Flow Energy Management & Pressure Energy Recovery (031-DP-4)
Discussion Paper Summary
Once wastewater leaves a home or business, it can often take a great deal of energy to convey it to a treatment plant. Flow energy management looks at alternatives that aim to reduce the pumping energy required to convey wastewater to a plant. Recent technologies, such as turbines or pump turbines, also can harness the flow of wastewater itself, turning flow energy into a power source.
Wastewater Flow Management
Flow energy savings can be achieved through:
- Locating wastewater treatment facilities at low elevations to minimize or avoid pumping
- Maintaining high water levels in pump station wet wells to minimize the height wastewater is lifted
- Installing low flow plumbing devices to reduce the amount of wastewater that passes through sewer pipes
Pressure Energy Recovery Technology
Pressure energy uses a mechanical device such as a turbine or pump as turbine to capture energy contained in flowing water. Pumps and turbines are installed inside wastewater pipes; these technologies are in use in large hydro projects but are not currently being marketed for use with raw wastewater.
Flow Energy Recovery Potential
The topography of the CRD Core Area is favourable for flow energy recovery—40% is estimated to be recoverable using in-pipe turbines.
The regional potential for energy recovery was calculated based on the scenario of a large wastewater plant in the Macaulay/McLaughlin area and smaller distributed facilities in the West Shore and Saanich East areas. Using dry weather flow rates, energy recovery would amount to approximately 305 MWh today and 540 MWh in 2065. This could provide enough energy to power approximately 30 and 50 households.
© Image courtesy of Evan Leeson