City of Whitehorse earth energy innovations for Whistle Bend February 28, 2009

As Whitehorse plans for the new Whistle Bend development on the lower Porter Creek bench, the city is giving significant consideration to innovative heating solutions using earth energy for the proposed neighbourhood developments. Determining what the optimal system could look like is the job of EBA Engineering Consultants supported by FSC Architects & Engineers in Whitehorse.

“The concept plan is before the city right now, and once that’s finalized we’ll look at options for geoexchange – also known as low-temperature geothermal – technology for groups of buildings, or small neighbourhood clusters, or the whole development as one district energy concept,” says EBA’s Scott Schillereff. “Because this is a completely new site, there’s an opportunity to plan ahead and get the most efficient use of space and ground conditions to extract earth energy and apply it for building conditioning.”

EBA’s ongoing project began in 2008 and has included background studies, drilling test holes and studying information on soils, bedrock, groundwater and thermal conditions in the development area. Once a template of the neighbourhood is selected by the city, the team will examine several approaches including open loop and closed loop geoexchange as well as waste heat recovery.

“This project is unique because of its size and northerly location – this would be the biggest, and certainly the most northerly application of district scale geoexchange technology that I know of,” says Schillereff, who leads EBA’s geoexchange practice and also heads up the B.C. industry association GeoExchange BC. “Geoexchange technology is well-known in the world and it has become more widely applied across Canada in last 20 years; it’s growing rapidly.”

“We’re looking at every option for earth energy, from a standard closed loop borehole arrangement where antifreeze liquid is pumped through a loop of pipe and conducts heat to and from the ground, to the open loop scenario where you pump warm groundwater and extract heat from that,” he says. “The other big option is waste heat recovery from sewer lines and water effluent, where you essentially transfer heat from sewer pipes. Whenever you’re pumping water anywhere that’s above freezing, that’s an energy source. If you can extract it efficiently, you have a heat source that would otherwise have been wasted.”

Given Whitehorse’s location, the team is looking at different approaches to address challenges presented by the northern climate as well as capitalize on some of its advantages. For example, if too much heat is extracted from sewer pipes that they approach freezing, it could create operational problems. Also, the temperature of the effluent affects biological activity in the sewage lagoon. These challenges necessitate that all players involved in planning the municipal systems for Whistle Bend are working closely and communicating regularly.

Another possible strategy is to integrate several types of heat with a district concept and different sources and sinks, such as combining geoexhange with solar thermal applications. For example, on long summer days black fluid-filled solar panels could return heat underground to restore balance by recharging the geoexchange system for the coming cold season.

“If it’s all heating-dominated, then you’re always extracting heat out of the ground. If it can’t naturally replenish fast enough, a method to balance the heat transfer to and from the ground is required for long-term sustainable use. One option is to circulate solar-heated fluid into the closed loop ground boreholes and warm up the ground in summer. The heat waits there until winter – like recharging the batteries – and then you have a balanced system that can operate in perpetuity,” Schillereff explains. “It’s not a new idea, but it’s probably a new technology application in the North.”

For more information on the Whistle Bend earth energy project, contact City of Whitehorse planner Kinden Kosick.