Studies on the improvement of biogas production from anaerobic digestion of animal wastes
- Authors: Sebola, Mmabyalwa Rebecca
- Date: 2015
- Subjects: Biogas , Sewage - Purification - Anaerobic treatment , Renewable energy sources , Biomass energy
- Language: English
- Type: Master’s Thesis
- Identifier: http://hdl.handle.net/10210/57296 , uj:16377
- Description: Abstract: The unsustainability of intensive reliance on fossil fuels and none-renewable resources as the main sources of energy, frequent rises in energy prices, the need for climate change mitigation and environmental protection have intensified the need for green energy. In this respect, green energy, in the form of biogas, has gained increased attention as a cost effective and environmentally cautious approach. This dissertation presents various studies aimed at improving the biogas production from anaerobic digestion of animal wastes. The experiments were conducted using the batch scale mesophilic tests. Characterisation studies (ultimate and proximate analysis) were conducted to identify key characteristics of the selected feedstocks. In addition, an economic assessment on the feasibility of anaerobic technology was conducted. The waste had average moisture content (MC) ranging from 7 – 34% and 70 – 81% for the dry and wet samples, respectively. The average volatile matter (VM) varied between 44 – 58% with the C/N for CD, CM, PM and SW being 26.20, 8.13, 17.64 and 8.57, respectively. Decreasing the particle size of the feedstock increased the amount of biogas significantly by increasing the total surface area of the material exposed to the anaerobic microbes. At optimal particle size (25μm), methane production was 3 – 30 % higher as compared to that of 100μm and above. Highest methane yields were achieved from CD to CM, PM and SW at ratio of 1:1:1:1. At optimum temperature (40˚C), the highest methane yield (62% CH4/ d) was obtained on Day 6. Adding 50% VS resulted in more methane yields (64% CH4/d) than 30 and 40%. An introduction of 40% recycled liquid and 60% fresh water to the digester gave the best performance, with 73% CH4/d of biogas produced within 5 days. Soaking the feedstock prior digestion improved both the methane and biogas yields and stability of the process. An economic evaluation over a period of 5 years with 8 hours daily operation and a breakeven of 1.5 years was assessed. The proposed model has debt repayments of R 2,478,551 with the total revenue from years 2 – 5 being R 2,360,800, R 2,930,158, R... , M.Tech. (Chemical Engineering)
- Full Text:
- Authors: Sebola, Mmabyalwa Rebecca
- Date: 2015
- Subjects: Biogas , Sewage - Purification - Anaerobic treatment , Renewable energy sources , Biomass energy
- Language: English
- Type: Master’s Thesis
- Identifier: http://hdl.handle.net/10210/57296 , uj:16377
- Description: Abstract: The unsustainability of intensive reliance on fossil fuels and none-renewable resources as the main sources of energy, frequent rises in energy prices, the need for climate change mitigation and environmental protection have intensified the need for green energy. In this respect, green energy, in the form of biogas, has gained increased attention as a cost effective and environmentally cautious approach. This dissertation presents various studies aimed at improving the biogas production from anaerobic digestion of animal wastes. The experiments were conducted using the batch scale mesophilic tests. Characterisation studies (ultimate and proximate analysis) were conducted to identify key characteristics of the selected feedstocks. In addition, an economic assessment on the feasibility of anaerobic technology was conducted. The waste had average moisture content (MC) ranging from 7 – 34% and 70 – 81% for the dry and wet samples, respectively. The average volatile matter (VM) varied between 44 – 58% with the C/N for CD, CM, PM and SW being 26.20, 8.13, 17.64 and 8.57, respectively. Decreasing the particle size of the feedstock increased the amount of biogas significantly by increasing the total surface area of the material exposed to the anaerobic microbes. At optimal particle size (25μm), methane production was 3 – 30 % higher as compared to that of 100μm and above. Highest methane yields were achieved from CD to CM, PM and SW at ratio of 1:1:1:1. At optimum temperature (40˚C), the highest methane yield (62% CH4/ d) was obtained on Day 6. Adding 50% VS resulted in more methane yields (64% CH4/d) than 30 and 40%. An introduction of 40% recycled liquid and 60% fresh water to the digester gave the best performance, with 73% CH4/d of biogas produced within 5 days. Soaking the feedstock prior digestion improved both the methane and biogas yields and stability of the process. An economic evaluation over a period of 5 years with 8 hours daily operation and a breakeven of 1.5 years was assessed. The proposed model has debt repayments of R 2,478,551 with the total revenue from years 2 – 5 being R 2,360,800, R 2,930,158, R... , M.Tech. (Chemical Engineering)
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Performance and emission evaluation of a bi-fuel car
- Authors: Kukoyi, Temitope Oladayo
- Date: 2016
- Subjects: Alternative fuel vehicles , Spark ignition engines - Alternative fuels , Motor fuels , Biogas , Renewable energy sources
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/242306 , uj:24988
- Description: M.Ing. (Mechanical Engineering) , Abstract: A fundamental shift towards alternative sources of energy particularly in the transport sector has led to the use of fuels such as liquefied petroleum gas and natural gas in spark ignition (SI) engines. However, these fuels retain the challenges associated with fossil fuels which are primarily their finite reserves and negative effects on the ecosystem. This study assesses the use of biogas, a renewable and environmentally friendly high octane fuel in the more popular spark ignition powered passenger vehicle using the simplest single-point fuel delivery conversion kit available on the market. The vehicle powered by a 1.5 litre 1UF-ZE spark ignition engine was converted to a bi-fuel vehicle. Torque, power, and transient emissions were measured with a single roller chassis dynamometer and a gas analyser while running on vehicle quality biogas also referred to as biomethane. The data collated from the use of biogas was pitched with that of petrol in the same system to compare performance and tailpipe emissions. The biogas was simulated by mixing 95% methane (CH4) with 5% carbon dioxide (CO2). The experiments also afforded the opportunity to validate biogas similarity with natural gas (CNG) when used to power vehicles. The research further looked into enhancing system efficiency by investigating the addition of a measure of 2% hydrogen to create a biomethane-hydrogen mix (HCBG) which is within allowable limits of the mix used in a conventional spark ignition (SI) system to curb the negative impacts associated with hydrogen use as a fuel in internal combustion engines. The HCBG was derived by mixing 93% CH4 with 5% CO2 and 2% H2. Biogas recorded a reduction of 16% in maximum power and torque values when pitched with petrol while similar maximum power and torque values to that of biogas were derived from the experiments using natural gas to power the same vehicle. When the hydrogen-biomethane mix was utilised, a 1% power drop was noticed. However, slight increments in power and torque values at mid-speed ranges showed promise for higher hydrogen concentrations in the HCBG in fine-tuned systems. With respect to the mass emission of pollutants, the Inspection and Maintenance 240 (IM240) Drive Cycle was employed to determine the carbon dioxide (CO2), carbon monoxide(CO), hydrocarbon (HC), nitrous oxide (NOx) values in grammes per kilometer (g/km). Biogas recorded an 18% CO2 emission reduction compared to the data obtained using petrol (152.2 g/km). With reference to biogas, CNG recorded 0.4 g/km more CO2 mass emissions while the enhanced HCBG...
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- Authors: Kukoyi, Temitope Oladayo
- Date: 2016
- Subjects: Alternative fuel vehicles , Spark ignition engines - Alternative fuels , Motor fuels , Biogas , Renewable energy sources
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/242306 , uj:24988
- Description: M.Ing. (Mechanical Engineering) , Abstract: A fundamental shift towards alternative sources of energy particularly in the transport sector has led to the use of fuels such as liquefied petroleum gas and natural gas in spark ignition (SI) engines. However, these fuels retain the challenges associated with fossil fuels which are primarily their finite reserves and negative effects on the ecosystem. This study assesses the use of biogas, a renewable and environmentally friendly high octane fuel in the more popular spark ignition powered passenger vehicle using the simplest single-point fuel delivery conversion kit available on the market. The vehicle powered by a 1.5 litre 1UF-ZE spark ignition engine was converted to a bi-fuel vehicle. Torque, power, and transient emissions were measured with a single roller chassis dynamometer and a gas analyser while running on vehicle quality biogas also referred to as biomethane. The data collated from the use of biogas was pitched with that of petrol in the same system to compare performance and tailpipe emissions. The biogas was simulated by mixing 95% methane (CH4) with 5% carbon dioxide (CO2). The experiments also afforded the opportunity to validate biogas similarity with natural gas (CNG) when used to power vehicles. The research further looked into enhancing system efficiency by investigating the addition of a measure of 2% hydrogen to create a biomethane-hydrogen mix (HCBG) which is within allowable limits of the mix used in a conventional spark ignition (SI) system to curb the negative impacts associated with hydrogen use as a fuel in internal combustion engines. The HCBG was derived by mixing 93% CH4 with 5% CO2 and 2% H2. Biogas recorded a reduction of 16% in maximum power and torque values when pitched with petrol while similar maximum power and torque values to that of biogas were derived from the experiments using natural gas to power the same vehicle. When the hydrogen-biomethane mix was utilised, a 1% power drop was noticed. However, slight increments in power and torque values at mid-speed ranges showed promise for higher hydrogen concentrations in the HCBG in fine-tuned systems. With respect to the mass emission of pollutants, the Inspection and Maintenance 240 (IM240) Drive Cycle was employed to determine the carbon dioxide (CO2), carbon monoxide(CO), hydrocarbon (HC), nitrous oxide (NOx) values in grammes per kilometer (g/km). Biogas recorded an 18% CO2 emission reduction compared to the data obtained using petrol (152.2 g/km). With reference to biogas, CNG recorded 0.4 g/km more CO2 mass emissions while the enhanced HCBG...
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Modified SEPIC DC-to-DC boost converters with high output-gain configuration for renewable applications
- Authors: Muranda, Charles
- Date: 2018
- Subjects: SPICE (Computer file) , MATLAB , SIMULINK , Renewable energy sources , Electric circuit analysis , Low voltage integrated circuits , Simulation methods , Computer simulation - Software
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/280529 , uj:30145
- Description: Abstract: Renewable energy sourcing has increased popularity these days because of the issues with burning fossil fuels as an energy sources and as a way of combating global gas emission. Thus, renewable energy has become the principal focus of most energy-based researches. Most of the sources energy is however produce electricity with low voltage levels and grid connection requires very high voltage electricity for efficient transmission. This calls for step up converters with very high voltage gains to synchronize the sourced electricity with the grid. Also, the popular boost converters do not have high enough step up voltage gain as their efficiency and effectiveness degrades with increasing switch duty ratio. This research thus introduces a higher voltage gain topologies that can be alternatives to the voltage stepping up problem in renewable energy systems. Three different topologies that are modifications of the SEPIC converter are presented in this research and each of the converters has a different voltage gain of 10, 20 and 29 times the input voltage at 0.9 duty ratio. Theoretical analysis will be used to derive the gain of the converters. Simulations with the Matlab/Simulink and SPICE simulation software’s will be used to verify the theoretical results. Hardware prototypes will be presented to demonstrate the workings of the prototypes. , M.Ing. (Electrical Engineering)
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- Authors: Muranda, Charles
- Date: 2018
- Subjects: SPICE (Computer file) , MATLAB , SIMULINK , Renewable energy sources , Electric circuit analysis , Low voltage integrated circuits , Simulation methods , Computer simulation - Software
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/280529 , uj:30145
- Description: Abstract: Renewable energy sourcing has increased popularity these days because of the issues with burning fossil fuels as an energy sources and as a way of combating global gas emission. Thus, renewable energy has become the principal focus of most energy-based researches. Most of the sources energy is however produce electricity with low voltage levels and grid connection requires very high voltage electricity for efficient transmission. This calls for step up converters with very high voltage gains to synchronize the sourced electricity with the grid. Also, the popular boost converters do not have high enough step up voltage gain as their efficiency and effectiveness degrades with increasing switch duty ratio. This research thus introduces a higher voltage gain topologies that can be alternatives to the voltage stepping up problem in renewable energy systems. Three different topologies that are modifications of the SEPIC converter are presented in this research and each of the converters has a different voltage gain of 10, 20 and 29 times the input voltage at 0.9 duty ratio. Theoretical analysis will be used to derive the gain of the converters. Simulations with the Matlab/Simulink and SPICE simulation software’s will be used to verify the theoretical results. Hardware prototypes will be presented to demonstrate the workings of the prototypes. , M.Ing. (Electrical Engineering)
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The impact of slow uptake of renewable energy in South Africa with emphasis on the solar energy type systems
- Authors: Mncube, Innocent Mduduzi
- Date: 2015
- Subjects: Solar energy , Renewable energy sources
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/56132 , uj:16334
- Description: Abstract: The dissertation examines the slow uptake of renewable energy in South Africa, especially solar type energy systems. It aims to identify and understand the issues and the unique dynamics involved in the local government (municipalities) since they are at the forefront of electricity distribution. The dissertation takes a qualitative research approach and a triangulation of data collection methods, combined with a relatively broad literature study to capture the complexity of the related issues. The contextual focus includes the macro-economic factors that contribute to the environment in which municipalities operate, developmental, economic, political and social aspects and the related experience of poverty, urbanization and unemployment. Furthermore, the dissertation attempts to show that a relationship exists between a slow uptake of renewable energy technologies, particularly solar energy and the loss of electricity sales revenue by municipalities in recent times. Key findings indicate that the electricity sales revenue of municipalities is affected by the introduction of renewable energy technologies. This in turn causes reluctance in promoting such technologies from the decision makers at municipal level, because electricity distribution income is a key contributor to municipal revenue without which municipalities will not be able to meet their constitutional obligations. These findings are supported by the view of this dissertation when comparing electricity sales revenue of metropolitan municipalities over the past five years and also studying municipal legal framework. A variety of related theoretical work is chosen in this dissertation as a useful framework for analysis in order to approach issues of comparing the relationship between depleting municipal electricity sales revenue and the slow uptake of the renewable energy type system with a major focus on solar energy. , M.Ing. (Engineering Electrical and Electronics)
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- Authors: Mncube, Innocent Mduduzi
- Date: 2015
- Subjects: Solar energy , Renewable energy sources
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/56132 , uj:16334
- Description: Abstract: The dissertation examines the slow uptake of renewable energy in South Africa, especially solar type energy systems. It aims to identify and understand the issues and the unique dynamics involved in the local government (municipalities) since they are at the forefront of electricity distribution. The dissertation takes a qualitative research approach and a triangulation of data collection methods, combined with a relatively broad literature study to capture the complexity of the related issues. The contextual focus includes the macro-economic factors that contribute to the environment in which municipalities operate, developmental, economic, political and social aspects and the related experience of poverty, urbanization and unemployment. Furthermore, the dissertation attempts to show that a relationship exists between a slow uptake of renewable energy technologies, particularly solar energy and the loss of electricity sales revenue by municipalities in recent times. Key findings indicate that the electricity sales revenue of municipalities is affected by the introduction of renewable energy technologies. This in turn causes reluctance in promoting such technologies from the decision makers at municipal level, because electricity distribution income is a key contributor to municipal revenue without which municipalities will not be able to meet their constitutional obligations. These findings are supported by the view of this dissertation when comparing electricity sales revenue of metropolitan municipalities over the past five years and also studying municipal legal framework. A variety of related theoretical work is chosen in this dissertation as a useful framework for analysis in order to approach issues of comparing the relationship between depleting municipal electricity sales revenue and the slow uptake of the renewable energy type system with a major focus on solar energy. , M.Ing. (Engineering Electrical and Electronics)
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Torrefaction of landfill food waste and characterization of the torrefied biomass
- Authors: Pahla, Godwell
- Date: 2016
- Subjects: Waste products as fuel , Renewable energy sources - Environmental aspects , Biomass energy , Renewable energy sources
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/243012 , uj:25081
- Description: M.Tech. (Chemical Engineering) , Abstract: Greenhouse gas emissions and municipal solid waste management have presented challenges globally. This study aims to help mitigate these challenges by producing renewable energy from landfill food waste. Food waste is carbon neutral since plants use carbon dioxide for growth, so its application in coal-fired boilers will reduce the amount of carbon dioxide emissions thereby mitigating greenhouse effects. The problem with food waste is that it has high moisture content and it is heterogeneous. This limits its heating value and increases energy requirements for grinding. This study investigated the possibility of upgrading the fuel properties of food waste to produce biochar with similar properties to bituminous coal. The food waste was treated by torrefaction. The main aim was to optimize torrefaction conditions and analyze thermal evolution of the sample during torrefaction. The food waste samples were collected from Marie Louis landfill site in Soweto. The samples were dried and milled for particle size reduction. The samples were further analyzed by proximate and ultimate analyses to determine its fuel properties and elemental composition before torrefaction. A tube furnace was used for the torrefaction process. Temperature was varied from 200 – 300 oC at a constant residence time of 40 min and 10 oC/min heating rate. Calorific value, mass yield, energy yield and energy density were computed and used to determine the appropriate torrefaction temperature. Residence time was then varied from 20 – 60 min at a constant torrefaction temperature of 275 oC and 10 oC/min heating rate. Heating rate was then varied keeping residence time at 20min and torrefaction temperature at 275 oC. Torrefaction temperature had a more pronounced effect than residence time and heating rate. The calorific value was upgraded from 19.76 MJ/kg for dried raw food waste to 26.15 MJ/kg for torrefied food waste at the optimum conditions which were 275 oC, 20 min and 10 oC/min. The higher heating value was comparable to that of bituminous coal currently being used for power generation in South Africa. Elemental analysis of biochar showed an increase in carbon content with temperature due to loss of oxygen containing volatiles. It was also observed that biochar obtained at the optimum conditions could easily be pelletized since it assumed the shape of the crucible...
- Full Text:
- Authors: Pahla, Godwell
- Date: 2016
- Subjects: Waste products as fuel , Renewable energy sources - Environmental aspects , Biomass energy , Renewable energy sources
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/243012 , uj:25081
- Description: M.Tech. (Chemical Engineering) , Abstract: Greenhouse gas emissions and municipal solid waste management have presented challenges globally. This study aims to help mitigate these challenges by producing renewable energy from landfill food waste. Food waste is carbon neutral since plants use carbon dioxide for growth, so its application in coal-fired boilers will reduce the amount of carbon dioxide emissions thereby mitigating greenhouse effects. The problem with food waste is that it has high moisture content and it is heterogeneous. This limits its heating value and increases energy requirements for grinding. This study investigated the possibility of upgrading the fuel properties of food waste to produce biochar with similar properties to bituminous coal. The food waste was treated by torrefaction. The main aim was to optimize torrefaction conditions and analyze thermal evolution of the sample during torrefaction. The food waste samples were collected from Marie Louis landfill site in Soweto. The samples were dried and milled for particle size reduction. The samples were further analyzed by proximate and ultimate analyses to determine its fuel properties and elemental composition before torrefaction. A tube furnace was used for the torrefaction process. Temperature was varied from 200 – 300 oC at a constant residence time of 40 min and 10 oC/min heating rate. Calorific value, mass yield, energy yield and energy density were computed and used to determine the appropriate torrefaction temperature. Residence time was then varied from 20 – 60 min at a constant torrefaction temperature of 275 oC and 10 oC/min heating rate. Heating rate was then varied keeping residence time at 20min and torrefaction temperature at 275 oC. Torrefaction temperature had a more pronounced effect than residence time and heating rate. The calorific value was upgraded from 19.76 MJ/kg for dried raw food waste to 26.15 MJ/kg for torrefied food waste at the optimum conditions which were 275 oC, 20 min and 10 oC/min. The higher heating value was comparable to that of bituminous coal currently being used for power generation in South Africa. Elemental analysis of biochar showed an increase in carbon content with temperature due to loss of oxygen containing volatiles. It was also observed that biochar obtained at the optimum conditions could easily be pelletized since it assumed the shape of the crucible...
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Renewable energy sources microgrid design for rural area in South Africa
- Longe, O. M., Ouahada, K., Ferreira, Hendrik C., Chinnappen, S.
- Authors: Longe, O. M. , Ouahada, K. , Ferreira, Hendrik C. , Chinnappen, S.
- Date: 2014
- Subjects: Microgrids , Renewable energy sources , Umhlabuyalingana Local Municipality
- Type: Article
- Identifier: uj:4798 , http://hdl.handle.net/10210/12052
- Description: Approximately 1.4 billion people around the world lack access to electricity, of which 85% are rural dwellers, mostly living in Sub-Saharan Africa. In South Africa, 55% of rural dwellers lack access to electricity. The Umhlabuyalingana Local Municipality is the least electrified municipality in the country with an electrification rate of 20%. It is therefore taken as a case study, investigating the implementation of a Renewable Energy Sources (RES) microgrid compared to grid extension. HOMER software was the tool used to carry out the simulation, optimization and sensitivity analyses in this research. It was discovered that a Photo Voltaic (PV) with Battery system is the optimal microgrid combination for the proposed microgrid yielding $0.378/kWh cost of electricity, 0 kg/person CO2 emission, 100% renewable penetration compared to $0.328/kWh cost of grid electricity, 8.9 kg/person CO2 emission from grid extension and 0% renewable penetration from the national grid. The microgrid had a standalone breakeven Electric Distance Limit of 34 km less than the 150 km transmission powerline required for Umhlabuyalingana. This microgrid design is proposed as a better solution to electricity access in unelectrified areas of Umhlabuyalingana local municipality than grid extension.
- Full Text: false
- Authors: Longe, O. M. , Ouahada, K. , Ferreira, Hendrik C. , Chinnappen, S.
- Date: 2014
- Subjects: Microgrids , Renewable energy sources , Umhlabuyalingana Local Municipality
- Type: Article
- Identifier: uj:4798 , http://hdl.handle.net/10210/12052
- Description: Approximately 1.4 billion people around the world lack access to electricity, of which 85% are rural dwellers, mostly living in Sub-Saharan Africa. In South Africa, 55% of rural dwellers lack access to electricity. The Umhlabuyalingana Local Municipality is the least electrified municipality in the country with an electrification rate of 20%. It is therefore taken as a case study, investigating the implementation of a Renewable Energy Sources (RES) microgrid compared to grid extension. HOMER software was the tool used to carry out the simulation, optimization and sensitivity analyses in this research. It was discovered that a Photo Voltaic (PV) with Battery system is the optimal microgrid combination for the proposed microgrid yielding $0.378/kWh cost of electricity, 0 kg/person CO2 emission, 100% renewable penetration compared to $0.328/kWh cost of grid electricity, 8.9 kg/person CO2 emission from grid extension and 0% renewable penetration from the national grid. The microgrid had a standalone breakeven Electric Distance Limit of 34 km less than the 150 km transmission powerline required for Umhlabuyalingana. This microgrid design is proposed as a better solution to electricity access in unelectrified areas of Umhlabuyalingana local municipality than grid extension.
- Full Text: false
South Africans’ willingness to pay for renewable and nuclear energy to avoid power outages
- Authors: Nkosi, Nomsa Phindile
- Date: 2016
- Subjects: Electric power failures - South Africa , Electric power failures - Economic aspects , Renewable energy sources , Nuclear energy
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/124244 , uj:20894
- Description: Abstract: At the end of 2007, as electricity demand surpassed supply, South Africa began experiencing widespread blackouts. Given the threat this posed to the national grid, ‘load shedding’ was introduced. Losses due to power outages are often associated with industry and business; but households too are end users of electricity, and their welfare is negatively affected by power outages, the result of increased electricity dependence over the years. South African households – like households in many developing countries – are faced with regular power outages. This is a serious problem, since the outages that households experience are both frequent and long in duration. Despite the efforts of all concerned, South African households will continue to face electricity supply challenges for the foreseeable future. The primary objective of this study is to quantify household’s willingness to pay (WTP) to avoid power outages. The second objective is to estimate households’ WTP for nuclear-generated energy. The third objective is to assess the level of support for renewable energy. In this study, the contingent valuation method (CVM) is used to elicit outage costs, to estimate WTP for South Africa’s proposed second nuclear power plant, and to identify the determinants of support for renewable energy. Face-to-face surveys were undertaken around Gauteng province, as well as in areas in close proximity to the proposed Thyspunt nuclear power plant in the Eastern Cape province. The surveys were conducted using electronic equipment (devices, or tablets) rather than the orthodox paper method. This analysis of power outages caters for different outage situations, including planned and unplanned outages, summer and winter outages, peak and off-peak outages, and weekday and weekend outages. Models used to assess the determinants of WTP to avoid power outages were the random parameter Tobit model, the standard Tobit model, and the Spike model, consisting of a probit model followed by a truncated regression model. With a few exceptions, all the outage scenarios’ estimated parameters are significant at the one percent level, except for the off-peak scenario. The coefficients of all the slopes are positive, meaning that on average, costs are higher for planned outages, during winter, during peak times, and on weekdays. Moreover, WTP increases with duration, which was expected. Overall, WTP is driven mainly by duration of power outage, and by seasonality... , M.Com. (Economics)
- Full Text:
- Authors: Nkosi, Nomsa Phindile
- Date: 2016
- Subjects: Electric power failures - South Africa , Electric power failures - Economic aspects , Renewable energy sources , Nuclear energy
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/124244 , uj:20894
- Description: Abstract: At the end of 2007, as electricity demand surpassed supply, South Africa began experiencing widespread blackouts. Given the threat this posed to the national grid, ‘load shedding’ was introduced. Losses due to power outages are often associated with industry and business; but households too are end users of electricity, and their welfare is negatively affected by power outages, the result of increased electricity dependence over the years. South African households – like households in many developing countries – are faced with regular power outages. This is a serious problem, since the outages that households experience are both frequent and long in duration. Despite the efforts of all concerned, South African households will continue to face electricity supply challenges for the foreseeable future. The primary objective of this study is to quantify household’s willingness to pay (WTP) to avoid power outages. The second objective is to estimate households’ WTP for nuclear-generated energy. The third objective is to assess the level of support for renewable energy. In this study, the contingent valuation method (CVM) is used to elicit outage costs, to estimate WTP for South Africa’s proposed second nuclear power plant, and to identify the determinants of support for renewable energy. Face-to-face surveys were undertaken around Gauteng province, as well as in areas in close proximity to the proposed Thyspunt nuclear power plant in the Eastern Cape province. The surveys were conducted using electronic equipment (devices, or tablets) rather than the orthodox paper method. This analysis of power outages caters for different outage situations, including planned and unplanned outages, summer and winter outages, peak and off-peak outages, and weekday and weekend outages. Models used to assess the determinants of WTP to avoid power outages were the random parameter Tobit model, the standard Tobit model, and the Spike model, consisting of a probit model followed by a truncated regression model. With a few exceptions, all the outage scenarios’ estimated parameters are significant at the one percent level, except for the off-peak scenario. The coefficients of all the slopes are positive, meaning that on average, costs are higher for planned outages, during winter, during peak times, and on weekdays. Moreover, WTP increases with duration, which was expected. Overall, WTP is driven mainly by duration of power outage, and by seasonality... , M.Com. (Economics)
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High output gain modified DC-DC Cuk converters for renewable energy applications
- Authors: Adepoju, Webster Oluwafemi
- Date: 2017
- Subjects: DC-to-DC converters , Distributed generation of electric power , Renewable energy sources
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/280173 , uj:30101
- Description: M.Ing. (Electrical Engineering) , Abstract: Renewable energy application has become a focal point of most researches in recent times. This is motivated by the need to achieve an eco-friendly atmosphere and to mitigate the environmental hazards such as global warming and climate change which are drawbacks of conventional energy generation. High power application is equally on fast rising demands especially for industrial use making conventional DC-DC converters less applicable. Three High gain Modified DC-DC Cuk converters were proposed in this thesis. Voltage Lift Technique (VLT) is used to increase the voltage gain of the proposed converter. The converters produced amplified versions of the supply voltage by the inclusion of passive components and switch capacitor network. In perspective view, by a simple addition of diodes, capacitors and inductor to the classical Cuk circuit, the first, second and third proposed high gain modified Cuk circuits generated voltage gain of 10, 20 and 29 respectively when the switching gate is driven at 90% duty ratio. MATLAB/Simulink and Lt-spice simulations validate the numerical analysis and prototype results for different values of the duty ratio.
- Full Text:
- Authors: Adepoju, Webster Oluwafemi
- Date: 2017
- Subjects: DC-to-DC converters , Distributed generation of electric power , Renewable energy sources
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/280173 , uj:30101
- Description: M.Ing. (Electrical Engineering) , Abstract: Renewable energy application has become a focal point of most researches in recent times. This is motivated by the need to achieve an eco-friendly atmosphere and to mitigate the environmental hazards such as global warming and climate change which are drawbacks of conventional energy generation. High power application is equally on fast rising demands especially for industrial use making conventional DC-DC converters less applicable. Three High gain Modified DC-DC Cuk converters were proposed in this thesis. Voltage Lift Technique (VLT) is used to increase the voltage gain of the proposed converter. The converters produced amplified versions of the supply voltage by the inclusion of passive components and switch capacitor network. In perspective view, by a simple addition of diodes, capacitors and inductor to the classical Cuk circuit, the first, second and third proposed high gain modified Cuk circuits generated voltage gain of 10, 20 and 29 respectively when the switching gate is driven at 90% duty ratio. MATLAB/Simulink and Lt-spice simulations validate the numerical analysis and prototype results for different values of the duty ratio.
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Selection and coordination of surge arresters for switching transient mitigation in photovoltaic power plants
- Oliveira, R., Bokoro, P., Paul, B., Ndlovu, E.
- Authors: Oliveira, R. , Bokoro, P. , Paul, B. , Ndlovu, E.
- Date: 2017
- Subjects: Renewable energy sources , Photovoltaic power plants , Surge arresters
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/221807 , uj:22243 , Citation: Oliveira, R. et al. 2017. Selection and coordination of surge arresters for switching transient mitigation in photovoltaic power plants.
- Description: Abstract: Photovoltaic energy generation has become a popular renewable alternative to conventional energy generation that utilise fossil fuels. However, given the diversity and complexity of these PV plants, it is imperative that such plant equipment be protected against the greatest contributor to equipment failure; surges. Software simulation using EMTP-RV version 3.3, this paper implements a proposed methodology for the insulation coordination study of a PV plant. The overvoltages associated with the opening of vacuum circuit breakers, at various test points along the network are considered in order to recommend possible selection criteria of surge arresters as well as location thereof. The study finds that for a reduction of surge magnitudes from 8 p.u to within 1.2 p.u would require surge arrester energy capabilities to be greater than 2.8 kJ/kV for the medium voltage (MV) arresters , and capabilities exceeding 259kJ/kV for the low voltage (LV) arrester. For the high voltage (HV) section of the plant, no surge propagation was identified thus exempting it from the insulation coordination. The above mentioned, along with surge current and overvoltage levels comprise the findings of the study providing parameter guidelines for arrester selection.
- Full Text:
- Authors: Oliveira, R. , Bokoro, P. , Paul, B. , Ndlovu, E.
- Date: 2017
- Subjects: Renewable energy sources , Photovoltaic power plants , Surge arresters
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/221807 , uj:22243 , Citation: Oliveira, R. et al. 2017. Selection and coordination of surge arresters for switching transient mitigation in photovoltaic power plants.
- Description: Abstract: Photovoltaic energy generation has become a popular renewable alternative to conventional energy generation that utilise fossil fuels. However, given the diversity and complexity of these PV plants, it is imperative that such plant equipment be protected against the greatest contributor to equipment failure; surges. Software simulation using EMTP-RV version 3.3, this paper implements a proposed methodology for the insulation coordination study of a PV plant. The overvoltages associated with the opening of vacuum circuit breakers, at various test points along the network are considered in order to recommend possible selection criteria of surge arresters as well as location thereof. The study finds that for a reduction of surge magnitudes from 8 p.u to within 1.2 p.u would require surge arrester energy capabilities to be greater than 2.8 kJ/kV for the medium voltage (MV) arresters , and capabilities exceeding 259kJ/kV for the low voltage (LV) arrester. For the high voltage (HV) section of the plant, no surge propagation was identified thus exempting it from the insulation coordination. The above mentioned, along with surge current and overvoltage levels comprise the findings of the study providing parameter guidelines for arrester selection.
- Full Text:
Dynamic model and control of power converters for grid connected renewable energy systems
- Nnachi, A. F., Nicolae, Dan-Valentin, Jimoh, A. A.
- Authors: Nnachi, A. F. , Nicolae, Dan-Valentin , Jimoh, A. A.
- Date: 2008
- Subjects: Electric current converters , Renewable energy sources
- Language: English
- Type: Conference procedings
- Identifier: http://hdl.handle.net/10210/20449 , uj:16099 , Citation: Nnachi, A.F., Nicolae, D.V. & Jimoh, A.A. 2008. Dynamic model and control of power converters for grid connected renewable energy systems. Proceedings of the Second IASTED Africa Conference Power and Energy Sysyems (Africa PES 2008), 8-10 September, 2008, Gaborone, Botswana.
- Description: Abstract: In order to investigate certain dynamic events of a grid connected renewable energy system (RES), a systematic model and control is developed. The RES with its converter is taken as a controlled dc current source and the grid side converter model is based on approximate power balance of the dc-link and the ac-side. Here an AC-side decoupled current controller in dq reference frame and simplified net dc-bus voltage controllers are implied. Among different dynamic events that is studied, the response of the system during three-phase to ground fault, step change in reference DC voltage, active and reactive power change are studied and presented.
- Full Text:
- Authors: Nnachi, A. F. , Nicolae, Dan-Valentin , Jimoh, A. A.
- Date: 2008
- Subjects: Electric current converters , Renewable energy sources
- Language: English
- Type: Conference procedings
- Identifier: http://hdl.handle.net/10210/20449 , uj:16099 , Citation: Nnachi, A.F., Nicolae, D.V. & Jimoh, A.A. 2008. Dynamic model and control of power converters for grid connected renewable energy systems. Proceedings of the Second IASTED Africa Conference Power and Energy Sysyems (Africa PES 2008), 8-10 September, 2008, Gaborone, Botswana.
- Description: Abstract: In order to investigate certain dynamic events of a grid connected renewable energy system (RES), a systematic model and control is developed. The RES with its converter is taken as a controlled dc current source and the grid side converter model is based on approximate power balance of the dc-link and the ac-side. Here an AC-side decoupled current controller in dq reference frame and simplified net dc-bus voltage controllers are implied. Among different dynamic events that is studied, the response of the system during three-phase to ground fault, step change in reference DC voltage, active and reactive power change are studied and presented.
- Full Text:
Mathematical modelling for biogas production
- Authors: Matheri, Anthony Njuguna
- Date: 2016
- Subjects: Sewage - Purification - Anaerobic treatment , Sewage - Purification - Mathematical models , Renewable energy sources , Biomass energy , Biogas
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/213006 , uj:21066
- Description: Abstract: The main focus of this dissertation is the experimental, modelling and simulation of anaerobic digestion processes from pilot bio-digesters. For this purpose, biochemical kinetic models were utilized together with corresponding simulation software; DYNOCHEM. By application of the anaerobic digestion (AD), different parameters have been investigated and simulated including adjustments of the process model and corresponding modifications. To validate the process model, the modelled data was compared with experimental monitored laboratory results. Bio-chemical kinetics modelling was applied as a systematic tool in order to support the process design and optimization of a demonstration of the biogas processes which constitutes the main scientific framework and background of this dissertation. Monitored laboratory-scale biogas production data were used for parameter calibration in order to predict plant performance. The calibration focused on the influent characterization of both substrates and on selection of kinetic of the coefficients in order to generate a uniform set of parameters which are applicable for the simulation of codigestion. In this study, it was observed that the experiment work under laboratory scale using conventional bio-methane potential (BMP) analyzers under mesophilic optimum temperature of 35 oC and 37 oC, and pH of 7 for co-digestion of organic fraction of municipal solid waste (OFMSW) with cow dung and manure with grass clippings. The substrate characterization moisture content ranged from 60-95%, volatile content 55-95%, total solid 10-90% and carbon to nitrogen ratio 16-20 for manure and 5-15 for OFMSW. All trace elements concentration were below the threshold of 32 mg/l that leads to inhibition of micro-organisms activity. The rate of conversion increased with retention time. According to the findings, 54-62% of methane composition was evaluated. The kinetics constant evaluated ranged from 0.009-0.35 d-1 and coefficient of determination (R2) ranged from 0.9989-0.9998. The Michaelis-Menten and Monod models provided goodness of fit of 0.9997 with confidential level of 95%. The simulations confirmed that the rate of conversion increased as temperature increases and conversion of reactants increased with retention time, until an equilibrium state was reached. The AD process modelling using DYNOCHEM was successfully modified and implemented to account for unsteady operation which is generally the case of full-scale reactor by developed methodology. , M.Tech. (Chemical Engineering)
- Full Text:
- Authors: Matheri, Anthony Njuguna
- Date: 2016
- Subjects: Sewage - Purification - Anaerobic treatment , Sewage - Purification - Mathematical models , Renewable energy sources , Biomass energy , Biogas
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/213006 , uj:21066
- Description: Abstract: The main focus of this dissertation is the experimental, modelling and simulation of anaerobic digestion processes from pilot bio-digesters. For this purpose, biochemical kinetic models were utilized together with corresponding simulation software; DYNOCHEM. By application of the anaerobic digestion (AD), different parameters have been investigated and simulated including adjustments of the process model and corresponding modifications. To validate the process model, the modelled data was compared with experimental monitored laboratory results. Bio-chemical kinetics modelling was applied as a systematic tool in order to support the process design and optimization of a demonstration of the biogas processes which constitutes the main scientific framework and background of this dissertation. Monitored laboratory-scale biogas production data were used for parameter calibration in order to predict plant performance. The calibration focused on the influent characterization of both substrates and on selection of kinetic of the coefficients in order to generate a uniform set of parameters which are applicable for the simulation of codigestion. In this study, it was observed that the experiment work under laboratory scale using conventional bio-methane potential (BMP) analyzers under mesophilic optimum temperature of 35 oC and 37 oC, and pH of 7 for co-digestion of organic fraction of municipal solid waste (OFMSW) with cow dung and manure with grass clippings. The substrate characterization moisture content ranged from 60-95%, volatile content 55-95%, total solid 10-90% and carbon to nitrogen ratio 16-20 for manure and 5-15 for OFMSW. All trace elements concentration were below the threshold of 32 mg/l that leads to inhibition of micro-organisms activity. The rate of conversion increased with retention time. According to the findings, 54-62% of methane composition was evaluated. The kinetics constant evaluated ranged from 0.009-0.35 d-1 and coefficient of determination (R2) ranged from 0.9989-0.9998. The Michaelis-Menten and Monod models provided goodness of fit of 0.9997 with confidential level of 95%. The simulations confirmed that the rate of conversion increased as temperature increases and conversion of reactants increased with retention time, until an equilibrium state was reached. The AD process modelling using DYNOCHEM was successfully modified and implemented to account for unsteady operation which is generally the case of full-scale reactor by developed methodology. , M.Tech. (Chemical Engineering)
- Full Text:
Effect of nutrient addition during anaerobic digestion of potato peels and maize husk
- Ramatsa, Ishmael, Sibiya, Noxolo, Huberts, Roberth
- Authors: Ramatsa, Ishmael , Sibiya, Noxolo , Huberts, Roberth
- Date: 2014
- Subjects: Anaerobic bacteria , Renewable energy sources , Biomass energy , Biogas
- Type: Article
- Identifier: uj:5091 , http://hdl.handle.net/10210/13681
- Description: The composition of the substrate and nutrients addition plays a very significant role during the production of the biogas. For this reason this paper tries to evaluate the effect of nutrients addition during biogas production under anaerobic conditions. Potato peels wastes and maize husk were anaerobically digested in a 5 liter scale reactor at mesophilic conditions (32 o C). The characteristics of the potato peels were and maize husk are presented in Table 1. The results obtained indicated that the addition of the nutrients during anaerobic digestion has an influence on the biogas production, meanwhile methane content in biogas varied from 48 to 64%.
- Full Text:
- Authors: Ramatsa, Ishmael , Sibiya, Noxolo , Huberts, Roberth
- Date: 2014
- Subjects: Anaerobic bacteria , Renewable energy sources , Biomass energy , Biogas
- Type: Article
- Identifier: uj:5091 , http://hdl.handle.net/10210/13681
- Description: The composition of the substrate and nutrients addition plays a very significant role during the production of the biogas. For this reason this paper tries to evaluate the effect of nutrients addition during biogas production under anaerobic conditions. Potato peels wastes and maize husk were anaerobically digested in a 5 liter scale reactor at mesophilic conditions (32 o C). The characteristics of the potato peels were and maize husk are presented in Table 1. The results obtained indicated that the addition of the nutrients during anaerobic digestion has an influence on the biogas production, meanwhile methane content in biogas varied from 48 to 64%.
- Full Text:
Appropriate solar spectrum usage : the novel design of a photovoltaic thermal system
- Elshik, Ebrahim, Bester, Rudolf, Nel, Andre
- Authors: Elshik, Ebrahim , Bester, Rudolf , Nel, Andre
- Date: 2017
- Subjects: Sustainable buildings , Photovoltaic power systems , Renewable energy sources
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/217739 , uj:21677 , Citation: Elshik, E., Bester, R. & Nel, A. 2017. Appropriate solar spectrum usage : the novel design of a photovoltaic thermal system.
- Description: Abstract: The path towards zero energy buildings is fraught with many challenges, the onsite renewable energy production to drive consumer appliances that are not low or zero energy is an important challenge. Therefore, developing the energy production such that the production mode is matched to the usage mode is the simplest manner to improve efficiency. As such, energy consumption for lighting could be significantly reduced by optimizing the building`s design to maximize direct daylight usage, similarly cooking using solar stoves, or water heating using solar geysers eliminates the need for PV cells to generate electricity. The most important energy consumption in most buildings is HVAC (accounting for approximately 40% of a building`s energy consumption) which can be addressed with the use of a solar power absorption chiller. This article introduces the design of a novel solar concentrated photovoltaic thermal (CPVT) system that produces electricity and thermal energy simultaneously from the same surface area. The goal of the proposed system is to provide sufficient heat for an absorption cooling system, water heating as well as to produce electricity in a cost effective way. The CPVT system is designed to operate over a wide spectrum (400nm upward contains around 90% of the incident solar radiation spectrum). In the proposed system, solar irradiation is highly concentrated (to the equivalent intensity of approximately 100 suns) onto a single point, using a dual axis sun tracking concentrator with a Fresnel lens. A filter then separates the infrared (IR) from the visible light (VL) components using an imaging lens (viz. a hot mirror which has approximately a 98% filter efficiency). The IR is then utilized for heating while the VL components power the PV cell. The efficiency of the electricity generation in the PV cell improves when the IR component is removed from the incident solar irradiance. High-temperature high pressure water, at approximately 95-120oC (203–248oF), is generated by the IR and serves as a heat source for the absorption cooling system (lithium bromide water / ammonia-water). The proposed system is expected to deliver electricity at the rate of 0.08 W/cm2 (0.2032 W/in2) of PV cell area, and around 0.04W/cm2 (0.1.016 W/in2) collector area. Given that the ratio of collector area to PV cell area is ±9:1 this allows us to design the relative size to suit the building requirements.
- Full Text:
- Authors: Elshik, Ebrahim , Bester, Rudolf , Nel, Andre
- Date: 2017
- Subjects: Sustainable buildings , Photovoltaic power systems , Renewable energy sources
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/217739 , uj:21677 , Citation: Elshik, E., Bester, R. & Nel, A. 2017. Appropriate solar spectrum usage : the novel design of a photovoltaic thermal system.
- Description: Abstract: The path towards zero energy buildings is fraught with many challenges, the onsite renewable energy production to drive consumer appliances that are not low or zero energy is an important challenge. Therefore, developing the energy production such that the production mode is matched to the usage mode is the simplest manner to improve efficiency. As such, energy consumption for lighting could be significantly reduced by optimizing the building`s design to maximize direct daylight usage, similarly cooking using solar stoves, or water heating using solar geysers eliminates the need for PV cells to generate electricity. The most important energy consumption in most buildings is HVAC (accounting for approximately 40% of a building`s energy consumption) which can be addressed with the use of a solar power absorption chiller. This article introduces the design of a novel solar concentrated photovoltaic thermal (CPVT) system that produces electricity and thermal energy simultaneously from the same surface area. The goal of the proposed system is to provide sufficient heat for an absorption cooling system, water heating as well as to produce electricity in a cost effective way. The CPVT system is designed to operate over a wide spectrum (400nm upward contains around 90% of the incident solar radiation spectrum). In the proposed system, solar irradiation is highly concentrated (to the equivalent intensity of approximately 100 suns) onto a single point, using a dual axis sun tracking concentrator with a Fresnel lens. A filter then separates the infrared (IR) from the visible light (VL) components using an imaging lens (viz. a hot mirror which has approximately a 98% filter efficiency). The IR is then utilized for heating while the VL components power the PV cell. The efficiency of the electricity generation in the PV cell improves when the IR component is removed from the incident solar irradiance. High-temperature high pressure water, at approximately 95-120oC (203–248oF), is generated by the IR and serves as a heat source for the absorption cooling system (lithium bromide water / ammonia-water). The proposed system is expected to deliver electricity at the rate of 0.08 W/cm2 (0.2032 W/in2) of PV cell area, and around 0.04W/cm2 (0.1.016 W/in2) collector area. Given that the ratio of collector area to PV cell area is ±9:1 this allows us to design the relative size to suit the building requirements.
- Full Text:
Managing the design and development of high performance buildings through integrated design
- Authors: Beetge, Willem Gerhardus
- Date: 2016
- Subjects: Sustainable buildings - Design and construction , Sustainable design , Buildings - Energy conservation , Renewable energy sources
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/213042 , uj:21070
- Description: Abstract: The world population has doubled during the past 45 years [9]. This has created a huge increase in the demand for natural resources. Extremely high levels of carbon dioxide emissions have been witnessed during the last decade. Natural resources like plantations, construction aggregate, coal, oil, water, and agriculture land have come under extreme pressure due to the high demand for these and other scarce resources. During the last two to three decades there have been increased efforts to reduce greenhouse gasses, to save and to protect water sources, and to use materials and products sparingly. Phrases like green buildings, sustainable construction and high-performance buildings are being used more widely amongst role players in the construction industry. High-performance buildings also referred to as green buildings or sustainable buildings are designed and developed with the aim of reducing the demand on fossil fuel energy and potable water. The indoor environmental quality, another major aspect of highperformance buildings, ensures that building occupants show signs of being healthier and more productive. To ensure the successful implementation of green building design and development, some important aspects like design implementation strategies, integrated design, building life cycle assessment, and passive design have to be considered. Management of the design and development processes also requires some technical knowledge of sustainability. The main barriers that prevent the implementation of the development of high-performance buildings have to be addressed and removed. The urgent need for developing energy-efficient and waterefficient buildings has to be acknowledged and supported by senior management and executive officers of organisations involved in building development. The development of highperformance buildings is most effectively achieved through a process referred to as integrated design. This process requires the early involvement of all relevant role players. The development of high-performance buildings through the process of integrated design is regarded by a number of experts as two inseparable concepts. It is therefore essential that managers and leaders who are involved in the development of high-performance buildings are equipped with knowledge and skills in the principles of sustainability and integrated design. , M.Ing. (Engineering Management)
- Full Text:
- Authors: Beetge, Willem Gerhardus
- Date: 2016
- Subjects: Sustainable buildings - Design and construction , Sustainable design , Buildings - Energy conservation , Renewable energy sources
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/213042 , uj:21070
- Description: Abstract: The world population has doubled during the past 45 years [9]. This has created a huge increase in the demand for natural resources. Extremely high levels of carbon dioxide emissions have been witnessed during the last decade. Natural resources like plantations, construction aggregate, coal, oil, water, and agriculture land have come under extreme pressure due to the high demand for these and other scarce resources. During the last two to three decades there have been increased efforts to reduce greenhouse gasses, to save and to protect water sources, and to use materials and products sparingly. Phrases like green buildings, sustainable construction and high-performance buildings are being used more widely amongst role players in the construction industry. High-performance buildings also referred to as green buildings or sustainable buildings are designed and developed with the aim of reducing the demand on fossil fuel energy and potable water. The indoor environmental quality, another major aspect of highperformance buildings, ensures that building occupants show signs of being healthier and more productive. To ensure the successful implementation of green building design and development, some important aspects like design implementation strategies, integrated design, building life cycle assessment, and passive design have to be considered. Management of the design and development processes also requires some technical knowledge of sustainability. The main barriers that prevent the implementation of the development of high-performance buildings have to be addressed and removed. The urgent need for developing energy-efficient and waterefficient buildings has to be acknowledged and supported by senior management and executive officers of organisations involved in building development. The development of highperformance buildings is most effectively achieved through a process referred to as integrated design. This process requires the early involvement of all relevant role players. The development of high-performance buildings through the process of integrated design is regarded by a number of experts as two inseparable concepts. It is therefore essential that managers and leaders who are involved in the development of high-performance buildings are equipped with knowledge and skills in the principles of sustainability and integrated design. , M.Ing. (Engineering Management)
- Full Text:
The effect of GHG emission on climate change due to inefficient usage of energy in South African steel foundries
- Authors: Rasmeni, Z.Z. , Pan, Xiaowei
- Date: 2014
- Subjects: Electricity generation , Greenhouse gas emissions , Climate change - South Africa , Energy efficiency - South Africa , Renewable energy sources
- Type: Article
- Identifier: uj:4778 , http://hdl.handle.net/10210/11961
- Description: Mitigation of CO2 emission is the Lessing of CO2 produced that have or could have a serious threat on climate change. South Africa is known to have a coal addiction. This paper attempts to identify the major opportunities for climate change mitigation through foundry energy efficiency. It does so by analysing key areas of carbon and energy efficiency policy in South Africa. The report further considers a number of important areas concerning future carbon and energy efficiency policy development in the country. Electricity generation and renewable energies are clearly discussed with their advantages and dis advantages in the operation of foundry industry; furthermore it highlights the effect of burning of coal on climate change raising regulation such as carbon tax to be proposed to reduce the growth of CO2 emission. Mitigation of CO2 through foundries by using best energy efficiency practices is highlighted as part of assisting in fighting excessive CO2 emission.
- Full Text:
- Authors: Rasmeni, Z.Z. , Pan, Xiaowei
- Date: 2014
- Subjects: Electricity generation , Greenhouse gas emissions , Climate change - South Africa , Energy efficiency - South Africa , Renewable energy sources
- Type: Article
- Identifier: uj:4778 , http://hdl.handle.net/10210/11961
- Description: Mitigation of CO2 emission is the Lessing of CO2 produced that have or could have a serious threat on climate change. South Africa is known to have a coal addiction. This paper attempts to identify the major opportunities for climate change mitigation through foundry energy efficiency. It does so by analysing key areas of carbon and energy efficiency policy in South Africa. The report further considers a number of important areas concerning future carbon and energy efficiency policy development in the country. Electricity generation and renewable energies are clearly discussed with their advantages and dis advantages in the operation of foundry industry; furthermore it highlights the effect of burning of coal on climate change raising regulation such as carbon tax to be proposed to reduce the growth of CO2 emission. Mitigation of CO2 through foundries by using best energy efficiency practices is highlighted as part of assisting in fighting excessive CO2 emission.
- Full Text:
Energy sustainability : Fischer-Tropsch synthesis over mesoporous material supported ruthenium
- Okonye, Leonard Uchejim Odikowu
- Authors: Okonye, Leonard Uchejim Odikowu
- Date: 2018
- Subjects: Fischer-Tropsch process , Renewable energy sources , Ruthenium
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/401528 , uj:33562
- Description: Abstract : Sustainable energy has remained a challenge across the world due to over-dependence on fossil fuels. This has resulted in energy crises in terms of the shortfall in supply, global price instability and continual adjustment of energy policies. The issues of environmental degradation and the quest for a long-term solution to the importation of fossils fuels necessitated the call for relentless engagement and development of sustainable alternative sources of energy that can also serve to bridge the unavoidable gap between demands and supply. Amongst the alternative and sustainable sources of energy generation is the Fischer-Tropsch (FT) synthesis, which could play a very important role, if not to a great extent, an improvement on the efficiency of fossil fuel reserve exploitation and utilisation. The process of Fischer-Tropsch Synthesis (FTS) produce liquid hydrocarbons generated from the synthesis gases (CO, H2), which rely on the potential of carbon monoxide to exchange hydrogen for oxygen when a catalyst is present. The FT process conversion reaction more often than not is heterogeneously catalysed by an active metal phase, dispersed on a support which might contribute to the catalytic activity, and is considered a surface-catalysed polymerization reaction. However, surface scientists have shown that in addition to the actual FT catalysis which generally takes place on the metal surfaces, the nature of the metal/oxide interfaces still plays a role in the reaction. Hence, the need for a suitable and stable support system with active surface sites for proper metal dispersion. This will be suitable for high FTS activity, achieved by the use of nano-sized particles and novel meso-structured materials. The arrival of novel meso-structured materials can facilitate the design of heterogeneous catalysts and promises to have the potential for FT synthesis, because of their tunable porous interconnected networks that have a large surface area (with a pore size of 2 - 50nm) and uniform pore size distribution. This is because of the metal-support interaction in smaller particles that is noticeably stronger compared to larger particles, which could lead to high FTS activity through the use of nano-sized particles, and periodic mesoporous supports... , Ph.D. (Chemistry)
- Full Text:
- Authors: Okonye, Leonard Uchejim Odikowu
- Date: 2018
- Subjects: Fischer-Tropsch process , Renewable energy sources , Ruthenium
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/401528 , uj:33562
- Description: Abstract : Sustainable energy has remained a challenge across the world due to over-dependence on fossil fuels. This has resulted in energy crises in terms of the shortfall in supply, global price instability and continual adjustment of energy policies. The issues of environmental degradation and the quest for a long-term solution to the importation of fossils fuels necessitated the call for relentless engagement and development of sustainable alternative sources of energy that can also serve to bridge the unavoidable gap between demands and supply. Amongst the alternative and sustainable sources of energy generation is the Fischer-Tropsch (FT) synthesis, which could play a very important role, if not to a great extent, an improvement on the efficiency of fossil fuel reserve exploitation and utilisation. The process of Fischer-Tropsch Synthesis (FTS) produce liquid hydrocarbons generated from the synthesis gases (CO, H2), which rely on the potential of carbon monoxide to exchange hydrogen for oxygen when a catalyst is present. The FT process conversion reaction more often than not is heterogeneously catalysed by an active metal phase, dispersed on a support which might contribute to the catalytic activity, and is considered a surface-catalysed polymerization reaction. However, surface scientists have shown that in addition to the actual FT catalysis which generally takes place on the metal surfaces, the nature of the metal/oxide interfaces still plays a role in the reaction. Hence, the need for a suitable and stable support system with active surface sites for proper metal dispersion. This will be suitable for high FTS activity, achieved by the use of nano-sized particles and novel meso-structured materials. The arrival of novel meso-structured materials can facilitate the design of heterogeneous catalysts and promises to have the potential for FT synthesis, because of their tunable porous interconnected networks that have a large surface area (with a pore size of 2 - 50nm) and uniform pore size distribution. This is because of the metal-support interaction in smaller particles that is noticeably stronger compared to larger particles, which could lead to high FTS activity through the use of nano-sized particles, and periodic mesoporous supports... , Ph.D. (Chemistry)
- Full Text:
Maximizing demand response aggregator compensation through optimal RES utilization : aggregation in Johannesburg, South Africa
- Authors: Essiet, Ima O. , Sun, Yanxia
- Date: 2020
- Subjects: Demand response , Day-ahead market , Renewable energy sources
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/415946 , uj:35165 , Citation: Essiet, I.O., Sun, Y. Maximizing demand response aggregator compensation through optimal RES utilization : aggregation in Johannesburg, South Africa. DOI: 10.3390/app10020594
- Description: Abstract: , This paper examines the role of demand response aggregators in minimizing the cost of electricity generation by distribution utilities in a day-ahead electricity market. In this paper, 2500 standard South African homes are considered as end users. Five clusters (and aggregators) are considered with 500 homes in each cluster. Two cases are analysed: (1) Utilization of renewable energy sources (RES) is implemented by the distribution supply operator (DSO), where it meets excess demand for end users during peak hours by purchasing electricity from the renewable sources of the energy market, and (2) Utilization of RES is implemented by end users alone, and it is assumed that every household has one plug-in electric vehicle (PEV). The aggregators then compete with each other for the most cost-effective energy usage profile; the aggregator with the least energy demand wins the bid. In both cases, energy pricing is estimated according to the day-ahead energy market. A typical day during winter in Johannesburg is considered for the simulation using a genetic algorithm (GA). Results obtained demonstrate the effectiveness of demand response aggregators in maximizing the benefits on both sides of the electricity supply chain.
- Full Text:
- Authors: Essiet, Ima O. , Sun, Yanxia
- Date: 2020
- Subjects: Demand response , Day-ahead market , Renewable energy sources
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/415946 , uj:35165 , Citation: Essiet, I.O., Sun, Y. Maximizing demand response aggregator compensation through optimal RES utilization : aggregation in Johannesburg, South Africa. DOI: 10.3390/app10020594
- Description: Abstract: , This paper examines the role of demand response aggregators in minimizing the cost of electricity generation by distribution utilities in a day-ahead electricity market. In this paper, 2500 standard South African homes are considered as end users. Five clusters (and aggregators) are considered with 500 homes in each cluster. Two cases are analysed: (1) Utilization of renewable energy sources (RES) is implemented by the distribution supply operator (DSO), where it meets excess demand for end users during peak hours by purchasing electricity from the renewable sources of the energy market, and (2) Utilization of RES is implemented by end users alone, and it is assumed that every household has one plug-in electric vehicle (PEV). The aggregators then compete with each other for the most cost-effective energy usage profile; the aggregator with the least energy demand wins the bid. In both cases, energy pricing is estimated according to the day-ahead energy market. A typical day during winter in Johannesburg is considered for the simulation using a genetic algorithm (GA). Results obtained demonstrate the effectiveness of demand response aggregators in maximizing the benefits on both sides of the electricity supply chain.
- Full Text:
The role of ecological governance on the success and sustainability of solar energy initiatives
- Authors: Netshiozwi, Edzisani Ellen
- Date: 2019
- Subjects: Energy development , Solar energy industries , Sustainable development , Renewable energy sources , Solar energy - Economic aspects - South Africa - Limpopo
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/410974 , uj:34515
- Description: Abstract: Climate change phenomenon has in recent years made countries to rise together with concerted efforts to deal with its impact on the ecosystem, economy, public health and the socio-economic conditions. The energy sector in South Africa, much as globally, is the highest contributor to climate change because of its high emission levels of Green House Gasses (GHGs) that are mostly contributed by the electricity supply industry. Thus, the majority of climate change causes in South Africa are anthropogenic. Anthropogenic causes of climate change can only be addressed if there are proper strategies to internalise negative externalities of the current growth and development trajectory. In South Africa, where energy generation is dominated by coal burning, it became evident that this problem must be addressed, not as an option but a priority. The country embarked on a number of initiatives which among others include solar energy programmes... , D.Phil. (Development Studies)
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- Authors: Netshiozwi, Edzisani Ellen
- Date: 2019
- Subjects: Energy development , Solar energy industries , Sustainable development , Renewable energy sources , Solar energy - Economic aspects - South Africa - Limpopo
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/410974 , uj:34515
- Description: Abstract: Climate change phenomenon has in recent years made countries to rise together with concerted efforts to deal with its impact on the ecosystem, economy, public health and the socio-economic conditions. The energy sector in South Africa, much as globally, is the highest contributor to climate change because of its high emission levels of Green House Gasses (GHGs) that are mostly contributed by the electricity supply industry. Thus, the majority of climate change causes in South Africa are anthropogenic. Anthropogenic causes of climate change can only be addressed if there are proper strategies to internalise negative externalities of the current growth and development trajectory. In South Africa, where energy generation is dominated by coal burning, it became evident that this problem must be addressed, not as an option but a priority. The country embarked on a number of initiatives which among others include solar energy programmes... , D.Phil. (Development Studies)
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Design of a temperature controllable demand water heater
- Authors: Duff, Craig Andrew
- Date: 2012
- Subjects: Renewable energy sources , Hot-water supply , Solar energy , Heat exchangers
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/256890 , uj:26975
- Description: Abstract: The purpose of this study is to investigate ways to reduce the wastage of electricity and water during domestic hot water applications. Contemporary electric water heaters do not use water and electricity in an efficient manner due to their methods of operation, the placement of the water heater unit away from the point‐of‐use and the lack of direct user‐control. The aim of this study is to consider the feasibility of decentralising water heating to the point‐of‐use by combining a compact heating chamber with the tap, providing scope for the user to be in direct control of the water heating system. This study is necessary in order to support the development of products that improve the efficient use of essential resources, in this case electricity and water. The method used to study the feasibility of user‐controlled decentralised water heating is laboratory‐based experimentation, for which a compact heating chamber and user‐operated controls are designed. This study uses mixed‐methods research to measure both the heating chamber and the user‐control simultaneously. The experimental findings confirm that it is possible to heat flowing water in a compact heating chamber and the user is able to directly control the water heating system. These findings support further research and development of the user‐controlled point‐of‐use water heating concept as a method to save electricity and water. Further research and development should aim to determine to what extent this concept saves water and electricity when compared to existing water heating systems. , M.Tech. (Industrial Design)
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- Authors: Duff, Craig Andrew
- Date: 2012
- Subjects: Renewable energy sources , Hot-water supply , Solar energy , Heat exchangers
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/256890 , uj:26975
- Description: Abstract: The purpose of this study is to investigate ways to reduce the wastage of electricity and water during domestic hot water applications. Contemporary electric water heaters do not use water and electricity in an efficient manner due to their methods of operation, the placement of the water heater unit away from the point‐of‐use and the lack of direct user‐control. The aim of this study is to consider the feasibility of decentralising water heating to the point‐of‐use by combining a compact heating chamber with the tap, providing scope for the user to be in direct control of the water heating system. This study is necessary in order to support the development of products that improve the efficient use of essential resources, in this case electricity and water. The method used to study the feasibility of user‐controlled decentralised water heating is laboratory‐based experimentation, for which a compact heating chamber and user‐operated controls are designed. This study uses mixed‐methods research to measure both the heating chamber and the user‐control simultaneously. The experimental findings confirm that it is possible to heat flowing water in a compact heating chamber and the user is able to directly control the water heating system. These findings support further research and development of the user‐controlled point‐of‐use water heating concept as a method to save electricity and water. Further research and development should aim to determine to what extent this concept saves water and electricity when compared to existing water heating systems. , M.Tech. (Industrial Design)
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Hybrid-renewable energy : a methodology for identifying communities that can benefit from off-grid systems
- Authors: Kekana, Hlologelo Maesela
- Date: 2020
- Subjects: Renewable energy sources
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/452518 , uj:39914
- Description: Abstract: In a world of increasing demand for electrical energy, renewable energy is Africa’s calling-card to come to the forefront of renewable energy generation. Solar energy can be harnessed in different ways; and the technology to increase the energy output efficiency continues to develop daily, growing exponentially towards achieving efficiency levels, which can substantiate its greater use in everyday lives. This study has attempted to model a hybrid-energy power plant that utilises solar PV and wind energy to power the electricity demand of a community in South Africa. The hybrid-energy system operates with the support of a Battery Energy Storage (BES) system, together with a diesel generator, in order to access an energy supply whenever solar or wind energy are not harnessed... , M.Ing. (Mechanical Engineering Science)
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- Authors: Kekana, Hlologelo Maesela
- Date: 2020
- Subjects: Renewable energy sources
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/452518 , uj:39914
- Description: Abstract: In a world of increasing demand for electrical energy, renewable energy is Africa’s calling-card to come to the forefront of renewable energy generation. Solar energy can be harnessed in different ways; and the technology to increase the energy output efficiency continues to develop daily, growing exponentially towards achieving efficiency levels, which can substantiate its greater use in everyday lives. This study has attempted to model a hybrid-energy power plant that utilises solar PV and wind energy to power the electricity demand of a community in South Africa. The hybrid-energy system operates with the support of a Battery Energy Storage (BES) system, together with a diesel generator, in order to access an energy supply whenever solar or wind energy are not harnessed... , M.Ing. (Mechanical Engineering Science)
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