Flexi-biogas system: an innovative and alternative source of energy reduces deforestation and provides households with cheap clean energy

Written by Marie Clarisse Chanoine

In December 2012, 10 vulnerable households (seven widowed and one orphan headed households), received flexi-biogas systems which provided them with enough gas to cook the main meal each day and having enough hot water for tea. This was a pilot phase of the IFAD-KWAMP launched in Kirehe district, Eastern Province of Rwanda.

The flexi-biogas digester blows up when full of gas.
©IFAD/Karan Sehgal

This innovative technology requires 20 to 30 kg of dung per day to produce large volumes of biogas. Any household with one cow can establish a flexi-biogas system in one day and can be producing gas to cook within 7 days. Other conventional biogas systems require major excavations and skilled artisans for construction, and take at least four months before becoming operational and require the dung from at least three cows.

A beneficiary fulfilling the flexi-biogas digester
using manure mixed with water.
©IFAD/Karan Sehgal

The flexi-biogas system is proving to be both the most affordable and accessible alternative source of energy to smallholder farmers in sub-Saharan Africa. Once the flex-biogas system has been installed and initially filled with dung, providing the essential bacteria for the fermentation process, the system can run with any biodegradable matter from poultry, pig and other livestock dung to water hyacinth, kitchen waste, market waste, garden clippings, to name a few. This makes the system versatile and applicable to users with limited access to livestock dung.

The inventor, Dominic Wanjihia, stresses that the flexi-biogas system is much more than a cooking fuel solution. The excess gas can be used as a fuel source for a growing array of agro-applications, from heating chicken brooders through to generators to power chaff cutters, water pumps, and milk processing machines. Thus, the system allows farmers to improve efficiency, productivity, and quality of their farming products from small-scale farms. This is a crucial aspect considering that energy requirements at the farm level are often related to agricultural production and processing, fish farming, livestock rearing, water pumping or small-scale industries - many requiring small amounts of power (from 100w to 3kw) and yet, existing expenditures on low-quality energy sources (kerosene, firewood, charcoal and other traditional biomass sources) being too high, both in terms of cost, time and labour involved.

A well-settled flexi-biogas system.
©IFAD/Karan Sehgal
The pilot phase was so successful that the project coordinator and the Ministry of Agriculture and Animal Resources of Rwanda (MINAGRI) have just signed a contract with Biogas International Ltd, to provide a hundred more flexi-biogas units for Kirehe district. Targeted beneficiaries will contribute up to 50% of flexi-biogas system cost.