An Integrated Sustainability Evaluation of Waste-to-Energy Technologies for Energy Generation and Co-Benefits in South African Metropolitan Municipalities

This study assesses the integrated sustainability performance of waste-to-energy (WtE) technology pathways across eight of South Africa’s metropolitan municipalities, which are home to 40.14% of the country’s population. The assessment considers energy generation, GHG emission-reduction potential, landfill space savings, waste diversion, economic viability, and technology readiness, in alignment with the national waste, energy and resource management strategies. Seven scenarios were modeled for the period 2028–2050, with recovery rates rising every 7–8 years so that feedstock supply remains sustainable. S1 represents business-as-usual; S2 enhanced landfill-gas recovery (LFG+); S3 LFG+ with anaerobic digestion (AD); S4 LFG+, AD, and incineration; S5 LFG+, AD, and pyrolysis; S6 LFG+, AD, and gasification; and S7 LFG+, AD, and plasma gasification. An Integrated Sustainability Performance Index (ISPI), combining nine normalized energy, environmental, financial, and technological indicators, identified S4 as the highest-ranked scenario within the ISPI framework, with an average score of 0.681 ± 0.007 and first place ranking in all municipalities. S3 and S6 had nearly identical mean ISPI scores (0.5208 ± 0.027 and 0.5207 ± 0.004, respectively), with their relative positions varying across municipalities and sensitivity conditions, while S7 ranked last. S2–S3 remained financially attractive, whereas advanced thermal technologies benefited municipalities with larger waste amounts with respect to energy generation. Overall, integrated WtE can contribute to South Africa’s energy transition and sustainable waste management objectives.