KEY CONCEPTS
• A study was conducted to evaluate how switching from gasoline to electric motorcycle taxis in Kampala, Uganda, impacts air pollution emissions.
• The use of electric motorcycle taxis in Kampala, Uganda, led to a reduction of greenhouse gas emissions. 
• Some emissions increased because of local pollution produced through power generation. 

Electrification of automobiles is accelerating due to the potential benefit in reducing emissions. Theoretical and empirical studies are now being conducted to evaluate how significantly emissions can be reduced. In a previous TLT article,¹ researchers conducted a theoretical study that shows the use of electric vehicles in the U.S. will lead to a significant reduction in carbon dioxide emissions. Six model scenarios were generated that have electric vehicles representing 0%, 25% and 75% of the total U.S. light-duty passenger vehicle fleet with three different energy producing scenarios. Carbon dioxide emissions could decline by hundreds of millions of tons, which could lead to a savings of $17 billion in damages attributed to air pollution and health and climate changes per year, if 25% electric vehicles are used.

Much of the work done in evaluating the impact of electric vehicles has occurred in the developed world. But the developing world also is in the process of examining options to reduce emissions and improve air quality.

Michael Craig, assistant professor in energy systems at the University of Michigan’s School of Environment and Sustainability in Ann Arbor, Mich., says, “Very little research has been done to evaluate how extensively emissions can be reduced in low and middle income countries if electrified vehicles are introduced in place of gas-powered vehicles. One of the focus points needs to be the evaluation of motorcycles (see Figure 3). In cities located in Africa, Southeast Asia and South America, millions of gas-powered motorcycles are utilized by individuals on a daily basis. Past studies project that motorcycle fleets will continue to grow rapidly, such as by 4% in the 10 largest Asian markets.”


Figure 3. Mixed results were found when a study was conducted to determine how emissions levels changed in Kampala, Uganda, when operators switched from gasoline to electric motorcycle taxis. Figure courtesy of the University of Michigan.

A developing country that has witnessed rapid growth in motorcycle use is Uganda, which is located in the Sub-Sahara region of Africa. The number of motorcycles driven in this country increased dramatically between 2007 and 2014 to just over 400,000, which represents one-third of total vehicles.

Approximately 10% of total motorcycles are used as taxis in the Ugandan capital of Kampala. Craig says, “Motorcycles have gained popularity in cities such as Kampala due to lower upfront costs, ease of use, lack of regulation and excellent mobility in congested urban areas.”

Electrification of motorcycles in Uganda has now increased particularly for their use as taxis. Craig says, “The added benefit of using electric motorcycles is the potential for reduced costs because no gas needs to be purchased and reduced maintenance costs.”

Craig and his colleagues have now conducted a study to determine how the use of electric motorcycle taxis in Kampala reduces air pollution emissions.

Battery swapping
The researchers developed a model of the trips conducted by electric motorcycle taxis through the use of two observational datasets. The first one is the log of battery swapping that was done when the lithium iron phosphate batteries used by an electric motorcycle taxi needed to be recharged. The company that provided the data to the researchers swapped out a battery with a low energy level for a freshly charged one.


‘In cities located in Africa, Southeast Asia and South America, millions of gas-powered motorcycles are utilized by individuals on a daily basis. Past studies project that motorcycle fleets will continue to grow rapidly, such as by 4% in the 10 largest Asian markets.’

The second dataset was acquired from the raw GPS data that provided details on where the taxis went each day, how many trips were taken and the status of the taxi outside of operational hours. This data was collected for about one year between November 2019 and January 2021 when nearly 55,000 swaps occurred for over 130 electric motorcycle taxis. Craig says, “While 80 electric taxis were used in Kampala during the time of the study and the number is growing, the total percentage of taxis that are electrified is less than 1%. For gas-powered motorcycle taxis, we determined what the emissions would be for trips identical to those taken by electric motorcycle taxis. We factored in the amount of gas they used for every kilometer traveled including idling on the side of the road.”

Another factor taken into consideration by the researchers is the source of the power used to recharge the batteries during the swapping process. Craig says, “Uganda uses three sources of power, which are hydroelectric, heavy fuel oil and bagasse cogeneration (combustion of a byproduct pulp residue of sugarcane). Fortunately, most of the capacity is from hydroelectric, but its use is dependent on the weather, and Uganda does have periods of dry weather limiting its use.” 

The researchers determined that switching from gasoline to electric motorcycle taxis led to a reduction of carbon dioxide emission by 36%, nitrogen oxides by 58% and hydrocarbons by 99%. But emissions of sulfur dioxide increased by 870%, coarse particulate matter (PM10) by 109% and fine particulate matter (PM2.5) by 97%.

The reason for the increase in certain emissions is due to the use of electricity from bagasse cogeneration in the charging of batteries. Besides evaluating emissions produced by 80 electric motorcycle taxis, calculations were made by the researchers for the use of 250, 1,000 and 10,000 electric motorcycles. Significant emission reductions were found when 250 and 1,000 electric motorcycles are used. But the contribution of bagasse for charging batteries used for the 10,000 electric motorcycle case limits the emission reduction benefits. Craig concludes, “We found that movement to electric motorcycle taxis will lead to a reduction in GHG emissions, but local pollution produced through power generation can reduce the benefit depending upon the power source.”

This study shows that the developing world also is moving toward electrification and is focusing on modes of transportation that differ from the developed world. Additional information can be found in a recent article² or by contacting Craig at mtcraig@umich.edu.

REFERENCES
1. Canter, N. (2020), “How will electric vehicle use affect air quality and the health of individuals,” TLT, 76 (12), pp. 18-19. Available here.
2. Vanatta, M., Rathod, B., Calzavara, J., Courtright, T., Sims, T., Sernin, E., Clack, H., Jagger, P. and Craig, M. (2022), “Emissions impacts of electrifying motorcycle taxis in Kampala, Uganda,” Transportation Research Part D, 104, 103193.