In order to facilitate modeling analysis of the ability to achieve power and power cost savings, the project team met with Guelph Hydro to establish the calculation protocol for power cost for each water supply and distribution facility within the City of Guelph. The calculation is a complex one which factors in elements such as the Hourly Ontario kW∙Hr Energy Price (HOEP), the monthly 15 minute maximum instantaneous kW power consumption, Distribution Surcharges, time of use rates and others. These are integrated into the total cost differently depending on the size of the electrical service and averaged monthly maximum instantaneous power consumption for the service. The calculations are developed in e.RIS, Eramosa’s Reporting and Information System. This software has direct links into the SCADA system database and pulls power consumption, real-time, from each site within the City of Guelph’s water supply and distribution system. Automated reports provide daily and monthly site power consumption and cost metrics to the operations management team. These reports are used to establish the baseline operational condition and analyze the improved performance when changes are made.
Minute interval data files, with the power consumption and power cost data for each site are then compared with the City’s hydraulic model and used to calibrate it with respect to power consumption and power cost. This enables the modeling team to then run off-line simulations of various operating scenarios versus the baseline condition, ensuring that changes are managed within safe operational guidelines maintaining fire storage, minimum system pressures, and water age.
This analysis demonstrated the potential ability to operate the system safely and realize energy cost savings between 10 to 20% in the Guelph Water Supply and Distribution system depending on the type of day analyzed (typical day versus summer average day).
Potential energy cost savings were then demonstrated through field trials. Working with operations staff, the City-wide operational strategy was implemented and the system was operated in this fashion for the month of December, 2014. Comparing to system wide energy costs for December, 2013 and November, 2014 savings of 17.3 % and 26 %, respectively, were realized.
These findings, along with the power cost and consumption data available on a site specific basis, led to an internal optimization of each individual facility. Often well pumps are oversized to allow for fluctuations in well water level. Historically this oversizing was taken to an extreme. The City embarked on an exercise of “right sizing” all pumps and implementing variable frequency drives to maintain operational flexibility while optimizing pump performance as shown in the final graphic.
We acknowledge and thank all of the industry partners on this project, City of Guelph and Eramosa Engineering.