Current Status and Recommendations for Methane Emissions in China under the Background of Carbon Neutrality

Comparison of methane emissions from major anthropogenic sources in China, the European Union, and the United States (unit: %)

The Second Biennial Update on Climate Change Report of the People's Republic of China (hereinafter referred to as the "Report") is the latest official greenhouse gas emissions report released by China. The Report shows that in 2014, China's total methane emissions amounted to 55.292 million tons, equivalent to 1.161 billion tons of carbon dioxide, accounting for 10.4% of total greenhouse gas emissions. Energy activities, agricultural production, and waste disposal are the main sources of methane emissions in China.

Energy activities are the main source of methane emissions.

In 2014, China's energy activities emitted 24.757 million tons of methane, accounting for 44.8% of total emissions, a significantly higher proportion than in Europe and the United States. Further breakdown reveals even more pronounced differences between China and Europe/the United States. In China, methane emissions from energy activities primarily originate from the coal industry (accounting for 38% of total emissions and 85% of energy sector emissions), while in the United States, methane emissions from the energy sector mainly come from the oil and gas industry. This is related to China's energy structure. In 2014, raw coal accounted for 73.5% of China's total primary energy production (and remained high at 67.6% in 2020). Unorganized methane emissions during coal mining also increase the difficulty of emission reduction. Although methane emissions from the oil and gas industry are currently not high, with the adjustment of China's energy structure, the proportion of coal in primary energy has begun to decline, while the proportion of natural gas is continuously increasing. Natural gas's main component is methane. At the same time, methane leaks from the oil and gas industry cannot be ignored.

Agricultural production is the second largest source of methane emissions.

In 2014, methane emissions from agricultural production in China totaled 22.245 million tons, accounting for 40.2% of total emissions, higher than the United States but lower than the European Union. The breakdown also differs from that of Europe and the United States. In Europe and the United States, methane emissions from agriculture mainly come from livestock farming such as cattle and sheep, while in China, they mainly come from rice cultivation and livestock farming. This is related to dietary habits: European and American countries consume more milk and beef and mutton, while more than 65% of Chinese people rely on rice as their staple food; rice is China's main food crop, with a rice planting area exceeding 300 million hectares. Therefore, methane emissions from rice paddies in China account for 16.1% of total emissions, while in Europe and the United States, methane emissions from rice paddies are generally less than 1% of total emissions.

Methane emissions during waste treatment are significantly lower than expected.

In 2014, methane emissions from waste treatment in China totaled 6.564 million tons, accounting for 11.9% of total emissions, significantly lower than in Europe and the United States, and less than half that of the European Union. Landfill and wastewater treatment accounted for 6.9% and 4.9% of methane emissions from waste treatment in China, respectively. However, with the increasing proportion of municipal solid waste incineration in China, methane emissions from landfill will continue to decrease, while the proportion of methane emissions from wastewater treatment will continue to increase.

Recommendations for methane emission reduction in China

Improve the methane monitoring network and emissions data reporting system.

The production of methane differs from the combustion of fossil fuels to produce carbon dioxide. Whether in rice paddies, animal intestines (such as those of cattle and sheep), or wastewater treatment, the reduction of organic matter to produce methane generally requires microbial action, making the process complex and its estimation highly uncertain. Strengthening monitoring is an effective way to understand actual methane emissions and can provide technical support for future revisions to emission indices, while also providing theoretical guidance for China's participation in the formulation of relevant international rules. Regarding environmental baseline monitoring, real-time monitoring of methane and other greenhouse gases can be achieved by adding methane and other greenhouse gas detection equipment to the existing nationwide atmospheric environmental quality monitoring stations.Meanwhile, satellite remote sensing equipment can be used to obtain overall methane background data for the region. Regarding pollution source monitoring, for some key pollution sources, methane monitoring sensors can be added to existing online monitoring systems, or real-time monitoring can be conducted via remote sensing satellites; for other pollution sources, the sampling frequency should be increased to obtain more accurate emission data.For key industries and key enterprises, the reporting system for methane-related data should be improved, pollution emission coefficients should be revised, and the quality of methane emission data should be continuously improved.

Improve the legal, regulatory and standard system for methane emission reduction

While methane and other greenhouse gases do not directly harm human health, their potential hazards cannot be ignored. Therefore, it is necessary to clarify their classification in relevant laws and regulations such as the Air Pollution Prevention and Control Law, and to gradually improve related laws and regulations, raising existing methane emission standards. For example: raising the emission standards for methane in GB21522-2008, and further developing and improving mandatory standards for methane extraction rate, methane utilization rate, and methane emission rate; raising the leakage identification concentration standards in GB39728-2020, improving mandatory standards for recycling, gradually reducing flaring, and prohibiting venting; raising the concentration limits for methane emissions in GB18918-2002 and GB16889-2008, and improving recycling standards. Adding methane emission requirements to standards that include methane emissions but do not set emission concentration requirements (such as the "Emission Standard for Pollutants from Petroleum Refining Industry"). Gradually incorporating enterprise methane emissions into the carbon emission trading market, and through policy guidance, increasing enterprises' enthusiasm and initiative in recycling methane.

Methane emission reduction will be gradually implemented, with the oil and gas industry serving as a pilot sector.

China's oil and gas industry has a relatively good foundation for methane emission reduction, and most countries also prioritize the oil and gas sector for methane emission reduction. Therefore, the oil and gas industry can serve as a pilot sector for methane emission reduction in China. Regarding the current emission situation in the oil and gas industry, it is necessary to strengthen infrastructure construction to reduce venting and flaring activities and improve methane recovery and utilization rates; for methane emissions that cannot be avoided, they must be fully combusted before release; simultaneously, a pipeline leak monitoring and maintenance system should be established to promptly detect and repair emission sources; furthermore, it is necessary to further improve the system to enhance the transparency and accuracy of methane emission performance data from oil and gas companies.

With the adjustment of the energy structure, the total consumption of coal has been declining. However, due to factors such as the country's coal-dominated natural resource endowment and the insufficient stability of new energy sources, coal will remain the primary source of energy production and consumption in China for some time to come. As shallow coal resources are depleted, more coal mines in China will relocate to deeper mines. Generally, the deeper the mine, the higher the methane content of the coal seam. Therefore, coal mining and post-mining activities will remain a significant source of methane emissions in China, making the coal industry a key sector for methane emission reduction. To address the low utilization rate of low-concentration methane, it is necessary to increase research efforts in this area, develop efficient technologies for its utilization, and achieve centralized, networked recovery and utilization of methane in mining areas.

As the second largest greenhouse gas, methane emission reduction is an inevitable trend. China, as the world's largest methane emitter, will inevitably face increasing international pressure to reduce emissions. Although China started its methane emission reduction efforts relatively late and faces significant pressure, with continuous adjustments to its energy structure, stabilizing grain production, and decreasing landfill waste, China's methane emissions can peak simultaneously with carbon dioxide emissions before 2030.

Source of reference material:

Research on Methane Emission Reduction Strategies in China under the Background of Carbon Neutrality