India to mandate isobutanol-diesel blending this year to cut emissions

India may soon mandate blending isobutanol with diesel and issue new rules for truck-trailers to boost energy security and cut carbon emissions. Speaking at a CII summit on Friday, V. Umashankar, secretary at the ministry of road transport and highways, said the blending mandate is being taken very seriously and is expected to roll out later this year.

“Bharat Petroleum is already undertaking strategic research for isobutanol blending with diesel. And the results are very encouraging. It is quite likely that the blending mandate will start coming in somewhere later this year. And diesel consumption is almost two times that of petrol consumption. So, blending diesel will have a far greater impact on our energy security than blending petrol,” Umashankar said.

The ministry has also commissioned the Automotive Research Association of India (ARAI) to study flex-fuel engines that can run on up to 100% isobutanol as an alternative to diesel. This research will include vehicle tests to see how engines perform with isobutanol-blended fuel.

Isobutanol is a biofuel made from ethanol using fermentation. It has higher energy density than ethanol and is less corrosive, properties that make it suitable for blending with diesel.

Data from initial tests suggests that isobutanol blending substantially reduces pollution from diesel vehicles without altering their running. Using this biofuel may not require any major changes to a vehicle's engine or exhaust system.

Mint reported in August 2025 about the government’s plan to undertake isobutanol blending with diesel and develop flex fuel engines that could use up to 100% isobutanol as fuel.

Umashankar noted that the ministry will soon release a draft notification for truck trailers. The move is designed to support a new ecosystem for heavy-duty electric trucks, specifically addressing the infrastructure needed for battery swapping and charging, he said.

Umashankar explained that the ministry is exploring "tractor-trailer interchangeability" as a more efficient alternative to long charging times or complex battery-swapping stations. Under this plan, instead of charging the vehicle or swapping the battery, the entire front of the truck would be detached and replaced with a fully charged unit, allowing the trailer to remain in use while the power source is swapped out at specific locations.

He added that hydrogen-powered public buses were recently launched on routes connecting Delhi with Faridabad and Noida.

“Hydrogen refuelling stations have already been set up under this scheme. These buses can travel 450 km before needing a refuel. So for the Delhi-Mumbai corridor, maybe three refuelling stations will be needed,” the secretary said, responding to a question by Ashwani Gupta, chairman, CII national committee on ports and shipping, and whole time director & CEO, Adani Ports and SEZ, on the country’s plan for alternative fuels for commercial trucks.

The secretary also said multi-lane free flow (MLFF), a barrier-less tolling system that eliminates the need for vehicles to stop or slow down at toll plazas, is likely to be introduced in the “forthcoming year”.

“This (MLFF) has already been introduced in two toll plazas and it's working very successfully. The third one is likely to go live in the next 8-10 days. We plan to expand this to all four-lane-plus toll plazas across the country within the forthcoming year. We are also going to put in place an advanced traffic management system. We have got the first proposal for Delhi NCR approved. Issuing bids and the project implementation will start very shortly,” he added.

To increase the average speed of vehicles on roads and highways, the ministry plans to focus on segregating slow and fast-moving traffic on expressways and access-controlled highways.