Flexi-Biogas systems in Kenya showing promise

Similar to an open-ended pillow case, the FBS consists of a plastic digester envelope housed in a greenhouse tunnel. The tunnel acts like an insulated jacket, trapping heat and keeping the temperature between 25 and 36 degrees Celsius. The combination of the tunnel and the plastic bag reduces the retention time - the time it takes for the biodegradable material to ferment - and so increases the volume and rate of gas production[i]. 

The study highlights how FBS devices have the potential to address important and pressing issues in sub-Saharan Africa and in Asia and the Pacific. Issues such as agricultural and energy difficulties related to cooking and lighting needs, climate change and household income.

The paper constructs a thorough study of these FBS units through analysis of peer-reviewed papers, project documents and research interviews. It has been found that this technology can reduce energy instability[ii], reduce time spent collecting firewood and contribute to the reduction of greenhouse gas emissions (especially methane which is 22 times more damaging to the atmosphere than carbon dioxide).

The project, funded by IFAD, remains in its pilot phases. However  there is a large amount of data available so some conclusions can be made. The overriding benefit is that FBS units synergise solutions to three major concerns within Kenya's rural population.

Time collecting firewood, mostly performed by women, takes from 3-5 hours daily. This time can now be allocated to income generation opportunities and spending time with children (imparting knowledge and education).

The use of biogas digesters produce a by-product which is a high nutrient quality organic fertilizer. This helps agricultural and food security needs but also income savings from the reduced purchase of chemical fertilizers. The use of it in Kenya has shown increased production yields and also a higher quality of vegetables.

Due to promising results in Kenya, the project (and technology) has been replicated within an on-going IFAD project in Rwanda. Here we are implementing the Flexi Biogas systems in conjunction with small-scale drying machines (powered by biogas) for maize/bean farmers to dry their produce and therefore reduce post-harvest losses.

Positive feedback has lead the Government of Rwanda to install 100 additional systems and mainstreamed the technology within their national programs (i.e. The Girinka or 'One Cow per Every Poor Family' programme). The Government of Rwanda intends to support the installation of another 200 Flexi biogas systems after this larger pilot phase.

The paper concludes that because these units show such promising results, continued effort needs to be made to communicate the benefits of these systems to the target audience and support continued assistance to the purchase and use FBS. Actions such as well-targeted subsidies on renewable energy sources and the removal of subsidies for fossil-fuel based sources such as firewood, charcoal and kerosene will be powerful incentives for people to take an interest in biogas.

There is also a YouTube video available to watch on the operations.