If carbon capture ever gets going in Ontario, where will we put it all?

The Ontario government is proposing legislative changes that would open the door to storing carbon dioxide underground in the province, but it’s unclear where the captured greenhouse gas would go.

In a discussion paper released in January, the Ministry of Northern Development, Mines, Natural Resources and Forestry proposes allowing carbon dioxide storage on Crown land. The proposed amendments would still prohibit using carbon dioxide to enhance oil and gas extraction — a concern among some environmentalists since most captured carbon is used to make it easier to produce more oil and gas. Instead, the proposed legislation would focus on options for storing carbon dioxide generated by other large emitters.

According to the discussion paper, storing carbon dioxide deep underground is “one way of reducing the impact of greenhouse gases” from high-emitting sources like gas-fired power plants or heavy industrial activity.

Geology experts say southwestern Ontario’s saline aquifers — where deep rock is saturated with saltwater — could provide the transition plan to help meet the government’s 2030 emission reduction targets, especially for heavy industries like steel and cement that are still years away from removing planet-warming greenhouse gases from their operations. Experts also say there isn’t enough information about the geology below the surface to know exactly where carbon dioxide could safely go or how much could be stored.

“We’re not blessed with a geology like Alberta or Saskatchewan,” said Maurice Dusseault, a professor of engineering geology at the University of Waterloo. “We need more geological and engineering data to start helping companies make decisions.”

Dusseault said the best potential location for carbon dioxide storage in Ontario is a 100-kilometre-wide band stretching roughly from Port Dover to Windsor, extending underneath Lake Erie and about 50 or 60 kilometres from the shoreline. In this region, he said, the sedimentary rock is deep enough, and potentially porous enough, to store carbon dioxide.

In much of southwestern Ontario, the pore space in this rock is filled with saltwater brine. Pushing that brine out of the rock would create space to inject carbon dioxide gas for permanent underground storage. Dusseault said industry would need at least two to three years of intense geological and engineering studies to determine what is even feasible.

Carbon dioxide could also potentially be stored in old oil and gas reservoirs, but Ontario’s thousands of abandoned and orphaned wells pose risks. Dusseault said there are many legacy abandoned well bores in Ontario, but not many penetrate into the deep rock suitable for storing carbon dioxide. “We’ve got to identify where those well bores are and make sure they do not become leakage pathways.”

Even so, Dusseault said there are some locations worth studying, such as the Innerkip natural gas field near Woodstock, which might have the right mix of conditions to support carbon dioxide storage.

“It’s a depleted gas field that’s almost at the end of its life, so the pressure in that gas field now is very, very low,” Dusseault said. “That probably means it has a good seal.”

Bruce Hart, a geologist and adjunct professor of earth sciences at the University of Western Ontario, said finding the right location is like looking for the perfect intersection on a Venn diagram.

“The game becomes, where is it deeper than 800 metres? Where is it thick enough? Does it have the porosity? Does it have the storage capacity?” said Hart. “That’s one of the big unknowns right now because so few people have drilled into it.”

Hart said setting clear rules for storing carbon dioxide underground is just as important as having rules for taking oil and gas out of the ground.

“If you want to put stuff into the ground, you want to make sure that it’s not the Wild West, either,” Hart said.

The non-profit group Environmental Defence has advocated against using carbon capture and storage to boost efficiency in the oil and gas sector. But for sectors like the cement industry, it might make sense, said Julia Levin, senior program manager for climate and energy at Environmental Defence.

“People list a lot of sectors that we can’t decarbonize, but really, cement is the last question mark,” Levin said. “I’m still skeptical that we’ll figure out carbon capture and storage before we figure out some other way to decarbonize.”

Despite the challenges, Dusseault said carbon capture and storage is still worth exploring in Ontario.

“If we’re going to try to meet the commitments that have been made by the federal government by the year 2030, then we’re going to have to do something pretty radical in many parts of Canada,” he said.

The comment period on the discussion paper closes March 14.