Emissions of N20 have a role in the enhanced greenhouse effect. N20 is a long-lived gas, surviving in the atmosphere for about 130 years. The concentration of N20 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 N20 from coal use. This report evaluates these emissions and considers measures which may be taken to prevent increased emissions of N20 from such technologies. It is estimated that global coal use is currently . . .