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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.
41

Food secure : Farmers on their modes of production

Heed, Josefin January 2018 (has links)
The thesis explores contradictions that farmers see between current mode of production, and how they imagine that modes of production would need to change if there were no fossil fuels. Based on qualitative interviews with farmers, the aim of the study is to contribute to a discussion on strategies to increase the farms’ capabilities to produce food without fossil fuels. This topic is relevant from both environmental and contingency perspectives. I understand society of today as mainly driven by capitalist logic, meaning that the logics of capital are what most people perceive as the normal and rational way to organize society. The analysis is based on a theoretical framework that sees the dominant energy source as specific and conditional for the historical organization of different societies, focusing on the role of fossil fuels as specific to the current capitalist society. The analytical tools are derived from the concept mode of production, which puts focus on how the farm production is organized in regard to labor, skills, inputs and machines. By using a specific focus on how farmers describe contradictions between the current mode of production of farms and in the case of a sudden lack of fossil fuels, I elucidate features of current food production that are made logical and rational by using fossil fuels, but which seem less logical when there are no fossil fuels. I argue that the threat to food security is not due to the fossil fuel dependency per se, but due to how fossil fuels have and are enabling 1) social relations where the purpose of food is to be a commodity rather than to be nutrition for people, 2) spatial concentrations of refineries, distribution and consumers, 3) social relations with dispossession of means of productions for consumers and concentration of ownership of land for producers, 4) technical relations which drive deskilling of knowledge on how to produce food. For policymaking, this means that exchanging fossil fuels with other energy sources would not necessarily increase food security, as long as the above mentioned mechanisms are reproduced. To increase food security, agricultural policies need to aim at making food more than a commodity and decrease the distance between production and consumption, both in spatial terms but also in terms of knowledge and skills. These strategies are not necessarily compatible with the logics of the capitalist mode of production.
42

Impacts of primary energy constraints in the 21st century

Nel, Willem P. 25 March 2010 (has links)
D.Phil. / Global society has evolved into a complex multi-dimensional system in which it has become increasingly difficult to construct and maintain a systemic model of cause and effect. Specialisation and abstraction in the various disciplines of scientific and societal complexity has led to divergent theories of sustainability. Failure to integrate real life problems across disciplines poses a threat to modern society because the causal links between disciplines are unattended in many instances and events in one dimension could lead to catastrophic unintended consequences in another. In light of the above, this thesis contributes towards the multi-disciplinary integration of some of the most important sustainability concerns of modern society, namely Energy Security, Economic Growth and Global Warming. Analysing these real-life sustainability issues in a multi-disciplinary context leads to conclusions that are controversial in terms of established philosophical worldviews and policy trends. Firstly, the thesis establishes deterministic expectations of an imminent era of declining Energy Security resulting from the exhaustion of non-renewable fossil fuel resources, despite optimistic expectations of technology improvements in alternative energy sources such as renewable and nuclear. Secondly, the exhaustion of non-renewable fossil fuel resources imposes limits to the potential sources of anthropogenic carbon emissions that render the more pessimistic emissions cases considered in the global warming debate irrelevant. The lower level of attainable carbon emissions challenges the merits of the conventional carbon feedback cycle with the result that the predicted global warming is within acceptance limits of the contemporary global warming debate. Thirdly, the consequences of declining Energy Security on socio-economic welfare is a severe divergence from historical trends and demands the reassertion of the role of energy in human development, including Economic Growth theory. The thesis develops a novel economic growth model that treats energy as an explicit and Autonomous Factor of Production, thereby facilitating plausible predictions of future Economic Growth potential. The results challenge the sustainability of the current free-market capitalist economic system and demand strong policy responses to avoid the collapse of modern society.
43

A New Strategy for Climate Change Litigation: Recovering the Rising Costs of Rising Sea Levels

Carrade, Elizabeth Marie 01 January 2018 (has links)
This thesis assesses the promise and potential failures of five tort cases filed in California city and county governments in 2017. The plaintiffs in these cases are suing the fossil fuel industry, claiming that the actions of the industry contributed substantially to global climate change, which is now causing sea level rise in their coastal communities. If these cases are successful, the budget-constrained city and county governments will be provided with funds necessary for climate change adaptation and mitigation measures that will allow residents to continue living in a hotter climate, with higher sea levels. As the effects of global climate change materialize, it is essential that local governments find ways to adapt.
44

Principal component analysis based combustion models

Isaac, Benjamin 12 March 2014 (has links)
Energy generation through combustion of hydrocarbons continues to dominate, as the most common method for energy generation. In the U.S. nearly 84% of the energy consump- tion comes from the combustion of fossil fuels. Because of this demand there is a continued need for improvement, enhancement and understanding of the combustion process. As computational power increases, and our methods for modelling these complex combustion systems improve, combustion modelling has become an important tool in gaining deeper insight and understanding for these complex systems. The constant state of change in computational ability lead to a continual need for new combustion models that can take full advantage of the latest computational resources. To this end, the research presented here encompasses the development of new models, which can be tailored to the available resources, allowing one to increase or decrease the amount of modelling error based on the available computational resources, and desired accuracy. Principal component analysis (PCA) is used to identify the low-dimensional manifolds which exist in turbulent combustion systems. These manifolds are unique in there ability to represent a larger dimensional space with fewer components resulting in a minimal addition of error. PCA is well suited for the problem at hand because of its ability to allow the user to define the amount of error in approximation, depending on the resources at hand. The research presented here looks into various methods which exploit the benefits of PCA in modelling combustion systems, demonstrating several models, and providing new and interesting perspectives for the PCA based approaches to modelling turbulent combustion. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished
45

Mobilizing Microbes: The Path to China’s First Renewable Energy Industry, 1892-1946

Revells, Tristan Edward January 2021 (has links)
China is a leading producer of alternative energy in the present day, while much of its economic rise under the CCP in the late 20th century was driven by the successful development of domestic coal and gas resources in the 1960s and 70s. But the drive to secure autonomous sources of energy to propel economic development and protect national security well predates China’s transition to socialism at midcentury. This dissertation explores the emergence of technocratic state rule in 20th century China by investigating the development of a biofuel industry designed to ensure energy security during war with imperial Japan. During the early to mid-1930s, Chiang Kai-Shek’s KMT government began supporting scientific research on ethanol-based biofuel production as a means of preserving fuel supplies should Japanese forces successfully blockade supply routes into the country during wartime. As exactly this scenario came to pass in the late 1930s, a network of more than 100 private and state-run ethanol plants were constructed along new roadways spanning the country’s southwestern interior. By 1945, millions of gallons a year of ethanol-based “dongli jiujing” fueled the logistical chains of both Chinese and US troops stationed throughout the China theater. The fusion of statecraft and science manifested in the dongli jiujing program both points forward to state-led energy and heavy industrial development in the 1950s and 1960s under Mao’s CCP, and represents one of the top accomplishments of KMT agencies like the National Resources Commission, a powerful technocratic agency which held up the wartime biofuel industry as a paradigmatic example of successful state-led economic development. While scholarship on heavy industry in China often focuses on the latter half of the 20th century, this dissertation demonstrates that by the mid 1930s, the development of the biofuel industry welded political visions for a sovereign, industrially powerful China with the technical expertise of chemists and microbiologists at the National Bureau of Industrial Research (NBIR), a state funded institution for applied science research oriented at developing heavy industries. And it points out that many of the scientists involved in the dongli jiujing program would continue development work in fields like agricultural chemistry and the biochemical industry under the CCP. Engaging with and contributing to recent scholarship on the history of science and technology in Asia, “Mobilizing Microbes” also traces the global circulation of fermentation-related knowledge that informed NBIR attempts to harness microbial life for the industrial production of alcohol. And finally, it explores connections that brought together in unexpected ways the craft knowledge and practices of China’s domestic brewing industry with modernizing visions for a powerful, fully sovereign China propounded by scientists and statesmen as the midpoint of the 20th century drew near.
46

We Are Like Oil: An Ecology of the Venezuelan Culture Boom, 1973-1983

Acosta, Santiago January 2020 (has links)
This dissertation examines the explosion of the cultural field in Venezuela during the 1970s oil boom through the lens of nature-society relations. I argue that cultural production was an agent of state-led ecological transformation and, at the same time, a space where artists and intellectuals negotiated spaces of autonomy that nonetheless were entangled with oil-funded projects of environment-making. By analyzing the cultural politics, visual arts, institutions, and infrastructure projects that blossomed during this era, I seek to uncover the role of cultural and aesthetic forms in processes of rapid urbanization and large-scale resource extraction. In doing so, I situate my work within recent efforts in the environmental humanities aimed at picking apart the cultural narratives that sustain or challenge the power of extractive regimes, particularly in the global South. My chapters analyze the cultural policies that oil-money made possible, the visual art that intersected with energy infrastructure projects, and the photography and film that dealt with the shocks of accelerated development and oil-led globalization. Supported by archival research and close examinations of understudied examples, I focus on the debates and cultural politics that defined the transition from the Instituto National de Cultura y Bellas Artes (Inciba) to the more powerful Centro Nacional de la Cultura (Conac); the role of the kinetic artworks of Carlos Cruz-Diez and Alejandro Otero in urbanization projects and the construction of the Guri hydroelectric dam in South-Eastern Venezuela; the photographic making of Caracas during the 1970s construction boom in the books of Soledad Mendoza and Ramón Paolini; and, finally, the crisis and breakdown of the dream of unlimited wealth in two film pieces by Carlos Oteyza and Antonio Llerandi. While studies about oil and cultural production usually trace the relations between fossil fuels and the formation of modernity in the global North, I contend that a vision from the nature-exporting societies of the global South is fundamental to understand the cultural logics of nature extraction at a planetary scale. Similarly, I propose that the relationship between culture and petroleum will not be clarified by tracking its representations in literary or artistic works, but rather by looking at how often the realm of culture is already intertwined with a global ecology of nature, capital, and power. Finally, in arguing this, I seek to highlight the cultural work of states in the extractive peripheries as an essential object of analysis for the environmental humanities, as well as for a broader rethinking of the uneven ecology of capitalism and the geopolitics of socioecological change.
47

'Investigating the appropriate Renewable Energy Technologies in the Mauritian context'

Khadoo - Jeetah, Pratima Devi January 2011 (has links)
With limited indigenous conventional energy resources, Mauritius imports over 80% of its energy supply from foreign countries, mostly from the Middle East. Developing independent renewable energy resources is thus of priority concern for the Mauritian government. A tropical island surrounded by the Indian Ocean, Mauritius has enormous potential to develop various renewable energies, such as solar energy, biomass energy, wind power, geothermal energy, hydropower, etc. However, owing to the importance of conventional fossil energy in generating remarkably cheap electricity, renewable energy has not yet fully developed in Mauritius, resulting from a lack of market competition. So, in order to reduce the external dependency of fuel, and also to cut down the expenses involved in the imported fuels, the Mauritius Government introduced attractive policies and invited investors of the homeland and abroad to invest in renewable energy technologies. Consequently, numerous promotional and subsidy programs have recently been proclaimed by the Mauritian government, focused on the development of various renewable energies. Thus, the Government of Mauritius has a long-term vision of transforming Mauritius into a sustainable Island. One important element towards the achievement of this vision is to increase the country’s renewable energy usage and thereby reducing dependence on fossil fuels. Democratisation of energy production is determined to be the way forward. A step in this direction is to transfer citizens the ability and motivation to produce electricity via small-scale distributed generation (SSDG), i.e. wind, photovoltaic, Hydropower. As a stepping stone the Government and the Central Electricity Board, with the help of the UNDP, established a grid code in May 2009 which encompasses tariffs and incentive schemes that have in many countries proved essential in order to achieve any substantial development in renewable electricity production based on SSDG.   In line with the government’s vision on renewable energy, the University of Mauritius is working as a partner with DIREKT team to promote renewable energy infrastructure locally. The DIREKT (Small Developing Island Renewable Energy Knowledge and Technology Transfer Network) is a teamwork scheme that involves the participation and collaboration of various universities from Germany, Fiji, Mauritius, Barbados and Trinidad & Tobago.  The aim of the DIREKT project is to reinforce the science and technology competency in the domain of renewable energy through technology transfer, information exchange and networking, targeting ACP (Africa, Caribbean, Pacific) Small Island developing states. This study was therefore initiated to investigate the main renewable energy technologies that stakeholders, institutions as well as businesses and organizations would like to invest in Mauritius based in the attracting incentive schemes provided by the Government.   From the study it was found that the majority of the Organizations, Institutions, Businesses and stakeholders are ready to accept and invest in the solar photovoltaic technology. Moreover, the economic evaluation for the implementation of the photovoltaic technology revealed that within a period of 4.3 years (payback period), the total capital invested can be recovered and after that, the capital generated from the excess electricity produced will contribute to the profit of the organization, Business or Institution.
48

'Investigating the appropriate Renewable Energy Technologies in the Mauritian context'

Khadoo - Jeetah, Pratima Devi January 2011 (has links)
With limited indigenous conventional energy resources, Mauritius imports over 80% of its energy supply from foreign countries, mostly from the Middle East. Developing independent renewable energy resources is thus of priority concern for the Mauritian government. A tropical island surrounded by the Indian Ocean, Mauritius has enormous potential to develop various renewable energies, such as solar energy, biomass energy, wind power, geothermal energy, hydropower, etc. However, owing to the importance of conventional fossil energy in generating remarkably cheap electricity, renewable energy has not yet fully developed in Mauritius, resulting from a lack of market competition. So, in order to reduce the external dependency of fuel, and also to cut down the expenses involved in the imported fuels, the Mauritius Government introduced attractive policies and invited investors of the homeland and abroad to invest in renewable energy technologies. Consequently, numerous promotional and subsidy programs have recently been proclaimed by the Mauritian government, focused on the development of various renewable energies. Thus, the Government of Mauritius has a long-term vision of transforming Mauritius into a sustainable Island. One important element towards the achievement of this vision is to increase the country’s renewable energy usage and thereby reducing dependence on fossil fuels. Democratisation of energy production is determined to be the way forward. A step in this direction is to transfer citizens the ability and motivation to produce electricity via small-scale distributed generation (SSDG), i.e. wind, photovoltaic, Hydropower. As a stepping stone the Government and the Central Electricity Board, with the help of the UNDP, established a grid code in May 2009 which encompasses tariffs and incentive schemes that have in many countries proved essential in order to achieve any substantial development in renewable electricity production based on SSDG.   In line with the government’s vision on renewable energy, the University of Mauritius is working as a partner with DIREKT team to promote renewable energy infrastructure locally. The DIREKT (Small Developing Island Renewable Energy Knowledge and Technology Transfer Network) is a teamwork scheme that involves the participation and collaboration of various universities from Germany, Fiji, Mauritius, Barbados and Trinidad & Tobago.  The aim of the DIREKT project is to reinforce the science and technology competency in the domain of renewable energy through technology transfer, information exchange and networking, targeting ACP (Africa, Caribbean, Pacific) Small Island developing states. This study was therefore initiated to investigate the main renewable energy technologies that stakeholders, institutions as well as businesses and organizations would like to invest in Mauritius based in the attracting incentive schemes provided by the Government.   From the study it was found that the majority of the Organizations, Institutions, Businesses and stakeholders are ready to accept and invest in the solar photovoltaic technology. Moreover, the economic evaluation for the implementation of the photovoltaic technology revealed that within a period of 4.3 years (payback period), the total capital invested can be recovered and after that, the capital generated from the excess electricity produced will contribute to the profit of the organization, Business or Institution.
49

A modified Adams fusion method for the synthesis of binary metal oxide catalysts for the oxygen evolution reaction

Soudens, Franschke A January 2020 (has links)
>Magister Scientiae - MSc / The majority of the global energy is sourced from conventional fossil fuels. The high demand for energy is accelerating along with the depletion of these fossil fuels. Hence, the shift to renewable energy sources and technology becomes indispensable. Hydrogen is considered a promising alternative to fossil fuels. Polymer electrolyte membrane water electrolysers offer an environmentally friendly technique for the production of hydrogen from renewable energy sources. However, the high overpotential and acidic environment at the anode is one of the challenges faced by polymer electrolyte membrane water electrolysers. This harsh environment requires distinct electrocatalysts which currently consist of expensive precious metals such as Ir, Ru and their oxides.
50

Screening the gut of dung beetles and dung beetle larvae for hemi-cellulolytic fungi and enzymes for application in the biofuel industry

Makulana, Livhuwani January 2021 (has links)
Thesis (Ph.D. (Microbiology)) -- University of Limpopo, 2021 / Biofuel production from lignocellulose material is an attractive alternative to fossil fuel. The use of lignocellulose material for biofuel production is imperative because of the numerous advantages that it offers. Biofuel is environmentally friendly and in developing countries such as South Africa, it has the potential to reduce the use of imported fuel and create jobs. Currently, several constraints are affecting the implementation of biofuel. One of the constraints is the cost-effectiveness and the efficiency of the enzymes involved in the enzymatic degradation of lignocellulose polymers to monomers, which can further be fermented to bioethanol. The potential way to reduce enzymatic degradation cost could be by supplementing the fungal enzymes with accessory enzymes such as endo-xylanase. The enzyme production cost is also dependent on the carbon source used. Lignocellulose materials that are regarded as waste must be assed for their use as enzyme inducer carbon sources and as biomass for biofuel production. This is a potential route that will reduce enzyme and biofuel production costs. Biofuel production cost can further be reduced by finding a yeast that can ferment xylose and ferment in the presence of inhibitors released during lignocellulose pretreatment. This study sought to tackle the enzymatic hydrolysis constraints and also search for xylose-fermenting yeast by exploring the gut microbiota of dung beetle. The gut of the dung beetle has recently received great attention since it is proposed to be a bioreactor for lignocellulolytic microorganisms that can be used in biofuel applications. This is because dung beetles feed on the dung of herbivorous animals and the dung is composed of 80% undigested plant material. In this study the guts of four Scarabaeidae dung beetles Kheper nigroanaeus Boheman, Heteronitis castelnaui, Pachylomerus femoralis, Anachalcos convexus and dung beetle larvae, Euoniticellus intermedius were screened for hemicellulolytic fungi and xylose-fermenting yeast. Hundred and thirty-two yeast isolates and two-hundred and twenty-two filamentous fungi were isolated and identified using ITS and D1/D2 regions. The yeast isolates were assigned to 8 genera and 18 species, Trichosporon was the most dominant genus while Candida tropicalis was the most dominant specie. Some of the yeast isolates were identified as uncultured fungi. This yeast must be characterised to be certain if they are novel species. The fungal isolates were assigned to 12 genera and 25 species, Aspergillus was the most dominant genus while Hypocrea lixii was the most dominant specie. The yeast isolated could assimilate xylose and could grow at a maximum temperature of 40 °C. Furthermore, these yeast isolates could also grow in the presence of 3 g/L acetic acid. Most of the fungal isolates had xylanolytic activity. The phylogenetic analysis revealed close genetic relatedness between isolates from the different dung beetle species and dung beetle larvae. The profile of the fungal genera was similar in the different dung beetles. Both guts and the larvae had Aspergillus, Hypocrea, Trichoderma, Talaromyces and Penicillium. The filamentous fungi that showed good xylanolytic activity were further screened for their ability to produce xylanase enzyme using thatch grass as an inductive carbon source. Thatch grass was selected in this study since it is in-house plant-based biomass. Thatch grass is abundantly available in South Africa; it is used for animal grazing but the more it grows it loses its nutritional content. Once it reaches this stage, it is no longer used and most of it is burnt. The fire from burning grass contains higher levels of nitrogen-containing chemicals that pollute the environment. Its compositional analysis (cellulose 46%, hemicellulose 27% and lignin 10%) also attributed to its selection as potential inductive carbon and attractive lignocellulose biomass for biofuel production. The higher xylanase activity of 283.43, 270 and 287.03 nkat/ml were observed from Aspergillus fumigatus L1XYL9 (Euoniticellus intermedius larvae), Hypocrea lixii AB2A3 and Neosartotya sp AB2XYL20 (Anachalcos convexus), respectively. This was achieved when acid pretreated thatch grass was used as an inductive carbon source. Aspergillus fumigatus L1XYL9 (Euoniticellus intermedius larvae), Hypocrea lixii AB2A3 and Neosartotya sp AB2XYL20 (Anachalcos convexus) showed xylanase activity of 393,22, 313,06 and 200 nkat/ml when grown on synthetic xylan. Neosartotya sp AB2XYL20 showed higher xylanase activity on thatch grass. The suitable production process for xylanase enzyme on acid pretreated thatch grass was assessed by conducting a comparative study on solid-state and submerged fermentation using L1XYL9 (Euoniticellus intermedius larvae), Hypocrea lixii AB2A3 and Neosartotya sp AB2XYL20 (Anachalcos convexus) as the best xylanase producer on acid pretreated thatch grass. The strain showed better xylanase activity when submerged fermentation was used. In this study, Hypocrea lixii AB2A3 was selected for further studies since it was the most dominant species and also showed good xylanase activity. Thatch grass was pretreated differently to evaluate the suitable chemical for pretreating thatch grass. Thatch grass was pretreated with dilute sulphuric acid 1.2% and maintained the pH of 5.5 by using sodium hydroxide while another batch was pretreated the same way and was washed with distilled water till pH of 5.5. The other batch was then pretreated with ammonium solution and was also washed with distilled water to maintain a pH of 5.5. The above-mentioned pretreated thatch grass was tested as an inductive carbon source as well as untreated thatch grass. The xylanase activity was determined to assess a good inductive carbon. All the thatch grass pretreated and washed with distilled water showed very low xylanase activity. The untreated thatch grass resulted in lower xylanase activity as compared to xylanase activity achieved when pretreated thatch grass was used. Parameters such as agitation speed and initial inoculum size were also assessed during xylanase production by Hypocrea lixii AB2A3 on acid pretreated thatch grass. Xylanase activity increased from 525 nkat/ml (Inoculum size 2×106 spore/ml and agitation speed 150 rpm) to 584.8 nkat/ml (Inoculum size 2×106 spore/ml and agitation speed 200 rpm). The crude xylanase from Hypocrea lixii AB2A3 was used to hydrolyse acid pretreated thatch grass. This resultant in xylose yield of 138 mg/g of substrate and glucose yield of 49 mg/g of substrate. Crude xylanase was mixed with commercial celluclast™. This enzyme mixture resulted in a xylose yield of 128 mg/g substrate and a glucose yield of 549 mg/g of substrate. The results obtained in this study show that indeed gut of the dung beetles and dung beetle larvae are a rich source of microorganisms that can play an important role in biofuel application and remediating the environment by degrading plant-based biomass regarded as waste into valuable products. It is imperative to evaluate the gut microbiota of dung beetles from different regions in South Africa for their application in the biofuel industry to reinforce its implementation. Thatch grass is a potential inductive carbon and lignocellulose biomass for biofuel production. / NRF (National Research Foundation)

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