A Study on Applying Biomass Fraction for Greenhouse Gases Emission Estimation of a Sewage Sludge Incinerator in Korea: A Case Study

According to the IPCC (Intergovernmental Panel on Climate Change) guidelines, when calculating CO2 emissions, CO2 emissions from biomass should be excluded from the total amount of CO2 emissions and should be separately reported due to their “carbon neutrality”. Sewage sludge is one of the representative biomass fuels. It is mixed with fossil fuels to achieve greenhouse gas reduction or is used by itself as a fuel to replace fossil fuels. According to the results of this study, biomass fractions of both the sewage sludge and the sewage sludge incineration exhaust gases did not amount to 100%. At present, in many countries (South Korea, Japan, and Germany), when calculating greenhouse gas emissions from sewage sludge incinerators, all CO2 emissions from sewage sludge are judged to be biomass and only the greenhouse gas emissions that correspond to non-CO2 gases are calculated as greenhouse gas emissions. However, since, according our results, the content of sewage sludge is not 100% biomass, if CO2 emissions are excluded according to the existing greenhouse gas emission calculation method, the amount of emissions may be underestimated. Therefore, to accurately calculate greenhouse gas emissions from a sewage sludge incinerator, CO2 emissions should be calculated in consideration of the fossil carbon fractions of sewage sludge.