Strategies for reducing emissions of air pollutants from the Swedish transportation sector

Different strategies for reducing emissions of nitrogen oxides and carbon dioxide from the Swedish transportation sector are evaluated by making scenarios for the year 2015, using a bottom-up approach. Methods for reducing emissions of carbon monoxide, hydrocarbons, and sulphur dioxide are discussed more briefly. The scenarios are based on official forecasts of future passenger and goods transport. They indicate that tail-pipe nitrogen-oxide (NOx) emissions from the transportation sector can be reduced by 50% by 2015, compared to 1991, if the average performance of vehicles (with respect to energy efficiency and tailpipe emissions) in 2015 equals that of today's best commercially available technology. Tail-pipe emissions of carbon dioxide (CO2) can be stabilized at today's level. With further technical development and the use of fuels from renewable sources of energy, NOx emissions can be reduced by 75% and CO2 emissions by 80% compared to 1991. The average cost of reducing CO2 emissions, by replacing fossil fuels with biomass-based methanol in all road vehicles, using internal combustion engines, is estimated to $1993 260/tonne C, at current fuel prices. Current Swedish carbon-taxes are some $160/tonne C. More advanced end-use technologies, such as fuel cells, could reduce the cost of using methanol in the future. Electric vehicles are not studied in the scenarios but are found in a comparison to have the potential to reduce not only local air pollution but also total emissions of CO2 and NOx.