Carbon and nitrogen isotope characterization of imported coals in South Korea

Abstract

Since the Industrial Revolution in the late 1700s, coal has been a major energy source widely used in transportation, industries, and electricity generation. According to recent statistics on total global coal production, the coal consumption rate has continuously increased from 4,699 Mton in 2000 to 8,025 Mton in 2022 (International Energy Agency, IEA, 2022). The increase in coal consumption is closely related to the production of electricity. In 2017, the International Energy Agency, IEA, 2019 reported that coal-fired power plants generated 40% of total electricity worldwide. Despite the necessity of coal, its use contributes to a rise in the Earth's temperature due to the emission of greenhouse gases (e.g., CO 2 ) into the atmosphere during combustion. Global warming, due to the use of fossil fuels, including coal, has increased the global mean surface air temperature by 0.89 °C in 2022 (National Oceanic and Atmospheric Administration National Centers for Environment Information, NOAA, 2022). Recently, at the Paris Climate Conference in 2015, nearly 200 countries adopted an international agreement that aims to reduce greenhouse gas emissions to keep the global average temperature at <2 °C above pre-industrial levels (UNFCCC, 2015).China is the largest coal-producing country in the world, with >48% of global coal production (International Energy Agency, IEA, 2020). However, since 2005, China's average annual coal consumption rate has slightly exceeded the national coal production rate. Consequently, approximately 7% (300 million tons) of the total coal consumption in China has been imported from Indonesia (65.8%), Russia (17.4%), and Mongolia (3%) (International Energy Agency, IEA, 2022). However, in South Korea, the coal consumption rate (157 million tons) has largely exceeded the coal production rate (1.9 million tons) (CEIC, 2021). Therefore, the coal consumed in South Korea relies entirely on imports from other countries. In 2022, the largest amount of coal was imported from Australia (37%), followed by Russia (22%), Indonesia (20%), Canada (7%), South Africa (5%), the United States (3.7%), the Philippines (1.6%), and Colombia (1.4%) (Korea Institute of Geoscience and Mineral Resources, 2023). In contrast, imports of coal from China have gradually decreased, accounting for only 0.03% of total coal imported into South Korea in 2022.Geographically, South Korea is located to the east of China, and air pollutants (including greenhouse gases) emitted from thermal power and industrial plants in China are