Nanaimo: Harvests Energy from Drinking Water Support System
The City of Nanaimo implements a unique water energy harvesting system to offset GHG emissions.
By replacing its old, open air water ReservoirNo.1 with a new enclosed reinforced concrete water reservoir that incorporates energy recovery equipment, the City is not only reducing emissions but also expecting potential energy savings between 750,000 – 1,000,000 kWh per year. The new system works in tandem with the City’s new Water Treatment Plant and supplies filtered water to Nanaimo residents.
The City of Nanaimo replaced its century old, open air water Reservoir No. 1 with a 14-million litre enclosed reinforced concrete water reservoir, associated pipelines and an energy recovery facility. The new reservoir has been constructed in tandem with the City’s new South Fork Water Treatment Plant. The reservoir will receive and protect filtered water that will supply 30 per cent of the city.
The reservoir also incorporates energy recovery equipment in the control building. Energy recovered from the reservoir is fed into BC Hydro’s grid. The energy will generate enough electricity for at least 60-70 homes. This is an example of a sustainable means of managing the City’s water supply infrastructure, meeting a key goal in the Water Supply Strategic Plan, and bringing the region a step closer to meeting a community-wide GHG emissions reduction target of reaching 39% of 2007 levels by 2050 under the Community Sustainability Action Plan (CSAP).
The new water supply system takes advantage of the area’s topography and hydraulics. The city’s main source of water supply is from the Jump Creek Reservoir on a tributary of the Nanaimo River. Due to the elevation difference, the distribution of water from the Jump Creek reservoir to the water treatment plant and subsequently to Reservoir No 1 can be done without the use of pumps. Reservoir No 1 is about 110 meters below the elevation of the new water treatment plant, creating a significant amount of potential energy to recover.
Nanaimo’s gravity municipal water system uses common globe-styled control valves to control the filling of a reservoir. Water filling the reservoir by gravity passes through a control building containing pressure reducing valves (PRV’s); the PRV’s dissipates the excess pressure, which is hydraulic potential energy, enabling the filling of a reservoir to a set water level. In most cases, this potential energy is lost; however, in the case of the new Reservoir No 1, there was a potential to use hydroelectric turbines instead of PRV’s to dissipate the excess energy while filling the reservoir; recovering this energy in the form of electricity to be sold back into BC Hydro’s grid.
Energy Savings/GHG reductions
Thirty per cent of water delivered to the city flows though Reservoir No 1, and the control building associated with the reservoir. Based on the projected year 2025 average annual demand of 21,100 MegaLitres(ML)/year, this equates to additional available power of approximately 0.75-1.0 Gigawatt Hour (GWh) per year (assuming 75% power recovery efficiency) generated by three turbines that can be harvested back to the BC Hydro grid annually. This amounts in enough energy to power about 60-70 homes.
According to the greenhouse gas (GHG) factors from the BC Greenhouse Gas Assessment Guide, potential annual energy savings are 750,000-1,000,000 kWh per year.
Nanaimo’s current GHG output for its entire waterworks department is approximately 29 tonnes carbon dioxide equivalent (CO2e). Introducing the energy recovery system will reduce the waterworks total GHG production to 9 tonnes CO2e.
“Nanaimo is very pleased to conclude this agreement with our partner, BC Hydro. This initiative has long been a priority of Council, and demonstrates the city’s commitment to reducing greenhouse gases and supporting a healthy environment. It will also provide the city with revenue as we can sell power back into the grid, and help recover operating costs of the water supply system.” – John Ruttan, Mayor, City of Nanaimo
“This agreement makes sense – it’s an innovative use of new infrastructure and the project reflects the types of future projects we hope to see under a new stream of the Standing Offer Program that targets small-scale projects with less than one megawatt of capacity. The project will inform how we design the new stream, which will help us meet our clean energy commitments moving forward.”- Doug Little, VP, Energy Planning and Economic Development, BC Hydro
The new water supply system takes advantage of the area’s topography and hydraulics.
This project marks an important collaboration between the City of Nanaimo and BC Hydro under the Energy Purchase Agreement to provide locally-generated power to the community. Through BC Hydro’s Standing Offer Program, the City is able to create revenue by selling the electricity generated from the energy recovery system back into the power company’s grid. This further agrees with both partners’ goals in carbon footprint reduction set out in the 2007 BC Energy Plan and the 2010 Clean Energy Act.Of the total project cost of $11.2 million, the City of Nanaimo received $7.68 million on funding from the federal Gas Tax Fund administered through the Union of BC Municipalities (UBCM). The remaining $3.5 million cost was covered by the City Water Fund.
The new Resevoir No 1 and Energy Recovery Facility went on-line in April 2014. Since then, the facility has provided 750 Megawatt-hours (MWh) of energy to BC Hydro’s grid, averaging about 65MWh production per month during the ‘low flow’ months. This hydro-electric power generation is expected to generate between $70,000 and $90,000 in additional annual revenue to the City’s water fund. As a result of the cost sharing, the project has a short payback period of less than ten years and will remain operational for at least the next 50 years. The Energy Purchase Agreement has a 20 year duration, with an opportunity to extend.
Prior to the collaboration with BC Hydro, the City of Nanaimo worked though water licensing process to apply for a power production water license. Other close working relationships included the Ministry of Forests, Lands and Natural Resource Operations, Water Stewardship Branch which enabled smooth operation of the process.
The creation of improved infrastructure is a driver for economic and social development, providing several short term jobs over the design and construction period and providing surety to the community of Nanaimo, increasing the attractiveness of the city as a place to invest, work and live.
Nanaimo is a leader in demonstrating how a municipality’s water system can offset GHGs and recovery energy. It may also encourage competition in a growing number of small and green projects in the marketplace.
The new facility ensures that residents will have continued access to safe, clean drinking water.
The configuration of the water supply system involves feeding water from the reservoir throughout the lower elevations of the city. As a result, the new reservoir provides a provision of fire protection from Chase River to Departure Bay as well as emergency storage. If the entire North Nanaimo system were to be taken off-line, or it there were to be increase fire flow requirements, the new reservoir can be used to augment or replace the system.
This energy recovery project supports the Province’s commitment to reducing provincial GHG emissions by at least 33 per cent below 2007 levels by 2020 and meets a key goal in the Water Supply Strategic Plan and bringing the region a step closer to becoming a carbon neutral community.
Collaboration was a vital component of the success of the project. It would not have succeeded without the leadership shown by City of Nanaimo Mayor and Council and their vision of a sustainable community. The Council has been extremely supportive and enthusiastically encouraging throughout the project’s development and implementation. BC Hydro also demonstrated tremendous leadership with a partnered approach in the project.
Completion of the new reservoir and facility was a great accomplishment for the city. The $11.2-million reservoir will help Nanaimo meet new drinking water guidelines, and replaces a 100 year old asset that stored untreated water in an open-air reservoir.
Local government contact
Bill Sims, Manager
Water Resources, City of Nanaimo
T: (250) 756-5302