Walking on sunshine: Pairing electric vehicles with solar energy for sustainable informal public transport in Uganda

Abstract

Minibus taxi public transport is a seemingly chaotic phenomenon in the developing cities of the Global South with unique mobility and operational characteristics. Eventually this wide-spread fleet of minibus taxis will have to transition to electric vehicles. This paper examines the impact of this inevitable evolution on a city-wide scale in Kampala, Uganda. We present a generic simulation environment to assess the grid impact and charging opportunities, given the unique paratransit mobility patterns. We used floating car data to assess the energy requirements of electric minibus taxis, which will have a knock-on effect on the region's already fragile electrical grid. We used spatio-temporal and solar photovoltaic analyses 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. The results showed energy demand from a median of 224 kWh/day to a maximum of 491 kWh/day, with a median charging potential (stationary time) across taxis of 8 h/day to 12 h/day. The potential for charging from solar PV was 0.24 kWh/m^2 to 0.52 kWh/m^2. Our simulator and results will allow traffic planners and grid operators to assess and plan for looming electric vehicle roll-outs to the most-used mode of transport in Africa.

Why taxi tracking trumps tracking passengers with apps in planning for the electrification of Africa’s paratransit

“…Reliable statistics on the number of taxis would have also been useful for downscaling the power and energy profiles in Figure 1, to get the average taxi's energy demand. In the following paragraphs, we will nevertheless downscale the Kampala profile by the number of taxis to compare its power profile to one we computed from independently gathered, reliable, vehicle-based paratransit data (Booysen et al, 2022b).…”

“…One is the passenger-based power profile from Figure 1C, which was downscaled by the number of taxis in Kampala (25,000, as shown in Table 5 (Spooner et al, 2020)). The second plot is a vehicle-based power profile of Kampala obtained in a small study by Booysen et al (2022b). The differences are stark.…”

Idealized analysis of relative values of bidirectional versus unidirectional electric vehicle charging in deeply decarbonized electricity systems

“…The value of EV in terms of power system operation cost, levelized and marginal cost of electricity generation, power plant dispatch, and environmental emissions could substantially be affected by the EV charging strategy employed (Borlaug et al, 2020). The effect of EV on some of the above parameters has been examined for different countries (Bellocchi et al, 2019b(Bellocchi et al, , 2019aBooysen et al, 2022;Broadbent et al, 2022;Dioha et al, 2022aDioha et al, , 2022bDumlao and Ishihara, 2022;Greaker et al, 2022;Hill et al, 2019;Jenn and Highleyman, 2022;Kejun et al, 2021;Mangipinto et al, 2022;Tarroja and Hittinger, 2021;Zhang et al, 2022). Although there are numerous other studies on the value of EVs, this paper focuses on the relative value of EVs based on the plausible circumstances of different regions in an idealized context.…”