Optimizing Waste-to-Energy Technologies in Sub-Saharan Africa: A Systematic Review and Comparative Analysis of Nigeria and Malawi

This review compares Nigeria and Malawi to assess the status of Waste-to-Energy (WtE) technologies and Circular Economy (CE) practices in two contrasting African economies. Using PRISMA 2020 methods, literature reports from 2010–2025 were systematically synthesized from major databases to examine solid waste management (SWM) with respect to CE adoption, WtE applications, and implementation of policies such as the extended producer responsibility (EPR) policy. Across Sub-Saharan Africa, waste is still treated largely as a disposal burden rather than a recoverable resource. Nigeria, a large and complex economy, faces severe logistical challenges in handling massive urban waste volumes. Lagos and Abuja generate 13,000–15,000 t/day and 0.59–0.77 kg/cap/day, respectively. However, there is no substantial record of tapping this potential's energy. Malawi, a smaller, agro-based country, generates lower per-capita waste (0.45–0.6 kg/day), but with extremely high organic content (60–90%), and weak collection systems. The MSW profile of high organic and moisture content, as well as low calorific value in both nations, makes biological WtE pathways such as anaerobic digestion (AD) more suitable than thermochemical options. Generally, the literature shows below-average resource recovery from CE and WtE applications. A vital fraction of the economy (informal recyclers) remains vulnerable to health risks, while weak governance and poor funding undermine system optimization. The existing literature, while valuable, is marked by significant gaps, such as a lack of rigorous comparative and feasibility analyses that connect technical, socio-political, and financial realities. The critical understudy of these key aspects is vital for landfill gas-to-energy (LFGTE), anaerobic digestion (AD), and refuse-derived fuel (RDF) applications in Nigeria, as well as for decentralized AD, controlled landfills, and plastics CE enforcement in Malawi. By doing so, it will provide broader guidance for sustainable SWM in Sub-Saharan African contexts.