Improved Assessment of Energy Recovery Potential in Water Supply Systems with High Demand Variation

Laura Monteiro,João Delgado,Dídia Covas

doi:10.3390/w10060773

Abstract

Enhancing energy efficiency of water supply systems by recovering part of the excessive pressure is currently an issue of growing interest for water companies. The installation of micro hydro plants for energy recovery can be profitable in sites with excessive pressure, though requiring proper technical and economical evaluation. This paper presents a methodology for assessing the energy recovery potential in water supply systems under high seasonal demand variation. The methodology is based on the calculation of head and flow rate conditions that maximize energy production for a specific energy recovery technology, given available head and flow rate ranges. The methodology is applied to the inlet of a storage tank of a water transmission system using hourly collected data over one year. Results show that, in systems of high variability of flow rate, the installation of turbomachines in parallel is necessary for maximizing energy recovery and that the developed methodology returns lower, but more realistic, energy production estimates than other approaches based on average head and flow rate data.

Highlights

Drinking water transport from the source to the consumer is a highly energy intensive process [1], with significant associated operational costs
This paper aims at presenting and applying a methodology for an improved assessment of the energy recovery potential in water supply systems under high seasonal demand variation
The methodology is based on the calculation of head and flow rate conditions that maximize energy production for a specific energy recovery technology, given the available head and flow rate values over one year

Summary

Introduction

Drinking water transport from the source to the consumer is a highly energy intensive process [1], with significant associated operational costs. Water utilities are currently aware of the need for reducing energy consumption and corresponding costs and are looking for innovative ways to improve energy efficiency. In water systems supplied by gravity, water often carries more energy than what is needed to supply the downstream consumers In such cases, the excessive pressure is dissipated in pressure reducing valves or flow control valves. The installation of micro hydropower plants in parallel with these valves allows the simultaneous recovery of energy and pressure reduction [5] This strategy can be an economical option by simultaneously controlling pressure, reducing water losses and producing energy [6]

Objectives

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Results

Conclusion