Reliance may expand the capacity at its dual refinery complex in Jamnagar in Gujarat by 30 million tonnes a year to 100 million tonnes per year, according to the sources, who saw the expansion plans in a presentation by the company on potential energy scenarios to 2030.

Reliance made the presentation to India's Center for High Technology (CHT), a unit of the Ministry of Petroleum and Natural Gas that evaluates projects and assesses their technological requirements.

The plans signal that Reliance remains bullish on the outlook for India's fuel demand even as the government is considering plans to electrify all of the country's vehicles by 2032. Still, India's demand for diesel and gasoline to power existing and expecting combustion engine vehicles will likely remain strong as its population grows and becomes more wealthy.

"The plan to is to have petrol and diesel output capacity of close to 60 million tonnes by 2030, produced from cheaper heavy grades," said one of the sources.

Reliance did not respond to an emailed request for a comment on the possible expansion.

Reliance operates two refineries at the Jamnagar complex with an installed capacity of 1.2 million barrels per day (bpd), or 60 million tonnes per year.

The plants typically operate above their installed capacity and process 1.4 million bpd of crude, or about 70 million tonnes per year. The refineries are among the most complex in the world and have facilities that can maximize the production of diesel and gasoline from so-called heavy, or higher density, crude oil that typically sells for less than other crude grades.

Raising the refining capacity at the Jamnagar complex to 100 million tonnes per year would equal about 2 million bpd.

The expansion makes sense in light of forecasts for strong fuel demand growth in the country, the world's third-biggest oil consumer. Consultant FGE estimates India's fuel demand to rise to 6.5 million bpd in 2030 from an estimated 4.2 million bpd in 2017.

Although, Reliance has not yet prepared a blueprint for the expansion and details of the costs are yet to be worked out, it would require around $10 billion to complete the plan, said the one source.

In 2014, Reuters reported that Reliance was planning a 400,000 bpd expansion at the Jamnagar site. That plan is yet to be approved by the environment ministry, according to the ministry website.