Amid Global Decarbonization Commitments, How do Methane Emissions in China Compare with the US and Canada?

By Hua-Ke (Kate) Chi

While countries worldwide gauged progress towards greenhouse gas emissions reduction targets at the recent climate talks in Egypt, China continues to be the world’s top carbon dioxide emitter.

Although many countries have committed to carbon neutrality, global methane emissions have increased by 10 percent in the past 20 years. Methane is a less-studied greenhouse gas, but it has a much higher global warming potential than carbon dioxide. How do methane emissions from China’s fossil fuel industry compare with those of the US and Canada? A new study examines methane emissions from the three countries to provide a critical overview of the current research landscape.

To begin, the authors found that although previous research has identified that methane emissions from the natural gas industry in the US and Canada are higher than reported, there is limited information on China’s natural gas sector due to dissimilar resource endowment, energy consumption structure and accounting methods. Therefore, the authors set out to assess methane emission in China’s natural gas industry, current Chinese research progress on the subject and relevant emissions mitigation efforts in China.

Methane emissions from the oil and gas industry account for a very low share of total methane emissions in China, relative to the US and Canada. This is due to the characteristic differences in the national energy structure across these countries. China’s natural gas consumption is approximately 8 percent in primary energy consumption compared to 30 percent in the US or Canada. However, as China is highly dependent on coal-fueled electricity production, coal mining has become the largest methane emissions source in China in comparison with natural gas related activities. Furthermore, the proportion of methane emissions by phase in the natural gas supply chain in China is vastly different from that in the US or Canada. China has the highest proportion of methane emissions in the natural gas distribution phase, while emissions are high in the production phase in the US and Canada. In addition, because longer transmission pipelines require more compressor stations, where methane leakage tends to occur, the differences in the length of natural gas transmission pipelines in China, Canada and the US contribute to dissimilarities in methane emissions in this phase.

The authors also compared the various methods used to estimate methane emissions in each country. Current levels of data accuracy make comparisons challenging due to objective differences in methane quantification methods across China, the US and Canada. The authors divided calculation methods into three categories: Tier 1 and Tier 2, classified as “bottom-up” methods, quantifying methane emissions based on emission factors, while Tier 3, considered the most accurate method, includes both “top-down” methods, such as the aircraft mass balance method, and bottom-up methods like point-to-point detection and implements field measurements. At present, Tier 1 methods are commonly adopted in China while the US and Canada have implemented Tier 3 top-down methods such as aircraft measurement, remote sensing technology. To address the comparability gap, the authors suggest research on China’s methane emissions expand to Tier 2 and Tier 3 approaches to collect more accurate measurement results. As the natural gas industry is not the largest source of methane emissions in China, relevant and robust studies are limited. Historic research focuses on leakage point detection in China, with research sites concentrated in the Sichuan or Chongqing regions. Thus, further comprehensive data collection and studies are necessary to form an understanding of methane emissions at the national level in China.

Lastly, the authors compare methane emissions reduction measures across the three countries. Regulatory measures in the oil and gas industry are increasingly more strictly enforced in the US since 2016, when leak detection and repair (LDAR) technology was required in energy enterprises. In China’s 14^th Five-Year Plan announced in 2021, methane was newly included in greenhouse gas control objectives. Although China is encouraging the formation of a methane emissions control system, current regulations have not yet established specific requirements for methane emissions reduction technology. Opportunities to rapidly advance mitigation technology, research methods and data-driven research are present in China, and joint development of interdisciplinary methane quantification technology across the three countries is critical to facilitate future studies and emissions reduction measures.

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Hua-Ke (Kate) Chi is a Research Assistant with the Global China Initiative and an MA Candidate in Economics at Boston University.

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