- The use of biodigesters inspired by those used in India is allowing small farmers in Brazil’s semi-arid Caatinga biome to produce their own cooking fuel from a renewable source: animal manure.
- About 2,000 biodigesters have been built and new projects are underway to spread the technology in this region, where it largely benefits women.
- In addition to having a positive impact on the household economy, human health and the environment, biodigesters generate biofertilizer, which can be used on family farms as an organic alternative to chemical fertilizers.
- Biodigesters are best utilized when combined with other strategies for strengthening families, such as cisterns to combat the long dry spells.
“My husband would go to the neighbor’s barn two or three times a week to get pig manure. He’d throw it in the biodigester and we were able to cook all week long,” says Fatima Souto, a farmer in Brazil’s Pernambuco state. “People were complaining about how expensive gas was and I didn’t even know how much it cost.”
A member of the Agroecological Association of Farmers of the Sertão do Pajeú (AASP), Souto had one of the first biodigesters built in São José do Egito, a municipality that is part of the Pajeú River Basin in Brazil’s semi-arid northeast region.
The construction of artisanal biodigesters began in Pernambuco in 2008. Inspired by the India model, this social technology is composed of a cargo box, loaded with water and manure, a fermentation tank isolated from atmospheric air, and a discharge box. The materials decompose and generate biogas that includes methane, and which can then be used for cooking, replacing commercially available liquefied petroleum gas (LPG) canisters.
“There’s no smell at all. You dilute the manure with water, put it in there and that’s it,” says Iraneide Maria de Oliveira, a farmer from Afogados da Ingazeira, Pernambuco. “It’s great. It really has made life better. We can use the money we save on LPG cylinders, which is almost 100 reais [$20], to buy other things.”
Biodigesters benefit women in the backlands
This renewable energy technology has a positive impact on the quality of life of farming families, and mainly benefits women. Many women in this region are heads of households and, historically, the ones mainly responsible for domestic work, such as preparing food, stocking firewood, and sourcing water for drinking and cooking. Due to the high cost of LPG, it’s common to cook on wood-burning stoves, which is harmful to human health due to smoke inhalation and ash generated. The practice is also harmful to the environment, because it requires cutting down trees to supply firewood and charcoal.
“It is our intention to keep taking pressure off the Caatinga biome, which suffers from the extraction of wood to produce energy, partially by families, much more significantly by factories, bakeries, pizzerias and the plaster industry in certain parts of the northeast,” says Ita Porto, coordinator of the Sertão do Pajeú Territory of Diaconia, a social organization that promotes and implements biodigester technology.
Almost half of the total area of Brazil’s Caatinga scrubland has been deforested and is now being subjected to desertification; about an eighth of the biome has already been degraded into desert. The constant extraction of wood from the biome increases deforestation rates, including on land owned by small farmers, negatively impacting the biodiversity and generating long-term economic losses.
In addition to contributing to the household economy and having a positive impact on human health and the environment, the use of manure from nearby livestock farms to generate methane reduces greenhouse gas emissions and prevents the propagation of flies and other pests due to the barns being continuously cleaned. Another byproduct of biogas generation is biofertilizer — manure with lower levels of gases and which is rich in nutrients — suitable as an organic fertilizer for orchards and crops grown on family farms.
Multiplying the technology
Experts estimate there are roughly 2,000 biodigesters currently operating in Brazil’s semi-arid northeast. “In the first project, three units were built in the municipality of Afogados da Ingazeira, Pernambuco, and it started growing from there,” says Mário Farias Jr., coordinator of the Civil Society Organization Cetra in Sobral, Ceará state.
Since the first installations in 2008, implemented by the Dom Helder Câmara Project with financing from the International Fund for Agricultural Development (Fida), along with Diaconia, other projects have been encouraging and implementing the technology. “I did several trainings in Bahia, Maranhão, Rio Grande do Norte and Ceará, in different territories,” Farias says.
Supported by financial sponsors, Diaconia built about 500 biodigesters in the northeast and also implemented the technology in other locations in Brazil. Cetra has international funding for the Biogás Sertão+100 project, which aims to build 100 biodigesters. It is also expected to install more than 800 biodigesters under the Paulo Freire Project, managed by the Ceará state government and financed by Fida.
“Our intention is for this to become an increasingly accessible public policy for people to produce their own energy,” Porto says.
The word is spreading fast. The Paraiba Research, Rural Extension and Land Regularization Company (Empaer) learned of biodigester technology in neighboring Pernambuco and began to instruct families to procure microloans. “In Paraíba state, we already have more than 10 instances of families who accessed microcredit to build their own biodigester,” Porto says.
In the Pajeú River Basin, made famous by the popular song “Riacho do Navio” by singer Luiz Gonzaga, the semi-arid climate is marked by extreme droughts and periods of reduced rainfall, usually from March to May. The drought also affects the source of the Pajeú River, causing the river to grow in symbolic importance in Pajeú culture. Antônio Marinho, a poet from São José do Egito, defines the river as a “current of enchantment that combined with the heavens and the wind and gave up being water to become a verb.” For families in this region, the production of renewable energy through biodigesters is linked to other enhancement strategies such as cisterns.
“I have lettuce, chives, cilantro,” says Iraneide Maria de Oliveira. “There’s a water problem here in our backlands. You need to have a lot of water to water things. Now we’re starting to plant. I couldn’t before because I only had the water from the cistern for human consumption.”
In 2017, de Oliveira participated in the Housing with Ecodignity project, an initiative of Diaconia under the National Rural Housing Program (PNHR), and received a house with integrated technologies, such as two water cisterns, technology for water reuse, and a biodigester. Without water, there would be no crops, and without crops, food security would be compromised. The biofertilizer produced by the biodigester would also go to waste.
“A sack of corn here is 110 [$22],” says Fatima Souto. As the COVID-19 pandemic brought economic turmoil, many people have had to sell their animals. “There was a time when I had more than 400 chickens. I vaccinated them. Now with this crisis, where’s the vaccine?” Souto asks.
Because of the high price of corn, and unable to obtain the necessary vaccines for her chickens, Souto and her neighbors sold most of their animals. Due to the lack of manure, Souto has also had to reduce the use of her biodigester, but she has plans for the future.
“I had to sell the chickens, but I kept the seeds,” she says. With the corn seeds, Souto wants to produce food for the animals with which she dreams of once again sharing her half-hectare of land.
Banner image of Aluísio Brás de Souza of the Sítio Jatobá community in Carnaíba, Pernambuco, one of the farmers who has started using biogas as an energy source. Image by Ana Mendes.
This story was reported by Mongabay’s Brazil team and first published here on our Brazil site on July 1, 2021.