Group 1 - Coal is referred to as "industrial food" and remains crucial for human society despite the rise of new clean energy sources [1][3] - The global proven coal reserves amount to 984.211 billion tons, with significant contributions from the US, Russia, and China [3][5] - Coal is a non-renewable fossil fuel formed over millions of years, making it a precious resource [5][7] Group 2 - Major coal-producing countries like the US, Russia, and China significantly influence the global coal market due to their large reserves [5][9] - The US has the largest coal reserves in the world, estimated at over 3000 billion tons, primarily sourced from the Appalachian coalfield [9][11] - The Appalachian coalfield covers 180,000 square kilometers and produces over 400 million tons of coal annually, accounting for 50% of US coal production [11] Group 3 - Russia holds over 2000 billion tons of coal reserves, primarily located in Siberia and the Ural Mountains, with a focus on environmental sustainability and technological innovation in recent years [13][15] - China is the largest coal producer globally, with a production of over 4 billion tons in 2021, reflecting a 5.99% increase from 2020 [15][17] - China's total coal reserves are approximately 2028 billion tons, ranking fourth globally, with significant production from Shanxi, Shaanxi, Inner Mongolia, and Xinjiang [15][17] Group 4 - China's coal mining technology has advanced, improving efficiency and quality, but the industry faces challenges such as land subsidence and environmental pollution [17][19] - The coal structure in China is unbalanced, with low proportions of high-quality and clean coal, leading to inefficiencies and increased pollution risks [19] - The government is promoting clean coal utilization, but further efforts are needed to address the industry's challenges for better development [19]