditure on transport, income level, age, and education level of the head of household; household size; and home size, are important factors in explaining the level of energy poverty in South Lunzu Township. Further, the results revealed that expenditure on housing and marital status could not be relied upon as important predictors of the probability of energy poverty in South Lunzu. Expenditure on education was associated with lower levels of energy poverty. Households who spent more on schooling also spent more on food items and their expenditure on energy resources was less than 10 percent of the total expenditure per month. In addition, those households that spent more on food were also likely to be energy well-off. Energy Poverty and Sustainable Development Results of the multinomial logit (MNL) model suggest that most socioeconomic variables under study were inelastic in influencing the probability for the outcomes, at the household level, to be used for the purposes of cooking. Statistically, age, income and education level of the head of household, together with household size, were important factors that influenced the choice of most of the outcomes for cooking purposes, including electricity, charcoal, firewood and LP gas. The major recommendation of this study is that campaigns emphasising the abilities of renewable energy be developed and disseminated. That renewable energy is relegated to poor and uncivilised societies is a notion that must be rooted out of the mindset of the average, civilised urban dweller. Also, the use of LP gas for cooking purposes must be encouraged. Import tax regimes that discourage international trade of renewable energy resources must be removed to encourage lower prices on such facilities. These policies would ensure sustainable development by reducing reliance on biomass, which is depleting at a faster rate than it is regenerating. / Thesis (PhD (Economics))--North-West University, Vaal Triangle Campus, 2013
448

Hydrodynamic Impacts of Tidal Lagoons in the Upper Bay of Fundy

Cousineau, Julien 16 July 2012 (has links)
Among sources of renewable energy, development of tidal energy has traditionally been plagued by relatively high costs and limited availability of sites with sufficiently high tidal amplitudes or flow velocities. However, many recent technology developments and improvements, both in design (e.g. dynamic tidal power, tidal lagoons) and turbine technology (e.g. new axial turbines, crossflow turbines), showed that the economic and environmental costs may be brought down to competitive levels comparing to other conventional energy sources. It has long been identified that the Bay of Fundy is one of the world’s premier locations for the development of tidal power generating systems, since it has some of the world’s largest tidal ranges. Consequently, several proposals have been made in the recent years to find economical ways to harness the power of tides. Presently, there is considerable interest in installing tidal lagoons in the Bay of Fundy. The lagoon concept involves temporarily storing seawater behind an impoundment dike and generating power by gradually releasing the impounded seawater through conventional low-head hydroelectric turbines. A tidal lagoon will inherently modify the tides and tidal currents regime in the vicinity of the lagoon, and possibly induce effects that may be felt throughout the entire Bay of Fundy. The nature of these hydrodynamic impacts will likely depend on the size of the tidal lagoon, its location, and its method of operation. Any changes in the tidal hydrodynamics caused by a tidal lagoon may also impact on the transport of sediments throughout the region and upset ecosystems that are well adapted to existing conditions. The scale and character of the potential hydrodynamic impacts due to tidal lagoons operating in the Bay of Fundy have not been previously investigated. The present study endeavours to investigate these potential impacts to help the development of sustainable, science-based policies for the management and development of clean energy for future generations. After outlining fundamental aspects of tidal power projects taken in consideration in the Bay of Fundy, an analysis of present knowledge on tidal lagoons was conducted in order to provide a focus for subsequent investigations. Hydrodynamic modeling was used to quantify any of the potential hydrodynamic changes induced in the Bay of Fundy due to the presence of tidal lagoons. In the last part of the thesis, new relationships were derived in order to describe the amount of energy removed from tidal lagoons associated with its hydrodynamic impacts.
449

Kukurūzų grūdų trupinimo tyrimas / Corn grain crushing studies

Milašius, Andrius 16 June 2014 (has links)
Tirtas kukurūzų frakcijų kiekio pasiskirstymo priklausomybė nuo atstumų dydžio tarp trupintuvo valcų. Tyrimai atlikti 2013-2014 metais Aleksandro Stulginskio universitete. Tyrimo objektas – diskinių valcų trupintuvas-traiškytuvas, kurio našumas iki 15 t.h-1. Valcai – apvalūs, dantyti, sukimosi dažnis ns = 4000 min-1. Trupintuvą-traiškytuvą sudaro keturi valcai, dvi poros – pakopos. Trupintuvo diskiniams valcams sukti, reikalinga aktyvioji galia, matuota elektros energijos tinklo analizavimo prietaisu ME-MI2492 („Metrel“). Frakcijų atskyrimui buvo naudojami penki sietai: 3,5 mm; 3 mm; 2,4 mm; 2 mm; 1 mm. Iš viso gautos šešios frakcijos. Valcų atstumas kito nuo 4,5 iki 6 mm pirmos pakopos ir nuo 1,5 iki 3 mm antrosios pakopos. Tyrimais nustatytas žymus, frakcijų didesnių nei 3,5 mm, kiekio didėjimas. Grūdų drėgniui sumažėjus pastebėtas galios poreikio padidėjimas esant minimaliems atstumams tarp valcų. Apdorojus duomenis nustatytas esminis skirtumas tarp frakcijų didesnių nei 3,5 mm kiekio procentinės dalies, esant santykiniam grūdų drėgniui ωg1=37,77±0,5% ir frakcijų kiekio kai drėgnis ωg3=33,25±0,88%. / Studied corn fraction pattern on the cracker rolls gap wide. Investigations were carried out in 2013-2014 at Aleksandras Stulginskis University. Research object was a disc roller crusher, with a capacity of up to 15 t.h-1. Rollers - rounded, toothed, rotation speed n = 4000 min -1. Crusher consists of four rolls, two pairs in all. Crusher disc rolls turn required active power, measured electricity network analysis device ME- MI2492 ( Metrel ) sievs was used in five screens: 3.5 mm; 3 mm; 2.4 mm; 2 mm; 1 mm. A total of six groups. The results demonstrated significant groups larger than 3.5 mm, the increase in volume. Grain moisture decreased observed a increase in power consumption at the minimum roller distance. After processing the data a fundamental difference been set between the groups of larger than 3,5 mm the percentage of grain moisture ωg1 = 37.77 ± 0.5% and the volume fraction when humidity ωg3 = 33.25 ± 0.88 %.
450

Refractive integrated nonimaging solar collectors design and analysis of a novel solar-daylighting-technology

Pelegrini, Alexandre Viera January 2009 (has links)
A novel and original category of low-cost static solar-daylighting-collectors named Keywo solar energy, solar collectors, daylighting systems, nonimaging optics, Refractive Integrated Nonimaging Solar Collectors (RINSC) has been designed and thoroughly tested. The RINSC category is based on nonimaging optics and integrates several optical elements, such as prismatic arrays and light guides, into a single-structured embodiment made of solid-dielectric material. The RINSC category is sub-divided in this thesis into four distinctive and original sub-categories/systems: Prismatic Solar Collectors (PSC), Multi-Prismatic Solar Collectors (MPSC), Integrated Multi-Prismatic Solar Collectors (IMPSC) and Vertically Integrated Nonimaging Solar Collectors (VINSC). The optical configuration and compact embodiment of these systems allows them to be integrated into a building façade without creating any protrusion, indicating that they can lead to solar collector systems with high building integration potential. Laboratory and outdoor experimental tests conducted with a series of demonstration prototypes made of clear polymethyl-methacrylate (PMMA) and manufactured by laser ablation process, yield peak transmission efficiencies TE varying from 2% to 8%. Computer simulations indicated that transmission efficiencies TE > 30% are possible. The design and development of the innovative optical systems introduced in this thesis were backed-up with extensive computer ray-tracing analysis, rapid-prototyping, laboratory and outdoor experimental tests. Injection moulding computer simulations and surface analysis concerning the development of the RINSC systems were also conducted. Basic theory and comprehensive literature review are presented. This research has also resulted in the design and prototyping of a novel optical instrumentation named Angular Distribution Imaging Device (ADID), specially developed to analyse the spatial distribution of light emerging from the exit aperture of solar collectors/concentrators. The systems and knowledge described in this thesis may find application in areas such as solar collector systems to harvest sunlight for natural illumination in buildings, solar-photovoltaic and solar-thermal.

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