Integrating water-energy synergies into urban planning

There is potential for energy recovery from water and sewage systems.

Energy recovery from wastewater can take several forms: biogas generation or combustion of the dry matter resulting from treatment, and use of wastewater as a heat source or sink. This resource is still largely under-exploited worldwide, even though it represents a significant energy potential. Numerous waste-to-energy projects have been successfully implemented around the world, demonstrating the technical feasibility of exploiting the water-energy nexus.

For Montreal, the potential for wastewater heat recovery has been estimated at 5.4 PJ/year, based on conservative assumptions. This quantity of energy corresponds to the heating needs of 110,000 Montreal households, or more than 10% of the population of the Greater Montreal area. More specific studies of neighborhoods undergoing transformation have shown that wastewater-fed heating networks could supply 100% of the heating needs of new buildings, making it possible to decarbonize entire sectors without significantly increasing peak electricity demand. Such networks exist in Vancouver and Europe, for example.

A recent study of the potential of wastewater heat recovery for the City of Ottawa shows that the cost of the heat produced is higher than that of natural gas, but is competitive with other decarbonation technologies. What's more, the Quebec context is particularly favorable to municipal initiatives to recover waste heat, with the Quebec government's call for projects, which makes it possible to envisage better economic performance than in the study cited above. The valorization of waste heat is one of the main measures of the 2022-2027 Implementation Plan of the 2030 Green Policy for buildings.

Energy and water systems are at the heart of the urban transformation needed to meet the growing challenges generated by global change. However, the planning of these urban infrastructures results from compartmentalized, sector-based approaches that ignore the widely recognized interdependencies between water and energy resources (known as the "water-energy nexus"). This project, whose full title is "Development of a decision-support framework for integrating synergies through the water-energy nexus in urban infrastructure planning", aims to advance knowledge on modeling the water-energy nexus in urban environments. In collaboration with the user community, a decision-support tool integrating synergies between water and energy systems will be developed and applied to the Montreal area.

The main objective of the research project is to understand, quantify and map the potential of the water-energy nexus, and to operationalize this knowledge for decision-making, in order to support municipal decision-makers when designing or upgrading urban infrastructures with a view to sustainability and resilience. The project results will be integrated into a planning tool. This tool will be based on data from the City of Montreal's built ecosystem, but will be flexible enough to be adaptable to other Quebec urban municipalities. The approach envisaged to meet this overall objective is organized into three sub-projects: integrated modeling, spatial analysis framework for planning assistance and knowledge transfer.