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Relevance: GS-II (Governance) | GS-III (Energy & Environment) | Source: The Hindu
The Context: While India’s fuel policy caps ethanol blending in regular petrol at 20% (E20), recent retail fuel tests across several Karnataka districts revealed ethanol levels going as high as 31.2%. The state government has flagged a serious transparency deficit by Oil Marketing Companies (OMCs), noting that uncalibrated over-blending risks damaging standard vehicle engines and lowering mileage.
1. The Transparency Row: Lab Tests vs. Oil Companies
- Breaching the 20% Cap: Samples tested by Karnataka’s Department of Legal Metrology showed public-sector pumps reaching up to 31.2% (IOCL) and 30.5% (HPCL) ethanol, while private retailers like Nayara (up to 26.1%) and Shell (up to 25.5%) also exceeded the 20% limit.
- The In-House Lab Omission: When samples were first given to the oil companies’ own in-house labs (IOCL and BPCL), their reports omitted the ethanol percentage altogether, despite it being a prescribed testing parameter.
- Disputed Audits: After NABL- and ISO-accredited independent labs confirmed the high ethanol levels, state-owned OMCs rejected the findings, claiming the samples were not collected according to statutory technical procedures.
2. Core Science: Why Over-Blending Hurts Regular Engines
- Part Corrosion: While specialized Flex-Fuel Vehicles (FFVs) can run on up to 85% ethanol (E85), standard engines built for E10 or E20 limits generally face corrosion in rubber hoses, plastic seals, and metals like aluminium and brass when exposed to 30%+ blends.
- Water Absorption (Phase Separation): Ethanol is hygroscopic (absorbs moisture from the air). In high concentrations, water-ethanol mixtures can separate from petrol and sink to the bottom of the tank, leading to internal rust and engine stalling.
- Lower Mileage: Ethanol has roughly 30% less energy by volume than pure petrol. Uncalibrated over-blending typically reduces fuel efficiency (mileage) and alters air-fuel ratios, which can cause engine knocking.
Practice MCQ
Q. Consider the following statements regarding ethanol properties and India’s biofuel framework:
- Ethanol possesses a higher energy density by volume than pure petrol, which increases vehicle mileage when blended above 20%.
- The 2022 amendment to the National Policy on Biofuels advanced India’s target of achieving 20% ethanol blending in petrol from 2030 to 2025–26.
Which of the statements given above is/are correct?
(a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2
Answer: (b) 2 only
Hint: Statement 1 is incorrect because ethanol has roughly 30% lower energy density by volume than pure petrol, meaning higher uncalibrated blends reduce fuel efficiency (mileage). Statement 2 is correct; the 2022 amendment moved the E20 target forward from 2030 to 2025–26.
Hint: Statement 1 is incorrect because ethanol has roughly 30% lower energy density by volume than pure petrol, meaning higher uncalibrated blends reduce fuel efficiency (mileage). Statement 2 is correct; the 2022 amendment moved the E20 target forward from 2030 to 2025–26.
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