In the late 1990s, Oscar Ortiz had just moved to a remote ranch in central Colombia when he heard of a mythical-sounding device that promised to make cooking fuel and fertiliser out of the piles of cow manure that littered his farm. Not only would it stop the manure from polluting the runoff that flows into nearby rivers, it could also save him a lot of money.

Yet, despite the biodigester’s benefits to Colombia’s smallholder farmers, Ortiz couldn’t find anyone who could make one. Undeterred, he set out to make his own. “I made a lot of attempts and I lost a lot of money,” Ortiz says, with a laugh, from his home in San Antonio de Tequendama, a humble farming town, about 50 kilometres southeast of the Colombian capital. He spent years reading books and talking to experts, but his first designs failed to produce even a hint of gas.

Today, things are different. A network of tubes and channels sprawls across Ortiz’s two-hectare farm, directing manure from his small herd of cows, hogs, and rabbits into a hard plastic sack that balloons with gas. The fuel is channelled into the kitchen stove, where it’s used to cook sweets that are sold at the market. The coffee shrubs and plantain trees, interspersed among the stables, are nourished with a stream of biol – the liquid organic fertiliser produced by the biodigester – that he also sells at 40 cents per litre.

Affordable farm-tech

This transformation was made possible when Ortiz finally found a biodigester on the market that he could afford. Sistema Bio, the social enterprise behind the design, has made it its mission to bring this piece of rural technology to as many small and mid-size farms around the globe as possible. It provides farmers with energy that is cleaner than fossil fuels, as no new amounts of carbon are released into the atmosphere. So it also helps farmers reduce their carbon footprint, as well as improving waste disposal practices that often contaminate local water supplies.

Small and mid-size farms are responsible for producing up to 70% of the world’s food, yet the kind of forward-thinking technology that could improve their lives and their relationship to the environment is often out of reach for smaller farms. “Because the agricultural industry has developed to support industrial farms, there’s not really technology training and financing that’s specifically designed for smallholder farmers,” says Alex Eaton, founder of Sistema Bio.

Eaton founded Sistema Bio in 2010 after travelling across Latin America and witnessing the precarious state of smallholder farmers there. In 2005, he came across a biodigester for the first time in Nicaragua, a country where half of the rural population lives in poverty.

In theory, the biodigester promised to be a gamechanger, with farmers no longer having to buy fuel to cook or fertiliser to nourish their crops. But, in practice, the device, made out of old plastic and bricks, turned out to be a literal sack of poo, says Eaton. “When it works, biodigesters are a beautiful exercise in alchemy and transformation and treating waste and providing energy. But when it doesn’t work, it’s a horrible mess.”

Eaton realised that if biodigester technology were to take off in small and mid-size farms, it needed urgent investment and development. After getting his master’s degree in environmental engineering, he went back to Latin America, this time with a sturdy biodigester design that he could sell at a cheaper price.

In the rural parts of central Colombia, where Ortiz lives with his wife, many farmers own small herds of cows, hogs, and rabbits. “Farmers often dispose of manure in open pastures that washes into a nearby river whenever it rains, entering the drinking water and causing serious health risks,” Ortiz explains.

Many farmers in the region have adopted the biodigester system out of necessity, Ortiz says. The regional environmental authority has threatened to close down local farms that dump animal waste into the water supply. Ortiz encourages these farmers to purchase the Sistema Bio model, about $400 for the smallest unit. For farms that can’t afford this, Ortiz offers a cheaper model he has learned to make. In the past five years, he has installed 15 across the country.

How does it work?

Through an anaerobic process, the bacteria found in the sealed biodigester break down the organic material and help rid the manure of the dangerous pathogens. It also reduces the amount of methane coming from the manure. Methane is a powerful greenhouse gas that traps heat in the atmosphere, more potent than CO2 in accelerating climate change.

For Eaton, bringing biodigesters into the equation allows smallholder farmers, who have had their livelihoods pummelled by longer droughts, floods, and natural disasters, become part of the solution to climate change. The technology also helps smallholder farmers resist the encroachment of factory farming, which in most countries is swallowing up family farms.

With more than 30,000 biodigesters installed in over 30 countries around the world to date, Sistema Bio estimates that 17 million tons of waste have been treated and almost 350,000 tons of carbon dioxide equivalents have been saved from contaminating the air. At the same time, more than 72 million cubic metres of biogas were produced a year and 337,000 hectares fertilised with organic biol that otherwise would require chemical fertilisers.

The potential global impact is enormous. Eaton explains that if Sistema Bio were able to install biodigesters in just 10% of the world’s 500 million smallholder farms, about 1% of humanity’s greenhouse gas emission would be reduced.

“It’s a massive opportunity,” says Eaton.

One of the challenges to bringing more farmers on board is price. Sistema Bio has developed a payment plan that spans up to 24 months that makes purchasing biodigesters more accessible. Recently, carbon offsets programmes have also helped to cut the price in half in areas where there are especially high greenhouse emissions.

But once a biodigester is installed, people also have to be educated on how they work. “People have to be trained and people have to care about them. There has to be a clear understanding of the benefits and the responsibilities that people have to operate them. The cost-benefit ratio has to be appropriate or farmers won’t do it because they don’t have extra time to waste,” said Eaton.

Operating a biodigester is daily work. In the morning, Ortiz mixes about 30 kilos of manure into 120 litres of water that is injected into a container before entering the biodigester. Much of this work is done by gravity. With the cattle stable located up on a hill, gravity pulls the waste down tubes and channels into the biodigester, a system that Ortiz experimented with on his own.

Other farmers must do this manually.

From gas to rabbit food

Yet, the benefits are countless, says Ortiz. He produces far more biogas and biol than he needs. While he currently sells the biol to plant stores, he stores the gas in a plastic vessel that functions like a balloon. There, he stores enough gas for 15 days of use. With the help of local experts, he has obtained a gas compressor, which he plans to use to store excess gas in containers and sell at a low price to his neighbours.

“Gas is a source of power,” says Ortiz. “It can help me do a lot of things. This year, we’re waiting on some filters, which would allow me to fill up the car, fill up my motorcycle, power an electric generator, power the dehydrator, and power my stove.”

Ortiz is especially excited about making his own rabbit feed, which has become increasingly expensive as commodity prices go up. The process shows how nothing goes to waste on Ortiz’s farm. The fruits he harvests would be processed into an organic feed by a machine powered by biogas, created by rabbit manure. “If you explore and put in the hard work, you can go far.”