Unintended mitigation benefits of China's coal de-capacity policies on methane emissions

Coal de-capacity policies are often used to promote the integration of coal resources and optimize the production structure in China. This study used a bottom-up approach to evaluate the unintended effect of China's coal de-capacity policies on methane emissions mitigation from 2011 to 2019. Under the effect of such policies, the closed coal capacity was 46% of the total coal capacity in 2011. A total of 9567 coal mines with 1610 Mt of capacity were closed. The capacity of low CH4-content coal mines accounted for 77% in 2019, and the capacity of high and outburst CH4-content coal mines decreased by 9% compared to 2011. The adjustment in coal production structure in turn affects coal mine methane emission intensity, hence the national average coal mine emission factor decreased from 9 m3/t in 2011 to 8 m3/t in 2019. The coal de-capacity policies generated a cumulative 10.70 Tg of methane emissions mitigation from 2011 to 2019, even with rebounded coal production. As the number of coal mine closures continues to increase, the priority phase-out of high and outburst CH4-content mines will further lead to greater methane mitigation. In the future, more attention should be paid to methane emissions from abandoned mines.