In 2021, the Government of India had stated it can transfer to twenty% ethanol mixing in petrol by 2025 with the two-pronged purpose of chopping carbon emissions and decreasing the nation’s dependence on overseas oil. While autos modified to be suitable with the brand new composition began rolling out in April 2025, the federal government’s push for 20% ethanol-blended petrol (E20) has left vehicle-owners apprehensive concerning the impression on their older autos and a couple of surge in upkeep prices.
Ethanol, or ethyl alcohol, is a biofuel: it’s created from plant waste referred to as biomass. Regular petrol is a hydrocarbon created from the fossilised stays of natural matter buried for thousands and thousands of years.
When blended with a fossil fuel like petrol, ethanol acts as an oxygenate that helps the petrol burn higher.
Making ethanol
Under India’s ethanol-blending programme, the federal government procures ethanol both from sugarcane-based uncooked supplies like C-heavy molasses, B-heavy molasses, sugarcane juice, sugar or sugar syrup, or broken meals grains like damaged rice, maize or cellulosic and lignocellulosic supplies.
Molasses is a byproduct of sugarcane manufacturing. It is a thick, darkish syrup about 40% wealthy in sugars that may be fermented however which might’t be extracted additional.
C-heavy molasses are the ultimate byproduct of the sugar manufacturing course of, with molasses content material round 28-32%. B-heavy molasses are an middleman byproduct of the identical course of and have a better molasses content material, round 48-52%.
Ethanol is created from molasses by fermentation — utilizing yeast enzymes to catalyse the breakdown of sugar molecules within the presence of water. An on a regular basis instance of fermentation is ginger soda. If you place ginger, sugar, and water in an hermetic container for a number of days, it turns into fizzy. This is as a result of the microbes in ginger feed on the sugar, releasing carbon dioxide, which makes carbonic acid with water.
In step one of ethanol manufacturing from molasses, sucrose molecules within the syrup are diluted with water. Then they break down into glucose molecules within the presence of invertase.
These glucose molecules additional react within the presence of zymase to kind ethanol and launch carbon dioxide.
Producing ethanol from meals grains and lignocellulosic supplies additionally entails different processes that break them all the way down to fermentable sugars first. Lignocellulosic biomass is plant matter with a excessive carbohydrate content material and is often composed of components not used for meals or feed. This biomass is wealthy in cellulose, hemicellulose, and lignin.
Chemical nature, power effectivity
Two elements are key to understanding ethanol’s power effectivity: the calorific worth and the octane quantity.
The calorific worth of a fuel denotes its yield: a better calorific worth means extra power. The calorific worth of ethanol is considerably decrease than that of petrol, so the fuel’s total burning effectivity ought to theoretically lower. However, the federal government has maintained that the drop in fuel efficiency will not be vital and that it’s ruled by a mixture of different elements, together with “driving habits, maintenance practices such as oil changes and air filter cleanliness, tyre pressure and alignment, and even air conditioning load”.
The octane quantity is a measure of a fuel’s resistance to engine knocking or burning prematurely. Ethanol has a better octane quantity than petrol. Thus it has the potential to scale back the knock resistance considerably. However, due to its decrease power content material, the quantity of power the engine can extract per litre of blended fuel decreases with rising ethanol content material.
This stated, the drop in mileage drivers have raised issues about gained’t be vital, Sudheer Kumar Kuppili, a analysis fellow at London School of Hygiene and Tropical Medicine, stated.
“The compensation for having lower energy would be quite low when you are moving from E10 to E20,” Kuppili stated. “It would be significant only when we shift to 100% ethanol. Most of the uproar these days about the reduction in vehicular mileage is fuelled by many factors, which are difficult to assess.”
In reality, specialists stated the factor to concentrate on right here is ethanol’s hygroscopic nature. That is, ethanol has a substantial tendency to draw and fasten water molecules to itself. This in flip impacts the automobile’s elements and fuel efficiency in new methods.
Independent skilled Noble Varghese stated the principle concern is the elevated risk of corrosion.
“Ethanol affects the rubber components of a fuel system, which is mainly the piping, the fuel tank, the injectors, the filters, and the combustion chambers. The combustion chamber and the engine block itself are not as affected by ethanol, but what is affected is the fuel tank, the rubber piping, and the injector,” Varghese stated.
“Ethanol tends to attract water, so if the vehicle is not used everyday, water tends to collect in the fuel tank, which is corrosive for the tank. This causes another problem too: rust particles mix with fuel and go into the fuel line and clog it,” he added.
“That in itself will reduce the mileage. This is not primarily because of ethanol’s thermodynamic properties but more because of the components which are not suited to E20 fuel.”
The authorities has nonetheless maintained that changing older rubber components and gaskets designed for the non-blended fuel is “inexpensive and can be easily managed during routine servicing.”
A press release launched by the Ministry of Petroleum and Natural Gas (MoPNG) on August 12 additionally stated this modification can be required solely “once in the lifetime of the vehicle” and at “any authorised workshop”.
Kuppili additionally stated moisture gained’t be a big drawback.
“This might be a problem for older vehicles, which are probably already worn out. This should not be a problem for BS-IV or BS-VI vehicles. The fuel’s hygroscopic nature might have a noticeable effect when you are in colder parts of the country. However, in those regions, fuels are usually mixed with additives to avoid freezing,” he defined.
“Also, when you are using a vehicle regularly, any moisture that accumulates will be evaporated by the high engine temperatures (>400º C),” he stated.
Kuppili wished to make clear that he hasn’t labored on this explicit situation of the fuels.
Comparisons with Brazil
Comparing the Indian ethanol-blending story with that of Brazil might not be justified because the South American nation at present makes use of E27 petrol in addition to paced this improve out over many years.
Brazil first determined to decrease its dependence on imported petrol in 1975 with its Proálcool programme through the oil disaster within the Nineteen Seventies. Over the following few years, it targeted on constructing capability by working with researchers, increasing the manufacturing of ethanol from sugarcane with the precise function of blending it with petrol, offering subsidies, incentives, and tax breaks to scale back the prices of manufacturing, and rising the competitiveness of ethanol.
The nation additionally has a big marketplace for autos match with flex-fuel engines that permit autos to readily adapt to petrol with totally different ethanol fractions.
This isn’t the case with Indian autos. According to Varghese, the digital management unit in an engine is hypersensitive to fuel content material, which it detects robotically.
“If you put more ethanol in fuel, its chemical properties change and therefore the engine management system has to be able to adapt, and older cars might not be able to do that,” he stated.
By manner of answer, he stated mechanics may shortly join the unit to a pc and replace the fuel composition setting.
However, one senior trade government instructed The Hindu that autos that don’t have digital management models and injectors can’t be made suitable with E20 as fuel. The government stated “about 95%” of all autos till the rollout of the BS-VI emission requirements (in April 2020) had been mechanically carbureted, that means they didn’t utilise any digital models with sensors to manage the supply and therapy of fuel.
“When the blending happens, it alters the stoichiometric ratio, i.e. air-to-fuel ratio, which in turn affects the speed of combustion and heat release,” Kuppili stated. “Modern vehicles have sensors called electronic control units, which monitor the oxygen content and alter the amount of fuel and air needed.”
With ethanol-blended petrol, he added, “you would need less air than usual, as ethanol has an oxygen atom. So this reduction can actually reduce pollutant emissions such as NOX, PM, and CO.”
“The ethanol-blending policy itself is excellent. It has been successful in other parts of the world,” Varghese stated. “The ideas of energy security and saving import duty are excellent and true. It just needs to be paced better.”
The precept of recalibration
The government stated the sensor’s fundamental function is to handle the spark timing — which determines the discharge sample of the fuel and combustion contained in the cylinder. The digital management unit makes use of the spark plug to create the spark that ignites the fuel-air mix within the combustion chamber. Older autos, i.e. these missing the unit, have been tuned to a special fuel and are thus hard-coded for a special spark timing.
Since E20 brings extra oxygen to the fuel-air combine, the manager defined, engines might should be recalibrated by, amongst different measures, advancing the strain for combustion and its eventual timing by two to 3 levels. In different phrases, the engine should be certain combustion occurs earlier in order that there aren’t any points with beginning the automobile and with sustaining an ample air-fill ratio throughout all load circumstances and speeds.
This customisation isn’t attainable with mechanically carbureted autos.
The government additionally affirmed that the adjustment would improve value.
“You have to pay the calibration engineer and the vehicle component engineers,” he stated. The latter “charge good money.”
(With inputs from Saptaparno Ghosh)
