Assessment of the Quality of Gasoline and Cross-contamination Across the Kenyan Market

Abstract

Small and medium-sized motor cars are the majority of the vehicles found in urban areas around the world are often the main sources of air pollution, good-grade gasoline is fit-for-purpose fuel that complies with the technical parameters and requirements set forth in the design for the vehicle or equipment it is being used in. The Kenya Standard KS EAS 158: 2019 for Automotive Gasoline Specification specifies the legal and accepted requirements for gasoline qualities in Kenya. The engine performance, efficiency, and output suffer when the aforementioned qualities stray from the established specifications. This leads to the raise in the cost of service and maintenance. It also contributes to increased air pollution. The study aimed to comprehensively outline the petroleum supply chain in Kenya, covering the entire process from importation to consumer distribution. To assess the properties and regulatory compliance of Kenyan gasoline, the study focused on key parameters, including density, atmospheric distillation, research octane number, and unwashed gum. Samples were collected from various points in the supply chain, including the top, middle, and bottom of tanks and pump nozzles. To prevent the loss of light hydrocarbons, the samples were securely corked. The tests were conducted using American Standards for Test and Materials protocols for evaluating density, distillation, research octane number, and unwashed gum. The Kenyan petroleum supply chain, starting from importation, includes several depots such as Mombasa, inland deports: Konza, Nairobi, Nakuru, Nanyuki, Eldoret, and Kisumu, as well as intermediary stations. Throughout the supply chain, gasoline density ranged from 0.7498 to 0.7521 g/cm3, within recommended limits. Final boiling points at the Kenya Pipeline Company Kisumu depot remained within authorized ranges despite an increasing trend from 189.8 °C to 210.5 °C due to changes in atmospheric pressure. It is worth noting that the RON were within the KPC's approved range of 93.2 to 94.9. Unwashed gum levels at pre-discharge were permissible of 5 mg/100 mL but exceeded limits of 7 to 41 mg/100 mL during delivery, especially from KPC Mombasa. Increasing distances correlated with higher deviations, indicating greater pollution as gasoline interacts with delivery vehicle and pipeline walls. Notable deviations occurred from Mombasa to Kisumu, including a high final boiling point deviation of 21.7 in 2021 and 17.8 in 2022, a 32-unit unwashed gum deviation in 2021 and 12 in 2022, and a -1.0, research octane number deviation in 2021 and -1.5 in 2022. This implies an increase in gasoline pollution with prolonged exposure to delivery systems