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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.
61

Determining the carbon footprint of Sishen South Mine and evaluating the carbon reduction opportunities in the opencast mining environment

Naidoo, Anesan 12 1900 (has links)
Thesis (MBA (Business Management))--University of Stellenbosch, 2009.
62

Carbon disclosure and company performance : a portfolio performance approach

Adam, Shalima 03 1900 (has links)
Thesis (MBA)--Stellenbosch University, 2012. / The objective of this research study was to investigate whether socially responsible companies that disclose their carbon emission, referred to in this research report as ‘carbon disclosure leaders’, outperform their non-disclosing counterparts, referred to in this research report as ‘carbon disclosure laggards’. This research study attempted to substantiate the relationship between companies’ carbon disclosure practices and companies’ share price performance. An empirical analysis was conducted with a focus on South African-listed Johannesburg Stock Exchange (JSE) top-100 companies. A portfolio approach was utilised to establish if any significant relationship exists between company carbon disclosure and company share price performance. Portfolios were constructed based on companies that participated in the Carbon Disclosure Project (CDP) and were thus categorised into JSE industry sectors. It was assumed that by using industry-specific sectors, the macro-economic conditions would generally affect all companies in that specific sector in a similar way, thus enabling comparative analysis. The results from this study subsequently found, having done various analyses in terms of share price growth and carbon disclosure, that no significant correlation exists in terms of the CDP. This would, however, be correct in terms of the analysed data, which is limited at times, but cannot be necessarily inferred as a broader statement. Intuitively, it can be said that carbon disclosure and greater ratings in terms of the CDP would imply that companies are more positive in dealing with their carbon footprint, which would be more positive for their long-term existence and sustainability. Equally, it could also yield various cost savings that will translate into higher earnings and earnings per share that drive share price growth. In becoming more active in reducing the carbon footprint, companies would also reduce their risk profile since they would be better aligned to potential restrictive carbon emission legislation and improve their public profile, which could again boost profitability. Further arguments can be made to suggest that disclosure of a company’s carbon initiatives and footprint would benefit the company’s value and share price performance. Thus, having observed the outcomes of the analyses conducted in this report, the more appropriate question would be if other factors exist that could have affected the outcomes as observed and whether these factors could have overshadowed the proof that there is a positive correlation between share price growth and carbon disclosure.
63

An assessment of carbon emissions reduction potential through zero waste activities in South African municipalities.

Jagath, Rohini. January 2010 (has links)
The inception of global warming has resulted in mitigation efforts across all relevant sectors. Waste management activities produce approximately 12% of methane emissions in South Africa. The current scope of waste management favours sustainable strategies targeting zero waste and waste diversion, however landfill disposal of municipal solid waste (MSW) is still the primary strategy employed by South African municipalities. This study evaluated the greenhouse gas (GHG) impacts of various waste management scenarios that included recycling, composting, anaerobic digestion, and landfill gas recovery through case studies of the eThekwini Municipality (Mariannhill landfill) and uMgungundlovu District Municipality (New England Road landfill) MSW streams. Each waste management strategy was assessed on the basis of GHG emissions, landfill space savings and economic feasibility. A waste stream analysis (WSA) was conducted to obtain both the qualitative and quantitative data required. The results of the WSA determined that the biogenic fraction of the MSW stream for typical South African municipalities varies between 32-40% while the recyclable fraction ranges between 38-44%. The Waste Resource Optimisation Scenario Evaluation (WROSE) model was developed for the quantification of GHG emissions and is based on the US EPA emissions factors for landfill disposal, landfill gas recovery, recycling and composting. An emissions factor was derived to include the GHG impacts of anaerobic digestion using a streamlined life cycle analysis approach. The results confirmed that recycling, anaerobic digestion and composting all produce GHG reductions, in comparison with the baseline scenario of landfill disposal, and a combination thereof through Mechanical Biological Treatment (MBT) produced the greatest net GHG reductions (between -63,338 to -71,522 MTCO2e/annum for the New England Road MSW stream, and -71,280 to -86,123/annum MTCO2e for the Mariannhill MSW stream). The results indicated that the implementation of MBT scenarios would produce landfill space savings of 94,375 to 103,302 m3 for the Mariannhill landfill, extending the landfill lifespan by 12-14 years, while savings of 73,399 – 74,100 m3 could be realised for the New England Road landfill, extending the landfill lifespan by 2-3 years. The study concluded that while the focus of waste management has changed and zero waste/waste diversion goals require alternative waste management methods to be implemented, the capital and operational costs of some technologies are the main barrier for implementation in developing countries, and that the environmental and social benefits should be evaluated further to truly gauge the costs/benefits involved. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.
64

Numerical simulation of CO2 adsorption behaviour of polyaspartamide adsorbent for post-combustion CO2 capture

Yoro, Kelvin Odafe January 2017 (has links)
A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering. 10 February, 2017. / Climate change due to the ever-increasing emission of anthropogenic greenhouse gases arising from the use of fossil fuels for power generation and most industrial processes is now a global challenge. It is therefore imperative to develop strategies or modern technologies that could mitigate the effect of global warming due to the emission of CO2. Carbon capture and storage (CCS) is a viable option that could ensure the sustainable use of cheap fossil fuels for energy generation with less CO2 emission. Amongst existing CCS technologies, absorption technology using monoethanolamine (MEA) is very mature and widely embraced globally. However, the absorption technology has a lot of challenges such as, low CO2 loading, high energy requirement for solvent regeneration, corrosive nature etc. On this note, the adsorption technology using solid sorbents is being considered for CO2 capture due to its competitive advantages such as flexibility, low energy requirement for sorbent regeneration, non-corrosive nature etc. On the other hand, adsorbents have a very vital role to play in adsorption technology and there is need to understand the behaviour of adsorbents for CO2 capture under different operating conditions in order to adapt them for wider applications. On this note, the study contained in this dissertation investigated the adsorption behaviour of a novel polymer-based adsorbent (polyaspartamide) during post-combustion CO2 capture using experimental study and mathematical modelling approach. Polyaspartamide is an amine-rich polymer widely used in drug delivery. In addition, its rich amine content increases its affinity for CO2. Its porosity, thermal stability and large surface area make it a promising material for CO2 capture. In view of this, polyaspartamide was used as the adsorbent for post-combustion CO2 capture in this study. This dissertation investigated the kinetic behaviour, the diffusion mechanism and rate limiting steps (mass transfer limitation) controlling the CO2 adsorption behaviour of this adsorbent. Furthermore, effect of impurities such as moisture and other operating variables such as temperature, pressure, inlet gas flow rate etc. on the CO2 adsorption behaviour of polyaspartamide was also investigated. Existing mathematical models were used to understand the kinetics and diffusion limitation of this adsorbent during CO2 capture. Popularly used gas-solid adsorption models namely; Bohart- Adams and Thomas model were applied in describing the breakthrough curves in order to ascertain the equilibrium concentration and breakthrough time for CO2 to be adsorbed onto polyaspartamide. Lagergren’s pseudo 1st and 2nd order models as well as the Avrami kinetic models were used to describe the kinetic behaviour of polyaspartamide during post-combustion CO2 capture. Parameter estimations needed for the design and optimization of a CO2 adsorption system using polyaspartamide were obtained and presented in this study. The Boyd’s film diffusion model comprising of the interparticle and intra-particle diffusion models were used to investigate the effect of mass transfer limitations during the adsorption of CO2 onto polyaspartamide. Data obtained from continuous CO2 adsorption experiments were used to validate the models in this study. The experiments were conducted using a laboratory-sized packed-bed adsorption column at isothermal conditions. The packed bed was attached to an ABB CO2 analyser (model: ABB-AO2020) where concentrations of CO2 at various operating conditions were obtained. The results obtained in this study show that temperature, pressure and gas flow rate had an effect on the adsorption behaviour of polyaspartamide (PAA) during CO2 capture. Polyaspartamide exhibited a CO2 capture efficiency of 97.62 % at the lowest temperature of 303 K and pressure of 2 bar. The amount of CO2 adsorbed on polyaspartamide increased as the operating pressure increased and a decrease in the adsorption temperature resulted in increased amount of CO2 adsorbed by polyaspartamide. The amounts of CO2 adsorbed on polyaspartamide were 5.9, 4.8 and 4.1 mol CO2/kg adsorbent for adsorption temperatures of 303, 318 and 333 K, respectively. The maximum amount of CO2 adsorbed by polyaspartamide at different flow rates of 1.0, 1.5 and 2.5 ml/s of the feed gas were 7.84, 6.5 and 5.9 mmol CO2/g of adsorbent. This shows that higher flow rates resulted in decreased amount of CO2 adsorbed by polyaspartamide because of low residence time which eventually resulted in poor mass transfer between the adsorbent and adsorbate. Under dry conditions, the adsorption capacity of polyaspartamide was 365.4 mg CO2/g adsorbent and 354.1 mgCO2/g adsorbent under wet conditions. Therefore, the presence of moisture had a negligible effect on the adsorption behaviour of polyaspartamide. This is very common with most amine-rich polymer-based adsorbents. This could be attributed to the fact that CO2 reacts with moisture to form carbonic acid, thereby enhancing the CO2 adsorption capacity of the material. In conclusion, this study confirmed that the adsorption of CO2 onto polyaspartamide is favoured at low temperatures and high operating pressures. The adsorption of CO2 onto polyaspartamide was governed by film diffusion according to the outcome of the Boyd’s film diffusion model. It was also confirmed that intra-particle diffusion was the rate-limiting step controlling the adsorption of CO2 onto polyaspartamide. According to the results from the kinetic study, it can be inferred that lower temperatures had an incremental effect on the kinetic behaviour of polyaspartamide, external mass transfer governed the CO2 adsorption process and the adsorption of CO2 onto polyaspartamide was confirmed to be a physicochemical process (both physisorption and chemisorption). / MT2017
65

A techno-economic and environmental analysis of a novel technology utilizing an internal combustion engine as a compact, inexpensive micro-reformer for a distributed gas-to-liquids system

Browne, Joshua Benjamin January 2016 (has links)
Anthropogenic greenhouse gas emissions (GHG) contribute to global warming, and must be mitigated. With GHG mitigation as an overarching goal, this research aims to study the potential for newfound and abundant sources of natural gas to play a role as part of a GHG mitigation strategy. However, recent work suggests that methane leakage in the current natural gas system may inhibit end-use natural gas as a robust mitigation strategy, but that natural gas as a feedstock for other forms of energy, such as electricity generation or liquid fuels, may support natural-gas based mitigation efforts. Flaring of uneconomic natural gas, or outright loss of natural gas to the atmosphere results in greenhouse gas emissions that could be avoided and which today are very large in aggregate. A central part of this study is to look at a new technology for converting natural gas into methanol at a unit scale that is matched to the size of individual natural gas wells. The goal is to convert stranded or otherwise flared natural gas into a commercially valuable product and thereby avoid any unnecessary emission to the atmosphere. A major part of this study is to contribute to the development of a novel approach for converting natural gas into methanol and to assess the environmental impact (for better or for worse) of this new technology. This Ph.D. research contributes to the development of such a system and provides a comprehensive techno-economic and environmental assessment of this technology. Recognizing the distributed nature of methane leakage associated with the natural gas system, this work is also intended to advance previous research at the Lenfest Center for Sustainable Energy that aims to show that small, modular energy systems can be made economic. This thesis contributes to and analyzes the development of a small-scale gas-to-liquids (GTL) system aimed at addressing flared natural gas from gas and oil wells. This thesis includes system engineering around a design that converts natural gas to synthesis gas (syngas) in a reciprocating internal combustion engine and then converts the syngas into methanol in a small-scale reactor. With methanol as the product, this research aims to show that such a system can not only address current and future natural gas flaring regulation, but eventually can compete economically with historically large-scale, centralized methanol production infrastructure. If successful, such systems could contribute to a shift away from large, multi-billion dollar capital cost chemical plants towards smaller systems with shorter lifetimes that may decrease the time to transition to more sustainable forms of energy and chemical conversion technologies. This research also quantifies the potential for such a system to contribute to mitigating GHG emissions, not only by addressing flared gas in the near-term, but also supporting future natural gas infrastructure ideas that may help to redefine the way the current natural gas pipeline system is used. The introduction of new, small-scale, distributed energy and chemical conversion systems located closer to the point of extraction may contribute to reducing methane leakage throughout the natural gas distribution system by reducing the reliance and risks associated with the aging natural gas pipeline infrastructure. The outcome of this thesis will result in several areas for future work. From an economic perspective, factors that contribute to overall system cost, such as operation and maintenance (O&M) and capital cost multiplier (referred to as the Lang Factor for large-scale petro-chemical plants), are not yet known for novel systems such as the technology presented here. From a technical perspective, commercialization of small-scale, distributed chemical conversion systems may create a demand for economical compression and air-separation technologies at this scale that do not currently exist. Further, new business cases may arise aimed at utilizing small, remote sources of methane, such as biogas from agricultural and municipal waste. Finally, while methanol was selected as the end-product for this thesis, future applications of this technology may consider methane conversion to hydrogen, ammonia, and ethylene for example, challenging the orthodoxy in the chemical industry that “bigger is better.”
66

Ontario feedlot operators' willingness to accept carbon credit revenue for adopting management practices that reduce greenhouse gas emissions

Hristeva, Polina. January 2007 (has links)
No description available.
67

Economic feasibility of anaerobic digestion of swine manure for a grower-to-finisher hog operation in Quebec

Apushev, Nurlan January 2004 (has links)
Swine manure creates much public resentment in Quebec due to nutrient overloading, potential water pollution and odour. Anaerobic digestion is one of the solutions that allows to lessen the odour problem. Anaerobic bacteria in manure produce methane. The latter can be burnt to produce heat and electricity on farms. Moreover, there is a potential for receiving carbon emission reduction credits for the capturing of methane. / Investment analysis was performed to assess the economic feasibility of a potential anaerobic digestion system on a grower-to-finisher hog operation. The study was conducted for a case farm, which had plans to expand from 2000 to 4800 pigs. Greenhouse gas emission reduction credits were incorporated into one of the scenarios. A sensitivity analysis revealed the most important variables which affect the economic feasibility of anaerobic digestion.
68

Quebec hog producers' willingness to accept carbon credit revenue for adopting management practices that reduce greenhouse gas emissions

Guo, Yi, 1977- January 2007 (has links)
Canada's commitment to the Kyoto Protocol provides agricultural producers with an opportunity to supply carbon offset credits to a domestic carbon market and receive revenue from the sale of these credits. This study employed the multiple bounded discrete choice method to estimate Quebec hog producers' willingness to accept compensation to adopt two management practices that reduce carbon emissions; i.e. reduced protein feeding and adopting a manure storage cover. The average willingness to accept compensation for reduced protein feeding was $46.71 per tonne of CO2 equivalent and for the manure storage cover was $40.40 per tonne of CO2 equivalent. In addition, hog producers were asked what cost they would be willing to bear if they received $20 per animal unit in carbon offset credit revenue. The average cost they were willing to bear was $11.88. Key factors that influenced producers' decisions were identified. Results can be used to improve the institutional rules and public policy associated with developing a domestic carbon emission trading mechanism. Starting-point and sequencing bias were tested for with the convolution approach. Starting-point bias was found in all the hypothetical situations; while sequencing bias was not found.
69

The clean development mechanism : a comparison between South Africa and China.

Murray, Ryan Jeremiah Finbarr. January 2012 (has links)
The Clean Development Mechanism (CDM) is the only mechanism available for use by developing nations. It is there for highly important for the inclusion of these developing nations in the climate change regime. A consideration on the early implementation of the CDM in South Africa and China, being two countries with many similarities and differences and vastly different successes, provides important lessons on how to approach the climate change regime. Certain barriers exist purely due to the nature of countries in which the CDM applies as well as other barriers found within the CDM project life cycle and development. Through the comparison these barriers are explored and areas for development within South Africa are noted as well as weakness with the current climate change regime particularly the Kyoto Protocol. / Thesis (LL.M.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.
70

The power generation sector's demand for fossil fuels : a quantitative assessment on the viability of carbon fees for the reduction of greenhouse gas emissions

Seres, Stephen. January 2001 (has links)
The demand for fossil fuels by Ontario's conventional steam power generation sector is examined. It is hypothesised that the enactment of a carbon fee policy will induce a change in the relative prices of the three fuels used in this sector (coal, natural gas and heavy fuel oil). This would lead to substantial interfuel substitution and greenhouse gas abatement. The demand share equations for the three fuels are derived from the translog functional form and set in a simulation model to estimate the value of a carbon fee necessary, to reduce carbon dioxide emissions in compliance with the Kyoto Protocol. Results suggest that a fuel specific carbon fee policy would be successful in achieving the desired emissions reduction at a negligible net cost to society.

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