Greater Vancouver Regional District — Wastewater Treatment
The Story
"Improving the energy efficiency of our Annacis Island wastewater treatment plant has not only returned significant electricity savings but also reduced maintenance costs and extended the life of our equipment. Energy use awareness is very high at all our plants and everybody contributes in some way to our energy success stories." This is how Rudy Palsenbarg, Manager of the Wastewater Treatment Division, introduces his Division's energy use reduction programs.
The Situation
The Greater Vancouver Regional District (GVRD) is a partnership of 21 municipalities and one electoral area that make up the metropolitan area of Greater Vancouver. The GVRD serves more than two million residents, providing a variety of essential utility services, including the treatment of wastewater from homes, businesses, and industries throughout the region. This treatment occurs at the GVRD's five wastewater treatment plants (WWTP).
The Annacis Island WWTP is the largest plant within the GVRD, currently serving more than 900,000 residents. Built in 1975 as a primary treatment plant, the Annacis Island WWTP was first expanded in 1984. The plant's capacity was upgraded again in 1998 to increase its ability to meet the future growth of the region and to provide secondary treatment.
Constantly seeking opportunities to improve energy efficiency and reduce energy operating costs, the GVRD became a BC Hydro Power Smart Partner in 2002. With the help of BC Hydro, the GVRD conducted a comprehensive energy survey of the Annacis Island WWTP, which identified several areas in which energy use could be improved. These included:
- Lighting. The plant was overlit and there was a need to reset lighting controls.
- Cogeneration. Two of the plant's six cogeneration units were not being used because of old operating controls and inability to synchronize with the other gas users.
- Boiler operation. Digester gas (60% methane) generated from the wastewater treatment process is used to either power the plant's six cogeneration units or to fire a boiler, which heats water that is used in various processes within the plant. It was found that the boiler firing sequence could be optimized, with the potential to use more of the digester gas being produced by the plant and to buy less natural gas.
Energy efficiency audits and projects have also been carried out at the other WWTPs. The most savings, however, were achieved at the Annacis WWTP, which is the largest plant, offering most opportunities.
The Solution
Based on the energy survey, the GVRD outlined a Power Smart action plan for improving its overall energy efficiency. The following projects have been recently implemented at the Annacis Island WWTP:
- Lighting controls upgrade. Lighting controls were adjusted to correct lighting levels throughout the plant. No capital expenditure was required.
- Cogeneration improvement. The GVRD had the two idle cogeneration units restored to working condition, and BC Hydro provided a Power Smart Partner incentive to fund the automation of the units. The two units are now back in operation contributing up to 900 kW of cogenerated electricity to the plant.
- Boiler optimization. The boiler controls were modulated to optimize firing times based on the plant's heat demand and the use of digester gas by other users in the plant. This measure has freed up more digester gas for the cogeneration units and reduced the amount of natural gas purchased by the plant.
The Benefits
Reduced operating costs
The three energy efficiency upgrades are saving a total of 11.4 gigawatt hours of electricity each year, equivalent to $294,400 in annual electricity cost savings. In addition to the direct electricity savings, the GVRD is enjoying reduced maintenance costs and increased equipment life as a result of more efficient equipment operation, as well as natural gas cost savings.
Reduced environmental impacts
The improvements resulted in a marked increase in the beneficial use of digester gas which otherwise would have been flared with no energy recovery. The plant is currently generating 80% of its energy needs from its own digester gas, producing either electricity or heat. These resources are now available to other users, reducing the environmental impact.
Better working environment
Optimal lighting levels throughout the plant create a more comfortable working environment for employees.
Contact Us
Find out how Power Smart can energize your bottom line. Call us today at 604 453-6400 in the Lower Mainland or 1 866 453-6400 elsewhere in B.C.
