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N20 Emissions from Coal Use

AUTHOR: Mitsuru Takeshita, Lesley Sloss, Irene Smith
DATE: November 1993

The latest in the series of Perspectives from IEA Coal Research reviews the emissions of nitrous oxide (N2O) from coal combustion.

Emissions of N2O have a role in the enhanced greenhouse effect. N2O is a long-lived gas, surviving in the atmosphere for about 130 years. The concentration of N2O in the atmosphere is increasing due to a variety of sources including a small contribution from coal combustion. It has been suggested that NOx abatement and control technologies and fluidised bed combustion systems may increase emissions of N2O from coal use. This report evaluates these emissions and considers measures which may be taken to prevent increased emissions of N2O from such technologies.

It is estimated that global coal use is currently responsible for 2-6% of the total emissions of N2O from human activities or < 1-2% of total source of N2O. Flue gas desulphurisation technologies for SO2 control, combustion modifications and selective catalytic reduction for NOx control do not affect or may reduce N2O emissions. Selective non-catalytic reduction probably increases N2O emissions. Fluidised bed combustion of coal emits considerably higher concentrations of N2O than conventional combustion. Optimal measures for N2O control require verification on commercial fluidised bed combustion plants.