Biomethanation plants

Context: In her Budget 2023-24 speech on February 1, Finance Minister Nirmala Sitharaman had announced the setting up of 500 biogas plants across the country under the Gobardhan scheme. Of these, 75 plants were to be set up in urban areas. The Budget announcement of setting up 75 biomethanation plants, which convert wet waste into biogas, in cities has got underway, with the Union Housing and Urban Affairs Ministry approving plans for 42 such facilities.

More on News: While waste-to-energy plants, nine of which with capacity of 12,000 TPD are functional currently, use dry waste to produce power, the biomethanation plants use wet waste to produce biogas or bio-CNG, depending on the quality of the waste provided.

Biomethanation plants use anaerobic digestion to convert organic waste into biogas and biofertilizer. Anaerobic bacteria break down waste in the absence of oxygen to produce methane-rich biogas and nutrient-rich digestate.

Feedstocks for biomethanation plants

  • Food waste from households, restaurants, hotels, etc.
  • Crop residues like stover, straw, stalks, etc.
  • Livestock manure and dairy waste
  • Sewage and wastewater from industries

The anaerobic digestion process involves 4 stages

  1. Hydrolysis – Bacteria break down complex organic matter into simple soluble organic compounds like fatty acids.
  2. Acidogenesis – Acid-forming bacteria further convert the hydrolyzed products into organic acids, alcohols, hydrogen and carbon dioxide.
  3. Acetogenesis – Acetate-forming bacteria convert the products from acidogenesis into acetic acid, hydrogen and carbon dioxide.
  4. Methanogenesis – Methane-forming archaea use acetic acid and hydrogen to produce methane and carbon dioxide.

Benefits of biomethanation

  • Produces biogas which can generate heat, electricity or bioCNG/ bioLNG for vehicles. This provides renewable energy and reduces fossil fuel use.
  • Reduces waste volumes by up to 95% and produces nutrient-rich fertilizer for soil and plants. This supports a circular economy. 
  • Lowers greenhouse gas emissions by capturing methane, a potent GHG. The remaining digestate also produces little to no methane when applied as fertilizer. 
  • Requires low investments and provides quick returns as multiple revenue streams are possible from energy, fertilizer and waste disposal.
  • Provides rural and city waste management solutions. Decentralized small-scale plants can also meet local energy needs. 
  • Additional benefits include reducing pollution in water bodies and odour in the vicinity. The fertilizer can cut down chemical fertilizer costs for farmers.

However, there are also some challenges like lack of segregation of waste at source, shortage of skilled manpower, lack of standards and policies, etc. Capital and operating costs can be high for large centralized plants. Irregular supply of feedstocks also poses problems.

GOBAR (Galvanizing Organic Bio-Agro Resources) DHAN scheme is an initiative by the Government of India to effectively manage and convert cattle dung and solid waste in farms into useful compost, biogas and bio-CNG. It was launched in April 2018.

Key objectives of GOBAR-DHAN scheme

  • Improve livestock health and productivity by providing doorstep animal waste collection service to farmers. This helps in maintaining cleanliness and hygiene in villages.
  • Produce enriched organic manure using cattle dung to promote organic farming. This can reduce farmers’ expenditure on chemical fertilizers and pesticides.
  • Generate income from waste – Farmers can sell enriched compost and generate biogas for cooking requirements. Excess biogas can also be sold. 
  • Create new business and job opportunities through bio-gas plants, compost production units and biodegrading units. This boosts the rural economy.
  • Promote a circular economy by converting waste into resources and wealth. This supports sustainable development.
  • Reduce greenhouse gas emissions like methane by using cattle dung and waste to produce biogas and compost. This helps to mitigate climate change.
  • Improve sanitation and hygiene in rural areas by processing cattle dung and other waste. This prevents open defecation and reduces breeding of flies and mosquitoes.

Key components of GOBAR-DHAN scheme

  • Gobardhan Gram Panchayat Plant: Setting up of community bio-gas plants at Gram Panchayat level to collect and process cattle dung and waste to generate bio-gas for cooking and enriched compost.
  • Gobar Bank: Storage of cattle dung at Panchayat level and selling it to farmers and other buyers as per their requirements. This ensures regular supply of raw material to plants.
  • Galvanizing Organic Bio Agro Resources Fund: Provides financial assistance and capital subsidy for establishing biogas plants and composting units.
  • Awareness and outreach: Conducting training, campaigns and demonstrations to promote scheme benefits and encourage farmers and entrepreneurs to adopt waste management practices.
  • Monitoring: Reviewing the progress and impact of the scheme through periodic monitoring of physical and financial achievements. Taking corrective actions as needed.

The scheme utilizes appropriate technologies for waste management and treatment like anaerobic digestion technology, composting techniques, etc. It adopts a decentralized, cluster based approach for effective implementation across the country. Local bodies and village panchayats also actively support the scheme.


In the context of which one of the following are the terms “pyrolysis and plasma gasification’ mentioned?

  1. Extraction of rare earth elements
  2. Natural gas extraction technologies
  3. Hydrogen fuel-based automobiles
  4. Waste-to-energy technologies

Prelims Practice Question

Which of the following statements about biomethanation is/are true?

  1. Biomethanation is a process that converts organic waste materials into biogas through anaerobic digestion.
  2. Biogas produced through biomethanation can be used as a fuel for vehicles.
  3. Biomethanation is a process that can only be used to treat agricultural waste.

Select the correct answer using the code given below:

a) 1 only

b) 1 and 2 only

c) 1 and 3 only

d) 1, 2 and 3

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