Conference Proceedings (Electrical and Electronic Engineering)
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- ItemDecarbonising South Africa’s paratransit with hydrogen: a simulated case study(2023-07-10) Abraham CJ; Zenner T; Booysen MJ; Rix AJAs fuel prices climb and the global automotive sector migrates to more sustainable vehicle technologies, the future of South Africa’s minibus taxis is in flux. The authors’ previous research has found that battery electric technology struggles to meet all the mobility requirements of minibus taxis. They investigate the technical feasibility of powering taxis with hydrogen fuel cells instead. The following results are projected using a custom-built simulator, and tracking data of taxis based in Stellenbosch, South Africa. Each taxi requires around 12 kg of hydrogen gas per day to travel an average distance of 360 km. 465 kWh of electricity, or 860 m2 of solar panels, would electrolyse the required green hydrogen. An economic analysis was conducted on the capital and operational expenses of a system of ten hydrogen taxis and an electrolysis plant. Such a pilot project requires a minimum investment of € 3.8 million (R 75 million), for a 20 year period. Although such a small scale roll-out is technically feasible and would meet taxis’ performance requirements, the investment cost is too high, making it financially unfeasible. They conclude that a large scale solution would need to be investigated to improve financial feasibility; however, South Africa’s limited electrical generation capacity poses a threat to its technical feasibility. The simulator is uploaded at: https://gitlab.com/eputs/ev-fleet-sim-fcv-model.
- ItemUsing tracking data and an electro-mobility simulator to establish the energy requirements of electric minibus taxis in Tshwane(2023-07-10) Abdelgadir S; Giliomee S; Venter C; Booysen M JThe minibus taxi (MBT) is the dominant form of public transport across Sub-Saharan Africa (SSA). With a growing global call for greener transport, MBTs are seen as a key sector of implementation. The electrification of MBTs entails many challenges, including limited electricity resources and the lack of understanding of MBTs’ operational behaviour. In this paper, we estimate the electricity demand for future electric MBTs in the City of Tshwane, South Africa. We use existing origin and destination mobility data, which originated from vehicle-based tracking, and a micro-mobility simulation tool with an embedded electric vehicle model, called EV-Fleet-Sim. This simulation tool uses various SUMO packages to simulate mobility and calculate energy expenditure. The mobility dataset consists of various stop locations from a MBT fleet’s daily operation. The simulator uses a routing model, a virtual map, and a virtual driver model to convert the origin and destination data to high-fidelity mobility traces. The results are used in the electro-kinetic model to estimate the vehicles’ energy needs, from which charging opportunities can be derived. To illustrate this process and outputs, eight exemplar taxis with different operational patterns are selected for analysis. The results show a minimum and maximum median daily energy usage of 56 kWh and 215 kWh respectively, based on the mean observed daily distances travelled of 94 km to 330 km. While the energy demand varies significantly according to trip length and type of operation of the sub-fleet of 8 vehicles, clear morning and afternoon peaks are identified, along with charging opportunities during midday and at night.
- ItemSaving on household electric water heating : what works best and by how much?(Institute of Electrical and Electronics Engineers, 2017) Nel, P. J. C.; Booysen, M. J.; Van der Merwe, B.Electric heating of water for domestic use is a substantial component of total household energy costs. Thermal energy in a water heater is either used (as warm water) or lost to the environment. Various approaches to reduce the losses and improve the efficiency of these notoriously inefficient and costly water heaters have been proposed and are employed. However, given the complex factors at play, making sense of the savings approaches and choosing the right one for the right use case is not a simple task and often misunderstood. This paper addresses this problem by comparing some of the commonly employed approaches, including schedule control, change in set temperature, use of thermal insulation, and reduction in consumed volume. We also compare the impact of environmental factors, such as changing the ambient temperature around the water heater and the cold inlet temperature. The results show that for the consumption profiles and use cases evaluated, schedule control is the most effective, followed by insulation of the tank and piping. Combined, these two interventions save up to 25%. We also find that the effect of the temperature of the cold inlet water dwarfs that of the ambient temperature, is in line with other approaches, and means the installation status quo needs to be reconsidered.
- ItemSaving on household electric water heating : what works best and by how much(IEEE, 2017-12) Nel, P. J. C.; Booysen, Marthinus J.; Van der Merwe, B.Electric heating of water for domestic use is a substantial component of total household energy costs. Thermal energy in a water heater is either used (as warm water) or lost to the environment. Various approaches to reduce the losses and improve the efficiency of these notoriously inefficient and costly water heaters have been proposed and are employed. However, given the complex factors at play, making sense of the savings approaches and choosing the right one for the right use case is not a simple task and often misunderstood. This paper addresses this problem by comparing some of the commonly employed approaches, including schedule control, change in set temperature, use of thermal insulation, and reduction in consumed volume. We also compare the impact of environmental factors, such as changing the ambient temperature around the water heater and the cold inlet temperature. The results show that for the consumption profiles and use cases evaluated, schedule control is the most effective, followed by insulation of the tank and piping. Combined, these two interventions save up to 25%. We also find that the effect of the temperature of the cold inlet water dwarfs that of the ambient temperature, is in line with other approaches, and means the installation status quo needs to be reconsidered.
- ItemEvaluation of the energy model of a horizontally-mounted electric water heater through internal temperature measurement(Institute of Electrical and Electronics Engineers, 2017) Leeuwner, L. L.; Naude, N. H.; Roux, M.; Booysen, M. J.The resource-constraint energy sector faces an insatiable demand for energy, which necessitates improvements in efficiency. One key sector that has potential for savings is residential water heating, which makes up 32% of household energy. Previous studies have proven that with effective scheduling up to 29% savings can be achieved for a nominal consumption pattern. The model that was used to estimate the savings, calculates the energy usage for a given hot water consumption pattern and given heating schedule for a horizontally mounted water heater. This two-node model is used to aid user-informed scheduling and auto- scheduling, but was developed as a black-box model, validating the energy and not the internal temperatures, which could be misleading. This paper evaluates the accuracy of the model by performing temperature measurements inside the horizontal electric water heater. Moreover, two aspects neglected by the model are investigated: The node state transfer usage threshold, and the inter-nodal thermal resistance. The results show that the model significantly underestimates the stratification that occurs naturally. This underestimation also severely affects the modelled energy consumption and hides limitations of the model, preferring a lower threshold and higher inter-nodal resistance. The results also show that Legionella growth in the EWH could be a concern despite a high set point.