IBA pitches for up to 20pc CBG blending in CNG in Delhi to improve air quality

What Happened

• The Indian Biogas Association (IBA) has formally pitched to the Delhi government for up to 20% blending of Compressed Biogas (CBG) into Compressed Natural Gas (CNG) supplied to vehicles, arguing it could bring vehicular gaseous mobility close to carbon neutrality.
• CBG is a renewable fuel produced from organic waste — including agricultural residues, food waste, sewage sludge, and cattle dung — that, when burned, produces no net addition of carbon to the atmosphere (as the carbon was recently fixed by living biomass).
• The proposal builds on the central government's existing Compressed Biogas Obligation (CBO) mandate: mandatory CBG blending starting FY 2025-26 at 1%, scaling to 5% by FY 2028-29.
• IBA's proposed 20% blending rate for Delhi goes significantly beyond the national mandate, targeting Delhi's severe air quality crisis, which saw AQI readings in the "Severe" category for extended periods in winter 2025-26.
• The blending does not require new vehicle modifications — existing CNG engines can run on CBG-CNG mixtures up to 20% without hardware changes.

Static Topic Bridges

Compressed Biogas (CBG): Production, Properties, and Policy Framework

Compressed Biogas is biomethane — biogas (predominantly methane, CH₄) produced from anaerobic digestion of organic waste, then purified to remove CO₂, H₂S, and moisture, and compressed to 200 bar for storage and distribution. Its properties are virtually identical to CNG (which is fossil natural gas compressed to the same pressure), making it a drop-in fuel compatible with existing CNG vehicles and infrastructure. India's policy framework for CBG has two pillars: (1) the SATAT initiative (Sustainable Alternative Towards Affordable Transportation, launched October 2018) by the Ministry of Petroleum, which aims to set up 5,000 CBG plants producing 15 MMT of CBG annually by 2024 (target partially unmet); and (2) the GOBAR-DHAN scheme (Galvanising Organic Bio-Agro Resources Dhan) under the Ministry of Jal Shakti/Agriculture, targeting rural waste-to-energy. The mandatory Compressed Biogas Obligation (CBO) was notified by PNGRB (Petroleum and Natural Gas Regulatory Board) to create assured demand for CBG in the City Gas Distribution (CGD) sector.

Delhi's Air Quality Crisis: Causes and Policy Responses

Delhi consistently ranks among the world's most polluted megacities. Its Air Quality Index (AQI) breaches the "Severe" threshold (AQI >400) on multiple days each winter due to a combination of vehicle emissions, industrial activity, construction dust, crop residue burning in Punjab and Haryana, and meteorological factors (temperature inversions trapping pollutants). Vehicular emissions — particularly from diesel and CNG-powered buses, autos, and taxis — contribute approximately 28–40% of Delhi's PM2.5 pollution. The switch to CNG for public transport (mandated by the Supreme Court in 2001) significantly improved Delhi's air quality in the 2000s; a further switch from fossil CNG to CBG-blended CNG would provide incremental but meaningful reductions in carbon emissions and particulate matter.

Carbon Neutrality of CBG: The Circular Economy Logic

CBG's carbon neutrality claim rests on the carbon cycle: organic feedstocks (crop residue, cattle dung) absorb CO₂ from the atmosphere during growth. When decomposed anaerobically (in digesters) and burned as CBG, the same CO₂ is released — a closed loop with no net atmospheric carbon addition. This is distinct from fossil natural gas (CNG), where burning releases carbon locked away for millions of years. Additionally, anaerobic digestion of agricultural residue prevents open-field burning (stubble burning), which produces not just CO₂ but also black carbon, methane, and toxic particulates. Each tonne of agricultural waste processed into CBG prevents approximately 2.5 tonnes of CO₂-equivalent emissions. The digestate (residue from digestion) is a rich bio-fertiliser, completing the circular economy loop.

City Gas Distribution (CGD) Sector: Infrastructure for Blending

India's CGD network — managed by licensees like Indraprastha Gas Limited (IGL) in Delhi — distributes both CNG (for vehicles) and PNG (piped natural gas for homes and industry). As of 2025, the CGD sector covers 295 geographical areas across India. Delhi's IGL operates ~1,000 CNG stations and serves ~17 lakh CNG vehicles. Blending CBG into the CNG supply at the city gate (where gas enters the city distribution network) is logistically straightforward — CBG can be injected at production sites connected to the CGD grid without separate vehicle-end infrastructure. This "grid injection" approach is how European countries integrate biogas into natural gas networks.

Key Facts & Data

• IBA proposal: up to 20% CBG blending in Delhi CNG to achieve near-carbon-neutral vehicular mobility
• CBO mandate (central government): 1% (FY25-26) → 3% (FY26-27) → 4% (FY27-28) → 5% (FY28-29+)
• SATAT initiative (2018): target 5,000 CBG plants + 15 MMT output annually
• GOBAR-DHAN: rural waste-to-energy scheme; 37 plants operational, 133 in development (end 2024)
• CBG: drop-in replacement for CNG; no vehicle hardware modification needed up to 20% blend
• Each tonne of agricultural waste → CBG avoids ~2.5 tCO₂e emissions
• Delhi PM2.5 annual average: ~100 µg/m³ (20x WHO safe limit)
• Vehicular share of Delhi PM2.5: ~28–40%
• IGL (Delhi): ~1,000 CNG stations; ~17 lakh CNG vehicles
• Digestate from CBG production: nitrogen-rich bio-fertiliser (reduces synthetic fertiliser demand)