Relative impact on environment and health from the introduction of low emission city buses in sweden

摘要

This paper is focusing on the technical measures that have been implemented during the last decade to reduce the emissions from heavy-duty buses in Sweden. The emission tests carried out on these buses have been evaluated in order to assess the impact on the environment and on several health effects from switching to improved technology and to alternative fuels. Emission factors for the most important emission components (regulated and unregulated) have been determined for each option. Several effects from the emission components have been calculated using weighting factors for each component. Acidification, eutrophication, ozone forming potential, cancer risk, greenhouse gases and several other effects have been evaluated. The analysis showed considerable improvements by reformulation of the diesel fuel and by fitting aftertreatment devices. Particulate emissions and its effects are probably the most severe emission component from the diesel engines. Particulate filters are the only commercially available solution to that problem today. Some of the alternative fuels have a positive impact regarding several of the effects investigated, such as acidification. In other cases (e.g. ozone forming potential) the difference between the best options is small. It is expected that future development of engines and aftertreatment devices will diminish the advantage of the alternative fuels regarding many of the effects. On the other hand, the impact on the greenhouse gases from some biofuel options will be more pronounced in the future.