The relationship of carbon dioxide emissions with coal rank and sulfur content

Abstract

Carbon dioxide emissions, on an equivalent energy basis, were calculated for 504 North American coals to explore the effects of coal rank and sulfur content on CO2 emissions. The data set included coals ranging in rank from lignite through low-volatile bituminous from 15 U.S. states and Alberta, Canada. Carbon dioxide emissions were calculated from the carbon content and gross calorific value of each coal. The lowest CO2 emissions are calculated for the high-volatile bituminous coals (198 to 211 lbs CO2/ MMBtu) and the highest for lignites and subbituminous coals (209 to 224 lbs CCVMMBtu). The lower CO2 emissions from the high-volatile bituminous coals result in part from their generally higher sulfur content. However, even at equivalent sulfur contents the high-volatile bituminous coals give lower CO2 emissions than the lower-rank coals. On average, the lowerrank coals produce 5 percent more CO2 upon combustion than the highvolatile bituminous coals, on the basis of gross calorific value. This difference increases to 9 percent on the basis of estimated net calorific value. The net calorific value is better indicator of power plant energy production than the gross calorific value. The difference in CO2 emissions resulting from the use of high-volatile bituminous coals and lower-rank coals is of the same order of magnitude as reductions expected from near-term combustion efficiency improvements. These results are useful to those interested in current and future CO2 emissions resulting from coal combustion. © Taylor & Francis Group, LLC.