To achieve the Sustainable Development Goals by 2030, low-income sub-Saharan African countries urgently need to electrify. Biogas production from anaerobic digestion could make a contribution to a solution to improved electricity generation and access in these regions. This study evaluates its feasibility using Malawi as a case study. The aim is to provide households with a continuous supply of gas for cooking and electricity. The study examines different sizes of fixed dome reactors (3, 6, 12 m3) and assumes individual household ownership of 2, 4, and 6 cows. Several feedstocks and conditions are considered, such as cow dung alone, co-generation of cow dung with human faeces, cow dung with grass, and cow dung with maize residue. The economic benefits of selling biogas and fertilisers are calculated, and the cost of construction for different sizes of reactors is determined. Results show that co-generation of cow dung and grass silage in the reactor of 12 m3 with six cows has a positive net present value (NPV) of $8962, while for a small farm with a 6 m3 reactor capacity, co-digestion of cow dung with maize residue is preferable. The feasibility of the technology depends heavily on current national economic conditions, such as inflation, electricity prices, and construction material costs. A sensitivity analysis estimated that a 25% increase in the cost of electricity could increase the net present value (NPV) from − $3345 to $1526 for the generation of biogas from cow dung alone. Overall, this technology could have a significant impact on the lives of low-income households in sub-Saharan Africa by improving their access to electricity and providing a source of income through the sale of biogas and digestate.

中文翻译：

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探索分散式沼气厂在满足撒哈拉以南非洲国家能源需求方面的潜在作用：技术经济系统分析

为了到 2030 年实现可持续发展目标，撒哈拉以南非洲低收入国家迫切需要实现电气化。通过厌氧消化生产沼气可以为改善这些地区的发电和获取电力的解决方案做出贡献。本研究以马拉维为案例研究评估其可行性。目的是为家庭提供持续供应的燃气用于烹饪和电力。该研究考察了不同尺寸的固定圆顶反应器（3、6、12 立方米），并假设个人家庭拥有 2、4 和 6 头牛。考虑了几种原料和条件，例如单独牛粪、牛粪与人类粪便联产、牛粪与草、牛粪与玉米渣联产。计算出售沼气和化肥的经济效益，并确定不同规模反应器的建设成本。结果表明，在 12 立方米的反应器中，六头奶牛联产牛粪和草青贮饲料，其正净现值 (NPV) 为 8962 美元，而对于拥有 6 立方米反应器容量的小型农场，奶牛的共同消化最好是带有玉米渣的粪便。该技术的可行性在很大程度上取决于当前的国家经济状况，例如通货膨胀、电价和建筑材料成本。一项敏感性分析估计，仅用牛粪生产沼气，电力成本增加 25% 可能会使净现值 (NPV) 从 - 3,345 美元增加到 1,526 美元。总体而言，这项技术可以通过改善撒哈拉以南非洲低收入家庭的电力供应并通过销售沼气和沼渣提供收入来源，对他们的生活产生重大影响。