A Quantitative Estimate of the Air Quality Effects of Methanol Fuel Use

A three tiered photochemical modeling system was developed to quantitatively estimate the air quality impact of methanol fuel usage in the South Coast Air Basin of California. The first level utilized a chemical kinetic model to evaluate the performance of the condensed chemical mechanism chosen for use in the second and third level of this study. This mechanism was tested by reproducing experimental data and performing a pollutant sensitivity analysis. It modeled the data quite adequately and showed similar sensitivity to large explicit mechanisms. The second level used a Lagrangian trajectory model to determine the effects of various methanol penetration scenarios on ozone and other pollutant levels along three trajectories in the Basin. Because of limitations in the trajectory formulation, these runs were used to determine relative pollutant sensitivities to specific methanol utilization scenarios. Calculated ozone concentrations are given along one trajectory to illustrate the magnitude of changes resulting from various methanol usage scenarios. This will be fully investigated in the third tier by using an Eulerian grid modal, which does not have the trajectory model's limitations but is computationally very intensive. Results of the first two levels are presented as well as recommendations for specific scenarios to be investigated in the third tier.