Fugitive methane emission from open pit coal mining operations is one of the significant contributors for greenhouse gas (GHG) emission in the Scope 1 category. In Indonesia the calculation method that is still widely used is Tier 1 from IPCC 2006 method, which is based on global default emission factors and does not account for local site specific geological condition such as overburden thickness and actual gas in place content. This study aims to apply the implementation Tier 3 from IPCC Method based on direct methane gas measurement in order to produce more accurate and more applicable for represent methane fugitive emission estimate. The study was conducted at PT Borneo Indobara (BIB) by taking coal samples trough exploration drilling and methane gas desorption analysis using international standards such as GPA 2261 and ASTM D1946. The result showed that the average actual methane content of 0.40 m3/ton was much lower than the Tier 1 default of 2 m3/ton, indicating the potential for reducing CO2e emission from changing baseline calculation from Tier 1 IPCC into Tier 3 IPCC. This suggests a potential reduction in CO?e emission baseline estimates of up to 80%, which could translate into substantial carbon tax savings. The implementation Tier 3 contributes to increase the accuracy of GHG reporting, compliance with ESG standards, fairer and more data based carbon tax calculations. This study recommends the use of Tier 3 as transparent, scientific and replicable approach in other coal mine in Indonesia to support national decarbonization policies and strengthen the credibility of domestic carbon markets.
Santoso et al. (Tue,) studied this question.