Parshottambhai Shanabhai Patel, 65, says the biggest favor the people of his village did for him “was saying they would no longer put up with the stink from my cowshed at the entrance of the village.”

Reluctantly in 1994, Patel shifted his eight animals to his three-hectare (7.4 acre) farm 3 kilometers (1.9 miles) away from his village in Gujarat State’s Anand district. The district is where the Indian dairy cooperative AMUL started the country's "white revolution," a hugely successful grass-roots movement that has helped turn India into the world’s largest milk producer, with 2.5 million liters (660,000 gallons) of milk collected daily from more than 1,176 village cooperatives.

Now Patel's contentious cow dung could spark a revolution of a different kind.

After a decade of practicing organic farming, thanks to training provided by the Gujarat government-run Navsari Agricultural University, Patel decided in 2009 to push his farm even further into the green by building his own biogas plant.

With technical guidance from the university, he constructed a six cubic-meter (212 cubic foot) brick-and-mortar underground plant near his cowshed and connected it to his existing 12 horsepower irrigation pump. By turning the gases emitted by cow dung slurry into a clean, renewable fuel that Patel uses to run his irrigation system, the plant saves him money, increases his productivity, and boosts his profits.

Experts say biogas plants like Patel's are easy to build, operate, and maintain. And in a country dealing with changing rainfall patterns, and where only 35 percent of agricultural land is irrigated, they could transform the lives of India's small farmers.

Biogas plants, or digesters, work by encouraging the breakdown of organic matter (cow dung, in Patel's case) by bacteria in the absence of oxygen. The resulting methane gas can then be stored and burned as fuel. Each day, Patel's plant converts the 200 kg (440 pounds) of dung his livestock produce into 8 to 10 hours of power. It takes 30 kgs of dung to generate one cubic meter of gas. "But, yes, collecting all that dung from the cowshed unfailingly every day is highly labor intensive," he admits.

Before turning to biogas, Patel would struggle to come up with enough power to run his home and his farm. "The eight hours of power that the government grid supplies daily to a single tube used by 10 neighboring farms would always be usurped by large-holding farmers," says Patel. "Every day I would have to buy 1.7 liters of diesel to run my pump." For irrigation alone, Patel was spending 22,000 rupees ($400) annually and had to limit his farmed area in the summer to keep down costs.

Today, Patel's diesel bill is a fraction of what it was. His biogas plant produces more power than he can use, so after his farm and home requirements are met he sells the remaining power to area farmers, charging 60 rupees ($1) an hour.

He is forced to keep his rates competitive with the government-subsidized power supply to farmers in the area, which caps his profits. But he still has an edge when it comes to timing: The government supply is available for limited and often inconvenient night-time hours; Patel can give his clients power whenever they need it.

The affordability and reliability of biogas means Patel finally has the freedom to make the most of his land. In 2011 he took out a bank loan of 180,000 rupees ($3,330) to install a drip irrigation system, for which the government paid 50 percent. Now the half of his farm that is on the drip system – using a network of narrow pipes to deliver water directly to the base of individual plants – takes just an hour to water.

With water at his beck and call, Patel has ventured into high-value cash crops like tomatoes, watermelon, onions, and flowers. Today he can earn 200,000 rupees ($3,700) from the same three hectares that five years ago, without the biogas plant, fetched him just a quarter of that.

“I can repay the bank loan in 18 months, where earlier it would have taken me five long years to do so,” he says.

It used to be that his main concern was to grow enough grain to feed his family of six and his two farm hands. Now he has plenty to spare and enough cash to buy other food he needs.

And the biogas isn't the only money producer. The fermentation process that produces the gas also leaves behind a fertilizer that Patel can use and sell. He goes through 20 tractor loads of organic compost each season. For most farmers, that compost would cost 1,000 rupees ($19) per load. For Patel, it's free.

While Patel enjoys the higher income and savings his biogas plant generates, it's the environmental benefits that have activists and policymakers encouraging the use of biogas as an energy source in the developing world. Not only does it dispense with the need for fossil fuels and petroleum-based chemical fertilizers, it also uses up methane, a powerful greenhouse gas.

Biomass such as firewood, charcoal, animal dung, and agricultural residue are the main energy resource for the poor in the developing world, making up 17 percent of total energy used, compared to 3 percent in the developed world, according to 2007 figures from the International Energy Agency. But biomass is mostly used for cooking, with few farmers harnessing its power for irrigation.

“Parshottambhai Patel shows the way to save on irrigation costs and be environmentally benign too,” says Tushaar Shah, who leads the IWMI-TATA Water Policy Research Program, a partnership between the International Water Management Institute (IWMI), based in Colombo, Sir Lanka, and the grant foundation the Sir Ratan Tata Trust.

Patel says farmers from faraway districts have come to see his biogas plant, with the aim of replicating it back home. He hopes more of his fellow villagers will follow him in his move to biogas – and take their farms’ futures into their own hands.

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• Manipadma Jena is an environmental journalist based in India. She can be reached at manipadma.jena@gmail.com.

• This article originally appeared at AlertNet, a humanitarian news site operated by the Thomson Reuters Foundation.