Toronto’s first major wastewater energy transfer (WET) project is expected to be commissioned later this year, supplying heating and cooling to Toronto Western Hospital through thermal energy exchange technology. City Council is now sorting out general protocols for up to nine additional projects that would use Toronto’s sanitary trunk sewers as both heat sources and sinks.
A report from the Environment, Climate and Forestry division, to be discussed at Toronto Council’s next meeting in late March, proposes a review and approval process along with some cost-recovery fees for staff time and supply of sewer data that prospective energy customers may require. Earlier studies have determined that the trunk sewer network has the capacity to provide up to 300 megawatts (MW) of energy for heating purposes, displacing enough natural gas to avoid about 200,000 tonnes greenhouse gas (GHG) emissions annually.
To begin, the project at Toronto Western Hospital is projected to curb natural gas demand by 90 per cent, translating into an approximate 8,400 tonne annual reduction in GHG emissions, while heat rejection back into the sewer system will reduce the hospital’s cooling load by 5 MW of peak demand. In a letter to Council’s infrastructure and environment committee, Dennis Fotinos, founder and chief executive officer of the project’s developer, Noventa Energy Partners, maintained the nascent technology expands the range of practical renewable energy applications in dense urban environments.
“At our Toronto Western Hospital project, for instance, over 1,500 bore holes would have been required to provide the same environmental benefits with a geo-exchange system — something which simply was not viable,” he advised.
Wastewater energy transfer is also a potential revenue generator for the City of Toronto. It’s proposed that the Environment, Climate and Forestry division would negotiate an energy transfer fee (ETF) on a project-by-project basis, which would charge a specified rate per unit of energy recovered (heat) or rejected (cooling) through the thermal exchange.
“Access to the City’s sewer system and wastewater is provided on an ‘as is, where is’ basis, meaning the City makes no guarantees whatsoever with respect to resource quantity or quality of the City’s sewer system and wastewater and all projects are subject to the operational and other requirements of Toronto Water,” the report to Council states. “The City is not procuring any good or service in respect to any third-party wastewater energy program project, but simply providing limited access to the City’s wastewater infrastructure for projects approved under this program, provided that the project generates benefits to the City.”
