Clean energy solutions in Tanzania

13/12/2018

Tanzania’s dairy sector is based on traditional farming systems consisting of grazing on mostly communal land. Only 12 percent of the 2.5 billion litres of milk produced in Tanzania each year is sold through small-scale milk traders and collective bulking centres. Close to 90% of rural households do not have electricity. Therefore, when dairy farmers have problems delivering the evening milk, the raw milk is usually left unrefrigerated overnight. Between 30 to 40 percent of milk is lost due to minimal access to markets, poor milk handling practices and a lack of modern energy to cool and preserve milk.

“Often, the evening milk, which can be over 1/3 of the total milk produced during the day, is spoiled due to lack of chilling facilities,” explains Alessandro Flammini, Natural Resources Officer at FAO.

Through the Investing in Sustainable Energy Technologies in the Agrifood Sector (INVESTA) project, FAO is working closely with the Tanzanian Dairy Board to promote the use of milk cooling systems powered by biogas digesters. 

Now you may be asking: What is a biogas digester?

Biogas digesters are large tanks in which biogas is produced through the decomposition of organic matter, such as manure, by a process called anaerobic digestion. They are called digesters because organic material is eaten and digested by bacteria to produce biogas.

As an important by-product, the digesters leave behind nitrogen and other minerals such as phosphorus and potassium, which can be spread over the crops, reducing the need for chemical fertilizers.

At Mama Katarina’s house, potatoes boil nicely on her biogas stove, and the piles of cut wood visible outside most homes in the village are nowhere in sight. Mama Katarina has been using her digester since 2012. She is now a local expert in biogas digesters and has helped train other villagers. With her biogas digester fuelling her stove, she has the right amount of gas for the family of six to cook three meals a day; it is an essential part of her everyday life.  

What makes Mama Katarina’s biogas digester so efficient?

“I just follow the rules!” laughs Mama Katarina, who claims that her digester has never needed repairs.

She is very diligent about following the practices to keep it running effectively: She keeps it slightly elevated so that it doesn’t get submerged during the rainy season. She exposes it to the sun to keep the digester warm. She has it close to the kitchen to minimise the cost of the gas pipeline, but keeps it away from any drinking well to prevent water contamination and, lastly, she ensures that the area is free from trees or plants whose roots can creep into the digester and cause damage.

In a country where just 11 percent of rural Tanzanian homes have access to electricity, biogas digesters  that turn manure into a continuous source of renewable power have huge potential to fill this energy gap. This energy source is particularly appealing in a country where the livestock sector provides livelihoods for 37 percent of the 1.68 million rural households and which has the third largest cattle population in Africa.

How does it keep milk cold?

Biogas combustion is used to generate the power for the milk chiller. This energy is stored in an innovative compact storage system during the day and charges the system for a milk cooling cycle. The biogas technology can cool two milk cans of up to 5 litres each. 

The benefits of the digesters for Tanzanian farmers are threefold: cooking gas, fertilizer for the land and additional revenue from milk sales.

With the demand for milk and milk products estimated to more than double by 2020, and the high percentage of rural households living without electricity, biogas digesters can provide an effective, clean energy solution for families in Tanzania.

The FAO INVESTA project supports innovative and sustainable approaches to accelerate the uptake of clean energy solutions in agri-business and to increase food security in developing countries and emerging regions, helping to create a more sustainable, Zero Hunger world.

Related links

Learn More

• Web site: INVESTA project
  
• Publication: Costs and benefits of clean energy technologies in the milk, vegetable and rice value chains
• Web site: FAO in Tanzania