Country-Specific CO2 and Non-CO2 Emission Factor for Coal Electricity Generation in Malaysia

Abstract

Malaysia’s national greenhouse gas (GHG) emissions inventory for electricity generation utilises the default GHG emission factor values from the 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines. Electricity generation is the key source of GHG emissions; hence, improvement in the emissions assessment through developing country-specific emission factors (EF) will increase the accuracy and further reduce the uncertainty of reported national GHG emissions. In 2019, the uncertainty of the total inventory without Land Use, Land-Use Change and Forestry (LULUCF) was ±15.12%, and the uncertainty in trend was ±12.70%, which is in the higher range. Thus, this study analysed 2017-2019, carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) emission factors from the stationary combustion of coal-fired power plants to develop the representative country-specific emission factor of the coal used in Malaysia using the fuel analysis and flue gas method. This study also supplements an assessment of relevant country-specific oxidation factors. The results indicate that the weighted average of each year for the CO₂ emission factor of Bituminous coal is lower than IPCC default values from 93,078 kgCO₂/TJ to 93,224 kgCO₂/TJ, whilst Sub-Bituminous coal averages from 96,260 kgCO₂/TJ to 96,714 kgCO₂/TJ and Lignite coal higher than the IPCC values, from 101,720 kgCO₂/TJ to 105,116 kgCO₂/TJ. In deriving the emission factor, the carbon content was lowest for Bituminous coal, followed by Sub-Bituminous coal, and significantly higher for Lignite coal. The CO₂ emission factors values analysed are 1% lower for bituminous coal and 1% to 4% higher for sub-bituminous coal and lignite compared with 2006 IPCC Guidelines default values. For Bituminous, the calculated emission factor of CH₄ is 0.1011 kgCH₄/TJ and N₂O is 0.7047 kgN₂O/TJ. As for Sub-Bituminous, the calculated CH₄ emission factor is 0.0883 kgCH₄/TJ whilst for N₂O is 0.9516 kgN₂O/TJ. The emission factor for Lignite’s CH₄ is 0.0402 kgCH₄/TJ and N₂O is 0.5563 kgN₂O/TJ respectively. The coal CH₄ and N₂O emission factors are lower than the Tier-1, fuel-based method suggested by the IPCC. The significant variations for coal depend on the differences between the producing regions and characteristics, chemical properties, and annual fluctuations in fuel quality. This study has shown that emission factors changed due to the variations of coal used by the power plant, either due to the carbon content or calorific value. This fact certainly will influence the decision-making process, affecting the choice of coal used in the power plants that will be included in future national energy systems.