Localized nexus solutions could offer a global blueprint for agricultural waste

In the lush agricultural heartlands of Southern Brazil, a crisis is gradually building, as the region becomes a victim of its own success. The state of Paraná is a livestock powerhouse, home to massive dairy, pig and poultry operations that feed the world. However, this productivity comes with a considerable environmental price tag. Firstly, there’s the emitting of vast quantities of methane – a greenhouse gas roughly 80 times more potent than CO₂ in the short term.

Then, at the local level, the stakes are just as high. A significant portion of animal manure waste runs off into the watershed of the Itaipu Binacional, the world’s second-largest hydroelectric plant. The nutrient-rich runoff fuels algae blooms (eutrophication) that can clog turbines and threaten the energy security of both Brazil and Paraguay.

This is a classic water–energy–food–environment (WEFE) nexus problem and so served as a valuable cross-country lesson at the 6^th WEFE Nexus Policy webinar, Optimal livestock biogas networks for energy in southern Brazil, hosted by the CGIAR Policy Innovations Program.

The biomethane advantage

The conventional response to Paraná’s agricultural waste conundrum is to install biodigesters to turn manure into biogas, and use that gas to generate electricity. Essentially turning waste into watts. It is a solution deployed globally, often supported by heavy subsidies.

But a new analysis – led by researchers at Massachusetts Institute of Technology (MIT), Pontifical Catholic University of Paraná (PUCPR), and CIBiogás (International Center for Renewable Energy – Biogas), and presented at the WEFE Nexus Policy webinar – has scrutinized this default assumption in the Brazilian context.

The research team built an optimization model to test the local reality, running thousands of scenarios across four regions in Paraná. Their findings were clear: while generating electricity from manure is technically possible, it is often economically fragile. The problem is one of scale and logistics. To make electricity generation profitable, you need massive volume. This forces disparate municipalities to band together, building expensive networks of trucks and pipes to transport manure to large, centralized power plants.

You might generate power, but you burn up your profits (and create new emissions) just moving the manure around. What’s more, Brazil’s electricity grid is dominated by hydropower and electricity prices are relatively low. Competing with the grid would require massive subsidies.

The model revealed a highly promising alternative. Instead of trying to power the grid, farmers should focus on biomethane – purified gas that can be used as vehicle fuel or injected into local gas pipelines.

The numbers are compelling. Pivoting to biomethane could unlock nearly USD 1.5 billion in annual profits for the state of Paraná while slashing greenhouse gas emissions by 68.8 billion kg annually. Interestingly, estimates show that electricity requires 166,000 kg of manure per day to break even, while biomethane becomes profitable at just 500 kg per day in that region.

“The exciting finding in our case for biomethane, was that market prices of methane were used and we determined that would be sufficient to still provide a profit – you don’t actually need any subsidy,” said Afreen Siddiqi, Research Scientist at MIT.

By asking the nexus question first, the team is seeking to avoid costly investment in electricity generation and consider a self-sustaining market solution.

However, there is a limit to localization. The study also found that for smallholders – who make up the majority of producers in Paraná – individual biodigesters are economically unviable. The capital costs are simply too high. The optimal design identified by the model is the condominium approach: a network of gas pipelines connecting clusters of small farms to a centralized biodigester. This creates the necessary economies of scale to make biomethane purification affordable. Indeed, a pilot project in the Ajuricaba River Basin has successfully connected 33 small farms producing 820 m³ of biomethane daily.

This does, however, shift the challenge from engineering to governance. As noted during the webinar, a condominium requires deep trust. Farmers must trust the utility to manage the waste; the utility must trust farmers to supply the feedstock; and neighbors must cooperate on shared infrastructure. But it can also provide vital reassurance, as Felipe Souza Marques, President Director and CEO at CIBiogás, noted:

“If the farmer feels that the risk is all his, he will step back. Similarly, if he feels he’s on his own with respect to the decision of the technology approach, he usually steps back.”

Global lessons from local success

The upshot is that the future of sustainable farming in Brazil might include local gas pumps using biomass derived fuel to power the trucks that carry the harvest to market. It is a solution that is cleaner, more profitable, and crucially, closer to home. Stakeholders in Paraná have charted a path that protects the Itaipu reservoir, reduces global methane emissions and provides a new revenue stream for farmers – avoiding the “white elephants” of ill-suited infrastructure.

It also offers an attractive option in terms of developing skills and rewarding careers in agriculture, as Janaina Pasqual MBA Professor at PUCPR, found out when she interviewed the farms on the pilot as part of her PhD.

“The newer generation generally don’t want to stay in the farms, preferring to move to the city; but through this biogas systems they see the potential to pursue innovative engineering, which keeps them motivated to stay in agriculture.”

This case study offers a vital lesson for other WEFE Nexus Policy focus regions, such as Central Asia and the Indus Basin. In the concluding webinar discussions, Mohsin Hafeez, Strategic Program Director – Water, Food and Ecosystems at the International Water Management Institute (IWMI), noted that while Pakistan possesses 170 million livestock, it lacks the infrastructure to turn that waste into value on a commercial scale.

This reality extends to Africa, where the sector faces similar hurdles in scaling beyond the household level. For regions dominated by smallholders, the lesson from Brazil is clear: attempting to force manure-to-electricity onto the national grid can be a regulatory and financial dead end. Instead, the opportunity may lie, in some cases, in decentralized biomethane networks that fuel local transport and industry. By facilitating this cross-country learning, the WEFE Nexus Policy program allows stakeholders in the Indus and Nile basins to see around corners as they look to transform their own waste into value.

Afreen Siddiqi is Research Scientist, Engineering Systems Lab, Massachusetts Institute of  Technology, USA; Janaina Pasqual is Senior Sustainability Advisor and Researcher, Pontifical Catholic University of Paraná (Brazil) and Jacobs (USA); Felipe Souza Marques is President Director, CIBiogás; Mohsin Hafeez is Strategic Program Director – Water, Food and Ecosystems, International Water Management Institute (IWMI), and WEFE Nexus Policy Lead; Tosin Somorin is Researcher in Circular Economy and Waste Management, IWMI, and Lecturer (Energy), University of Strathclyde.

The modelling and analytical work, led by Afreen Siddiqi and Olivier de Weck, was conducted at MIT by a team that included Phil Schmedeman, Karthik Rajasekaran, Cristian Junge, and Chun Tan. The work wasfunded with a research grant from the Jameel Abdul Lateef Water and Food Security (J-WAFS) Program at MIT.

The results of the work were featured and discussed in a WEFE seminar program supported under the CGIAR Policy Innovations Program. We would like to thank all funders who supported this research through their contributions to the CGIAR Trust Fund (www.cgiar.org/funders).