Across much of India, an energy crunch caused by the Iran war has prompted long queues for cooking gas cylinders. That is not a problem for Gauri Devi.

On a stove with blue flames, she flips a chapatti flatbread, burning biogas produced from cow dung – an alternative fuel helping ease pressure on supplies.

“It cooks everything,” the 25-year-old said in her courtyard kitchen in Nekpur, a village in Uttar Pradesh, about 90km (55 miles) from New Delhi. “If the pressure goes down, we let it rest for half an hour and it works again.”

India consumes more than 30 million tonnes of liquefied petroleum gas (LPG) annually, importing over half its needs.

The government insists there is no shortage of cooking gas, but supply delays, panic buying and black marketeers have created long queues for cylinders.

However, since the 1980s, India has also promoted biogas as a low-cost rural energy source, subsidising more than five million “digester” units that convert farm waste into methane for cooking, and nitrogen-rich slurry for fertiliser.

For Gauri, it requires mixing a couple of buckets of dung with water, then pouring the mixture into a car-sized underground tank topped with a storage balloon.

It provides a piped methane supply so regular that she uses an LPG cylinder only for emergencies or large gatherings.

The biogas works for everything – “vegetables, tea, lentils”, she said.

Slurry in a hurry

The residual slurry is later spread on fields as fertiliser. It has better nitrogen availability for plants compared with raw dung, farmers say.

“The manure is so good,” said farmer Pramod Singh, who installed a larger unit in 2025, enough for six people, fuelled by 30kg (66lbs) to 45kg of dung daily from four cows.

And he said the slurry fertiliser was particularly valuable at a time when global supplies of artificial fertilisers had been hit by trade disruptions due to the war.

“The real benefit is not just the gas – that is like a bonus,” local farmer leader Pritam Singh said. “The slurry is ‘black gold’.”

The real benefit is not just the gas … The slurry is ‘black gold’

Pritam Singh, a local farmer

More than 45 per cent of India’s 1.4 billion people rely on farming, and the country has one of the largest cattle populations.

India – the world’s most populous nation and third-largest fossil fuel polluter – has pushed large-scale biogas production to achieve a goal of carbon neutrality by 2070.

The government last year required that biogas account for at least 1 per cent of liquid gas fuelling both vehicles and for domestic use – rising to 5 per cent by 2028.

Dozens of multimillion-dollar production plants are now in the pipeline.

But small-scale rural producers are also being rolled out – units cost around 25,000 to 30,000 rupees (US$260 to $315), often heavily subsidised by the government.

In a Hindu-majority nation where cows were revered and dung and urine are used in everything from floor plastering and fuel to ritual practices, it was easy to win supporters, Pritam Singh said.

He installed his first plant in 2007, and has helped put in 15 more in his village in the past year alone.

Interest has shot up after the LPG shortages.

“People who earlier were not interested now ask how to get it,” he said. “Once they see food being cooked and crops benefiting, they are convinced.”

Biogas barriers

But biogas is still a small fraction of household cooking fuel – with LPG considered more convenient because companies manage the supply chain.

“Biogas plants are not just equipment; they are mini factories,” said AR Shukla, president of the Indian Biogas Association.

“They need organised installation, regular operation and maintenance,” he added. “So, unless installation and upkeep are handled through community-based or cooperative enterprises, households will continue to treat biogas as secondary fuel.”

And even with government support, there are barriers to uptake, including cost and space.

“We work on other people’s farms the whole day. We don’t have land for it,” said labourer Ramesh Kumar Singh, standing in a line of around 100 queuing for LPG cylinders in the nearby village of Madalpur.

“I am standing in scorching heat, hungry and thirsty,” said Mahendri, 77, who had failed to secure a cylinder for three days in a row.