E20 Petrol: Ethanol Blending Facts, Concerns and Brazil Case
Why in the news
As the 2025 E20 goal neared, owners worried about mileage, corrosion and maintenance cost, though the policy aims to cut emissions and oil imports.
Key facts
- Target set in 2021: 20% ethanol in petrol by 2025.
- Ethanol is a biofuel from molasses, broken rice, maize or lignocellulosic matter, and an oxygenate that improves combustion.
- Molasses is fermented using enzymes invertase and zymase.
- Government says replacing rubber parts or gaskets is cheap and needed once.
| Aspect | Effect |
|---|---|
| Calorific value | Lower, so mileage may dip |
| Octane number | Higher, less knocking |
| Hygroscopic | Attracts water; corrosion risk |
| Older carbureted pre-BS-VI vehicles | Corrosion and clogging risk |
| BS-IV and BS-VI with ECU | Recalibrate easily; less affected |
Brazil comparison
- E27 after decades of phased policy, subsidies and flex-fuel engines; most Indian pre-2020 vehicles are not flex-fuel.
Exam angle
- E20 means 20% ethanol.
- Brazil blend: E27.