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WPCP Savings & Energy Conservation

Water Pollution Control Plant Aerial ViewCost & Energy Savings AT THE WATER POLLUTION CONTROL PLANT

In line with the City of Thunder Bay’s 2015-2018 Corporate Strategic Plan strategy 8.2 to “reduce greenhouse gas (GHG) emissions, energy and fuel consumption”, and goals set forth in the EarthCare Sustainability Plan 2014-2020, Thunder Bay's Water Pollution Control Plant (WPCP) has undertaken several projects aimed at lowering operating costs and reducing the City’s carbon footprint and air emissions. Spanning a few years (as reported in the fall of 2016), these savings initiatives have included:

  • new Building Automation System to control building heating and ventilation
  • replacement of two main sewage pumps
  • new higher-efficiency turbo blowers
  • new LED area lighting
  • optimization of the cogeneration system

Building Automation System (BAS)

This project has succeeded in reducing energy costs (natural gas and electricity) at the WPCP. According to earlier estimates, significant savings could be achieved by reducing the heating and ventilating (H&V) requirements in two of the main buildings (the “Biological Aerated Filter (BAF)” and the “Dissolved Air Floatation (DAF)” buildings) when unoccupied. A new, computer-based BAS was installed to manage the H&V for the two buildings.

WPCP Settling PondsBy code, specific minimum levels of ventilation and heating are required during both occupied and unoccupied times. The new BAS can be operated using either programmable schedules or occupancy sensors, to regulate the H&V systems.

Based on current utility rates and average heating degree days, the estimated total annual savings to-date as a result of this project are:

  • $ 84,000/yr Natural Gas
  • $ 29,000/yr Electricity
  • $113,000/yr Total

Main Sewage Pumps

WPCP Sewage PumpsPumping is a significant cost in operating the WPCP. Unfortunately, two of the original (500 HP) main influent pumps were not appropriately sized to meet current average flow rates, resulting in poor operating efficiency (60-70%) and high electrical costs.

It was determined that newer, smaller pumps, sized to meet current flow conditions, would allow for improved overall pumping efficiency (>80%) and reduced energy costs. The two original 500HP pumps were replaced with the new, more appropriately sized pumps. The estimated total annual savings achieved is approximately $110,000/yr.

Turbo Blowers

WPCP Turbo BlowersThe Biological Aerated Filtration (BAF) process at the WPCP is the highest energy consumer at the facility. To operate effectively, this process requires a great amount of compressed air. The original, 2005 design included eight 50 HP and seven 100 HP duty conventional air blowers.

On review, it was determined that considerable electrical savings could be achieved by replacing the existing pressure blowers with new, higher-efficiency turbo blowers. With financial assistance from the Government of Ontario, a project was undertaken to replace the existing 15 blowers with three 350 HP turbo blowers (2 base units + 1 spare).

Early results of this project indicate at least a 35 percent electrical energy reduction, or approximately $250,000 in annual hydro savings. In addition to the energy savings, other project benefits include:

  • much safer working environment due to:
    • a noise reduction from 120 dB to below 92 dB;
    • fewer oil spills and related housekeeping issues
    • reduced maintenance requirements and the potential of pinch points, lifting, and other related injuries
  • additional savings in reduced maintenance costs and spare parts inventory

LED Area Lighting

WPCP LED LightingA recent upgrade of one of the major WPCP process buildings (Screen & Grit) provided an excellent opportunity to investigate new, higher-efficiency high-bay and perimeter lighting. Based on this assessment, 23 new 122-166W LED hi-bay light fixtures were installed to replace the aging high-pressure sodium lighting.

The new lighting provides an estimated $2,300/yr in energy savings, in addition to longer bulb life (lower replacement cost) and improved overall lighting.

This project was partially funded by the Thunder Bay Hydro rebate program to reduce total connected kilowatts.

CogenERATION Optimization

WPCP Co-Generation EquipmentThe WPCP's 600 kW cogeneration ("cogen") unit burns waste methane gas to produce electricity and hot water. The hot water is used to heat buildings & processes when required. All generated power is used on site, reducing the need to purchase power from the hydro utility.

By optimizing the cogen to maximize electricity production, significant cost savings can be realized. Recent efforts have increased cogen performance by an average of 19%, resulting in additional projected annual savings of approximately $58,000/yr.

Summary

Thunder Bay's WPCP has made significant strides toward reducing the City’s carbon footprint, air emissions, and overall operating costs. Total savings to-date (October 2016) for these recent projects is estimated at approximately:

  • BAS H&V Controls $113,000/yr
  • Main Pumps $110,000/yr
  • BAF Turbo Blowers $250,000/yr
  • LED Lighting $ 2,300/yr
  • Cogen Optimization $ 58,000/yr
  • Total Savings $ 533,300/yr

These savings include both “bottom line” cost reductions, and economies in the form of ongoing cost avoidance. WPCP’s investment in new technologies and process improvements brings long-term benefits that will continue to return significant savings in the areas of pumping, process aeration, cogeneration, building heating and ventilation, and lighting.

Currently, opportunities for other energy savings and process optimization are being studied for consideration as possible future projects to enhance cost savings and reduce of the City’s carbon footprint and air emissions.