In the context of the global effort towards a sustainable future and minimizing the impact of climate change, the inventory and management of greenhouse gases (GHG) has become an urgent task. One of the most important tools to carry out this task is the CH4 emission factor. This is not only a scientific term but also a foundation for countries, businesses and organizations to accurately measure, report and manage their carbon footprint. Accordingly, in the article below, GREEN IN will provide a comprehensive view of CH4 emission factor in Vietnam, from legal regulations to practical applications in key areas.
What is Methane Gas (CH4)?
Methane (CH4) is a greenhouse gas with a significantly higher global warming potential than Carbon Dioxide (CO2). Depending on reports and calculation methods, this potential can be 25 to 29.8 times higher over a 100-year cycle. This means that each ton of CH4 emitted into the atmosphere has the same destructive power as dozens of tons of CO2. Therefore, understanding and correctly applying the CH4 emission factor is a decisive step in developing effective emission reduction strategies, contributing to Vietnam's commitment to achieving Net Zero by 2050.
CH4 emission factor according to Vietnam regulations
To standardize GHG inventory activities nationwide, the Ministry of Natural Resources and Environment issued Decision No. 2626/QD-BTNMT in 2022. This Decision announced a list of emission factors applicable to Vietnam, built on the methodology of the Intergovernmental Panel on Climate Change (IPCC). Below is an overview of CH4 emission factors applied to major socio-economic sectors.
Energy Sector: From Production to Consumption
Energy is the lifeblood of the economy but is also a major source of GHG emissions. Burning fuels to generate electricity, operate machinery and move around creates significant amounts of CH4.
Industrial fuel combustion:
- Power plants and manufacturing plants using anthracite coal and natural gas have an emission factor of 1 kg CH4/TJ.
- Liquid fuels such as diesel and fuel oil (FO) have higher coefficients, at 3 kg CH4/TJ.
- Biomass and charcoal energy sources, although considered renewable, have very high CH4 emission factors, 30 kg CH4/TJ and 200 kg CH4/TJ, respectively, due to incomplete combustion.
Transportation:
- Transportation is also an industry that generates large CH4 emissions, putting strong pressure on the living environment:
- Road transport is a major source of CH4 emissions, particularly from gasoline (33 kg CH4/TJ), liquefied petroleum gas (62 kg CH4/TJ) and natural gas (92 kg CH4/TJ). This highlights the need to transition to cleaner energy vehicles.
- The domestic aviation industry has a relatively low coefficient (0,5 kg CH4/TJ), while water and rail transport using diesel oil have coefficients ranging from 4,15 to 7 kg CH4/TJ.
Fugitive Emissions:
- This is the amount of gas leaked during the exploitation, processing and transportation of fuel.
- Underground coal mining (1,5789 m³ CH4/ton) and oil and gas exploitation (0,0196 thousand tons of CH4/10³m³ of product) are typical sources of CH4 emissions that need to be strictly controlled.
Agriculture, Forestry and Land Use (AFOLU) Sector
Agriculture is an important economic sector in Vietnam but is also a leading source of CH4 emissions, mainly from livestock and rice cultivation.
Rice cultivation:
- This is the source of the largest CH4 emission factor in Vietnam's agriculture. Decision 2626 has provided detailed emission factors for each crop (Spring/Winter-Spring, Summer-Autumn/Season) and each region (North, Central, South).
- For example, the Winter-Spring rice crop in the North has an emission factor of 1,61 kg CH4/ha/day. These factors are adjusted based on water management regimes and the addition of organic matter such as straw.
Breed:
- CH4 emissions from ruminant feed digestion are huge. A dairy cow can emit up to 78 kg CH4/year, beef cattle 54 kg CH4/year, and buffalo 76 kg CH4/year.
- Livestock waste management also generates CH4. The emission factor depends on the type of livestock, temperature, and treatment method. For example, an anaerobic digestion system (biogas digester) has a much higher CH4 conversion factor (MCF) than conventional composting.
Waste Sector
Anaerobic decomposition of organic waste in landfills and wastewater treatment systems is a huge source of CH4 emissions.
- Solid waste landfills: Emission factors depend on the type of landfill (managed or not), waste composition (food, paper, wood, etc.), and the percentage of biodegradable organic carbon (DOC). Landfill gas (LFG) typically contains about 50% CH4.
- Wastewater treatment: Both domestic and industrial wastewater have the potential to generate CH4, especially when treated by anaerobic methods or discharged untreated into the environment. Methane Correction Factor (MCF) will be very high in these cases.
Practical research: The numbers speak for themselves
To better understand the impact of these coefficients, we will present some case studies in Vietnam.
Research on cattle farming in Thua Thien Hue
A specific study in Thua Thien Hue has shown that waste management methods have a great influence on the amount of CH4 emitted.
- Solid Storage (SS) produced an average of 2,77 times more CH4 than the dry lot system (DL).
- Total emissions from manure and wastewater The average is 2,48 kg CH4/head/year. With a total herd of nearly 30.000 cows, it is estimated that this locality emits more than 70 tons of CH4 per year from cattle farming alone, equivalent to 1.758 tons of CO2. This figure shows the huge potential for emission reduction through improving livestock waste management methods.
Rice cultivation and emission reduction solutions
Rice cultivation accounts for up to 50% of the total GHG emissions of Vietnam’s agricultural sector, equivalent to nearly 50 million tons of CO2 per year. However, this is also a sector with many proven effective intervention solutions to reduce CH4 emissions:
- Alternate wetting and drying (AWD) irrigation technique: Helps reduce CH4 emissions by 30-70% compared to traditional continuous flooding methods.
- System of Rice Intensification (SRI): Changing farming techniques helps the soil to be more aerated and reduces the ability to produce CH4 gas.
- Using biochar: Potential to reduce CH4 emissions by 14% to 55% by improving soil properties.
- Crop structure conversion: Converting part of the rice land area to rice-aquaculture or upland crop models could reduce up to 5 million tons of CO2 equivalent per year.
Nam Son Landfill - "Mine" of CH4 emissions
Research at the Nam Son landfill (Hanoi) shows that landfill gas contains 45-60% CH4. The CH4 generation capacity here is 56,4 m³/ton of solid waste. In the first year alone, a landfill cell can generate nearly 5 million m³ of CH4. This huge number emphasizes the urgency of sorting waste at source, recycling, and applying modern waste treatment technologies such as waste incineration to generate electricity or landfill gas recovery to reduce emissions.
The Importance of the National Emission Factor
An important highlight in studies in Vietnam is the difference between national emission factors and the IPCC default factors.
Research shows that the emission factor from cattle farming in Vietnam is 3-5% lower than the default factor given by the IPCC for the Asia region. If the default factor of the IPCC is applied, the CH4 emission of Vietnam may be overestimated by 19,5% to 22%. This is equivalent to adding millions of tons of CO2 to the national inventory report each year.
This difference confirms that the development and continuous updating of a set of CH4 emission coefficients specific to Vietnam's natural, socio-economic and technological conditions is extremely important. It not only ensures the accuracy, transparency and reliability of GHG inventory work, but also helps us develop more appropriate and effective emission reduction policies and strategies, avoiding wasting resources on incorrect assessments.
Conclusion
CH4 emission factors are not just numbers in scientific reports, but are essential quantitative tools, helping us to see invisible emission sources and measure their impacts. Understanding and correctly applying these factors, from the national level to each business and production facility, is the foundation for all efforts to mitigate climate change.
GREEN IN believes that climate action must start with transparent and scientific data. By mastering and effectively using the CH4 emission factor, Vietnam can accurately identify priority areas, deploy appropriate technological solutions and optimize resources to successfully implement international commitments, firmly on the path of green transformation and sustainable development.