This company is helping small farmers turn waste into biofuel and fertilizer

Each year, farms around the world generate billions of tonnes of manure. It’s a big problem not only for farmers but also for the environment, because agricultural waste contaminates groundwater and emits greenhouse gases.

Biogas systems that capture methane from waste and turn it into energy and fertilizer have become increasingly popular.

But in many developing economies, where food is produced mostly on smallholdings, farmers can’t afford the technology and don’t have the knowhow or training to use it.

That’s where Sistema.bio comes in. The Mexico City-based social enterprise manufactures, distributes and services affordable biodigesters that convert waste into cooking fuel and fertilizer.

“Smallholder farmers have to live really intimately with their waste streams. And as farms grow, [that means] lots of cow dung in particular,” Alex Eaton, Co-founder and CEO of Sistema.bio, says.

“We try to help farmers basically through a form of biomimicry, taking that waste and turning it into a valuable resource.”

Scaling up

Eaton is an awardee of the Schwab Foundation for Social Entrepreneurship which, in partnership with the World Economic Forum, supports models of social innovation.

His organization helps farmers in Central America, East Africa and India and aims to expand to reach smallholders in other parts of the world.

Agricultural development is one of the most powerful tools to end extreme poverty, boost shared prosperity and feed a projected 9.7 billion people by 2050, according to the World Bank.

But the current food system is unsustainable, threatening the health of people and the planet. Land clearing and farming generate about 22% of the world’s greenhouse gas emissions.

“Ironically many of the people who go to bed hungry are actually small farmers and people that grow the food,” Eaton says.

“We could really work on poverty, food security and climate change if we were to improve the lot of small farmers today.”

Eaton’s biodigesters are specifically designed for small- and medium-sized farms. But many rural households cannot afford to pay for one upfront, so Sistema.bio provides flexible, interest-free repayment plans.

From manure to cooking gas

Eaton says his tubular biodigester system is actually fairly simple – not dissimilar to the fermentation process that takes place in the stomach of a cow.

“The raw material goes in and all the work is done by bacteria. The oldest form of life on Earth is a single-celled bacteria that actually evolved before there was free oxygen. It lives in this environment, breaking down the organic waste, and its only by-product is methane gas.

“We capture that gas and, through tubing, we can run it straight into someone's home so they can cook. Or we can run into an engine to produce mechanical or electrical energy.

“The by-product now is basically all that same organic material but in its purest form, broken down into the raw nutrients that can be used as a fertilizer.”

Age-old technology

This is a modern version of a technology that has been around for a long time. Historians think the Assyrians may have used biogas to heat bath water in the 10th century BC and the anaerobic digestion of solid waste may also have been used in ancient China.

In the late 19th century, the city of Exeter, in the UK, had an anaerobic digester that converted biogas from a sewage treatment facility to power street lamps.

“The idea of turning waste into natural gas is something that's existed for a long time,” says Eaton. “We just realized that it wasn't being done well and it wasn't being done in a scalable way.”

Eaton, who grew up in the US on a small farm himself, says his 'eureka' moment came when he saw an opportunity to improve access to energy in rural areas and produce organic fertilizer at the same time.

“That nexus was something that was really fascinating and where we realized that biodigesters were something that could be done much better.”

“We basically take what is a stinky mess and turn it into an amazing opportunity.”