INNOVATION March-April 2014

The third photo depicts a heat exchanger located in- side a building. Liquids that have absorbed sub-surface solar energy flow through the heat exchanger, which extract that energy—or heat—which is then distributed through the building.

f ea t ures

than almost anywhere on the continent. Geoexchange in North America was first developed primarily in parts of the Southern and Midwestern US where the geology and climate were consistent across entire states or regions and a cookie cutter approach could be applied. That’s not the case in BC. “You’ve got volcanic rock formations, igneous, metamorphic and sedimentary rocks all within a short distance of each other,” says Arellano. “The sediments on top range from loose boulders off the mountains and sand from the rivers to glacially densified mixes. The thickness of these sediments and the amount of water in them all vary and you have these changes within short distances. The design, testing and installation change for all these settings. It’s a geological engineering exercise and must be integrated with the rest of the design and through construction.” Despite such challenges, a number of major geoexchange systems have been installed in the Province in recent years. In March 2011, the City of Richmond broke ground on its Alexandra District Energy Utility and construction was completed 15 months later. The vertical geoexchange field is located under a green belt and consists of 385 boreholes drilled to a depth of 76 metres, or 250 feet. The boreholes are connected by 1.3 kilometres of 20-inch polyeth- ylene supply and return mains that distribute fluid throughout the field and return it to an energy centre where the heat is extracted in Is your project prepared for avalanche season?

order to be distributed to buildings connected to the system. It was designed to provide heating and cooling for some 400 nearby multi- unit residences as well as a daycare. Another major geoexchange system has been installed beneath PCI Group’s mixed use Marine Gateway project, which is located at 8400 Cambie Drive in Vancouver and is slated for completion in 2015. The 820,000-square foot complex includes a 14-storey office tower, a 46,000-square foot Loblaws, an 11-screen Cineplex, 416 residential units in two towers as well as retail outlets, restaurants and a variety of services. FortisBC Alternative Energy Services installed the $9.2-million geoexchange system and will own, operate and maintain it. It consists of 330 boreholes drilled to a maximum depth of 45 metres, or 147 feet and spaced at 4.5 metres. Assuming normal weather conditions over the course of a year, the system will meet 80% of the complex’s heating and cooling needs, while natural gas-fired boilers will provide the balance and serve as back up. Fortis and PCI estimate that the use of geoexchange will reduce greenhouse gas emissions by a minimum of 50% compared to the levels generated by conventional heating and cooling systems. A number of school districts in the Okanagan have opted for geoexchange systems, says Quibell, and his company also designed a number of systems for homeowners in communities in Northern BC that are not connected to the natural gas grid and must rely on either electricity or trucked-in propane to heat their homes—both of which are expensive options. As well, he and his team designed a geoexchange system for Manitoba Hydro’s head office in Winnipeg. It consisted of 280 boreholes drilled to depths of 380 feet and it meets the heating and cooling needs for the 24-storey building. GeoTility, meantime, installed its first system in 1990 and has since become a fully-integrated company that designs, builds and installs. It is now the largest company of its kind in the country, with offices in Kelowna, Vancouver, Victoria and Seattle and it operates a fleet of eight drilling rigs of its own design. “We’ve been pushing the technology,” says Yanow. “We have a good climate for it. It’s more expensive initially to go with geoexchange because the drilling is an added cost. But your energy costs are lower in the long run and these systems will outlast the buildings to which they’re connected.”

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