It is impossible to improve air quality, and in particular to reduce air pollution caused by the transportation sector, without reduc-ing the sulphur content of fuels. Sulphur is a naturally occurring part of crude oil and must be removed during the refining process. Despite this removal, some sulphur remains in finished products, including both gasoline and diesel fuel. When these fuels are burned, sulphur dioxide (SO2) and sulphate particulate matter are emitted. Reduction in the sulphur content of transport fuels will immediately reduce the emissions of these sulphur pollutants. As the sulphur levels decline to very low levels, the benefits can increase to help reduce the total pollutant levels being emitted.Because of its direct pollutant impact, high sulphur levels pre-vents the adoption of major pollution control technologies from being used in today’s vehicles. Sulphur causes fouling of conventional and advanced vehicle emissions control technolo-gies, which in turn affects the control of other pollutants, like carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and particulate matter (PM). Reduction in sulphur lev-els in fuels helps reduce emissions from existing vehicles and allows the use of more advanced technologies in new vehicles.BENEFITS ON VEHICLE EMISSIONSAs developing countries achieve global phase-out of leaded gaso-line, the use of low sulphur gasoline and diesel fuels will become the norm. This will enable the introduction of cleaner vehicles and technology that can help further reduce transport-related air pollution. Figure 1 demonstrates the general progression of clean fuel and vehicle technology development implemented over time to reduce emissions. Reduction of sulphur enables advanced vehicle exhaust after-treatment technologies to work at their optimum efficiencies. For traditional vehicle technologies, sulphur is the most important param-eter for emission reductions, especially for sulphur dioxide, PM and nitrogen oxides. Sulphur removal can immediately reduce the emissions levels from current vehicles and is a necessary step to using improved catalytic systems, filters (for diesel fuel engines) and other advanced technologies capable of eliminating most vehicles exhaust emissions. Since vehicles and fuels must work together as a system, the greatest benefits are achieved when lower sulphur fuels combine with appropriate vehi-cle emissions control technologies.Studies indicate the degree of required reduction in sulphur levels varies around the world. In the industrialized countries where vehicles soon will have to follow the most advanced emission limitations for NOx and CO, ultra-low sulphur fuels at 10 ppm have been requested by the automobile industry. In general, the next step for countries that have finalized the phase-out of leaded gasoline is reducing sulphur levels in gaso-line and diesel fuel. Although the timeline is different for every country, the drive is to reduce sulphur in gasoline and diesel to 50 ppm (or below) by the end of this decade. Figure 2 (page 3) illustrates the range of gasoline sulphur limits across the globe.SULPHUR REMOVAL PROCESSESCrude oil quality is the main indicator of how much sulphur is present in the feed used by the refinery and how that refin-er operates processing units. Sulphur is A Monthly Publication by Asian Clean Fuels AssociationVol. 6 Issue 6 - Aug/Sept 2008You can reach us at acfanews@acfa.org.sg. Visit our Web site at www.acfa.org.sg. Copyright 2008. Asian Clean Fuels Association.Disclaimer: The Asian Clean Fuels Association does not represent or warrant the accuracy, adequacy or completeness of the information and materials contained in this newsletter (the “Content”), and expressly disclaims any liability for any error or omission in the Content, or for any action taken in reliance on the Content.Sulphur Reduction – The Key to Lower Vehicle EmissionsINSIDE THIS ISSUESulphur Reduction - The Key to Lower Vehicle EmissionsExpert Talk: Interview with Cal Hodge, President, A 2nd Opinion, Inc.North African Program Advances Gasoline Lead Phase-Out and Sulphur ReductionACFA News Updates Figure 1 – Evolving Levels of Clean Fuels and Vehicle TechnologySource: IPIECA, 2006(Continued on p3)
