Renewable Pathways for Decarbonizing Wastewater Treatment Plants Worldwide

This study develops a global, data-driven framework to quantify renewable-energy pathways for decarbonizing wastewater treatment plants worldwide. Using operational, geographic, and resource data from over 54,000 facilities, this study integrates biogas generation modeling with solar and wind potential assessment and multiscenario energy analysis, linking organic loading, renewable availability, and plant-level electricity and thermal demands. Results reveal strong spatial variability. Photovoltaic yields range from ∼90 to 500 MWh/year, while solar-thermal output spans ∼230–2600 MWh/year, both following climatic gradients. Wind energy exceeds 3000 kWh/kW/year in coastal regions but remains below 500 kWh/kW/year in tropical zones. Biogas and hydrogen potentials are highest in densely populated regions, reflecting wastewater loads. The demand-to-production ratio indicates that WWTPs in North America, Europe, Australia, South Africa, and parts of South America can achieve renewable surpluses (R < 1), whereas deficits (R > 1) persist in Eastern China, northern India, central Europe, and the Middle East. Energy production increases from 1 to 3 GWh/year for single technologies to nearly 6 GWh/year for integrated systems, while hydrogen-based configurations produce ∼3 GWh/year and improve supply–demand matching through storage. CO2 mitigation ranges from 0.9 to 2 Mt/year for single-resource systems to ∼3.3 Mt/year for integrated pathways. Self-sufficiency remains limited for single technologies (0–38%) but rises to 40–65% for hybrids and ∼66–70% for fully integrated and hydrogen-supported systems.