- 2070 Chaitra · 1+3 marks
E number and biofuels
Short answer
E number is the percentage of ethanol blended in petrol by volume (e.g. E10 = 10% ethanol). Bio fuels differ from fossil fuels as they are renewable, near carbon-neutral liquid or gas fuels from recent biomassthat can replace transport fuels, but compete with food and need land.
Define E number. How do biofuels differ from other sources of energy?
E number (biofuels)
The E number in the fuel context shows the percentage of ethanol blended with petrol by volume. For example E10 = 10% ethanol + 90% petrol; E20 = 20% ethanol; E85 = 85% ethanol + 15% petrol; E100 = pure ethanol. Similarly, B20 means 20% biodiesel in diesel. (Nepal has plans and trials for ethanol blending, with ethanol mainly from sugar-cane molasses; this needs a government policy on the blending ratio.)
How biofuels differ from other sources of energy
| Point | Biofuels | Fossil fuels | Other renewables (solar, wind) |
|---|---|---|---|
| Source | Plants, oils, waste (recent biomass) | Ancient buried organisms | Sun, wind, water |
| Renewability | Renewable, if crops are replanted | Non-renewable | Renewable |
| Form | Liquid or gas fuels (ethanol, biodiesel, biogas) | Solid, liquid and gas fuels | Mostly electricity or heat |
| Carbon | Near carbon neutral (CO₂ absorbed by growing the plant) | Adds new CO₂ | Zero operational emissions |
| Use in existing engines | Yes, as blends | Yes | Need conversion or EVs |
| Storage | Easy to store and transport | Easy | Intermittent, need storage |
| Concerns | Food vs fuel competition, land use, water, deforestation | Pollution, climate, imports | Intermittency, cost |
Biofuels are therefore the main renewable source that can directly replace liquid transport fuels, and they can be produced locally, but they need land and care to avoid competing with food crops.
✓ Answer checked by Claude Opus 5.5 (high effort)
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