The global transition toward sustainable and renewable energy sources has thrust biofuels into the absolute centre of macroeconomic and environmental policy. Among these, ethanol stands out as the most widely adopted, heavily researched, and aggressively scaled alternative to conventional fossil fuels. In India, the push for ethanol blending is not merely an environmental crusade; it is a critical pillar of energy security and geopolitical strategy. However, the path to a robust ethanol economy is fraught with agricultural challenges, economic debates, and technological hurdles.
The discourse around ethanol in India frequently intersects with agricultural economics, particularly the sugar industry. A stark example of this intersection unfolded recently, when India witnessed a sharp and sudden surge in domestic sugar prices. This forced the govt to allow duty-free import of 1 million tonnes of raw sugar. Almost immediately, a controversy erupted, with critics and opposition attributing the price hike and scarcity directly to the government’s aggressive Ethanol Blended Petrol (EBP) programme. The prevailing rumour was that excessive diversion of sugarcane juice and molasses to distilleries for ethanol production was starving the domestic sugar market, forcing the nation into an embarrassing position of having to import sugar.
The optics were awkward. India is the world’s second-largest sugar producer, and here it was importing sugar even as it was simultaneously exporting fuel-grade ethanol and hitting a landmark 20 per cent ethanol-blending target in petrol. Faced with this controversy, the Centre issued detailed clarification rejecting the “ethanol is stealing your sugar” theory. The govt dismissed the diversion of sugar towards ethanol as the primary reason for the price rise, attributing the spike instead to lower-than-projected production, weather-related crop damage in cane-growing belts, tightening global supplies, and speculative hoarding by parts of the trade.
Crucially, the govt also used the moment to make a broader point that deserves wider public understanding: sugarcane is only one of several feedstocks powering India’s ethanol programme, and its share is deliberately being reduced. This is not a new stance. Back in December 2023, when sugar prices had similarly spiked ahead of general elections, the Centre had ordered mills to stop using sugarcane juice and sugar syrup for ethanol altogether for that supply year, while still permitting the use of B-heavy molasses (a byproduct, not fresh cane juice), explicitly stating that ethanol production from grains like maize, rice and barley would take up the slack. The rule was eased again for 2024–25 once supply stabilised, with the Food Ministry allowing sugarcane juice, sugar syrup, B-heavy and C-heavy molasses back into the ethanol mix, subject to periodic review by the Food Ministry and the Petroleum Ministry to ensure year-round sugar availability isn’t compromised.
The latest official data bears this diversification out. For the current Ethanol Supply Year 2025–26, the allocation to Oil Marketing Companies (OMCs) shows maize holding the largest share at 45.68 per cent of the ethanol offered, followed by FCI rice at 22.25 per cent, sugarcane juice at just 15.82 per cent, B-heavy molasses at 10.54 per cent, damaged food grains at 4.54 per cent, and C-heavy molasses at 1.16 per cent. In other words, grain — chiefly maize — has overtaken sugarcane as India’s single largest ethanol feedstock, a structural shift the government has been actively encouraging precisely to insulate the sugar economy from the fuel economy. This diversification is also central to the discussion in this article on 2G, 3G and 4G ethanol, which rely on non-food or waste biomass rather than any edible crop at all.
It is worth stating plainly, since the sugar-import row has muddied public perception: ethanol in India is produced from a whole basket of renewable, biological sources, not sugarcane alone. As per the National Policy on Biofuels, 2018 (amended 2022), permissible feedstocks fall into three broad categories:
This basket underpins the entire generational classification of ethanol — 1G, 2G, 3G and 4G. Before getting there, though, it helps to understand what ethanol actually is, and why a molecule fermented from sugarcane juice or rice straw can power an engine designed to burn petroleum.
Ethanol (chemical formula C₂H₅OH, or ethyl alcohol) is a simple, two-carbon alcohol. It is the same molecule found in alcoholic beverages, just produced and denatured for industrial and fuel use rather than consumption. Structurally, it consists of an ethane backbone with a hydroxyl (–OH) group attached, which makes it fully miscible with water and, importantly, capable of being blended with petrol (which is itself a complex mixture of hydrocarbons — chiefly octane, heptane, and various branched and aromatic compounds).
Petrol-powered internal combustion engines work on the same basic principle regardless of what exact molecule is burned: a fuel-air mixture is compressed inside a cylinder and ignited by a spark, releasing energy that pushes a piston. What matters for combustion is that the fuel is volatile enough to vaporise readily, chemically reactive enough to combine rapidly with oxygen, and energy-dense enough to release useful heat when it does.
Ethanol satisfies all three conditions. Being a small, volatile organic molecule, it vaporises easily at ambient and engine-operating temperatures. When ignited, it oxidises according to the reaction:
C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O + heat.
This is chemically analogous to the combustion of petrol hydrocarbons, which follow the general form CₓHᵧ + O₂ → CO₂ + H₂O + heat. The key structural difference is that ethanol already carries an oxygen atom within its molecule, whereas pure hydrocarbons do not. This makes ethanol an “oxygenate” — a fuel additive that supplies its own oxygen during combustion, which promotes more complete burning of the fuel-air mixture inside the cylinder, reducing carbon monoxide and unburnt hydrocarbon emissions compared to running on petrol alone.
Engines built for petrol do not “know” or “care” what specific hydrocarbon or oxygenate they are burning, so long as the fuel’s physical and combustion properties fall within the tolerances the engine, fuel system, and emission-control equipment were designed around. Several properties make ethanol broadly compatible with petrol engines at low-to-moderate blend ratios:
This is why India’s blending programme has been introduced in careful stages — E5, E10, and now E20 — rather than an abrupt jump, and why the government has simultaneously been pushing for E20-material-compliant vehicles (with fuel-system components resistant to ethanol’s corrosive and hygroscopic — water-attracting — tendencies) and dedicated flex-fuel vehicles capable of running on much higher ethanol content, up to E85. Ethanol’s mild corrosivity towards certain rubber and metal components, and its tendency to absorb atmospheric moisture, are the main engineering reasons why blends beyond roughly 10–20 per cent generally require purpose-built or adapted engines rather than simply pouring ethanol into any old petrol tank.
Ethanol is classified into “generations” not by when it was invented, but by what feedstock it is made from and how directly that feedstock competes with food, land, and water resources. As the technology has matured, the industry — and policymakers globally, including in India — have pushed towards later generations that rely on waste, non-food biomass, and increasingly exotic biological or industrial routes.
1G bioethanol represents the oldest and most technologically mature method of producing fuel alcohol. It is produced by fermenting the sugars or starches found directly in food crops — principally sugarcane juice, sugar beet, molasses, maize (corn), wheat, and surplus or damaged foodgrain such as rice. This is the oldest and most mature ethanol production pathway, essentially the same biochemical process used for millennia to brew alcohol, scaled up industrially.
The process broadly follows these steps:
1G ethanol remains the backbone of India’s Ethanol Blended Petrol (EBP) Programme simply because the infrastructure — sugar mills, grain-based distilleries, and their supply chains — already exists and can be scaled relatively cheaply and quickly. It is why India’s blending percentage climbed rapidly: from under 1.5 per cent in 2013–14 to an average of 20 per cent achieved in Ethanol Supply Year 2025–26, five years ahead of the original 2030 target, and comfortably ahead even of the advanced 2025–26 target under the amended roadmap. Ethanol procurement by OMCs rose from around 38 crore litres in 2013–14 to over 900 crore litres by 2024–25, and India’s total installed ethanol distillation capacity now stands at roughly 1,700–2,000 crore litres a year.
The flip side, however, is precisely the tension exposed by the recent sugar-price episode: 1G ethanol draws directly on crops and land that could otherwise feed people or livestock, and on water resources in already-stressed agricultural belts. Cultivating crops exclusively to burn in car engines requires vast tracts of arable land, millions of litres of fresh irrigation water, and extensive fertilizer use. In heavily populated countries like India, diverting edible crops or premium agricultural land for fuel production can threaten food security and inflate food prices, leading to severe socio-economic distress. Sugarcane, rice, and maize are all water-intensive crops, and the Central Ground Water Board’s 2025 assessment has already classified several Indian regions as over-exploited or critical for groundwater.
This inherent conflict necessitated the technological leap to subsequent generations of biofuel. The fundamental “food versus fuel” dilemma that has driven global and Indian policy towards second-, third- and fourth-generation ethanol, which draw on non-food biomass, waste streams, and increasingly exotic feedstocks rather than edible crops.
2G ethanol, also called cellulosic or advanced biofuel, is produced from lignocellulosic biomass — agricultural residues (rice straw/parali, wheat straw, bagasse), forestry residues, bamboo, and other non-food plant material. This is the generation most directly aimed at solving both the food-versus-fuel dilemma and a very India-specific environmental crisis: the annual burning of crop stubble in Punjab, Haryana and western Uttar Pradesh, which is a major contributor to winter smog in the National Capital Region.
Unlike sugarcane juice or grain starch, the sugars in agricultural residue are locked up inside a tough structural matrix of cellulose, hemicellulose, and lignin — the same fibrous material that gives plant stalks their rigidity. Extracting fermentable sugars from this matrix is considerably harder than from 1G feedstocks, which is why 2G technology took decades longer to become commercially viable. The process typically involves:
The enzyme and pre-treatment technology is the crux of 2G’s cost challenge; producing the specialised enzymes at scale, and doing so economically, was for years the bottleneck that kept 2G ethanol commercially unviable, which is why India’s Department of Biotechnology has separately funded dedicated bioenergy centres — such as the DBT–ICGEB Bioenergy Centre and the DBT–IOCL centre in Faridabad — specifically to develop cheaper, more efficient cellulase enzymes for Indian feedstocks like rice straw.
India has made genuine, if slow-going, progress in commercialising 2G ethanol, largely through public-sector oil marketing companies:
The plant achieved a milestone of producing 99.7 per cent purified ethanol shortly before its inauguration by the Prime Minister in September 2025. In recognition of its performance, NRL was elevated to Navratna status (from Miniratna Category-I) by the Union Petroleum and Natural Gas Ministry in December 2025, giving it greater financial and operational autonomy for further expansion of its bio-refinery ecosystem.
Together, these plants represent India’s tentative but genuine pivot towards feedstocks that neither compete with food supply nor draw down groundwater reserves the way sugarcane and paddy cultivation do, while simultaneously tackling the stubble-burning air-pollution crisis in North India. Several more 2G ethanol plants are coming up, including in Karnataka’s Davangere by Mangalore Refinery and Petrochemicals Ltd and in Nandyal in Andhra Pradesh by RCPL.
While 2G ethanol solves the food vs. fuel debate, it still requires massive amounts of terrestrial land to grow the biomass. Enter Third-Generation (3G) ethanol, which completely departs from terrestrial agriculture by utilising algal biomass (microalgae and macroalgae/seaweed) as the primary feedstock.
Globally, 3G biofuel most commonly refers to ethanol or other fuels produced from algae — microorganisms that can be cultivated on non-arable land, in wastewater, or even using industrial flue gases, and which can achieve far higher biomass and oil yields per hectare than terrestrial food or energy crops. Algae-based routes remain largely at pilot and research stage worldwide, owing to the high capital cost of cultivation ponds or photobioreactors and the technical challenge of harvesting and processing algal biomass economically.
India’s flagship “3G” ethanol project, however, takes a related but distinct approach that is worth explaining carefully, since it differs from the textbook algae definition. Indian Oil Corporation’s 3G plant at its Panipat Refinery in Haryana converts refinery off-gases — specifically, gases from the Pressure Swing Adsorption (PSA) unit of the Hydrogen Generation Unit — into ethanol using gas fermentation technology. In this process, specialised anaerobic microorganisms metabolise carbon-monoxide- and hydrogen-rich waste gas streams that would otherwise be flared or wasted, converting them biologically into ethanol, without requiring any dedicated agricultural feedstock, land, or water-intensive cultivation at all.
Algae are highly efficient photosynthetic organisms. Compared to terrestrial crops, algae grow at astonishingly fast rates and can be cultivated in wastewater, brackish water, or on non-arable land such as deserts utilizing closed photobioreactors. Because algae lack the tough structural lignin found in terrestrial plants, their cellular makeup consists of high proportions of lipids (fats) and carbohydrates. This low lignin and high carbohydrate content makes the cellular breakdown and conversion process far simpler and yields much higher quantities of ethanol per acre compared to 2G crops.
The process involves cultivating the algae, harvesting and dewatering the biomass, and then extracting the intracellular carbohydrates. These carbohydrates are then subjected to enzymatic hydrolysis and fermented into ethanol.
On the other hand, for producing 3G ethanol in oil refineries, gases rich in CO, CO₂ and H₂ generated as a byproduct are captured rather than flared. These gases are fed into bioreactors containing specialised gas-fermenting bacteria, which use the carbon and hydrogen in the gas stream as an energy and carbon source, in a manner analogous to how yeast ferments sugar, except the “food” here is gaseous rather than a liquid sugar solution. The bacteria excrete ethanol as a metabolic byproduct, which is then recovered, distilled, and dehydrated to fuel-grade purity, exactly as in the 1G and 2G routes.
IOCL Panipat 3G Ethanol Plant: Commissioned in March 2023, this is India’s pioneering commercial-scale application of gas-fermentation-based ethanol production. Using its “innovative refiner off-gas conversion technology,” the plant produces around 4.2 crore litres of ethanol annually, while cutting greenhouse gas emissions by an estimated 1.8 lakh tonnes per year by capturing gas that would otherwise be flared. Notably, this plant sits at the very same Panipat refinery complex as IOCL’s 2G plant, making Panipat something of a live laboratory for India’s advanced-biofuel ambitions, with the DEF (diesel exhaust fluid), 2G ethanol and 3G ethanol units all commissioned there between 2021 and 2023.
TERI’s Algal Biorefinery Research (Gujarat): Under the Gujarat State Biotechnology Mission (GSBTM), The Energy and Resources Institute (TERI) has been conducting advanced applied research to evaluate microalgae as a scalable 3G biofuel system. The project integrates waste management directly with energy production. The team successfully utilized treated wastewater—rich in organic fractions and trace elements—for the mixotrophic cultivation of freshwater microalgae. This eliminates the need for fresh drinking water and expensive commercial fertilizers.
TERI cultivated indigenous Chlorella sp. and evaluated Micractinium reisseri biomass for lipid profiling and ethanol yield. The harvested biomass is processed through enzymatic hydrolysis and fermented using a proprietary in-house yeast isolate, Candida neerlandica. This established a robust, standardised framework for large-scale algal biorefinery systems in India.
Because this technology does not depend on any agricultural feedstock or non-food plant, it is, in principle, the most scalable pathway for oil refineries themselves to become net producers of biofuel from their own waste streams, an attractive proposition given that India operates a large number of oil refineries. However, replication at other sites is still at an early, evaluative stage, and 3G capacity nationally remains a small fraction of the overall ethanol pool, dwarfed by 1G and even 2G capacity for now.
A comprehensive techno-economic assessment of 3G ethanol in India reveals that while the yields are vastly superior, commercialisation faces cost hurdles. To offset high cultivation and dewatering costs, future 3G biorefineries in India will need to rely on the co-production of high-value by-products alongside ethanol to ensure long-term commercial success. However, with continuous research and technical improvements, 3G ethanol is widely considered the fuel of the future.
4G ethanol represents the cutting edge of biofuel science: the use of genetically engineered and synthetic-biology-modified microorganisms — bacteria, yeast, cyanobacteria (blue-green algae) and other microbes — deliberately redesigned at the genetic level to produce ethanol more efficiently, from a wider range of feedstocks, or even directly from carbon dioxide and sunlight. Where 2G improves the pre-treatment and enzymatic breakdown of biomass, and 3G exploits algae or waste gas streams, 4G goes a step further by re-engineering the biological “factory” itself — the microorganism — to be a better, faster, or more versatile ethanol producer.
The defining feature of 4G ethanol is its design as a highly efficient carbon capture and storage (CCS) system. In this generation, scientists genetically engineer microalgae or cyanobacteria to act as microscopic chemical factories. These organisms are engineered to optimise their photosynthetic pathways, allowing them to capture industrial carbon dioxide emissions at incredibly high rates.
In some of the most advanced 4G models, these engineered organisms do not even need to be harvested, dried, and chemically broken down. Instead, they are genetically programmed to secrete ethanol directly into the surrounding aqueous medium as they grow, converting sunlight, water, and CO₂ directly into fuel. Alternatively, 4G technology also encompasses the synthetic production of biofuels by converting industrially captured emissions and green hydrogen into fuel using advanced chemo-biological processes
4G approaches typically rely on tools such as:
4G ethanol in India remains firmly at the research and institutional-development stage rather than commercial deployment, but the groundwork is being laid seriously. The Government of India views 4G biofuels as a long-term strategic asset that aligns perfectly with the nation’s Net Zero emission targets, though commercial deployment remains decades away.
The Department of Biotechnology (DBT), under the Ministry of Science and Technology, funds several dedicated centres working on next-generation ethanol biology, including the DBT-Pan IIT Centre for Bioenergy, which has developed engineered, thermostable, glucose-tolerant β-glucosidase enzymes (useful for both 2G and more advanced routes), and the DBT-ICGEB Bioenergy Centre, which is scaling up cellulase enzyme technology.
The International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, has emerged as a notable Indian “biofoundry” hub. Its synthetic biology group is engineering microbial strains of E. coli and S. cerevisiae — described by researchers as “designing your dream car” but with microbes as the chassis — specifically targeting improved first- and second-generation ethanol production, alongside other fuel and cosmetic molecules, using the DBTL synthetic biology loop.
Indian academic centres, including the Center for Innovative and Applied Bioprocessing in Mohali, Punjab, are actively researching synthetic-biology tools to expand the ethanol-tolerance, thermotolerance and genetic versatility of non-conventional yeast strains for biofuel production.
No commercial-scale 4G ethanol plant yet operates in India; the technology is best understood today as the research pipeline that will, over the coming decade, feed improvements back into India’s 2G and 3G commercial plants — for instance, by supplying hardier, cheaper, more efficient enzymes and microbial strains to plants like Panipat, Bathinda, Bargarh and Numaligarh, rather than existing as a separate category of standalone plant just yet.
No honest discussion of ethanol blending in India can avoid the recurring consumer grievance around fuel efficiency — the widely reported anecdotal complaints that E20-compliant vehicles deliver somewhat lower mileage than pure petrol, a claim with a real scientific basis given ethanol’s lower calorific value per litre, as explained earlier in this article. This is a legitimate debate, and one that vehicle manufacturers, regulators and consumers will continue to have as blending percentages rise and flex-fuel vehicle technology matures. The Ministry has itself been at pains to clarify that, even as India touched the 20 per cent average blending milestone in ESY 2025–26, no decision has been taken to raise the nationwide base blend beyond E20 for now, with E85 reserved strictly for certified flex-fuel vehicles rather than the general vehicle population.
But set against this efficiency debate is a far larger and less negotiable strategic reality: India, and indeed the world, cannot indefinitely run its transport fleet on crude oil, because crude oil is a finite, depleting resource, and the geopolitics of securing it are becoming steadily less forgiving.
Consider the state of global oil exploration. Industry analysts at Wood Mackenzie have flagged a potential 300-billion-barrel supply gap by 2050, noting that production from currently producing and already-sanctioned fields is projected to decline by nearly 40 per cent between 2025 and 2040, even as exploration spending has stayed roughly flat at about $19 billion a year — a sum that buys progressively less exploration success as the easy, cheap, onshore fields run dry. The world has, in effect, already found and largely tapped its accessible onshore oil; new major onshore discoveries have become vanishingly rare across mature basins. What remains is increasingly concentrated offshore, and increasingly in deep and ultra-deep water that require enormously expensive floating production platforms, specialised deepwater rigs, and years-long lead times before a single barrel is produced.
Even so, 2025 was recorded as one of the weakest years in a decade for newly discovered oil volumes, with total additions hovering around just 1 billion barrels of oil equivalent worldwide — and a separate industry compilation found that global oil and gas discoveries fell to a record low of roughly 5 billion barrels of oil equivalent, with exploration costs for oil more than doubling, from $3.50 to $8.80 per barrel of oil equivalent, in a single year, as the remaining prospects grow ever more geologically and financially challenging. Analysts at Welligence have warned that the global oil and gas supply gap could reach as much as 25 million barrels per day by 2040 without sustained deepwater investment — investment that itself depends on oil prices staying high enough, for long enough, to justify the risk.
Layer on top of this the recurring geopolitical shocks that have periodically disrupted crude supply and pricing — conflicts and sanctions in the Middle East, Russia and elsewhere, OPEC+ production decisions, shipping-lane chokepoints, and tariff and trade tensions of the kind currently reshaping global sugar and ethanol trade flows between India, Brazil and the United States — and the case for energy diversification becomes not just environmentally desirable but a matter of basic national and economic security for an import-dependent country like India, which sources roughly 85–88 per cent of its crude oil requirement from abroad.
This is precisely why India’s Ethanol Blended Petrol Programme, whatever legitimate quibbles remain over mileage and vehicle compatibility, is best understood not as a discretionary green initiative but as a structural hedge against an oil market that is becoming scarcer, deeper, costlier and more geopolitically fraught with each passing year. The programme has already delivered tangible results: the government states that ethanol blending has saved more than ₹1.90 lakh crore (roughly US$22.8 billion) in foreign exchange since 2014–15, displaced over 310 lakh metric tonnes of crude oil imports, and cut carbon dioxide emissions by around 930 lakh metric tonnes.
The evolution from 1G to 2G, 3G and, eventually, commercial-scale 4G ethanol is the natural and necessary response to the legitimate criticisms of first-generation biofuel — namely, that it competes with food and water resources. Rice straw that would otherwise choke Delhi’s winter air, bamboo that grows wild across the Northeast, refinery off-gas that would otherwise be flared uselessly into the atmosphere, and eventually genetically engineered microbes that can manufacture ethanol from little more than sunlight and captured carbon dioxide — these are the feedstocks of India’s ethanol future, each one designed specifically to decouple the country’s fuel security from its food security. Sugarcane will remain part of the story, but increasingly, it will not need to carry the weight of it alone.
In this third and final part, we will unpack every single layer of India’s energy roadmap for the next 20 to 30 years.
This report explores the chemical and industrial shift behind India’s successful 20% ethanol blending (E20) target. It details the molecular benefits of ethanol, such as boosting petrol’s octane rating and reducing emissions.
When Indian retail sugar prices surged by up to 20% in mid-2026, rumors blamed the national ethanol blending program. This investigative report analyzes official government data to reveal the real culprits: hoarding, festive demand, and artificial market speculation.
Selected issues, clear explanations and thoughtful perspectives—delivered when we publish.
