Carbon emission factors of coal and lignite: analysis of Czech coal data and comparison to European values

A linear correlation between the carbon content and the net calorific value was found for three sets of Czech coals. The same regression line can be used for both coals and lignite without reference to the water and ash contents. The positive line intercept found by regression analysis implies that the Carbon Emission Factor (CEF) is dependent on the net calorific value. According to this dependence, the CEF is higher for lignite than for bituminous coal. Accuracy in the CEF determination is better for bituminous coal due to the shape of the curve. The conclusions obtained from Czech coal and lignite data were comparable to the results from a separate European data set. Because of this fact, a general procedure for the estimation of country-specific CEFs for hard and brown coals is proposed using country-specific net calorific values. This country specific estimation can change the default IPCC CEFs by a few percent. The IPCC default emission factors were shown to be acceptable for most coals except lignite of the lowest rank: for this case a somewhat higher value seems to be more appropriate.