Development of replacement policy to optimize fuel emission and consumption in taxi fleet: Dubai as case study

Abstract

This research presents a comprehensive methodology for a solution to the complex problem caused by air pollution. Since this problem cannot be solved by one unique solution due to the many environmental risk factors and human health hazards, the researcher proposes four different methods that reduce gas emissions with the lowest cost. The first experiment conducted to assess the improvement in air quality to substitute hybrid taxis for the conventional gasoline-powered taxis. The evaluation is carried out in terms of carbon monoxide (CO) and hydrocarbon (HC) concentrations. The results show that, the hybrid vehicles achieved a 46% fuel efficiency improvement, leading to an effective reduction of both, CO by 37% and HC by 93%. Furthermore, hybrid vehicles have an increase of benefit/cost ratio to 1.36, and the petrol version increased to 1.53. The second experiment, based on fuel magnetization, has been tested with the aim of improving fuel efficiency and reducing the rate of gas emissions into the environment. Two experiments were conducted, each using a different type of magnetic device. Each experiment was performed on 10 separate vehicles. When compared to the baseline data, reductions of 70 % for both hydrocarbon and carbon monoxide emissions, and 68 % for oxides of nitrogen were recorded. Results also demonstrated an average fuel consumption reduction of 18 %. Because of the nature of the diesel engine combustion process, the engines produce more toxic emission, more visible smoke and smell than gasoline engines. Two environmental-technology experiments were conducted to reduce the emissions rate from highly polluted diesel powered vehicles, namely, inspection and maintenance (I/M) programs and particulate filters (PF). Comparing the two experiments with a baseline vehicle the results indicate that, the inspection and maintenance experiment significantly reduced emissions. The outcomes indicate reductions in carbon monoxide of 300%, nitrogen oxides of 500% and hydrocarbons of 88%. However, the implementation of the diesel particulate filter leads to better emission reductions but at a higher cost. Indeed, hydrocarbons emissions decreased by 150%, while carbon monoxide by 500% and nitrogen oxides decreased significantly by 700%. The results are promising for future investigation for both experiments. The researcher proposes a fleet replacement policy from an environmental perspective. The policy is based on a mathematical model that minimizes the total cost of the replacement vehicle including emission tax rate. The model considers different depreciation methods. The decision variables are; the mileage of the vehicles, age of the vehicles, the annual operating and maintenance costs, and the estimated cost of emissions hazard. The application of the proposed model is based upon the fleet replacement model for mid-sized vehicles. This thesis proposes a comprehensive vehicle pollution control strategy based on improvements to the proposed four methods. Further study can be conducted to reduce the emission and improve the environment for many sectors. Thus, more studies regarding future technologies and their feasibility would also be critical for the expansion of this study to new, alternative vehicle systems.