Diesel, India’s largest transport fuel, accounts for nearly twice the country’s petrol consumption, making the proposed programme significantly larger than the E20 initiative.

India has initiated validating a 2 per cent isobutanol-diesel blend across commercial vehicles, laying the groundwork for what could become the country’s first diesel biofuel programme after previous ethanol-diesel blending attempts proved unsuccessful. The government-backed initiative brings together the Ministry of Road Transport and Highways (MoRTH), Hindustan Petroleum Corporation Limited (HPCL), the Automotive Research Association of India (ARAI), Praj Industries and commercial vehicle manufacturers to evaluate the fuel before any wider rollout.

Tata Motors Executive Director Girish Wagh, speaking on the sidelines of the Investor day media roundtable on Thursday, said the company will begin pilot trials this quarter once HPCL supplies the blended fuel. “We are working with HPCL to give us the blended fuel, and we will start trials in this quarter,” Wagh said.

Describing the government’s approach as collaborative, he added, “The government has been very consultative and participative on all these matters.” The trials will assess engine performance, durability and fuel efficiency before policymakers decide the roadmap for broader adoption.

Why India is moving beyond ethanol

Diesel, India’s largest transport fuel, accounts for nearly twice the country’s petrol consumption, making the proposed programme significantly larger than the E20 initiative.

While the initial 2 per cent blend is unlikely to require major hardware changes to BS-VI diesel vehicles, the larger investment challenge lies upstream.

Biofuel industry estimates suggest retrofitting an existing first-generation ethanol distillery to produce bio-isobutanol could require capital expenditure of around ₹140 crore for a plant with an annual capacity of about 68 million litres.

Leveraging India’s existing ethanol infrastructure could prove faster and more effective than building an entirely new production ecosystem. However, additional investments in refinery integration, logistics and long-term policy support will still be required.

India’s move follows the failure of earlier attempts to blend ethanol with diesel due to stability and compatibility issues. While ethanol blending has successfully reached E20 in petrol, it has proven unsuitable for diesel applications.

Union Road Transport and Highways Minister Nitin Gadkari had earlier said efforts to develop a 10 per cent ethanol-diesel blend were unsuccessful, prompting the search for an alternative fuel.

Isobutanol blends more uniformly with diesel, is less corrosive than ethanol and has a higher energy density, making it a more suitable candidate for diesel engines while limiting the fuel-efficiency penalty associated with ethanol blends.

Commercial vehicle industry gears up

Unlike the E20 programme, which primarily affected petrol vehicles, the proposed diesel biofuel initiative will have its greatest impact on commercial vehicles, buses, tractors and heavy-duty transport.

Industry executives say manufacturers are working on two parallel tracks—validating today’s 2 per cent drop-in blend using existing BS-VI diesel engines, while simultaneously studying the engineering changes that could be required if policymakers eventually raise blending levels. Current work focuses on combustion behaviour, fuel-system compatibility and long-term durability.

ARAI and Praj Industries are conducting a 10-month technical validation programme, while HPCL continues parallel on-road evaluations using BS-VI diesel vehicles. Bharat Petroleum Corporation Ltd (BPCL) is also understood to be undertaking similar work as oil marketing companies prepare for a potential future blending programme.

“The calorific value is lower than diesel, so there would be some impact, but at 2 per cent it is hardly anything,” Wagh said, indicating that the initial blend level is unlikely to materially affect vehicle performance.

A market larger than E20

Beyond reducing crude oil imports, diesel biofuels could create a significant new market for agricultural feedstocks such as sugarcane and grains, while complementing the commercial vehicle industry’s broader transition towards cleaner fuels.

For Wagh, the objective goes beyond regulatory compliance. “Energy independence is so important that I’m sure everybody will align and support this,” he said.

If the ongoing validation programme succeeds, India could finally establish a commercially viable pathway for diesel biofuels after years of unsuccessful ethanol-blending experiments, opening the next phase of the country’s biofuel transition, said an industry analysts.

Published on June 25, 2026