Energy saving potentials of water supply schemes in Sri Lanka

Abstract

The water supply industry and the energy sector are closely connected, with substantial energy requirements throughout the water supply process. This relationship is vital as climate change and global water and energy demands emphasize the urgency of enhancing energy efficiency in water supply sectors worldwide. Recognizing this, the National Water Supply and Drainage Board in Sri Lanka, responsible for water supply, acknowledges the need for strategic initiatives to optimize energy efficiency. This study aimed to identify factors influencing Specific Energy Consumption (SEC) variations and developed a novel tool for investigating energy conservation potentials within Water Supply Schemes (WSS) in Sri Lanka. Studies indicate that approximately 96% of energy consumed in surface water treatment and distribution is attributed to water pumping. Optimum SEC Model introduced in this study utilizes specific speed to identify pump operating characteristics, estimate equipment inefficiencies, and establish economical norms for hydraulic gradient in pumping systems. In contrast to the current energy management concepts used in Benchmarking SEC, this approach replaces traditional energy audits targeting equipment inefficiencies and promotes the use of historical and operational data. Also, this technique opens the opportunity to compare location-specific SEC elements like topology and connection density. Data gathered from the Matara Integrated WSS, operated by the National Water Supply and Drainage Board in Sri Lanka, was evaluated using the Optimum SEC model, revealing a 45% energy-saving potential compared to the actual electricity demand of 1716 kW. Furthermore, to corroborate these findings, a case study was conducted utilizing the WaterGEM model.