Doctoral Degrees (Electrical and Electronic Engineering)

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Browsing Doctoral Degrees (Electrical and Electronic Engineering) by Author "Abraham, Chris"

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    Evaluating the feasibility of electric vehicle technology for paratransit in Africa through simulation.
    (Stellenbosch : Stellenbosch University, 2024-03) Abraham, Chris; Booysen, Thinus; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.
    ENGLISH ABSTRACT: As the world rapidly takes up Electric Vehicles (EVs) as a replacement to the conventional Internal Combustion Engine (ICE) vehicles, no research has been done (prior to this issertation) to evaluate this new technology’s suitability for minibus paratransit, Africa’s most widespread public transport system. One of the main reasons for this gap is that, due to the unregulated, informal nature of minibus taxis, there is a severe lack of data of their routes and schedules, both in quality and quantity. This has led to African transportation planners to make uninformed decisions regarding the future of public transport and minibus taxis. In addition, there is no indication whether EV technology will be able to meet the technical performance requirements of taxis. This dissertation changes the research landscape in Africa as it evaluates the technical feasibility, challenges and opportunities of adopting EV technology for minibus paratransit in Africa. In order to achieve this, a simulation tool was developed which supports the two paratransit data collection approaches found for African taxis: passenger based and vehicle based data. The data quality is evaluated and compared. Although the diversity of geographical locations covered by passenger-based data allow an overall perspective, the information available from the approach is found to be limited for paratransit electrification e valuations. While passenger based simulations provide overall energy consumption estimates of their paratransit systems, vehicle based simulations also provide detailed findings on the opportunities for charging stations, renewable energy charging, and energy usage patterns of individual vehicles of the system. Some key findings include that around 120 kWh would be required for the average taxi on an average weekday (as calculated using vehicle-based data). Taxis across Africa exhibited a similar energy usage profile which p eaked i n t he morning a nd e vening r ush h ours. The o ff-peak hours presented a valuable opportunity for charging, reducing the battery size required in the EV. Since the off-peak h ours i ncluded a midday l ull i n a ctivity, t he o pportunity f or s olar charging was also investigated. In a South African scenario, around 170 m2 was required to power one taxi completely off the grid, neglecting battery storage opportunities and assuming that the taxi only utilised the Photovoltaics (PV) when it stopped to charge. Another finding was that conventional battery-powered EVs would not s tore enough energy to power the long-distance trips that many taxis make on weekends. As an alternative, Fuel Cell Vehicle (FCV) technology was investigated by extending the simulation tool to include FCV models. This analysis indicated that a taxi would require 40 kg of Hydrogen for each leg of its weekend trip. These and other findings presented in the dissertation provide metrics which highlight the feasibility, challenges and opportunities of adopting EVs in the minibus taxi sector. The findings will provide governmental transport and infrastructure planners to make data-driven decisions regarding the future state of paratransit. They will also allow EV manufacturers to tailor their designs more closely to the needs of minibus taxis. The simulation tool, available at https: //ev-fleet-sim.online, can also be used for evaluating EV feasibility of any vehicle fleet, aside from taxis, and can thus be useful for companies seeking to convert delivery vans, trucks, etc. As a result of this seminal work on taxi electrification, a number of further studies were derived by other authors, to apply the methodology onto various scenarios in other contexts. These further studies have provided valuable feedback which led to adaptations in the methodology. At the time of submission, the dissertation calls for future work on vehicle-to-grid (V2G) applications for taxis, smart route and schedule planning for EV taxis, optimum charging station positioning (especially for long-distance trips), the use of batteries and Renewable Energy Generators (REGs) to stabilise power requirements of charging stations from the grid, and verifying the results of this study with a physical taxi, amongst others.