Facing backlash, Government likely to delay higher 25% ethanol blend in petrol
The timeline for introducing a higher 25% ethanol blend (E25) in petrol is under review, with a phased, calibrated approach to the transition beyond the current 20% blend (E20) under consideration rather than a fixed near-term rollout date.
The reassessment follows technical findings on fuel-system material compatibility in older, E10-certified vehicles operating on E20 fuel, alongside reported concerns about reduced fuel efficiency in vehicles not originally designed for higher ethanol content.
Requirements under review before any move to E25 include engine calibration changes, fuel-system material upgrades, and corrosion-resistance testing, to be assessed in consultation with vehicle manufacturers.
The 20% ethanol blending target (E20) was achieved nationally by March 2025 — five years ahead of the original 2030 timeline set under the National Policy on Biofuels, 2018.
The Ethanol Blended Petrol (EBP) Programme and National Policy on Biofuels, 2018
The Ethanol Blended Petrol (EBP) Programme, launched in January 2003 and rolled out nationwide (barring Jammu & Kashmir and parts of the Northeast) from November 2006, mandates progressive blending of ethanol into petrol supplied by public-sector oil marketing companies. The National Policy on Biofuels, 2018 (effective 16 May 2018) set an indicative target of 20% ethanol blending (E20) by 2030; in 2022, an amendment to the policy advanced this target to 2025-26 in response to faster-than-expected progress. Blending levels rose steadily — 10% (E10) achieved in June 2022, five months ahead of schedule, followed by 12.06% (ESY 2022-23), 14.60% (ESY 2023-24), and 17.98% (ESY 2024-25) — before the 20% milestone was reached in March 2025. The EBP Programme also supports the domestic sugarcane and grain-based distillery sector by creating a stable procurement market for ethanol.
Key Details
- EBP Programme launched: January 2003; nationwide expansion: November 2006.
- National Policy on Biofuels, 2018: effective 16 May 2018; original E20 target of 2030, advanced to 2025-26 via a 2022 amendment.
- E10 achieved: June 2022; E20 achieved: March 2025.
- Permitted ethanol feedstocks under the policy: sugarcane juice, B-heavy and C-heavy molasses, damaged food grains, surplus rice and maize, and lignocellulosic biomass.
- Nodal ministry: Ministry of Petroleum and Natural Gas, in coordination with the Ministry of Consumer Affairs, Food and Public Distribution (ethanol procurement) and the Department of Food and Public Distribution.
The current review of the E25 timeline represents the next planned phase of the EBP roadmap — the policy's stated objective, having achieved E20 well ahead of schedule, is to calibrate any further increase against vehicle-fleet readiness rather than adhere to a fixed date.
Vehicle Fuel-System Compatibility and Material Standards for Higher Ethanol Blends
Ethanol is hygroscopic and more chemically reactive than pure petrol, which can degrade rubber and rubber-like elastomer components — hoses, gaskets, seals, and O-rings — in fuel systems not designed for high ethanol content, and can also promote corrosion in incompatible metals over sustained exposure. To manage this, the government mandated that all new vehicles sold in India from 1 April 2023 be "E20 material compliant," using ethanol-resistant fuel-system components, timed to align with the BS-VI Phase 2 emission-norms rollout. Vehicles sold before that date were certified only up to E10 fuel. A technical assessment examining engine durability and component wear under E20 use found that rubber fuel-system parts in E10-certified vehicles showed measurable deterioration, while metallic components and vehicle emissions remained within specification; engine durability testing (typically run to roughly 2,000 hours under the full Central Motor Vehicles Rules/Automotive Industry Standards protocol) showed acceptable results for two-wheelers and one BS-IV engine, alongside an isolated component failure in a BS-VI turbocharged engine after a partial test run — findings that inform the caution being applied to any further increase in blend percentage.
Key Details
- Mandatory E20-material-compliance cutoff for new vehicles: 1 April 2023, aligned with BS-VI Phase 2.
- E20 fuel specification is codified in BIS standard IS 17021:2018.
- Fuel-system component types most affected by ethanol exposure: rubber hoses, gaskets, seals, O-rings.
- Reported fuel consumption increase on E20 versus E10 in technical testing: approximately 2% to 6%.
- Full engine durability certification protocol: approximately 2,000 hours of continuous operation, against which the partial test runs (up to ~400 hours) referenced in the technical assessment are preliminary.
These material-compatibility and durability findings, concerning the still-large fleet of pre-2023 E10-certified vehicles, form the technical basis for treating any move to E25 as requiring a phased, vehicle-readiness-linked timeline rather than an immediate mandate.
Ethanol's Energy Density and the Fuel-Economy Trade-off
Ethanol contains roughly 34% less energy per litre than petrol (approximately 21.2 MJ/litre versus petrol's approximately 32 MJ/litre), so as the ethanol share of a blend rises, a vehicle must consume a larger fuel volume to deliver equivalent energy output — the primary driver of the fuel-efficiency loss reported by consumers and confirmed in technical testing. This is partly offset by ethanol's higher octane rating (approximately 108.5 versus petrol's approximately 84.4), which improves anti-knock performance and can support better combustion efficiency in engines specifically tuned for high-ethanol blends — a benefit realised more fully in flex-fuel vehicles (FFVs) than in vehicles merely certified as E20-compatible.
Key Details
- Ethanol energy content: ~21.2 MJ/litre; petrol: ~32 MJ/litre — roughly 34% lower for ethanol by volume.
- Ethanol octane rating: ~108.5 versus petrol's ~84.4.
- Flex-fuel vehicles (FFVs), engineered to run on any blend from E0 to E85/E100, are better positioned to exploit ethanol's higher octane rating than conventional E20-compatible vehicles.
- India's Corporate Average Fuel Efficiency (CAFE) norms, administered by the Bureau of Energy Efficiency under the Energy Conservation Act, 2001, regulate fleet-average fuel consumption and CO2 emissions across manufacturers.
The fuel-economy trade-off is a key input into the calibrated-timeline approach — moving too quickly to E25 without matching engine calibration and material upgrades would compound the efficiency losses already reported at the E20 stage.
- National Policy on Biofuels, 2018: original E20 target of 2030, advanced to 2025-26 via a 2022 amendment.
- E10 achieved: June 2022; E20 achieved nationally: March 2025.
- Mandatory E20-material-compliance cutoff for new vehicles: 1 April 2023 (aligned with BS-VI Phase 2).
- E20 fuel specification: BIS standard IS 17021:2018.
- Reported fuel-system components affected by ethanol exposure: hoses, gaskets, seals, O-rings.
- Reported fuel consumption increase, E20 vs E10: approximately 2% to 6%.
- Ethanol energy density: ~34% lower than petrol by volume; octane rating ~108.5 vs petrol's ~84.4.
- Standard full engine durability certification protocol: ~2,000 hours of continuous operation.