Water, Energy, and Emissions Nexus: Effect of Inflows in Urban Drainage Systems

Catarina Jorge,Rita Salgado Brito,Maria Do Céu Almeida,Dídia Covas

doi:10.3390/w14060868

Catarina Jorge, Rita Salgado Brito + Show 2 more

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https://doi.org/10.3390/w14060868

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Abstract

The urban water sector significantly contributes to energy consumption and greenhouse gas (GHG) emissions. Detailed assessment of the wastewater system input provides opportunities for improving the water, energy, and emissions nexus. The inflow of water not requiring treatment into wastewater systems is acknowledged worldwide. These undue inflows can increase the footprint of these systems. Together with flooding and discharges, monitoring of undue inflows is not a common practice in water utilities. Three levels of analysis are proposed to assess the magnitude of the impact of undue inflows in the water–energy–greenhouse gas (W-E-G) emissions nexus: at a national level, calculation of performance indicators using yearly data; at the utility level, performance indicators calculations using yearly, monthly, and sub-daily data; at the subsystem level, calculations using mathematical modeling. Results show the implications of undue inflows on energy and GHG emissions, including the effect of flooding and discharges. The importance of undue inflows in the W-E-G nexus is sustained by the results of three case studies in Portugal. Each level of analysis is tailored to the information available, allowing a step-by-step understanding of the relationship between water, energy consumption, and emissions of the urban drainage inflows.

Highlights

The relevance of the interdependence between water, energy, and greenhouse gas (GHG) emissions is widely acknowledged [1–4]
GHG emissions are higher in wastewater treatment (P13) than in wastewaterthis raw information, the impact with of undue inflows on these variables is significant even pumping (P12)
GHG emissions are higher in wastewater treatment (P13) than in wastewater pumping (P12)

Summary

Introduction

The relevance of the interdependence between water, energy, and greenhouse gas (GHG) emissions is widely acknowledged [1–4]. The environmental and societal burden of high energy consumption, heavily based on fossil fuels and increasing costs to consumers, is problematic in all sectors, the water sector not being an exception [6]. Many studies can be found on the water–energy nexus for water to energy production, but few exist on the energy for the water sector [1,8]. The latter often comprises the energy used for water heating having a relevant share [8–10]. The urban water sector has a substantial contribution to energy consumption and the production of GHG emissions

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Conclusion