Energy efficiency assessment of drinking water treatment plants incorporating technological differences and exogenous variables

Abstract

Assessing the energy efficiency (EE) of drinking water treatment processes through the integration of multiple indicators is essential for a comprehensive evaluation. This study proposes two composite indicators, namely group energy efficiency (GEE) index and metafrontier energy efficiency (MEE) index to assess the energetic performance of drinking water treatment plants (DWTPs). Its quantification was conducted using Stochastic Frontier Analysis (SFA) and the metafrontier framework. The analysis includes 96 DWTPs operating in Chile, categorized into two technological groups: pressure filtration (PF) and coagulation-flocculation with rapid gravity filtration (CF-RGF). The results indicate that CF-RGF facilities exhibit higher EE, with a mean MEE index of 0.506, compared to 0.423 for PF plants. The GEE index was also higher for DWTPs employing CF-RGF compared to those using PF, with average scores of 0.606 and 0.510, respectively. Additionally, factors such as plant age, raw water source, and ownership structure significantly influence energy consumption in DWTPs. This study provides empirical evidence to support targeted energy optimization strategies, helping to reduce energy consumption and enhance energy performance in the water treatment sector.