Sustainable biogas digester pilot project for subsistence farmers in rural Zambia

Rural Africa has a substantial energy problem. Whilst the USA uses 6902.43kg of oil-equivalent energy per capita, the Zambian average is 635.33kg. This is biased towards urban areas, leaving rural areas heavily dependent on inefficient fuel sources like firewood. Such energy inequality is important in Zambia because 60% of the country’s population is rural. To address energy poverty such that the least affluent people benefit from the biggest impact, the i-Team investigated the potential of producing biogas from animal waste by  subsistence farmers in rural Zambia.

A biogas ecosystem is comprised of animal waste inputs, digester technology, use of slurry as crop fertiliser, and use of biogas to fulfil energy requirements such as cooking, lighting, heating and refrigeration. The system is sustainable, as there can be a continuous cycle between animal waste, using biogas as a fuel, using slurry as a fertiliser for crops that can be used to feed more animals, whilst others can be sold to generate an income. However, in order to create the best possible set-up, the optimum options for each ecosystem component needed to be established.

After researching existing projects and failed project, and phone discussions with rural Zambian , it was clear that pig waste would the most suitable feedstock. Pigs are farmed locally,  can be kept in small contained areas, and produce high  waste and therefore  yields of gas yields with low maintenance costs. The fixed dome style was chosen as most appropriate digester design, because of its low maintenance requirements and can be built using available materials. Looking at the local area was important when choosing the ideal crop. The i-Team suggested maize and millet, because they are native to the area, and they can feed both humans and livestock which would help extend the sustainable cycle.  When looking at the use of the biogas, the team acknowledged that refrigeration could be a viable venture in the future, but at the moment, the most effective use was cooking. It is the most impactful, reducing health issues from inhaling wood smoke, and reduces the time required for women to collect fuel.

Financing the project was another hurdle in the team’s research. Microfinance rates are high and are usually accompanied by large minimum loans. Furthermore, it was clear that using this community digester model, the business plan would need to be adapted according to the scale. This would need further research. There were other research opportunities that were highlighted, including: the optimal scale of the project, whether to choose foreign or local management, and options for transport.  One of the team’s contact suggested that the community structure could be disrupted if one member became too wealthy or powerful, and other contacts were keen to impress the desire for other uses of biogas in transport.

The potential impacts of the technology are quite significant; environmentally, economically, and socially. The positive environmental impact comes with a reduction of greenhouse gases and reduced deforestation. Economic impacts relate to income generation from farmers selling fertiliser, meat from pigs, and maybe even excess biogas. As for the social effects, there would be benefits to health, on gender issues, cooking customs, and returnees within the program.

Whilst more research is needed, the team were keen to impress the positive effects that the technology could have on the local population. To take the project forwards, they suggested pilot projects to educate people on the technology, establishing a local project leader, and getting in contact with the Zambian government to start implementing their ideas.

iTeams website link:

Using the biogas ecosystem to alleviate the poverty of African subsistence farmers