A Study on the Potential Evaluation of Achieving Power Independence and Net Zero CO₂ Emission at Sewage Treatment Plant

Abstract

To achieve power independence and net zero CO₂ emission at sewage treatment plants, a performance evaluation system (PES) was used at five sites with a treatment capacity of 150,000 to 200,000 m³ day^-1, to estimate the power self-sufficiency rate and GHG (Greenhouse Gas) intensity. For power independence, the combination of energy saving and energy production measures was evaluated. When the energy saving measures were introduced at Treatment Plant A, the amount of power consumption decreased to 31,840 kWh day^-1 (reduction of about 20%) , and the power self-sufficiency rate improved to 83%. Moreover, when energy production measures were introduced, the amount of power generation increased to 38,800 kWh day^-1 (increase of about 50%) , and the power self-sufficiency rate was 105%, which was considered to indicate power independence. To promote net zero CO₂ emission, the GHG intensity and offset rate were evaluated. Even at Treatment Plant A, the GHG intensity was calculated to be 0.17 kg m^-3 that net zero CO₂ emission was not reached (offset rate of 48%) . By improving the operation of the incinerator, the GHG intensity may be improved to 0.08 kg m^-3 (offset rate of 70%) . Looking toward the two goals, the power independence and GHG emissions were evaluated, and high potential to realize the envisioned sewage treatment plant was confirmed.