CBG (CBG)

Compressed Biogas (CBG) is purified biogas that has been upgraded to natural-gas-grade methane content (95% minimum) and compressed to high pressure (200–250 bar) for use as a vehicle fuel, industrial gas, or piped gas substitute. The acronym CBG was formalised in Indian policy through the SATAT scheme — Sustainable Alternative Towards Affordable Transportation — launched by the Ministry of Petroleum and Natural Gas in October 2018, which set a target of 5,000 CBG plants and 15 MMT of CBG production by 2026, with offtake guaranteed by oil marketing companies at notified prices.

The CBG production pathway has four stages. Anaerobic digestion of organic feedstock — agricultural residues, animal manure, press mud, food waste, sewage — produces raw biogas containing 55–65% methane and 35–45% CO2. Biogas upgrading using water scrubbing, pressure swing adsorption (PSA), membrane separation, or amine scrubbing removes CO2 and trace H2S to raise methane content above 95%. Compression using two- or three-stage reciprocating compressors raises pressure from near-atmospheric to 200–250 bar. Dispensing into cascade cylinder banks or directly to vehicle dispensers completes the chain. The end product must meet IS 16087:2016 specifications: 90% minimum methane (higher than the 95% target most plants run), 4% maximum CO2, 7 mg/m3 maximum H2S, water dewpoint of -10 degC at delivery pressure.

CBG is chemically interchangeable with fossil-origin CNG and uses identical retail infrastructure — the same compressors, cascade storage, dispensers, and vehicle tanks. The economic case rests on three pillars: a notified offtake price (currently around Rs 54 per kg ex-plant in most states), capital subsidy support under MNRE's CBG-CFA scheme (up to Rs 4 crore per plant), and avoided fossil-fuel imports. CBG also generates fermented organic manure (FOM) as a co-product at roughly 1–1.5 tonnes per tonne of CBG, providing a secondary revenue stream of Rs 2,000–4,000 per tonne. As of early 2026, over 100 CBG plants are operational with several hundred more under construction, concentrated in Punjab, Haryana, Maharashtra, Karnataka, and Uttar Pradesh.