The potential of small-scale biogas digesters to improve livelihoods and long term sustainability of ecosystem services in sub-Saharan Africa
The project is working with households in Tiribogo village in Mpigi District, about 40km north-west of Kampala, to study the use of flexible-balloon biogas digesters. This is a simple technology that enables the use of human, animal and food waste material to produce both a reliable supply of methane gas for cooking and a valuable bio-slurry that can be applied to crops to increase yields.
Biogas digesters have proven to be successful in other areas of the world including China and India, where more than 40 million have been installed. The uptake of the technology in Africa has been considerably slower.
The DIGESTERS team hope to examine potential barriers that may exist and look for ways to overcome these. Dr. Jo Smith, Professor Liz Baggs, Dr. Nick Morley, along with colleagues from the Makerere University, Green Heat Uganda and the James Hutton Institute will explore the impact of these systems on soil nutrients within and around Tiribogo village and how this may help improve the productivity of the land and increase food production.
Work by Dr. Norval Strachan of the College of Physical Sciences and Dr. Lisa Avery from the James Hutton Institute will focus on the changes on microbial exposures due to the need to transfer animal manures to the digester. This work will also look at how the digester removes potential pathogenic organisms from the village environment and may produce health benefits in terms of reductions in incidence of diarrhoeal disease.
Cooking with biogas is likely to produce much lower levels of smoke within the home and Dr. Sean Semple and Dr. Andrew Apsley of the Respiratory Group will measure concentrations of fine particulate matter and carbon monoxide both before and after the homes install the digesters. This element of the study will also estimate the potential reductions in health problems including pneumonia and obstructive lung disease that are common in Africa as a direct result of exposure to smoke and cooking fuels in homes.
Socio-economic factors affecting uptake of biogas digesters in Africa will be examined by a team led by Dr. Jonny Mugisha and Dr. Peter Walekhwa from Makerere University, along with Dr. Bedru Balana from the James Hutton Institute and Dr. Klaus Glenk from the Scottish Agricultural College. This research will provide socio-economic analyses, explore costs/benefits and willingness to pay. Measurements of resource flows will provide a basis for the full economic value of flexible-balloon biogas digesters to households to be quantified.