Analysis on differences of carbon dioxide emission from cement production and their major determinants

Based on 15 production lines we surveyed in China, the widely accepted input and output methods were applied to compare the process emissions with CSI (Cement Sustainability Initiative), and IPCC (Intergovernmental Panel on Climate Change) default values. We found that the output method would magnify CO2 emissions from carbonate breakdown during clinker production. A reasonable method is to calculate carbonate content in raw meal using the CaO and MgO content in carbonate-containing material and their material ratio. Another finding is that the raw meals consumption recommended by CSI and CMBA (China Building Materials Academy) would enlarge and underestimate the calcining emissions, respectively. We applied the TC (total carbon) and LHV (lower heating value) methods for fuel emissions calculation and found that all of the samples' fuel emissions by the LHV method were higher than those by the TC method. Indirect emissions from different cement producing stages were also estimated by using regional electricity emission factor. In raw meal preparation and cement grinding stage, there were no differences in main production technologies, but in clinker production stage a remarkable difference appears. Replacing carbonate-containing materials with non-carbonate materials and changing clinker ratio are the main ways to reduce CO2 content in raw meal and process emissions. Lowering fossil fuel intensity, using clean energy and alternative fuel were strongly recommended for reducing cement energy emissions.