Indonesia's country-specific CO2 emission factor based on gas fuels for greenhouse gas inventory in the energy sector

Indonesia currently calculates CO2 emissions from gas fuels using Tier 1 emission factors adopted from the Intergovernmental Panel on Climate Change (IPCC). However, this method may not accurately capture the country's specific emission characteristics. To address this, this study aims to derive country-specific CO2 emission factors for gas fuels, including liquefied petroleum gas (LPG), liquefied gas for vehicles (LGV), natural gas (NG), and liquefied natural gas (LNG), by analyzing fuel samples collected nationwide. A total of 128 LPG samples from 25 regions, 5 LGV samples from 2 regions, 23 NG samples from 11 regions, and 2 LNG samples from 2 regions were analyzed. Emission factors were determined based on gas composition, carbon content, and net calorific value. The uncertainties were calculated to reflect the contributions of all key parameters in the emission factor calculation. The results show that LPG has the highest EF Tier 2, while LNG has the lowest. The average country-specific CO2 emission factors for Indonesia are 65.41 ± 0.67 tCO2/TJ for LPG, 64.89 ± 0.07 tCO2/TJ for LGV, 57.64 ± 10.18 tCO2/TJ for NG, and 57.27 ± 9.50 tCO2/TJ for LNG. We expect stakeholders to incorporate these EF Tier 2 values into greenhouse gas reporting, enabling more accurate assessments of carbon footprints, supporting evidence-based policymaking, and strengthening Indonesia's climate action efforts.