Mainstreaming portable biogas systems into IFAD-supported projects

What is it and how can it help? 

Access to modern renewable energy services is a key factor in eradicating poverty and ensuring food security. Today, 2.5 billion people rely on traditional biomass fuels (charcoal, dung, firewood) as their principal source of energy for cooking and heating. Shifting away from these traditional fuels with renewable energy sources such biogas can have direct benefits for farm productivity, along with multiple other socio-economic benefits for the household, the community and the environment. Biogas is a renewable energy obtained from biodegradable organic matter such as kitchen, animal and human waste.

Since May 2012, IFAD has been piloting a new biogas system, the Flexi Biogas system, which is a portable above-ground system that is simpler to use and less costly to build and operate than traditional fixed dome systems. The Flexi Biogas system does not require an agitator and its digester is not a sealed tank but simply a 6 m x 3 m envelope made of PVC tarpaulin and housed in a greenhouse tunnel.

When does it work best? 
  • Geographical: Biogas production bacteria need temperatures of more than 15°C therefore it works best in warm tropical and sub-tropical climates
  • It works best when communities use a participatory approach and take ownership of the process. Specifically:
    • Social:
      • Where there are evident drudgeries in collecting firewood (causing back pain and exhaustion) and rural households (especially women) realize the opportunity cost of the time spent collecting firewood.
    • Financial:
      • Opportunities to off-set monetary costs of conventional energy sources (mainly firewood and charcoal)
    • Health and sanitation:
      • A more demand-driven approach can be instituted in households that cook indoors and the combustion of smoke inhaled cause evident respiratory diseases and eye infections (especially for children). In addition, where animals are roaming around, they can be stalled to improve village sanitation. In this way, biogas can be used as a waste management technology
    • Other:
      •  In zero-grazing livestock systems where cattle are already stalled for easy collection of manure
      • In areas where water is sufficient (requires 400 litres to start-up and subsequently 20 litres of water daily)
      • Integrated within farming systems to enhance the use of crop residues and other organic waste
  • Where close by there are vegetable gardens given that the by-product of biogas is an optimal organic fertilizer (bioslurry) that can replace expensive chemical fertilizers
How do I use it? 

The toolkit provides a step by step guidance for design and implementation. Cost-effective biogas systems can stem methane emissions from livestock manure by recovering the gas and using it as an energy source. The organic matter is inserted into a sealed digester and, in the absence of oxygen, anaerobic bacteria consume the organic matter to multiply and produce biogas, which can be piped directly to a cooking stove. There is also a troubleshooting guide on the use of the Flexi biogas.

  • To start-up the system requires 400 litres of water and 400kg of fresh cow dung
  • Subsequently, daily requirements are 1:1 ratio (20 litres of water: 20 kg of dung) 
  • Excess gas can be used for other activities such as drying of fruits and spices or warming chickens (poultry brooding)
Where has it been used? 

IFAD funded projects. Specific case studies from Kenya, India, Rwanda and São Tomé e Principe.

More recently, in Nepal, pilot tested the technology in hilly areas where traditional fixed domes are logistically difficult to install through collaboration with US based philanthropic institution Global Good - Intellectual Ventures:

What are its limitations? 

Limitations to adopt this system could be the very criteria that are used for selecting beneficiaries: Very low-income levels, more than 2-3 hrs. collecting firewood, adequate supply of cow manure or other readily available agricultural residues or animal waste. Another limitation may be access to water supply to start up the biogas system. Initial cost of purchase (minimum$610 for the domestic model which can yield about 700-1000 litres of gas or approximately 2-3 hours of cooking time on a biogas stove) and subsequent maintenance costs can also hinder the adoption of the biogas system.

Because the pressure is low in this model, a biogas lamp cannot be attached to the biogas (therefore this model is solely for fulfilling cooking requirements and providing a high-quality nutrient organic fertilizer)

Where can I go to learn more? 

IFAD How-to-do Note:

IFAD site with various resources on the Environment and Climate Change: