Girish Wagh Confirms Q2 FY27 Kickoff for Isobutanol-Diesel Blending Trials

A pilot trial for blending isobutanol with diesel is expected to begin in the second quarter of FY27, targeting a 2% blend ratio to advance India’s goal of energy independence, Girish Wagh, MD & CEO of Tata Motors stated during a media roundtable on Thursday.

A government-led task force, which includes active participation from original equipment manufacturers (OEMs), oil marketing companies, testing agencies and others, is driving the initiative. Tata Motors is currently coordinating with Hindustan Petroleum Corporation Limited (HPCL) to secure the specialized blended fuel for the upcoming tests.

The development should be seen in the context of how ethanol is being blended with petrol, with the base blending level now at 20% (also called as E20). Amidst fuel supply challenges emanating from the West Asia war, the government recently notified standards for ethanol blending of E22, E25, E27 and E30. Plans are now being prepared to take blending levels up further, and the government also announced the rollout of E85 and E100.   

Autocar Professional had in May reported about how India's auto industry heavyweights which includes commercial vehicle OEMs, testing agency ARAI, the Council of Scientific and Industrial Research (CSIR), oil marketing companies, and others are moving to break a decades-long deadlock in diesel decarbonization by launching a nationwide validation program for isobutanol blending.

The Automotive Research Association of India (ARAI) will lead a 10-month technical assessment alongside bioenergy tech supply major  Praj Industries to determine if  isobutanol can serve as a seamless "drop-in" replacement for standard diesel. With nearly all major OEMs expected to  participate, the initiative indicates a shift away from problematic diesel-blending  trials, focusing instead on a molecule that promises better stability and safety for the nation's critical transport fleet.

Oil majors are already showing skin in the game. BPCL has been quietly testing isobutanol for two years, recently completing a three-month trial in stationary Cummins engines. They are now committing significant capital to validate data across 33 different vehicle types in India.

The Experiments Continue

To understand why isobutanol is causing a stir, one must look at the failures of ethanol-diesel blending. For years, engineers tried to force ethanol into diesel tanks, but the chemistry refused to cooperate. Ethanol is a two-carbon alcohol with a "polar" structure, meaning it doesn't like to mix with the oily consistency of diesel. Without expensive chemical binders, the two fuels simply separate in the tank.

More critically, ethanol is a fire hazard in a diesel ecosystem. Its "flashpoint"—the temperature at which it catches fire—is a mere 12 to 13 degrees Celsius. Diesel, by contrast, is regulated to a minimum of 35 degrees. This difference puts them in entirely different petroleum safety classes, making shared storage and transport a logistical nightmare. Even with proprietary binders, OEMs  were rarely comfortable going beyond a 5% blend before combustion issues emerged.

Praj Industries, the Pune-based bioenergy giant, has spent the last two years building the technical bridge that ethanol couldn't cross. As a four-carbon alcohol, isobutanol behaves much more like diesel. Its flashpoint sits between 27 and 30 degrees Celsius, which allows it to stay within the same "Class B" petroleum category as diesel. This means the existing network of tankers and pumps doesn't need a multi-billion-dollar overhaul. Initial investigation  found that isobutanol remained stable at 10% blends for over 40 days without any separation. Early dynamometer trials on standard Indian driving cycles showed that a 5%  blend slashed emissions with a negligible 1 to 2% impact on fuel mileage, a trade-off most fleet operators would take in a heartbeat.

Key Level of Self Reliance

According to Wagh, Isobutanol, a biofuel that can be mixed with diesel, is a key lever for reducing reliance on imported fuels. While isobutanol has a lower calorific value (energy content) than traditional diesel, the minimal 2% blend is expected to have a negligible effect on vehicle performance.

"We do expect that isobutanol, because the calorific value is lower than that of diesel, there would be some impact," said Girish Wagh, MD & CEO of Tata Motors. "But 2% is hardly anything to have an impact. But we will start these trials".

Wagh emphasized that the shift is essential for national energy security, noting that "energy independence is so important that I am sure... everybody will fall in line and do this".