The City of Prince George’s wood fibre-based district energy system (DES), commissioned in 2012, provides carbon-neutral energy to buildings in downtown Prince George. The early drivers for the project included reducing energy costs for civic buildings at a time when natural gas prices were high, reducing particulate emissions, and utilizing wood waste from pine beetle infestation.
A boiler system extracts heat from sawmill residues at Lakeland Mills, which is the closest sawmill to the downtown core. The heated water is distributed through approximately 2.7km of insulated pipes through the downtown, where it is used by a dozen buildings for space heating and domestic hot water.
Each connected building has an Energy Transfer Station (ETS), which utilizes heat exchangers to transfer thermal energy from the DES to the building system. The efficiency of these heat exchangers is 99.9% compared to traditional natural gas boilers that have an average efficiency of 80%. The efficiency of the DES is 92.5%, which includes the piping, ETS’s, pumps, and backup boilers. Once heat is recovered, the water returns to the sawmill via 2.7km of return piping to be reheated.
The City of Prince George commissioned the district energy system in 2012. The system includes the main plant at Lakeland Mills and the Peaking Backup Energy Centre, and a network of pipes and pumps. At time of commissioning, customers included City Hall, the Conference and Civic Centre, Rolling Mix Concrete Arena (formerly the Coliseum), Four Seasons Pool, main branch of the library, and Two Rivers Art Gallery. Since then, four new customers joined the system: the RCMP detachment and Wood Innovation and Design Centre in 2014, and the BC Law Courts and Plaza 400 (a Provincial government office building) in 2017. The City anticipates new connections in 2019.
As part of this project, current technology at the mill was upgraded to lower emissions and more sophisticated environmental equipment was purchased to help the boiler system operate more efficiently. The Peaking Backup Energy Centre, which contains distribution pumps and backup natural gas-fired boilers, was constructed to supply hot water to the DES when Lakeland Mills is shut down for maintenance or when there is high demand for heat during colder days.
The Prince George DES is currently peaking at 2.2 MWh and is designed to produce 5 MWh. Future expansion is possible: The current facility is able to accommodate additional equipment to increase to 10 MWh back-up as the system expands.
The City entered into a long-term energy supply agreement with Lakeland Mills for the supply of heat to the DES. The agreement will provide stable pricing for 10 years and there is an option to extend the agreement for a further 10 years.
Every project will have a different set of drivers, which may change over time. For some communities the driver for a similar project may be improving air quality, while for another it may be to retain and support the local forest industry, create jobs, or improve local energy security.
The City operates this system within existing City departmental structures, rather than a City-owned utility. This approach helped to build internal capacity, embedded the system within City operations and integrated it with other utilities, engineering and public works. If taking this approach, the City recommends that other internal roles be identified, including Economic Development and Communications, to build relationships with industry and the public.
District energy systems are generally invisible once they are operational. Ongoing public education is important to ensure there is political will to continue with a project and to build profile that will help attract new customers.
As of 2017 (with addition of the two newest customers) the estimated GHG emissions reduction is 2150 tonnes/year
Possibility for generating non-tax revenue and/or reducing heating and operational costs for City facilities
Avoids capital costs of facility upgrades in the future
Ongoing infrastructure improvements and operations are funded through a combination of user fees and contributions from the City’s General Operating Fund
Lowers particulate emissions in air shed by 100.7 tonnes each year (estimated during project design)
Reduces dependence on fossil fuels and helps to foster energy security and price certainty
Positions the community as a leader in bioenergy
Helps to renew the downtown core by attracting businesses
Supports the forestry industry
Ensures energy dollars remain in the community
The total project cost:
$5.3 million from Municipal Rural Infrastructure Fund
$4.3 million from Community Works Fund
$460,000 from FCM’s Green Municipal Fund