Grid and mobility interdependence in the eventual electrification of operational minibus taxis in cities in sub-Saharan Africa

Abstract

The electrification of minibus taxis in sub-Sahara’s paratransit sector is yet to take off. It transports nearly 70% of daily commuters in cities with its transformation being prohibited by multiple factors: an already fragile grid network, and energy scarcity in the region. Planning for eventual electrification is complicated by the sector’s unique, unscheduled, decentralised, and demand-driven nature. We introduce the concepts of vehicle-day and fleet-day to structure and quantify the relationship between mobility and electricity demand. This relationship is investigated with data from 17 minibus taxis in the city of Stellenbosch, in South Africa. Two scenarios are evaluated: charging at depots only, and also charging at home, with differing numbers of depot chargers. There is a strong dependence of mobility on the number of chargers available; however, this reaches a maximum point where the relationship is no longer linked, suggesting a fundamental change in mobility patterns for further improvement. For the depot-only scenario, only 55% of vehicle-days were successful, while 79% of vehicle-days were successful when charging at home, too. The maximum distance that could be travelled in a day for depot-only charging was 190 km, increasing to 220 km when also charging at home, for a 70 kWh usable battery capacity.