Technical Market Support » Thermal Coal
Recent international developments have led to a very careful examination of mercury emissions to the environment. Inevitably developments such as these will focus attention on mercury emissions from coal combustion. Mercury is present in small concentrations in coal, but the large quantities used, and the volatility of mercury at combustion temperatures, results in significant emissions. In the US, for example, around 30% of anthropogenic emissions results from coal combustion.
Initiatives to control coal-derived emissions are currently being developed or discussed in many countries. Mercury concentrations in imported coals are already being scrutinized and compared, and market decisions may be made on this basis in the not too distant future.
Coal properties, especially chlorine and calcium content, and carbon in ash levels can have significant influences on mercury emissions at full scale. It is also clear that these coal properties affect the levels of reductions in mercury emissions observed in air pollution control devices (APCDs) such as De-SOx and De-NOx plants.
The objectives of this project were to:
- review world-wide legislative developments in mercury control
- analyse the relevant properties of Australian and competitor coals to establish their likely behaviour in a range of APCDs with respect to mercury emissions
- survey the costs of add-on mercury control techniques which may be necessary to reduce emissions from some coals to acceptable levels; the best developed current approach is activated carbon injection, but this is very high cost, and alternatives are being intensively investigated worldwide
- develop a simple economic model to investigate the potential advantage of low mercury content coals under various pollution control regimes (eg, MACT, cap and trade), where coal substitution may be more cost effective than the introduction of costly add-on measures
- review existing methods for mercury sampling and analysis
The report concludes that it is probable that low mercury content coals will not have a significant market advantage where stringent air quality guidelines, leading to controls on SO2 and NOx emissions, are applied.