Revision of country specific NCVs and CEFs for all coal categories in Indian context and its impact on estimation of CO_2 emission from coal combustion activities

摘要

This paper highlighted the need for periodic change in country specific NCVs and CEFs of solid fuels. Accepted India specific NCV/CEF values of coking coal, non-coking coal and lignite were worked out during the India's Initial National Communication'2004 taking 1994 as the base year. Those values continued to be in use in CO2 estimations done by sectoralational/international agencies and also in estimations related to India's Second National Communication'2012 to UNFCCC. In present investigation fresh estimations taking base year as 2007 were done considering large numbers of relevant post 2006 coal-quality data for each Indian coal category and as a result NCV of non-coking and coking coal diminished by 6.6% and 2.1% respectively. The changes happened due to cumulative effect of slow changing quality of coking, non-coking coals and their grade-wise production pattern over the years. Using new NCV-CEF values, reduction of CO2 emission by 53.4 Tg, solid fuel (coal and lignite) emission by 5.4%, total fossil fuel emission by 3.8%, sectoral emissions by 2.7%-5.9% were observed. The relevance of new NCV-CEF values were examined in present context and the new values should be used for accurate estimation of CO2, which indicates energy efficiency and clean use of coals.