Methane quantification of LNG gas-fired power plant in Seoul, South Korea

Abstract. Methane emissions from a liquefied natural gas (LNG) gas-fired power plant in Seoul, South Korea were measured using a mobile greenhouse gas measurement platform. Twenty-one mobile measurements were conducted between February and July 12, 2023. Methane emissions were quantified using the Gaussian Plume Dispersion Model and the OTM-33A method. The measurements identified three key emission hotspots: two associated with natural gas pipelines (S1 and S2), and one linked to an exhaust pipe from internal facilities (S3). The average methane emission rates were 0.09 ± 0.0086, 0.018 ± 0.0015, and 0.55± 0.0583 tons hr^-1 at S1, S2, and S3, respectively. Notably, S3 had a significant methane emission rate of 2.053 ± 0.283 tons hr^-1, approximately six times greater than our corresponding bottom-up estimate of fugitive methane emissions (0.35 tons hr^-1). This significant discrepancy, particularly at S3, highlights the limitations of bottom-up inventory approaches and underscores the importance of field measurements for accurately assessing real-world emissions. This study provides crucial evidence that mobile measurements are useful in identifying and quantifying fugitive methane emissions from urban LNG power plants. These findings are essential for developing a more precise understanding of effective methods to reduce methane emissions from these facilities.