ABSTRACT

Urban air pollution, acidification and climate change are three major environmental problems resulting from emissions of air pollutants, primarily related to the use of fossil fuels. The effects of these emissions often entail complex, non-linear and poorly understood interactions between different pollutants and between the pollutants and the environment. Here we review these environmental problems with a view to understanding the limits they imply for future energy systems if these are to develop in ways that are compatible with environmental goals: goals such as air quality guidelines, critical load levels and acceptable rates of greenhouse gas emissions. Emissions reductions of the order of 50 to 95 per cent from existing levels for sulphur dioxide (SO2), nitrogen oxides (NOx), volatile organic compounds (VOCs) and carbon dioxide (CO2) are required to meet such goals.

Current efforts and plans to reduce emissions are inadequate to reach present environmental goals. In addition, demands for reducing emissions are likely to become more stringent as more is learned about the impacts on health and the environment, and as it becomes increasingly recognized that further policy decisions must be made in situations where the scientific knowledge is incomplete.

End-of-pipe technical measures, even with full implementation of advanced technologies, will not be sufficient to meet present environmental goals. Strategies that include system level changes are required. Energy efficiency 48improvements and a shift to renewable sources of fuels and electricity provide technical options for large emissions reductions. The resulting environmental effects of world energy systems could be minor or negligible compared to the effects of continued reliance on conventional sources of energy.