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Yellowknife takes steps to reduce its environmental footprint

The city's Multiplex has undergone a technological upgrade to save energy.


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February 1, 2016 by Beth McKay

The vortex degasser installation at the Multiplex.
The vortex degasser installation at the Multiplex.

In the summer of 2015, the City of Yellowknife installed a vortex degasser at its Multiplex facility to reduce energy consumption. The multi-purpose recreation facility houses an Olympic-size ice surface and an NHL-size ice surface. Ammonia is the refrigerant used at the arena.
Remi Gervais, community energy management specialist in Yellowknife, noted that heating surfacing water for ice pads is one of the largest heat loads of an arena, “so it made sense to investigate a way we [the city] could address that.”
Funding for the vortex degasser came from the Community Energy Plan – a project that strives to reduce the City of Yellowknife’s greenhouse gas emissions. Gervais said that prior to installation, rink water was being heated to 140F in a hot water tank, heated by oil boilers. With the vortex degasser however, the water is now being heated to 80F, which will save 16000 litres of oil per year.
“That volume of oil would have emitted 41 tonnes of CO2. This is equivalent to the emissions of heating about four houses in Yellowknife,” said Gervais. The vortex degasser was installed by in-house trades people. Dave Hurley, the facilities manager, said that installation was quick, as it only took one day.

“So far the ice appears to be better. We have only had compliments about the arena, I mean, it would be nice to save some money, but right now, there’s been no complaints about the ice,” said Hurley. Though bids for systems are confidential, Gervais expected the payback for the vortex degasser to take less than a year, noting that the system has not been active long enough to validate savings at time of print. According to a press release from the City of Yellowknife, an estimated $16000 should be saved each year in Yellowknife because of the vortex degasser technology.

HOW DOES IT WORK

The Measurement & Verification (M&V) Result report from FortisBC, explains that Vortex technology is a compact piping system, which removes air bubbles and filaments from the resurfacing flood water through cavitation instead of thermal activation. The resurfacing water is forced through guide vanes creating a pressure gradient to separate air bubbles and filaments from the potable water. As a result, vortex-treated water does not have to be heated to the high temperature as traditionally done before applying the water to the ice surface. This generates thermal and electricity savings through:

• reduction in thermal energy by significantly reducing the need to heat up resurfacing water; and

• reduction in electricity for the operation of the ice rink refrigeration plant as: vortex generated resurfacing water creates a lower refrigeration load since low temperature water is applied to the ice surface for ongoing resurfacing and the initial ice buildup; and the ice rink slab temperature is raised to allow the vortex generated resurfacing water to freeze at an appropriate rate. See www.realice.ca/tag/fortis-bc/ for more details.


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