Impacts of electric vehicle charging in South Africa and photovoltaic carports as a mitigation technique

Buresh, Kevin (2021-03)

Thesis (MEng)--Stellenbosch University, 2021.


ENGLISH ABSTRACT: The rise of greenhouse gas emissions having detrimental impacts on the environment have raised concerns. Efforts to combat these emissions have been agreed upon by countries across the globe, including South Africa. Reducing emissions, such as carbon, is commonly proposed as moving from coal-based generation sources to renewable sources for electricity,along with shifting from internal combustion engine (ICE) vehicles to electric vehicles(EVs). EVs have gained popularity internationally and are becoming widely adopted as a greener alternative. Research has uncovered that this may not always be the case, provided the different electricity generation sources utilized. South Africa, having a coal-dependent grid, might not see a reduction of emissions with the adoption of EVs. Mass charging of EVs can also jeopardize grid stability by creating new peak demands, which could be detrimental for South Africa’s currently fragile grid. Fortunately, through the use of renewable sources to offset electricity from the grid when charging EVs and implementing smart charging strategies, EVs could meet their acclaimed potential benefits.A simulation model was developed to examine the effects of varying EV fleet sizes in South Africa, and the potential of mitigation strategies such as large employers providing solar photovoltaic (PV) carport charging stations and smart charging methods. A varying fleet size aids in investigating the impacts of EV charging from the perspective of a vehicle owner, a large employer and the national grid. The model incorporates a solar PV model with measured weather data, along with an EV model consisting of a mobility model and battery model. A smart charging method was developed to limit the number of vehicles charging simultaneously based on a maximum load peak demand. This demand-side management (DSM) strategy determines the charging urgency of EVs to formulate a prioritized charging schedule. During this project, it was found that the current grid capacity would not be sufficient for more than four million EVs charging without any intervention. When supplementing charging with PV carports, the grid capacity could handle at least an additional 10% increase in fleet size. An employer providing PV carport charging would see an increase in revenue from electricity sales when customers only charge at work. A vehicle owner was found to have a cleaner carbon footprint travelling with a petrol ICE vehicle than an EV,except for scenarios where EVs utilize PV carports and would have the lowest operational costs when driving an EV that does not charge at home.Supplementary PV energy does prove to be a useful mitigation strategy, but when EVs are allowed to charge freely at work, they do not take advantage of the full potential. Employers, when coupling smart charging strategies with PV carports, gain further control of load demands, reductions in operational costs and grid energy consumption. An employer implementing charging imposed load limit restrictions, while still providing user comfort to vehicle owners, was seen to reduce the imposed peak demand by more than half and led to a doubling of the yearly revenue. Various levels of restrictions, when evaluated, were seen to have a significant impact on user comfort, with little impact on financial benefits.Overall, this project has demonstrated not only the need for EV charging mitigation strategies, but also the potential benefits of solar PV carports coupled with smart charging strategies.

AFRIKAANSE OPSOMMING: Raadpleeg teks vir opsomming

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