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Can biogas technology help reduce PM2.5!?
How can biogas technology help mitigate PM2.5 emissions to the atmosphere?
In this article, we will explore the possibility of this issue. Currently we know that this tiny particle called PM2.5 micron is a national issue that effect not only human health but also impact our economic and environment.
The negative effects of PM2.5 to human are such as eyes irritation, skin soreness, retard brain development, Attention Deficit Hyperactivity Disorder (ADHD), asthma and much more. The sensitive population can be highly effected such as small children or elderly people. Thailand and Southeast Asian countries are the hot spots for this kind of problems now. Furthermore, PM2.5 could result in reduction of the numbers of tourists, since they would not like to visit places where the air is polluted.
Fire in a rice field
Fire in a rice field from Kuanstol LAO, Satul Province, Thailand
Based on the research by Chulalongkorn University (Knowing PM2.5 by Chulalongkorn University), Thailand, major sources of PM2.5 could be different in urban and rural areas. For example, in urban areas such as Krungthep (Bangkok), Chiangmai, traffic, construction and industries generate most of PM2.5. While wildfire and agriculture residuals burning causes most PM2.5 in the reral areas, particularly burning of rice straw, corn leaves and sugar canes. Details are shown in the below figure.
Figure 1 – Proportion of hot spots classified following the land use pattern by Department of Land Development (DLD) and categorized based on the responsible areas in month January – April 2021 of Thailand
Source: Geo-Information and Space Technology Development Agency (GISTDA) via The Standard
In 2022, Thailand produced major crops as follows:
- Rice 22 million metric tons
- Corn 19 million metric tons
- Sugar cane 86 million metric tons
The agricultural residue from these crops are shown in the below table. Most of these residue are always burnt which generates significant amounts of small particulate matter or PM2.5 in the vicinity. With the current technology, we can harvest all these crop residues and put them into the anaerobic digestion (AD) process. Biogas from AD can be further processed to liquefied biomethane or liquid carbon dioxide. Details are shown in the below table.
| Residue | Weight (million MT per annum) | Electricity production (MW/hr) | Liquefied Biomethane (MT per day) | Liquid CO2 (MT per day) |
| Rice straw | 33 | 2,300 | 10,510 | 14,700 |
| Corn cobs and husks | 6.7 | 371 | 1,690 | 2,000 |
| Sugar cane leaves and shoots | 17 | 782 | 3,570 | 4,900 |
| Total | 56.7 | 3,453 | 15,770 | 21,600 |
If Thailand were to collect all agricultural wastes and turn into energy, It can possibly produces up to 3,000 MW/hr electricity or up to 15,770 MT of LBM per day. This can significantly decrease dependent of imported Liquefied Natural Gas (LNG) by almost 5.7 million metric tons per year. It can save the country up to 4.3 billion USD per year. Additionally and most importantly, this scheme can help alleviate around 50% of PM2.5 emissions to the atmosphere.
The possible benefits from this scheme are as follows.
- Assist in 100% PM2.5 mitigation from agricultural residue which is considered as 50% from the total PM2.5 generation in Thailand.
- Enhance farmers’ revenue from selling crops residues resulting in 8 billion THB per annum. This figure is based on the buying price of 135 THB per ton for rice straw and corn cobs and husks as well as 150-200 THB per ton for Laves and sugar cane shoots
- Increase the proportion of renewable energy for Thailand energy sources. This can be highly attractive for green energy funds and manufacturers who need low or zero carbon emissions for their facilities.
- Decrease 5.7 million tons of LNG per annum import to Thailand. This is equivalent to 46% of total LNG import to Thailand in 2023.
- Turn old style Thai industries to green industries due to green sources of energy.
- Reduce carbon emission to the atmosphere, thus, mitigate climate change.
- In line with Thai government’s Bio-Circular-Green Economy (BCG) Model and United Nations Sustainable Development Goals (SDGs) goals numbers 7 (Affordable and clean energy) and 13 (Climate action).
You can see now that biogas technology can actually help to fight PM2.5 from agriculture residue. In the next steps, the writer sincerely hope that Thai people can help to drive this kind of policy to the policy makers in Thailand and in the region. This will make significant to the air we create and the earth we inhabit and for our future generations.
One of a good and successful example of this kind of project can be seen in India where the government is turning rice straw to compressed biomethane gas (CBG). Please see details in the below link.
Punjab’s first bio-CNG plant starts paddy straw collection
Writer : Apipong Lamsam (D Eng) is the managing director at Papop and Secretariat at Thai Biogas Trading Association. With over 15 year in renewable energy sector, he is renown domestic and international “biogas expert”
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