Stellenbosch faces the same challenges that most South African urban areas face: rapid urbanisati... more Stellenbosch faces the same challenges that most South African urban areas face: rapid urbanisation, sluggish economic growth, growing inequalities, unsustainable use of natural resources, deteriorating biodiversity, social problems, unhealthy living, insecure supplies of healthy food, degrading soils, infrastructure backlogs and inadequate urban planning. At the same time, Stellenbosch has tremendous potential. It brings together in one beautiful place extra-ordinary intellectual capacity, social diversity, financial resources, creative potential, high value eco-systems, spiritual energy and some of South Africa’s most vibrant grassroots social movements in its poorest areas.
Turbines are critical components of electricity generating low grade WHR&U (waste heat recove... more Turbines are critical components of electricity generating low grade WHR&U (waste heat recovery and utilisation) systems, and determining the performance of the turbine is crucial to the successful implementation of these systems. In this paper, an experimental waste heat turbine kit – with the turbine rotor later replaced with an in-house designed and manufactured radial inflow turbine rotor – was sourced, assembled and tested in a designed and built test bench, using air as the working fluid. From the obtained test data, the turbine performance characteristics were determined, and plotted as turbine performance maps. The determined performance characteristics for the turbine working with air were then further used to scale the turbine for a refrigerant-123 application, thus predicting its performance for integration into an organic Rankine cycle low grade WHR&U system.
Nowadays, there exist many innovative daylighting technologies which could be used to enhance nat... more Nowadays, there exist many innovative daylighting technologies which could be used to enhance natural illumination for buildings that use more electric light during the day such as schools, industrial buildings. This study describes the passive zenithal light pipe daylighting technology's performance through the scale model method. The yield of passive zenithal light pipe was improved and was achieved by incorporating a light collimator in the light pipe. Through the design and fabrication of the light collimator, illuminance in the classroom has been improved from 178 lux distributed by commercial diffuser to 370 lux (illuminance average from 9 a.m. to 4 p.m. under sunny days from October to December 2013). A range of reflector materials were tested on the interior lining of the collimator for consistent illuminance distribution and it was discovered that rough re-used aluminum cooking foil distributed uniformly and increased illuminance. All data used has been obtained from measurements at a test location in Stellenbosch, South Africa throughout the year.
The Spiky Central Receiver Air Pre-heater (SCRAP) receiver shows good potential as a pressurised ... more The Spiky Central Receiver Air Pre-heater (SCRAP) receiver shows good potential as a pressurised air receiver for a combined cycle (CC). The spike tip is exposed to the highest solar flux which at the same time benefits from high cooling through the impinging jet of cold air. This study focusses on the development and validation of a numerical model that was further to be used to do an initial analysis on the effect of design parameters that can improve the performance. The numerical model is developed and validated using experimental data. This preliminary analysis on the effect of altering different parameters shows that the parameter that has the biggest effect is the nozzle diameter. Reducing nozzle diameters induces excessive pressure drops to the system while increasing the thermal efficiency. A compromise is made between pressure drop and radiation losses to determine an initial estimation of an improved nozzle diameter of 15 mm, but there is more design improvement potential...
ABSTRACT This paper presents a dynamic pricing concept that can be applied to hybrid electric pow... more ABSTRACT This paper presents a dynamic pricing concept that can be applied to hybrid electric power mini-grid systems to enable affordability of energy in these systems setup for the supply of energy to rural consumers. A location was identified in Eastern Uganda, resource assessment done, and a proposed hybrid electric power mini-grid system designed to supply electricity to this rural location. A theoretical deterministic demand profile was generated, and with it different supply configurations of the system were simulated to meet the daily load. The fluctuations in the demand and supply triggered a change in the cost of generating energy, due to the variations in the contributing electricity generating sources. Through communication, an intelligently designed and operated time-varying pricing scheme can be an effective tool for influencing the actions of price-responsive end-users such as rural consumers. A software program was used to simulate the hourly demand, supply, and corresponding cost of energy variations. This pricing model could potentially contribute to the ongoing search for the provision of affordable rural energy services.
SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems
A novel dual pressurised tubular cavity air receiver for solarised Brayton cycle pre-heating had ... more A novel dual pressurised tubular cavity air receiver for solarised Brayton cycle pre-heating had previously been proposed. The preheating receiver needs to obtain 800 °C pressurised air and 540 °C non-pressurised air for integration to be successful with a combined Brayton upstream and Rankine downstream cycle. Preliminary numerical investigations indicated that the non-pressurised air could not obtain the desired outlet temperatures. The ability of external fins to achieve this goal is investigated experimentally and compared to the theory to assess the ability of the theory to predict the thermal response of the two fluid streams. It was found that the theory employed accurate and that the receiver cannot obtain the desired non-pressurised temperatures at meaningful quantities in this design. The receiver demonstrated the ability to regulate the material thermal gradients which can potentially reduce cycling stress to some extent.
Most of the third-world rural areas, especially in sub-Saharan Africa, are still without electric... more Most of the third-world rural areas, especially in sub-Saharan Africa, are still without electricity. The few existing offgrid and upcoming installations are remote and characterized by limited resources that call for drastic conservation measures. For the majority of these emerging consumers, lighting is the priority load. Rural electrical lighting load models are characterized by inaccuracies due to technical omissions, highlighted in this paper, and result in energy wastage. Solutions to the third-world problems need not follow similar paths to those of the developed world. In fact, cutting-edge technologies like the cell phone have already leapfrogged rural communications where expensive infrastructure had been perennially cited as the impediment. In this paper, another futuristic technology, the white light emitting diode (LED), for general lighting, is poised to create yet another revolution in African rural electrification.
This paper presents the design and analysis of an electromechanical flywheel energy storage syste... more This paper presents the design and analysis of an electromechanical flywheel energy storage system to enhance rural electrification in sub-Saharan Africa. The system consists of a flywheel rotor, an electrical machine, control system, bearings, and a containment structure. With the exception of the power electronics and magnets, local materials were used for the manufacture of the flywheel system. The flywheel rotor is made from glass fiberepoxy composite, designed using novel shape profiles and utilizes a stress based solution by introducing a central hole for shaft inclusion. The system was accelerated to 6000 r/min storing up to 227 kJ. Numerical stress analyses were performed during the design stage to ensure that the maximum tensile strength is not exceeded. A lumped parameter thermal model is used to estimate the temperature distribution to ensure safe operating conditions of the flywheel system and environment. A life cycle cost analysis performed found that by integrating a flywheel system into a Solar Home System implies a cost savings of 35% per kilowatthour when compared with lead-acid batteries.
ABSTRACT The challenges faced by the socio-political economy of South Africa when attempting to d... more ABSTRACT The challenges faced by the socio-political economy of South Africa when attempting to diversify away from a legacy of over a century of near exclusive dependence on cheap and abundant coal for its energy needs, particularly electricity, are discussed in this paper. Existing government policy documentation would appear to advocate for energy resource diversification. In addition the National Energy Regulator of South Africa (NERSA) published renewable energy feed-in-tariffs (REFIT) for renewable energy generation (during the first quarter of 2009) which were billed by the media as well as a range of stakeholders as very promising. Notwithstanding these seemingly appropriate measures there is still a near total lack of real progress on the ground in terms of serious renewable energy (RE) investments. The authors subsequently attempt to make some recommendations as to what might have probable chance of success in terms of overcoming the barriers to the adoption of a more diversified energy resource environment, in particular renewable energy (RE).
Turbines are critical components of electricity generating low grade WHR&U (waste heat recovery a... more Turbines are critical components of electricity generating low grade WHR&U (waste heat recovery and utilisation) systems, and determining the performance of the turbine is crucial to the successful implementation of these systems. In this paper, an experimental waste heat turbine kit e with the turbine rotor later replaced with an in-house designed and manufactured radial inflow turbine rotor e was sourced, assembled and tested in a designed and built test bench, using air as the working fluid. From the obtained test data, the turbine performance characteristics were determined, and plotted as turbine performance maps. The determined performance characteristics for the turbine working with air were then further used to scale the turbine for a refrigerant-123 application, thus predicting its performance for integration into an organic Rankine cycle low grade WHR&U system.
Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2015
Electricity theft is the main source of non-technical losses in electricity distribution utilitie... more Electricity theft is the main source of non-technical losses in electricity distribution utilities. This paper presents data from an ongoing research to study the causes of electricity theft in Kampala, Uganda and people's response to the efforts being made to reduce it. Our study reveals that electricity theft in Kampala is largely due to economic reasons and corruption within the utility company. It confirms that people perceive electricity theft as the utility's problem and are not willing to report electric theft suspects. We propose ICT technologies to encourage consumer participation in reducing electricity theft.
ABSTRACT This paper conceptualizes the link between value chain theory and productive use (PU) fo... more ABSTRACT This paper conceptualizes the link between value chain theory and productive use (PU) focused energy projects based on microfinance mechanisms. Its main argument is that all PU of energy projects focusing on micro, small, and medium enterprises (MSME) development can be interpreted as value chain upgrading attempts. It is argued that successful upgrading greatly depends on the MSMEs embeddedness in specific market contexts. For that reason, the context must be assessed to derive energy based intervention points that cause additional income for MSMEs and consequently development. Based on this rationale, a problem-centred value chain approach is proposed. A case study of the Philippine rice market illustrates the usability of the method by outlining some risks and opportunities the rice value chain context poses to energy based upgrading attempts of rice farmers.
2010 IEEE Energy Conversion Congress and Exposition, 2010
Abstract This paper presents the thermal and structural analysis of an electromechanical battery ... more Abstract This paper presents the thermal and structural analysis of an electromechanical battery energy storage system designed to enhance rural electrification in sub-Saharan Africa. The system consists of a flywheel rotor, an electrical machine, bearings and a ...
Nowadays, there exist many innovative daylighting technologies which could be used to enhance nat... more Nowadays, there exist many innovative daylighting technologies which could be used to enhance natural illumination for buildings that use more electric light during the day such as schools, industrial buildings. This study describes the passive zenithal light pipe daylighting technology’s performance through the scale model method. The yield of passive zenithal light pipe was improved and was achieved by incorporating a light collimator in the light pipe. Through the design and fabrication of the light collimator, illuminance in the classroom has been improved from 178 lux distributed by commercial diffuser to 370 lux (illuminance average from 9 a.m. to 4 p.m. under sunny days from October to December 2013). A range of reflector materials were tested on the interior lining of the collimator for consistent illuminance distribution and it was discovered that rough re-used aluminum cooking foil distributed uniformly and increased illuminance. All data used has been obtained from measurements at a test location in Stellenbosch, South Africa throughout the year.
Stellenbosch faces the same challenges that most South African urban areas face: rapid urbanisati... more Stellenbosch faces the same challenges that most South African urban areas face: rapid urbanisation, sluggish economic growth, growing inequalities, unsustainable use of natural resources, deteriorating biodiversity, social problems, unhealthy living, insecure supplies of healthy food, degrading soils, infrastructure backlogs and inadequate urban planning. At the same time, Stellenbosch has tremendous potential. It brings together in one beautiful place extra-ordinary intellectual capacity, social diversity, financial resources, creative potential, high value eco-systems, spiritual energy and some of South Africa’s most vibrant grassroots social movements in its poorest areas.
Turbines are critical components of electricity generating low grade WHR&U (waste heat recove... more Turbines are critical components of electricity generating low grade WHR&U (waste heat recovery and utilisation) systems, and determining the performance of the turbine is crucial to the successful implementation of these systems. In this paper, an experimental waste heat turbine kit – with the turbine rotor later replaced with an in-house designed and manufactured radial inflow turbine rotor – was sourced, assembled and tested in a designed and built test bench, using air as the working fluid. From the obtained test data, the turbine performance characteristics were determined, and plotted as turbine performance maps. The determined performance characteristics for the turbine working with air were then further used to scale the turbine for a refrigerant-123 application, thus predicting its performance for integration into an organic Rankine cycle low grade WHR&U system.
Nowadays, there exist many innovative daylighting technologies which could be used to enhance nat... more Nowadays, there exist many innovative daylighting technologies which could be used to enhance natural illumination for buildings that use more electric light during the day such as schools, industrial buildings. This study describes the passive zenithal light pipe daylighting technology's performance through the scale model method. The yield of passive zenithal light pipe was improved and was achieved by incorporating a light collimator in the light pipe. Through the design and fabrication of the light collimator, illuminance in the classroom has been improved from 178 lux distributed by commercial diffuser to 370 lux (illuminance average from 9 a.m. to 4 p.m. under sunny days from October to December 2013). A range of reflector materials were tested on the interior lining of the collimator for consistent illuminance distribution and it was discovered that rough re-used aluminum cooking foil distributed uniformly and increased illuminance. All data used has been obtained from measurements at a test location in Stellenbosch, South Africa throughout the year.
The Spiky Central Receiver Air Pre-heater (SCRAP) receiver shows good potential as a pressurised ... more The Spiky Central Receiver Air Pre-heater (SCRAP) receiver shows good potential as a pressurised air receiver for a combined cycle (CC). The spike tip is exposed to the highest solar flux which at the same time benefits from high cooling through the impinging jet of cold air. This study focusses on the development and validation of a numerical model that was further to be used to do an initial analysis on the effect of design parameters that can improve the performance. The numerical model is developed and validated using experimental data. This preliminary analysis on the effect of altering different parameters shows that the parameter that has the biggest effect is the nozzle diameter. Reducing nozzle diameters induces excessive pressure drops to the system while increasing the thermal efficiency. A compromise is made between pressure drop and radiation losses to determine an initial estimation of an improved nozzle diameter of 15 mm, but there is more design improvement potential...
ABSTRACT This paper presents a dynamic pricing concept that can be applied to hybrid electric pow... more ABSTRACT This paper presents a dynamic pricing concept that can be applied to hybrid electric power mini-grid systems to enable affordability of energy in these systems setup for the supply of energy to rural consumers. A location was identified in Eastern Uganda, resource assessment done, and a proposed hybrid electric power mini-grid system designed to supply electricity to this rural location. A theoretical deterministic demand profile was generated, and with it different supply configurations of the system were simulated to meet the daily load. The fluctuations in the demand and supply triggered a change in the cost of generating energy, due to the variations in the contributing electricity generating sources. Through communication, an intelligently designed and operated time-varying pricing scheme can be an effective tool for influencing the actions of price-responsive end-users such as rural consumers. A software program was used to simulate the hourly demand, supply, and corresponding cost of energy variations. This pricing model could potentially contribute to the ongoing search for the provision of affordable rural energy services.
SOLARPACES 2018: International Conference on Concentrating Solar Power and Chemical Energy Systems
A novel dual pressurised tubular cavity air receiver for solarised Brayton cycle pre-heating had ... more A novel dual pressurised tubular cavity air receiver for solarised Brayton cycle pre-heating had previously been proposed. The preheating receiver needs to obtain 800 °C pressurised air and 540 °C non-pressurised air for integration to be successful with a combined Brayton upstream and Rankine downstream cycle. Preliminary numerical investigations indicated that the non-pressurised air could not obtain the desired outlet temperatures. The ability of external fins to achieve this goal is investigated experimentally and compared to the theory to assess the ability of the theory to predict the thermal response of the two fluid streams. It was found that the theory employed accurate and that the receiver cannot obtain the desired non-pressurised temperatures at meaningful quantities in this design. The receiver demonstrated the ability to regulate the material thermal gradients which can potentially reduce cycling stress to some extent.
Most of the third-world rural areas, especially in sub-Saharan Africa, are still without electric... more Most of the third-world rural areas, especially in sub-Saharan Africa, are still without electricity. The few existing offgrid and upcoming installations are remote and characterized by limited resources that call for drastic conservation measures. For the majority of these emerging consumers, lighting is the priority load. Rural electrical lighting load models are characterized by inaccuracies due to technical omissions, highlighted in this paper, and result in energy wastage. Solutions to the third-world problems need not follow similar paths to those of the developed world. In fact, cutting-edge technologies like the cell phone have already leapfrogged rural communications where expensive infrastructure had been perennially cited as the impediment. In this paper, another futuristic technology, the white light emitting diode (LED), for general lighting, is poised to create yet another revolution in African rural electrification.
This paper presents the design and analysis of an electromechanical flywheel energy storage syste... more This paper presents the design and analysis of an electromechanical flywheel energy storage system to enhance rural electrification in sub-Saharan Africa. The system consists of a flywheel rotor, an electrical machine, control system, bearings, and a containment structure. With the exception of the power electronics and magnets, local materials were used for the manufacture of the flywheel system. The flywheel rotor is made from glass fiberepoxy composite, designed using novel shape profiles and utilizes a stress based solution by introducing a central hole for shaft inclusion. The system was accelerated to 6000 r/min storing up to 227 kJ. Numerical stress analyses were performed during the design stage to ensure that the maximum tensile strength is not exceeded. A lumped parameter thermal model is used to estimate the temperature distribution to ensure safe operating conditions of the flywheel system and environment. A life cycle cost analysis performed found that by integrating a flywheel system into a Solar Home System implies a cost savings of 35% per kilowatthour when compared with lead-acid batteries.
ABSTRACT The challenges faced by the socio-political economy of South Africa when attempting to d... more ABSTRACT The challenges faced by the socio-political economy of South Africa when attempting to diversify away from a legacy of over a century of near exclusive dependence on cheap and abundant coal for its energy needs, particularly electricity, are discussed in this paper. Existing government policy documentation would appear to advocate for energy resource diversification. In addition the National Energy Regulator of South Africa (NERSA) published renewable energy feed-in-tariffs (REFIT) for renewable energy generation (during the first quarter of 2009) which were billed by the media as well as a range of stakeholders as very promising. Notwithstanding these seemingly appropriate measures there is still a near total lack of real progress on the ground in terms of serious renewable energy (RE) investments. The authors subsequently attempt to make some recommendations as to what might have probable chance of success in terms of overcoming the barriers to the adoption of a more diversified energy resource environment, in particular renewable energy (RE).
Turbines are critical components of electricity generating low grade WHR&U (waste heat recovery a... more Turbines are critical components of electricity generating low grade WHR&U (waste heat recovery and utilisation) systems, and determining the performance of the turbine is crucial to the successful implementation of these systems. In this paper, an experimental waste heat turbine kit e with the turbine rotor later replaced with an in-house designed and manufactured radial inflow turbine rotor e was sourced, assembled and tested in a designed and built test bench, using air as the working fluid. From the obtained test data, the turbine performance characteristics were determined, and plotted as turbine performance maps. The determined performance characteristics for the turbine working with air were then further used to scale the turbine for a refrigerant-123 application, thus predicting its performance for integration into an organic Rankine cycle low grade WHR&U system.
Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2015
Electricity theft is the main source of non-technical losses in electricity distribution utilitie... more Electricity theft is the main source of non-technical losses in electricity distribution utilities. This paper presents data from an ongoing research to study the causes of electricity theft in Kampala, Uganda and people's response to the efforts being made to reduce it. Our study reveals that electricity theft in Kampala is largely due to economic reasons and corruption within the utility company. It confirms that people perceive electricity theft as the utility's problem and are not willing to report electric theft suspects. We propose ICT technologies to encourage consumer participation in reducing electricity theft.
ABSTRACT This paper conceptualizes the link between value chain theory and productive use (PU) fo... more ABSTRACT This paper conceptualizes the link between value chain theory and productive use (PU) focused energy projects based on microfinance mechanisms. Its main argument is that all PU of energy projects focusing on micro, small, and medium enterprises (MSME) development can be interpreted as value chain upgrading attempts. It is argued that successful upgrading greatly depends on the MSMEs embeddedness in specific market contexts. For that reason, the context must be assessed to derive energy based intervention points that cause additional income for MSMEs and consequently development. Based on this rationale, a problem-centred value chain approach is proposed. A case study of the Philippine rice market illustrates the usability of the method by outlining some risks and opportunities the rice value chain context poses to energy based upgrading attempts of rice farmers.
2010 IEEE Energy Conversion Congress and Exposition, 2010
Abstract This paper presents the thermal and structural analysis of an electromechanical battery ... more Abstract This paper presents the thermal and structural analysis of an electromechanical battery energy storage system designed to enhance rural electrification in sub-Saharan Africa. The system consists of a flywheel rotor, an electrical machine, bearings and a ...
Nowadays, there exist many innovative daylighting technologies which could be used to enhance nat... more Nowadays, there exist many innovative daylighting technologies which could be used to enhance natural illumination for buildings that use more electric light during the day such as schools, industrial buildings. This study describes the passive zenithal light pipe daylighting technology’s performance through the scale model method. The yield of passive zenithal light pipe was improved and was achieved by incorporating a light collimator in the light pipe. Through the design and fabrication of the light collimator, illuminance in the classroom has been improved from 178 lux distributed by commercial diffuser to 370 lux (illuminance average from 9 a.m. to 4 p.m. under sunny days from October to December 2013). A range of reflector materials were tested on the interior lining of the collimator for consistent illuminance distribution and it was discovered that rough re-used aluminum cooking foil distributed uniformly and increased illuminance. All data used has been obtained from measurements at a test location in Stellenbosch, South Africa throughout the year.
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that use more electric light during the day such as schools, industrial buildings. This study describes the passive zenithal light pipe daylighting
technology’s performance through the scale model method. The yield of passive zenithal light pipe was improved and was
achieved by incorporating a light collimator in the light pipe. Through the design and fabrication of the light collimator, illuminance
in the classroom has been improved from 178 lux distributed by commercial diffuser to 370 lux (illuminance average from 9 a.m. to 4
p.m. under sunny days from October to December 2013). A range of reflector materials were tested on the interior lining of the collimator
for consistent illuminance distribution and it was discovered that rough re-used aluminum cooking foil distributed uniformly and
increased illuminance. All data used has been obtained from measurements at a test location in Stellenbosch, South Africa throughout
the year.
that use more electric light during the day such as schools, industrial buildings. This study describes the passive zenithal light pipe daylighting
technology’s performance through the scale model method. The yield of passive zenithal light pipe was improved and was
achieved by incorporating a light collimator in the light pipe. Through the design and fabrication of the light collimator, illuminance
in the classroom has been improved from 178 lux distributed by commercial diffuser to 370 lux (illuminance average from 9 a.m. to 4
p.m. under sunny days from October to December 2013). A range of reflector materials were tested on the interior lining of the collimator
for consistent illuminance distribution and it was discovered that rough re-used aluminum cooking foil distributed uniformly and
increased illuminance. All data used has been obtained from measurements at a test location in Stellenbosch, South Africa throughout
the year.