What if we refrigerated the Rideau Canal?

Wayne Borrowman has never skated on the Rideau Canal, but he just might have a cool idea to save Ottawa's famous attraction from climate change.

Borrowman is an engineer and director of research and development for CIMCO Refrigeration, a company headquartered in Burlington, Ont., that claims to have built more than half of the world's artificially cooled ice rinks.

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With more than three decades of experience in the industry and hundreds of major projects including Olympic venues under his belt, Borrowman knows a thing or two about the thermal systems required to maintain a top-quality ice surface.

Yeah it's a big surface, but we've done big refrigeration systems.- Wayne Borrowman, CIMCO Refrigeration

So when he learned this past winter that warm, wet weather had for the first time in its 52-year history prevented the Rideau Canal Skateway from opening, Borrowman saw an opportunity.

"I guess the first thought I had was, well, we're in the refrigeration business and we make ice," he told CBC. "Yeah it's a big surface, but we've done big refrigeration systems."

In a blog post, Borrowman estimated the skateway's ice surface to equal about 60 NHL rinks. To him, it's just a matter of scaling up.

"That may sound crazy to some, but I've spent my whole career involved with the design and installation of large cooling systems and I can assure you from an engineering perspective it is possible," he wrote.

Miles of pipes

Underlying a typical refrigerated rink is a network of some 15,000 metres of piping through which a brine solution or propylene glycol is pumped, extracting heat from the ground and keeping the ice surface above in a solid state.

Based on Borrowman's estimate, refrigerating the Rideau Canal would require nearly one million metres of piping, with chilling units about the size of a shipping container placed at regular intervals along its 7.8-kilometre length. 

The big question is where all those pipes will go — encased in concrete, set into the mud, or somehow suspended at an optimal depth — and whether they can coexist with the canal's other seasonal uses.

"The issue is that it may not be practical from an installation or operating cost perspective," Borrowman acknowledged in the blog post.

Undaunted, he began to consider the potential output of such a massive thermal system. 

Traditionally, the heat extracted from the ground during the refrigeration process was simply expelled into the atmosphere. More recently, CIMCO and other refrigeration companies have been putting that heat to better use to warm arenas and other buildings.

"It's not just about cooling, it's about what you can do with the heat that you would otherwise have lost," Borrowman explained.

Chilling ice, heating homes

One example is the Shipyards Skate Plaza in North Vancouver, where CIMCO installed a system that not only chills the ice, but also provides space heating and hot water to nearby buildings — enough to warm the equivalent of 40 homes.

Borrowman estimates the thermal output of a refrigeration system capable of chilling the Rideau Canal would be similar to that of a massive district energy system in Sweden, thought to be the world's largest. (A district energy system is already operating at the Zibi development on the Ottawa River.)

So the Rideau Canal could one day provide Ottawans with far more than winter recreation — it could heat their homes, too.

"I would want to be real clear here that this was sort of a thought exercise," Borrowman told CBC. "But think about some difficult things that humanity has done that are more complicated than this."

Shawn Kenny, a professor at Carleton University's department of civil and environmental engineering who has been working with the National Capital Commission (NCC) to improve ice conditions on the Rideau Canal Skateway, agrees that from a purely scientific perspective, Borrowman's idea is "doable."

"The concepts are there in terms of what's feasible and what's not, in an engineering sense … but I think there are other softer issues," Kenny said.

Chief among those is convincing the NCC and Parks Canada, which manages the UNESCO World Heritage Site, that refrigerating the canal is a viable solution. Then there's the enormous cost and upheaval that would be involved in constructing a district energy system capable of delivering heat to thousands of homes, businesses and institutions throughout central Ottawa.

In an emailed statement to CBC, the NCC did not respond directly to Borrowman's idea. Instead, it lauded its partnership with Carleton University "to identify strategies to adapt Skateway operations to the impacts of climate change."

'Snowbots' and thermosiphons

Among the innovations Kenny and his team have been working on is a "slush cannon" to help ice form at the front end of the skating season. They're also using 3D printers to assemble an army of "snowbots," remote-controlled snowblowers that can be used to clear the ice when it's too thin for heavier equipment.

This summer, the group also plans to experiment with thermosiphons, which are used in the Arctic to slow the degradation of the permafrost by removing heat, and which could potentially have the same chilling effect on the Rideau Canal. 

They'll also consider how such technology might fit into a larger district energy system, Kenny said.

"It'll be at the conceptual level of how much heat do you need, what kind of system would you need, how much power would it require and how much output would it have."

Borrowman suggests his idea to refrigerate the canal could be achieved in phases, beginning with a more manageable pilot project to demonstrate its practicality and environmental sustainability.

"I just think [this] is the kind of thinking that we have to talk about," he said. "Even if it went nowhere, I think it's worth the exercise of investigating it further."