• Energy Research
• engineering and technology close

Resolving imbalances on phases is performed using conventional trial and error approach which involves service interruption. Phase current and voltage may improve however the resultant effect does not last for too long. To improve the performance of the secondary distribution system there is a need for an on-line and automating technology. The aim of this paper is to pioneer a method and technology for resolving imbalances in a secondary distribution system as a result of the uneven distribution of single phase load across a three phase power system. The technology developed involves monitoring, acquisition/display of collected data and self changing switching actions electronically for rearrangement or transfer of consumer loads. The proposed switching technology is based on opentransition switch that enables transfer or rearrangement of consumer loads in a three-phase system within milliseconds with supervisory control system. Validation of the proposed technology was carried out using these methodologies: Matlab (Simulink), Virtual Instrumentation-Lab VIEW and Hardware implementation.

Abstract Occupant dynamic presence and characteristics associated with lighting loads/usage in residential buildings are not replicated in most practices currently adopted in modelling lighting profile. This study involves the use of adaptive neural fuzzy inference system (ANFIS) for lighting load profile prediction. Natural light, occupancy (active) and income level are the characterization (variables) factors considered in this investigation. The accuracy of the developed prediction models in relation to various income earners groups were analyzed using statistical measures; correlation output of the ANFIS approach and the impact of the characteristics on the lighting profile development in relation to trend analysis were also employed. Results obtained after validation of the developed models using investigative data, metering data and regression model showed a better correlation and root mean square error (RMSE) in comparison with actual values. The intelligence approach showed a better correlation of fit and good learning predictive accuracy in terms of behavioural and environmental variableness; and presents its output according to the complex nature of lighting usage in relation to the variables. The efficacy of the method was also validated.

Most polymer materials are thermal and electrical insulators, which have wide potential in advanced energy-power applications including energy conversion. However, polymers get softened when in contact with heat, which causes their molecular chains to flow as the temperature increases. Although polymer dielectrics exhibit high power density, they face challenges of low energy density which is due to the low dielectric permittivity associated with them. Therefore, this study tried to address the poor thermal energy management and low energy density of poly (vinylidene fluoride) (PVDF) while maintaining its flexible property using low content of hybrid carbon nanotubes (CNTs–0.05wt%, 0.1wt%) and boron nitride (BN–5wt%, 10wt%) nano-reinforcements. The nanocomposites were developed through solvent mixing and hot compression processes. The dielectric constant increased from 9.1 for the pure PVDF to 42.8 with a low loss of about 0.1 at 100 Hz for PVDF-0.1wt%CNTs-10wt%BN. The thermal stability of the nanocomposites was enhanced by 55°C compared to the pure PVDF. The nanocomposites also showed improved melting and crystallization temperatures. The developed PVDF-CNTs-BN nanocomposites showed significant enhancements in thermal energy management, stability, and dielectric properties. The significantly improved properties are credited to the synergetic effects between CNTs and BN in the PVDF matrix in promoting homogeneous dispersion, thermal barrier, interfacial polarization/bonding, insulative and conductive properties. Therefore, the developed nanomaterials in this study can find advanced applications in the energy-power sector owing to their enhanced performances.

Dye-sensitized solar cells (DSSCs) are characterized by several special attributes such as low cost, ease of fabrication, all year availability of sunlight, and capacity to operate under diffuse lighting conditions. However, their universal adoption is still restricted by a low efficiency photovoltaic output. Thus, this research seeks to explore avenues of present photon mitigation which could be corrected in future DSSC technology in order to improve on existing efficiency records. A preliminary phytochemical screening of Prunus dulcis (P. dulcis) leaf extract revealed a variety of chromophores which renders high possibility for charge transport. UV/VIS spectroscopy showed P. dulcis with peak absorbance wavelength within the visible region of the electromagnetic spectrum of light. Fourier transform infrared spectroscopy specifically highlighted the fingerprint of the chromophores present in this organic extract. Photovoltaic parameters such as short circuit current (Isc), open circuit voltage (Voc), maximum power (Pmax), fill factor (ff) and efficiency (ƞ) were the factors taken into consideration for the determination of the photovoltaic outcome. In P. dulcis DSSCs, KBr electrolyte recorded the best ƞ of 10.18%. However, P. dulcis DSSC with electrolyte KI indicated the best Isc, Voc and Pmax of 0.135 mA, 280 mV and 34.2 mW respectively. The similarity of this photovoltaic result with previous DSSC results necessitated further analysis. Consequently, scanning electron micrograph (SEM) of P. dulcis was modelled first with Gwyddion software and this output was analyzed with Excel and Origin programs. The outcome is a scientific discovery of electron tunneling in the P. dulcis shells, effect of dopant ions boosting the electrolytic Fermi level and a high probability of influencing the future efficiency outcome in P. dulcis DSSCs. Using mathematical algorithms from the Origin and Excel software applications, a direct function of the impact of doping, relative speed of electrolyte molecules as they percolate P. dulcis framework was obtained. Thus, the significance of this work lies in the relationship of behavioral dynamics of dopants to photovoltaic performance of P. dulcis. This indicates that a vital optical tunable characteristic of DSSCs lies in electrodynamics of dopant ions, which presents a viable prospect for application in DSSC technology research.

Load balancing on phases is performed using a conventional trial and error approach. With this approach, service interruption is unavoidable; hence rearrangement of consumers load distribution points on phases cannot be performed frequently. Also phase voltage and current imbalances might improve using this approach but the change does last for too long. To get the secondary distribution to operate at its optimal performance, a technique in the form of remote and automated technology is needed. This paper contributes such a technology at the low voltage side of the distribution network. The proposed static transfer switching technology is based on the open-transition switch that enables transfer or arrangement of consumer loads in a three-phase system within milliseconds and supervisory control system for effective co-ordination, computational and control of other intelligent units.

This paper focuses on the impact of Solar Water Heaters (SWH) at a higher institution of learning. An energy audit was conducted for the evaluation of the energy conservation measure: energy conoduction Energy is a key element in the development of any country or institution; as a result any shortage in energy will have a serious effect on the economy and social aspect of such country or institution. South Africa has, in recent years, experienced high economic growth as well as a rapid expansion in the elsumption analysis, correlation of consumption with weather; financial criteria, payback period and needed solar heater system (SWH) to determine the energy that may be termed as wastage or can be saved. The method of investigation includes assessment of the hot water usage within the institution campus and residencies, analysis of bills, metering and development of a software model for the analysis of energy use, system needed and environmental variables. This renewable measure (SWH) showed a high potential of energy and financial savings for higher education institutions especially those with residences.

National electricity supply utility in South Africa (Eskom) has been facing challenges to meet load demands in the country. The lack of generation equipment maintenance, increasing load demand and lack of new generation stations has left the country with a shortage of electricity supply that leads to load shedding. As a result, alternative renewable energy is required to supplement the national grid. Photovoltaic (PV) solar generation and wind farms are leading in this regard. Sunlight fluctuates throughout the day, thereby causing irradiation which in turn causes the output of the PV plant to become unstable and unreliable. As a result, storage facilities are required to mitigate challenges that come with the integration of PV into the grid or the use of PV independently, off the grid. The same storage system can also be used to supplement the power supply at night time when there is no sunlight and/or during peak hours when the demand is high. Although storage facilities are already in existence, it is important to research their range, applications, highlight new technologies and identify the best economical solution based on present and future plans. The study investigated an improved economic and technical storage system for generation of clean energy systems using solar/PV plants as the base to supplement the grid. In addition, the research aims to provide utilities with the information required for making storage facilities available with an emphasis on capital cost, implementation, operation and maintenance costs. The study solution is expected to be economical and technically proficient in terms of PV output stabilization and provision of extra capacity during peak times. The research technology’s focus includes different storage batteries, pumped storage and other forms of storage such as supercapacitors. The analysis or simulations were carried out using current analytic methods and software, such as HOMER Pro®. The end results provide the power utility in South Africa and abroad with options for energy storage facilities that could stabilise output demand, increase generation capacity and provide backup power. Consumers would have access to power most of the time, thereby reducing generation constraints and eventually the monthly cost of electricity due to renewable energies’ accessibility. Increased access to electricity will contribute to socio-economic development in the country. The proposed solution is environmentally friendly and would alleviate the present crisis of load shedding due to the imbalance of high demand to lower generations.

Advancements in computational technologies for residential energy management have become widespread due to increased energy usage and peak demand in households. Controlled switching of appliances during peak periods for energy reduction is one of such solutions. However, this technique may constrict the consumer’s flexibility to utilize desired appliances to fulfil their needs. This study proposes a peak load control technique based on an end-use appliance prioritization and event detection algorithm. A noteworthy feature of the technique is the users’ preferred appliance (UPA), which provides the occupants with the flexibility to use any electric load to fulfill their needs at any time whether peak demand control has been initiated or not. Furthermore, to address the challenging issue around the uncertain and varying nature of the users’ energy usage pattern, an empirical bottom-up approach is adopted to characterize the consumers’ diverse end-use behavior. The results obtained show good performance in terms of peak demand and energy consumption reduction, with 3% to 20% and at least 14.05% in demand reduction for time of use (ToU) periods and energy savings, respectively. These offer a further perspective on demand side management, affording load users a new cost-saving energy usage pattern.