Ray of hope for sub-Saharan Africa's paratransit: Solar charging of urban electric minibus taxis in South Africa

摘要

Minibus taxi public transport is a seemingly chaotic phenomenon in the developing cities of the Global Southwith unique mobility and operational characteristics. Eventually this ubiquitous fleet ofminibus taxis is expectedto transition to electric vehicles, which will result in an additional energy burden on Africa's already fragile electricalgrids. This paper examines the electrical energy demands of this possible evolution, and presents a genericsimulation environment to assess the grid impact and charging opportunities.We used GPS tracking and spatiotemporaldata to assess the energy requirements of nine electricminibus taxis aswell as the informal and formalstops atwhich the taxis can recharge. Given the region's abundant sunshine,wemodelled a grid-connected solarphotovoltaic charging system to determine howeffectively PVmay be used to offset the additional burden on theelectrical grid. The mean energy demand of the taxis was 213kWh/d, resulting in an average efficiency of0.93kWh/km. The stopping time across taxis, a proxy for charging opportunity, ranged from 7.7 h/d to 10.6 h/d. The energy supplied per surface area of PV to offset the charging load of a taxi while stopping, ranged from0.38 to 0.90kWh/m~2 per day. Our simulator, which is publicly available, and the resultswill allowtraffic plannersand grid operators to assess and plan for looming electric vehicle roll-outs.