[Article by the Department of Electrical and Electronic Engineering]
Paratransit in Africa’s developing countries differs substantially from that of developed countries, from its inception to its vehicle types to its operations. Minibus taxi public transport is a seemingly chaotic phenomenon in developing cities across South Africa with unique mobility and operational characteristics. These taxis transport more than 70% of the region’s commuters. Eventually, these ubiquitous minibus taxis will have to transition to electric vehicles to keep up with future trends. Recently, researchers from the Department of Electric and Electronic Engineering at Stellenbosch University and the College of Computing and Information Sciences, Makerere University in Uganda examined the impact of this inevitable evolution. The researchers, Professors Abraham, Booysen and Rix together with Doctor Ndibatya, presented a generic simulation environment to assess the grid impact and charging opportunities, given the unique paratransit mobility patterns.
The revolution in sub-Saharan Africa’s paratransit
One urgent outcome of the United Nations’ Sustainable Development Goals is to decarbonise paratransit in the region. However, due to the sector’s unstructured, unregulated and demand-driven nature, the lack of data on the mobility of minibus taxis poses a substantial challenge against these efforts. During the research, a structured approach for evaluating various metrics was formulated which can help to evaluate the feasibility and the design requirements of electric paratransit systems.
The approach used easily obtainable GPS tracking data and a traffic simulator to evaluate the electrical demand requirements of these vehicles, as well as the proportion of the demand that can be met by renewable energy. The research entailed using floating car data to assess the energy requirements of electric minibus taxis, which will have a knock-on effect on Africa’s already fragile electrical grids. Spatio-temporal and solar photovoltaic analyses were used to assess the informal and formal stops that would be needed for the taxis to recharge from solar PV in the region’s abundant sunshine.
Results
For the first time, using this method, an estimate could be given of the energy requirements of a hypothetical electrical paratransit system in sub-Saharan Africa. The results showed energy demand from a median of 215 kWh/day to a maximum of 490 kWh/day, with a median charging potential (stationary time) across taxis of 7.7 h/day to 10.6 h/day. The potential for charging from solar PV was 0.38 kWh/m2 to 0.90 kWh/m2. This indicated that the energy demand would be quite high, and the time for charging would be quite low.
It is hoped that the simulator and results will allow traffic planners and grid operators to assess and plan for looming electric vehicle rollouts and could lead to a new funding model for transport in Africa.
Read the complete research paper: Abraham, C., Rix, A., Ndibatya, I., & Booysen, M. (2021, June 18). Ray of hope for sub-Saharan Africa’s paratransit: solar charging of urban electric minibus taxis in South Africa. https://doi.org/10.1016/j.esd.2021.08.003
Photograph: Urban minibus taxi
