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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.
71

Promoting sustainable energy systems through networks a framework for network design developed using the case of BASE (Basel Agency for Sustainable Energy) /

Schlup, Michael. January 2001 (has links) (PDF)
Thesis (M.Sc.)--Lund University, 2001. / Title from title screen of PDF file (viewed 9 Dec. 2003). Includes bibliographical references.
72

Enhancing the saccharolytic phase of sugar beet pulp via hemicellulase synergy

Dredge, Roselyn Ann January 2010 (has links)
The sugar beet (Beta vulgaris) plant has in recent years been added to the Biofuel Industrial Strategy (Department of Minerals and Energy, 2007) by the South African government as a crop grown for the production of bio-ethanol. Sugar beet is commonly grown in Europe for the production of sucrose and has recently been cultivated in Cradock and the surrounding areas (Engineering News, 2008). The biofuel industry usually ferments the sucrose with Saccharomyces cerevisiae to yield bio-ethanol. However, researchers are presented with a critical role to increase current yields as there are concerns over the process costs from industrial biotechnologists. The beet factories produce a pulp by-product removed of all sucrose. The hemicellulose-rich pulp can be degraded by microbial enzymes to simple sugars that can be subsequently fermented to bio-ethanol. Thus, the pulp represents a potential source for second generation biofuel. The process of utilising microbial hemicellulases requires an initial chemical pre-treatment step to delignify the sugar beet pulp (SBP). An alkaline pre-treatment with ‘slake lime’ (calcium hydroxide) was investigated using a 23 factorial design and the factors examined were: lime load; temperature and time. The analysed results showed the highest release of reducing sugars at the pre-treatment conditions of: 0.4 g lime / g SBP; 40°C and 36 hours. A partial characterisation of the Clostridium cellulovorans hemicellulases was carried out to verify the optimal activity conditions stated in literature. The highest release of reducing sugars was measured at pH 6.5 – 7.0 and at 45°C for arabinofuranosidase A (ArfA); at pH 5.5 and 40°C for mannanase A (ManA) and pH 5.0 – 6.0 and 45°C for xylanase A (XynA). Temperature studies showed that a complete loss of enzymatic activity occurred after 11 hours for ManA; and 84-96 hours for ArfA. XynA was still active after 120 hours. The optimised lime pre-treated SBP was subsequently degraded using various combinations and percentages of C. cellulovorans ArfA, ManA and XynA to determine the maximal release of reducing sugars. Synergistically, the highest synergy was observed at 75% ArfA and 25% ManA, with a specific activity of 2.9 μmol/min/g protein. However, the highest release of sugars was observed at 4.2 μmol/min/g protein at 100% ArfA. This study has initiated the research within South Africa on SBP and its degradation by C. cellulovorans. Preliminary studies show that SBP has the potential to be utilised as a second generation biofuel source.
73

Generating guidance on public preferences for the location of wind turbine farms in the Eastern Cape

Hosking, Jessica Lee January 2012 (has links)
There is consensus that Eskom, South Africa’s main energy supplier, needs to expand its energy generating capacity in order to satisfy the growing demand for electricity, but there is less agreement on how it should do this. The existing supply is heavily reliant on thermal generation using coal, but the combustion of fossil fuels for electricity generation may contribute to climate change because it causes harmful greenhouse gases to be emitted into the atmosphere. This emission is something South Africa has committed itself to reducing. One way of achieving this is by the adoption of cleaner technologies for energy generation. One of these technologies is harnessing wind energy. The problem with harnessing wind energy is where to locate the turbines to harness the wind because these turbines ‘industrialise’ the environment in which they are located. They are a source of increased noise, a visual disturbance, cause increased instances of bird and bat mortality and the destruction of flora or the naturalness of the landscape in the areas in which they are located. The residents located near wind farm developments are most negatively affected and bear the greatest cost in this regard. A proper social appraisal of wind turbine projects would have to take this cost into account. Before such developments are approved there should be an assessment made of the impact on the residents, these impacts should be incorporated into the cost-benefit analysis. The negatively affected residents should also be compensated. The objective of this study was not to undertake a cost-benefit analysis of such a wind farm proposal, but to estimate the negative external cost imposed on nearby residents of such an industry, and thereby calculate appropriate compensation to be paid to these residents. Quantifying preferences for proposed, but not-yet developed, wind farms may be done by applying non-market valuation techniques, e.g. through one of the stated preference methodologies, such as a discrete choice experiment. The selected study site for providing guidance was one where Red Cap Investments Pty (Ltd) has proposed the development of a wind farm - in the Kouga local municipality. The basis for drawing conclusions was the analysis of the response samples of two groups of Kouga residents, distinguished by socio economic status; 270 from each group, 540 in total. The methodology applied to analyse the responses was a discrete choice experiment. The questionnaire administered included attitude, knowledge and demographic questions as well as a choice experiment section. The choice experiment section of the questionnaire required that the respondents choose between two different hypothetical onshore wind energy development scenarios and a status quo option. The hypothetical scenarios comprised different levels of wind farm attributes. The attributes included in the experiment were determined by international studies and focus group meetings. These attributes were: distance between the wind turbines and residential area, clustering of the turbines (job opportunities created by the wind farm development for underprivileged respondent group), number of turbines and subsidy allocated to each household. Three different choice experiment models were estimated for each socio-economic group: a conditional logit (CL), nested logit (NL) and a random parameters logit (RPL) model. It was found that, in the affluent respondent group, the simpler CL model provided the best fit. In the underprivileged respondent group, the RPL model, with the number of jobs created by the wind farm project as a random parameter1, explained by the gender of the respondent, provided the best fit. The estimated models identified distance as an important factor in both sampled respondent groups. Both respondent groups preferred that the wind farm be located further away from their residential areas. In addition to distance, the underprivileged respondent group also valued new job opportunities as an important determinant of choice. The affluent respondent group were very sensitive to densely clustered turbines but were almost indifferent between two of the effects coded levels of the clustering attribute “moderately close together” and “widely spaced apart”. Welfare estimates for the significant attributes in each socio-economic group were computed from the best fit models. Table 1 shows the resulting willingness to accept (WTA) compensation measures for distance in both socio-economic respondent groups.
74

Study of biomass combustion characteristics for the development of a catalytic combustor/gasifier

Dody, Joseph W. 10 June 2012 (has links)
The research reported here explored, a "new" approach to biomass energy conversion for small-scale process heat-applications. The conversion process uses close-coupled catalytic. combustion to burn combustibles in effluent generated by primary combustion or gasification of biomass fuels. Computer control of primary and secondary air flow rates allow control of the devices output power while maintaining fuel-lean or stoichiometric conditions in the effluent entering the catalytic combustion zone. The intent of the secondary combustion system is to ensure "clean" exhaust (i.e., promote complete combustion). A small-scale combustor/gasifier was built and instrumented. Characteristics of combustion were studied for three biomass fuels so that primary and secondary air flow control strategies could be devised. A bang-bang type controller was devised for primary air flow control. Secondary air as controlled based on feedback signals from an inexpensive automobile exhaust gas oxygen sensor. The control strategies and catalytic combustion were implemented on prototype combustor/gasifier and the device was tested with good results. Power turn down ratios of 4 to 1 and 3 to 1 were achieved. The zitconia-type automobile exhaust gas oxygen sensors adapted well to the combustion environment of biomass fuel, at least for short periods (long term durability tests were not conducted). The secondary air control system was able to maintain fuel-lean flows for the most part and, the secondary combustion system provided reductions of approximately three fourths in carbon monoxide emissions. / Master of Science
75

An economic evaluation of a bio-fuels industry in South Africa

Schuld, Renier A. 12 1900 (has links)
Thesis (MBA)--Stellenbosch University, 2006. / ENGLISH ABSTRACT: The adoption of the White Paper on the promotion of Renewable Energy and clean fuels in 2003, opened the playing field for participants from other industries than the conventional petroleum, to participate in the fuel industry in South Africa. South Africa is a net importer of crude oil, which accounts for 92% of liquid fuels supply in South Africa. Although the country has significant coal reserves which can supply the country's demand for approximately 200 years, this energy source contributes significantly to CO, emissions. South Africa's participation in the Kyoto Protocol compels it to abide by its commitments to reduce these emissions between 2008 and 2012. The country's dependence on energy to fuel its growing economy, and the infiationary impact that oil imports has had on the country's economy, has prompted government to explore alternative sources of energy to reduce its dependence on fossil fuels and especially importing crude oil. As a result of this, and in an attempt to increase the potential for the successful implementation of ASGISA, government is exploring the feasibility of introducing an E10 fuel blend to the South African petrol blend. In view of th is, government has in it Accelerated and Sustainable Growth Initiative (ASGISA) targeted the development of the bio-fuels industry as an industrial sector that presents opportunities to create opportunities for sustainable growth and development. In view of this, the fiedgling fuel-ethanol industry (which is in its construction phase at the t ime of writing this report), faces lucrative prospects for the agricultural industry, especially maize- and ethanol producers. It is anticipated that the fuel-ethanol industry will create between 8000 and 10000 direct and indirect employment opportunities per plant. This will result in significant investment in rural areas as well. The creation of employment in the rural areas will prevent the large-scale urbanisation that has become a phenomenon in the past decade, as a result of dwindling agricultural industries. The production of ethanol presents the opportunity to earn foreign exchange, especially if the industry embarks on large scale export strategies. In addition to the export market, the local market for ethanol consist of the possible E10 petrol-blend and to supply Eskom with ethanol to fuel its gas turbine electricity generators at Acacia, Port Rex, as well as the anticipated generators at Atlantis and Mossel Bay. This document is a report on the investigation of the economic evaluation of a bio-fuel industry in South Africa. It will explore the current outlook for fossil fuel reserves, supplies and demand, both internationally and locally. It will report on the phenomenon of peak oil production and some opinions thereon . An investigation into the most probable biomass that can be used as feedstock for bio-fuel production will conducted. In this regard, specific investigation into maize, sugar cane (for fuelethanol) and Jatropha eureas (for bio-diesel) will be conducted. The report will explore the most efficient ethanol production processes, for both maize- and sugar-to-ethanol production, with the weight of the document to be attributed to the economic impact that the adoption of the fuel-ethanol programme / AFRIKAANSE OPSOMMING: Die publisering van die Witskrif oor die promosie van hernieubare energiebronne en skoon brandstowwe in 2003, het die speelveld vir deelname aan die brandstof industrie oopgemaak vir rolspelers buiten die konvensionele petroleum maatskappye. Suid-Afrika is 'n netto invoerder van ru-olie en het in 2004 ongeveer 92% van die totale vloeibare brandstowwe ingevoer. Alhoewel die land aansienlike steenkool reserwes het om te voorsien in die aanvraag vir die volgende ongeveer 200 jaar, dra hierdie energiebron aansienlik by tot die koolstofdioksied vrystellings. Suid-Afrika se deelname aan die Kyoto Protokol van 1998, dwing die land om te voldoen aan die ondernemings wat gemaak is om hierdie koolstofdioksied vrystellings te verminder tussen 2008 en 2012. Die land se afhanklikheid van energiebronne om groei te stimuleer, asook die inflasionistiese effek van olie invoere op die ekonomie, het die regering genoop om alternatiewe bronne van energie te ondersoek sodat die afhanklikheid van olie verminder kan word. Uiteenlopend hiervan en om die implementering van ASGISA te stimuleer, ondersoek die regering tans die moontlikheid om 'n E10 petrol vermenging in die petrol formule te spesifiseer. Uit die oogpunt van ASGISA (Accelerated and Sustainable Growth Initiative) van Suid-Afrika, het die regering die ontwikkeling van die bio-brandstowwe industrie geoormerk om geleenthede te skep vir volhoubare ontwikkeling en groei. Met die oog hierop, voorspel die etanol bedryf, wat ten tyde van die skryf van hierdie verslag nog in kontruksie was, winsgewende potensiaal vir die landboubedryf, veral mielie produsente. Dit word verwag dat die etanol bedryf tussen ongeveer 8000 en 10000 direkte en indirekte werksgeleenthede sal skep, veral in die landelike gebiede. Dit sal grotendeels bydra tot die voorkoming van die voortslepende ontvolking van die platteland wat oor die afgelope jare 'n verlammende effek op plattelandse gebiede gehad het. Dit word ook voorsien dat daar aansienlike belegging in die platteland sal plaasvind en al hierdie faktore sal bydra tot die voorkoming van verstedeliking . Die etanol bedryf skep die geleentheid om buitelandse valuta te genereer, veral as die industrie op uitvoere gaan konsentreer. Indien 'n plaaslike mark beoog word , sal die implementering van die E10 vermenging 'n besliste mark skep. 'n Alternatiewe mark wat ondersoek kan word, en wat groot geleentheid skep, is Eskom, wat tans ingevoerde diesel verbruik om hul gas turbine krag opwekkers by Acacia en Port Rex van brandstof te voorsien . Indien die beoogde turbines by Atlantis en Mosselbaai gebou word, sal die mark vir plaaslike etanol verdubbel. Hierdie dokument is 'n verslag oor die ondersoek wat gedoen is na die lewensvatbaarheid van 'n brandstof etanol bedryf in Suid-Afrika. Dit berig oor die huidige uitkyk oor die fossiel brandstof reserwes in die wereld en plaaslik. Dit opper die vraagstuk oor piek olie produksie fenomeen wat uiteenlopende debate ontketen het. Die verslag dek die waarskynlike bronne van biomassa wat aangewend kan word in die produksie van etanol, met spesifieke verwysing na mielies, suikerriet en Jatropha curcas. Die mees effektiewe produksie metodes word verder ondersoek wat van toepassing is op beide mielies en suikerriet. Die mees relevante deeI van die verslag is die ondersoek na die ekonomiese impak wat die industrie op die Suid-Afrikaanse ekonomie mag hê, waarna die nodige gevolgtrekkings en aanbevelings gemaak sal word.
76

Public policy and clean energy venture capital private equity investments in South Africa

Dzenga, Bruce 03 1900 (has links)
Thesis (MDF)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: In 2007, Bürer and Wüstenhagen (2009) conducted a survey amongst European and United States venture capital and private equity investors (VC/PE) to ascertain their public clean energy policy preference and concluded that VC/PE investors view the feed-in tariff (FIT) scheme to be the most preferred policy option. In this research study, the author re-conducted part of the Bürer and Wüstenhagen (2009) survey with thirty South African VC/PE investors to determine their perceptions on clean energy public policy preference. It is evident from the survey, that opinions are varied and at times even contradictory. This in itself demonstrates an important feature of the South African VC/PE and clean energy industry: it is young, dynamic, changing rapidly and can look very different, depending on the vantage point. The investors surveyed were mainly optimistic about the long-term development of the South African renewable energy industry led by private investors. VC/PE investors in South Africa have mixed views on various investment options, and are concerned about both the regulatory and macro-economic trends. The interviews and survey results show a number of recurring issues. Altogether, the survey results indicate that VC/PE investors consider FITs to be the best public clean energy policy instrument in leveraging private investment and finance for renewable energy in South Africa. This study serves to illustrate and confirm, in line with empirical studies, that VC/PE investors in South Africa believe that clean energy market-pull policies provide an impetus and indeed spur private investor participation in clean energy in developing countries. While it is true that most VC/PE investors would prefer the price certainty associated with a FIT regime, this is almost an irrelevant question in South Africa since constitutionally the state is bound to procure through competitive tendering. This study also serves to highlight the need for more active research and attention in this field.
77

Law, regulation, and the promotion of renewable energy in South Africa

Murombo, Tumai January 2016 (has links)
thesis submitted in fulfilment of the requirements for the degree of DOCTOR OF PHILOSOPHY (PhD) in the School of Law at the University of the Witwatersrand / Many countries are under pressure to transition from fossil to renewable sources of energy. This pressure comes from multiple points including sustainable energy and climate change imperatives. The energy industry, especially electricity generation, is the main source of greenhouse gases, hence the significance of reductions in this industry. The purpose of this study was to conduct a legal analysis of the renewable energy law in the context of energy law generally in South Africa, to understand the regulatory function of law in promoting renewable energy. The study analysed government legal and policy positions, and the response by non-state actors to such policy positions and laws. Through a qualitative analysis of primary and secondary sources of law and public participation documents, the study found that; while South Africa is committed to renewable energy, its socio-economic, cultural, and environmental context superimposes other priorities that impede progress towards renewable energy. Several obstacles to renewable energy were identified, some internal to energy law and others external to it, coming from other areas such as environmental law, governance, economics, and behavioural sciences. Analysis at the convergence of environmental and energy law revealed misalignment and fragmentation as major obstacles to renewable energy. While barriers are common across the globe, countries cannot apply the same responses with the same results. Regulatory responses, beyond the traditional ‘command and control’ tools are context specific and tools that have worked, in other countries, may not be as effective in South Africa. Socio-economic dynamics determine the legal responses to the barriers to renewable energy or the efficacy of economic incentives to promote renewable energy. However, overall, law and regulation can, and must, play a crucial enabling role by removing barriers to renewable energy. Nevertheless, there are limits to the use law ‘as regulation.’ Renewables will not replace fossil sources yet; rather in the long-term, renewables should become a big part of the energy mix. Despite gaining price competitiveness, it is too early for renewables to displace conventional fossil sources in a context of entrenched structural and institutional obstacles. Concomitant technical, market, economic, and environmental and resource governance interventions are necessary to effectively promote an energy mix substantially composed of renewables. The study recommends that law should create an enabling regulatory environment for renewable energy. South Africa has not used law effectively enough to create this environment, thereby impeding the integration of renewable energy into its energy mix. Aligning energy and environmental law, among other incentives, can enhance this role of law. Legal reforms are necessary to remove the regulatory advantage afforded to conventional sources of electricity and level the playing field. / MT2017
78

中國能源安全戰略與中美關係 / China's energy security strategy and sino-U.S. relations

鄭雲杰 January 2018 (has links)
University of Macau / Faculty of Social Sciences. / Department of Government and Public Administration
79

Entropic Considerations of Efficiency in the West Texas Intermediate Crude Oil Futures Market

Unknown Date (has links)
For the last fifty years, the efficient market hypothesis has been the central pillar of economic thought and touted by all, despite Sanford Grossman’ and Nobel prize winner Joseph Stiglitz’ objection in 1980. Andrew Lo updated the efficient market hypothesis in 2004 to reconcile irrational human behavior and cold, calculating automatons. This thesis utilizes 33 years of oil futures, GARCH regressions, and the Jensen-Shannon informational criteria to provide extensive empirical objections to informational efficiency. The results demonstrate continuously inefficient oil future markets which exhibit decreased informational efficiency during recessionary periods, advocating the adaptive market hypothesis over the efficient market hypothesis. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection
80

Design of highly distributed biofuel production systems

Luo, Dexin 01 November 2011 (has links)
This thesis develops quantitative methods for evaluation and design of large-scale biofuel production systems with a particular focus on bioreactor-based fuel systems. In Chapter 2, a lifecycle assessment (LCA) method is integrated with chemical process modeling to select from different process designs the one that maximizes the energy efficiency and minimizes the environmental impact of a production system. An algae-based ethanol production technology, which is in the process of commercialization, is used as a case study. Motivated by this case study, Chapter 3 studies the selection of process designs and production capacity of highly distributed bioreactor-based fuel system from an economic perspective. Nonlinear optimization models based on net present value maximization are developed that aim at selecting the optimal capacities of production equipment for both integrated and distributed-centralized process designs on symmetric production layouts. Global sensitivity analysis based on Monte Carlo estimates is performed to show the impact of different parameters on the optimal capacity decision and the corresponding net present value. Conditional Value at Risk optimization is used to compare the optimal capacity for a risk-neutral planner versus a risk-averse decision maker. Chapter 4 studies mobile distributed processing in biofuel industry as vehicle routing problem and production equipment location with an underlying pipeline network as facility location problem with a focus on general production costs. Formulations and algorithms are developed to explore how fixed cost and concavity in the production cost increases the theoretical complexity of these problems.

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