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The Reduction of Photochemical Pollution and Gases Emissions Having a Greenhouse Effect. Impact of Existing and Coming Engines - Fuel Technologies
Published May 14, 1992 by Societe des Ingenieurs de l'Automobile in France
Since the start of the 1990s, the control of air pollution from automobiles has concentrated on three aspects: (i) the photochemical formation of ozone from hydrocarbons (HC) and nitrogen oxides (NOx), (ii) the emission of particularly toxic products (butadiene, formaldehyde, acetaldehyde, etc.), and (iii) the increase in the greenhouse effect of carbon dioxide and other constituents of exhaust gases, (CO, hydrocarbons, nitrogen protoxide, etc.).
After reviewing the general mechanisms of ozone formation in the troposphere, it is shown that such phenomena can be controlled by acting simultaneously on the engine, the post-treatment catalyst and the fuel. This analysis must obviously take into account comparison of "gasoline" and "diesel" engine behavior. The goal is to reduce the total quantity of pollutants emitted (HC + NOx), their concentration ratio (HC/NOx) and the relative reactivity of the different types of hydrocarbons emitted by the vehicle. In the light of recent findings by the U.S. auto/oil program it is indicated what formulation inflections can be planned for fuels (olefins and aromatics content, end boiling point) that will help to limit ozone formation in the major urban and suburban zones. These developments will also lead to less emission of directly toxic products.
Concerning the limiting of the greenhouse effect, this study highlights the comparative situation of different classic engine/fuel systems (gasoline, diesel) or prototypes (two-stroke, electric vehicle, natural gas, biofuels). This analysis takes into consideration emissions of all gases having a direct and indirect greenhouse effect for the entire fuel production, distribution and combustion line.
The study ends with a prospective reflection about the next century when, more than ever, three major goals will have to be reconciled: (i) increasing performances, (ii) reducing energy consumption and (iii) protecting the environment.