Why India’s Ethanol Journey Must Be Guided by Science, Not Speculation

India’s Ethanol Blended Petrol programme has just crossed a threshold few believed possible when the target was first set. Blending has climbed from under 1.5 per cent a decade ago to 20 per cent E-20 as the standard fuel on April 1, 2026, 5 years ahead of schedule.

Behind that number sits a quieter, more consequential story: nearly 1,200 crore litre of ethanol procured in a single supply year, foreign exchange savings exceeding ₹1.90 lakh crore, and new income flowing to farmers who grow the sugarcane, maize, and rice that feed the programme.

For a country that imports close to nine-tenths of the crude oil it consumes, this is not a peripheral achievement.

It goes to the heart of energy security. It is also a climate dividend: every 1 crore litre of ethanol-blended petrol avoids approximately 20,000 tonne of CO₂ emissions, a saving that compounds with every passing year of the programme.

And yet, as the blend has moved from E10 to E20, so has the volume of public unease.

Questions about mileage, engine wear, insurance cover, and the water and land used to grow feedstock have travelled faster on social media than the technical studies meant to answer them.

This is not surprising, and it should not be treated as a crisis of confidence in the programme itself.

Every meaningful transition in energy or infrastructure — from diesel to CNG; unleaded petrol to catalytic converters to BS-VI emission norms, etc. — has passed through a phase where public familiarity lagged behind technical readiness.

The test of a good transition is not whether it generates doubt, but whether that doubt is met with evidence rather than dismissal, and whether the system keeps learning as it scales.

Hesitation, taken too far, has its own consequences. A country that waits for unanimous public comfort before acting on energy security will simply keep importing crude at whatever price global markets set, keep ceding the upside of a fermentation-and-distillation industry to other economies, and keep farmers out of a market that could diversify their incomes beyond the vagaries of a single crop cycle.

Certainty of that kind rarely arrives before action; it is usually built through it; through pilot programmes, phased rollouts, independent testing, and course correction along the way.

That is precisely the pattern the Ethanol Blended Petrol (EBP) programme has followed.

Extensive testing by Society of Indian Automobile Manufacturers (SIAM), the Automotive Research Association of India (ARAI) and the Indian Oil Corporation Ltd. (IOCL), conducted jointly with vehicle manufacturers, preceded the move to E20; it did not follow it as an afterthought.

Science Deserves a Fair Hearing

Bioethanol is a fuel made by fermenting the sugar and starches of plants, primarily used for petrol blending in transport. 

The common feedstocks are derived from sugar crops such as sugar cane; sorghum; of starchy crops such as rice, wheat & corn; spoiled grains or cellulose plants waste.

India imports over 80% of its crude oil resulting in foreign exchange outflows and exposure to global oil price stocks. 

Current geopolitical conditions have demonstrated how fragile the ecosystem is for its availability and price shocks.

Much of the anxiety around E20 rests on a misunderstanding of what ethanol brings to the fuel tank.

Ethanol is not a diluted or inferior substitute for petrol; it is a high-octane fuel, with a research octane number of roughly 108.5 against petrol’s 84.4.

Blended at 20 per cent, it lifts the effective octane rating of petrol sold in India to around 95, allowing cleaner, more efficient combustion in engines designed or calibrated to use it, thus reducing tailpipe emissions.

The oft-cited figure of a 6 per cent mileage loss (few reports claiming even higher – up to 30%) is a description of ethanol’s lower calorific value relative to petrol on a laboratory basis.

The dip in mileage is more for older, particularly pre-BS6 and early BS4 cars and two-wheelers.

Ethanol’s corrosive nature and high solvent properties degrade rubber fuel lines, other plastic components, and metal fuel tanks.

Mileage, in practice, is also impacted due to traffic congestion, driving habits, tyre pressure, servicing intervals, air-conditioning load, and the ethanol content of the fuel.

This is where a knowledge-based approach to implementation matters most.

The engineering case for ethanol is strong, but it is contingent on vehicles being properly calibrated, on fuel meeting BIS specifications consistently at the retail pump, and on manufacturers, oil marketing companies and regulators sharing service and quality data transparently.

That knowledge base already underpins the decision to move to E20; much of it can now be shared more widely.

Wider public release of the test data on engine wear, retail fuel quality audits, and clear, non-technical explanations of what changes in an engine tuned for higher ethanol content would let citizens see the same evidence that has guided the transition at every stage.

The public conversation would benefit enormously from wider access to the underlying test data on engine wear, fuel quality audits at the retail level, and clear, non-technical explanations of what changes in an engine tuned for higher ethanol content and why.

Concerns about corrosion, water absorption, or residual sugars attracting insects are addressable through basic vehicle design and fuel processing standards, some of which already exist; and can be researched further.

What is needed is to appreciate the need of shifting to bio-fuels and moving towards energy security and through R&D, solve the teething problems and not a retreat from the policy.

India Is Not Experimenting Alone

In a global context, it also helps to put India’s experience in perspective. The United States has run on E10 as a national standard for years and E15 is now expanding, with a flex-fuel fleet already capable of running on blends as high as E85.

Brazil, further along this path than any other large economy, mandates E27 today and is moving toward E30, with most new cars sold there are flex-fuel capable.

Japan has taken a more gradual route through a phased E10 rollout, while Canada, Thailand, and several European countries have built ethanol into their fuel strategies too.

None of this guarantees a frictionless experience for India, and local conditions around feedstock, water use, and vehicle vintage differ.

But it does mean India is drawing on decades of accumulated global operating experience rather than proceeding on faith alone.

Next Phase Needs Discipline

It is about understanding the transition on its merits rather than abandoning it at the first sign of friction.

As the programme moves toward second-generation ethanol from agricultural residue and explores flex-fuel vehicles suited to even higher blends, three disciplines will matter.

First, continued and visible third-party testing, with results shared in formats the public can evaluate, not just industry bodies.

Second, sustained attention to feedstock sourcing, so that diversion of foodgrain for fuel remains surplus-based and does not compete with food security as blending targets rise further.

Third, honest public communication when costs shift; ethanol procurement now runs above refined petrol costs in some cycles, and that trade-off, made consciously for energy security and rural income reasons, should be explained clearly.

A transition sustained by evidence and openness earns public trust in a much better way.

About a decade ago, ethanol blending in India was a marginal idea running at under two per cent.

Today, it is a functioning industrial ecosystem reaching farmers, refiners, automakers, and every vehicle owner in the country. The transition deserves thoughtful evaluation, not premature judgement.

Every significant transformation tests our confidence before it demonstrates its full potential.

The task before us is to ensure that this confidence is anchored in evidence, strengthened by continuous learning, and guided by the shared objective of building a cleaner, more resilient and self-reliant energy future.

About the Author: The author is Director General of The Energy and Resources Institute (TERI), New Delhi.

(Disclaimer: This is an authored article. Views expressed are personal and does not reflect that of the editorial)