Road salt alternatives? They’re out there, but it’s about cost as much as chemistry

As a deep freeze continues to envelop southwestern Ontario at the same time municipalities deal with a pressing shortage of road salt, there’s a renewed focus on finding different ways to melt road ice.

It’s something Western University researchers have been examining in a study started in 2022. They’re expecting to release data from the study this summer.

The research is looking at nine different substances, testing each one’s ability to melt road ice under varying conditions.

Christopher Power, an assistant professor working on the study, said sodium chloride (also known as rock salt) has become the go-to for Ontario municipalities. Price is a big reason why.

“It’s so plentiful and easy to access, so the bottom line is it’s cheap, particularly for the volumes that every municipality needs,” he said.

Salt comes at an environmental cost

Power said rock salt is an effective way to clear ice from roads. It works by lowering water’s freezing temperature, which melts existing ice and makes it hard for new ice to form.

But salt also comes with well-documented downsides. It’s corrosive, which can shorten the lifespan of anything metal on or near the road, including bridges, guardrails and vehicles.

There’s an environmental cost as well. Much of the salt spread on streets winds up in rivers, streams and the Great Lakes. Experts have flagged the “rapid” salination of the Great Lakes as a significant threat to the environment.

“At the rate we’re seeing, our Great Lakes could start to look like salt water and that has a negative effect on freshwater ecosystems,” said Power.

Also, Power said the effectiveness of rock salt begins to drop off at about — 15 C.

Of the alternative ice-melting substances Western is studying, some are already being used to melt ice in different applications, such as sodium acetate and beet juice.

Part of the study involved blocking off areas of Western University’s campus and allowing the grounds crew to use different substances to clear the ice.

Power said while the study phase is now complete, he and other researchers are now busy compiling its data, including each substance’s melting efficiency and level of corrosiveness.

Power said right now there’s no clear winner as to which sodium chloride alternative is the best.

He also said whichever substance the study finds to be most effective won’t automatically be the one road crews start using after the next winter storm.

The low cost of rock salt to municipalities under constant budget pressure is big reason Power doesn’t believe rock salt will completely go away anytime soon.

“For widespread adoption, economics will always come into it,” he said.

However, he suggested sodium chloride could be supplemented by municipal road crews with other, less corrosive substances, for example, near bridges or bodies of water.

A more targeted approach to salt use is something many municipalities have started to embrace.

Faced with this winter’s salt shortage, the City of London is adding other substances to the road-clearing mix.

Joel Gillard, London’s division manager of road operations, said the city plans to plow more frequently while easing up on the salt distribution.

“When we get that deep freeze, we’ll transition to more of a sand-salt mix,” Gillard told CBC news. “The salt, even with our liquid brine solutions, just isn’t capable of melting snow and ice at this temperature.”