Air Pollution

CBG: Renewable energy revolution


From UPSC perspective, the following things are important :

Prelims level : CBG

Mains level : Stubble burning, air pollution and solutions, CBG



  • The beginnings of a renewable energy revolution rooted in agriculture are taking shape in India with the first bio-energy plant of a private company in Sangrur district of Punjab having commenced commercial operations on October 18. It will produce Compressed Biogas (CBG) from paddy straw, thus converting agricultural waste into wealth.


  • Stubble burning every year in north and northwest: It has become common practice among farmers in Punjab, Haryana and western Uttar Pradesh to dispose of paddy stubble and the biomass by setting it on fire to prepare fields for the next crop, which has to be sown in a window of three to four weeks. This is spread over millions of hectares.
  • Resultant smog polluting environment: The resultant clouds of smoke engulf the entire National Capital Territory of Delhi and neighbouring States for several weeks between October to December. This plays havoc with the environment and affects human and livestock health.
  • Stubble burning practice spreading rapidly across the country: Though paddy stubble burning in northwest India has received a lot of attention because of its severity of pollution, the reality is that crop residue burning is spreading even to rabi crops and the rest of the country. Unless these practices are stopped, the problem will assume catastrophic proportions.

 What is Stubble Burning?

  • Stubble (parali) burning is a method of removing paddy crop residues from the field to sow wheat from the last week of September to November.
  • It is usually required in areas that use the combined harvesting method which leaves crop residue behind.
  • This practice mostly carried out in Punjab, Haryana and UP contributes solely to the grave winter pollution in the national capital.


How stubble burning impacts environment and Human health?

  • Deteriorates air quality: The process of burning farm residue is one of the major causes of air pollution in parts of north India, deteriorating the air quality.
  • Source of various harmful gases: Stubble burning is a significant source of carbon dioxide (CO2), volatile organic compounds (VOCs), nitrogen oxides (NOx) and hydrocarbons (HC).
  • Air Pollution: Stubble burning emits toxic pollutants in the atmosphere containing harmful gases like Carbon Monoxide (CO), methane (CH4), carcinogenic polycyclic aromatic hydrocarbons, volatile organic compounds (VOC). These pollutants disperse in the surroundings and eventually affect air quality and people’s health by forming a thick blanket of smog. Along with vehicular emissions, it affects the Air Quality Index (AQI) in the national capital and NCR.
  • Soil degradation: Soil becomes less fertile and its nutrients are destroyed when the husk is burned on the ground. Organic content of soil is completely destroyed. Stubble burning generates heat that penetrates into the soil, causing an increase in erosion, loss of useful microbes and moisture.


Some of the measures taken by Government for the effective prevention and control of stubble burning

  • The Commission for Air Quality Management: The Commission for Air Quality Management in National Capital Region and Adjoining Areas (CAQM) had developed a framework and action plan for the effective prevention and control of stubble burning,
  • In-situ management: The framework/action plan includes in-situ management, i.e., incorporation of paddy straw and stubble in the soil using heavily subsidized machinery (supported by crop residue management (CRM) Scheme of the Ministry of Agriculture and Farmers Welfare).
  • Ex-situ management: Ex-situ CRM efforts include the use of paddy straw for biomass power projects and co-firing in thermal power plants, and as feedstock for 2G ethanol plants, feed stock in CBG plants, fuel in industrial boilers, waste-to-energy (WTE) plants, and in packaging materials, etc.
  • Awareness generation programme: Additionally, measures are in place to ban stubble burning, to monitor and enforce this, and initiating awareness generation.
  • Project by NITI Aayog along with FAO: NITI Aayog approached FAO India in 2019 to explore converting paddy straw and stubble into energy and identify possible ex-situ uses of rice straw to complement the in-situ programme.
  • Rice straw for producing CBG: A techno-economic assessment of energy technologies suggested that rice straw can be cost-effective for producing CBG and pellets. Pellets can be used in thermal power plants as a substitute of coal and CBG as a transport fuel.
  • SATAT initiative: With 30% of the rice straw produced in Punjab, a 5% CBG production target set by the Government of India scheme, “Sustainable Alternative Towards Affordable Transportation (SATAT)” can be met. It could also increase local entrepreneurship, increase farmers’ income and reduce open burning of rice straw.
  • Encouraging private players to produce CBG more and reduce CO2 emissions: Verbio India Private Limited, a 100% subsidiary of the German Verbio AG, got approval from the Punjab government in April 2018 to set up a bio-CNG project that will utilise about 2.1 lakh tonnes of a total of 18.32 million tonnes of paddy straw annually. The plant will use one lakh tonnes of paddy straw produced from approximately 16,000 hectares of paddy fields. Paddy residue will be collected from this year to produce 33 tons of CBG and 600-650 tonnes of fermented organic manure/slurry per day this will reduce up to 1.5 lakh tonnes of CO2 emissions per year.

FAO Study on developing crop residue supply chain

  • Use of Rice straw: In technical consultations with the public and private sectors, the FAO published its study on developing a crop residue supply chain in Punjab that can allow the collection, storage and final use of rice straw for other productive services, specifically for the production of renewable energy.
  • Required Investment and benefits farmers: The results suggest that to mobilise 30% of the rice straw produced in Punjab, an investment of around ₹2,201 crore ($309 million) would be needed to collect, transport and store it within a 20-day period. This would reduce greenhouse gas (GHG) emissions by about 9.7 million tonnes of CO2 equivalent and around 66,000 tonnes of PM2.5. Further, depending on market conditions, farmers can expect to earn between ₹550 and ₹1,500 per ton of rice straw sold, depending on market conditions.


Interesting to read: Compressed Bio Gas (CBG)

  • Biogas is produced naturally through a process of anaerobic decomposition from waste / bio-mass sources like agriculture residue, cattle dung, sugarcane press mud, municipal solid waste, sewage treatment plant waste, etc.
  • After purification, it is compressed and called CBG, which has a pure methane content of over 95%.
  • CBG is exactly similar to the commercially available natural gas in its composition and energy potential.
  • With calorific value (~52,000 KJ/kg) and other properties similar to CNG, CBG can be used as an alternative, renewable automotive fuel.
  • Given the abundance of biomass in the country, CBG has the potential to replace CNG in automotive, industrial and commercial uses in the coming years.


  • Encouraging private players for producing CBG appears to be a first win-win initiative in the form of environmental benefits, renewable energy, value addition to the economy, farmers’ income and sustainability. This initiative is replicable and scalable across the country and can be a game changer for the rural economy.

Mains Question

Q. What is Stubble burning? Discuss the measures taken by Government for the effective prevention and control of stubble burning and producing CBG could be a win-win situation.

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