Quirks and Quarks

Canadian concept to pump carbon into subsea rock could sequester gigatons of CO2

‘There’s so much more capacity in these aquifers than is actually needed to deal with the problem.’

‘There’s so much more capacity in these aquifers than is actually needed to deal with the problem.’

Over 90% of the Earth’s basalt rock is located on the deep ocean floor, such as this pillow lava bed seen west of Vancouver Island at a depth of 2195 metres. (Ocean Networks Canada / CSSF)

If we were to start injecting pure, pressurized carbon dioxide into the Earth's crust underlying the world's oceans, we could sequester more CO2 than we could produce by burning all the fossil fuels existing on the planet today, according to a recent study.

Geological sequestration is a strategy that involves capturing carbon dioxide and transporting it into the Earth's crust where it transforms into rock, and is thus permanently removed from the atmosphere. This carbon could be captured at smokestacks, but many groups are working on systems that would extract CO2 directly from ambient air, essentially scrubbing it out of the atmosphere.

One of the biggest limiting factors for currently operating direct-air carbon sequestration methods — one opened recently in Iceland — is that they require a lot of water to get the CO2 into the ground.

The world's largest current carbon capture and storage plant in Iceland went online early in September 2021 with the capacity to remove 800 cars worth of CO2 per year — a number they say they plan on scaling up — by mixing it with water before sequestering it. (Climeworks)

However Ben Tutolo, an associate professor of geoscience at the University of Calgary, and his colleagues have been working on a strategy that could be superior. The team has been working on a technology that would use offshore platforms similar to those used in the oil and gas industry, that would capture carbon from the atmosphere and pump high pressure, near-liquid "supercritical" CO2 into water-saturated rock under the sea bed. The CO2 would be trapped there and would gradually react with the sub-sea rock and become mineralized.

Tutolo told Quirks & Quarks' Bob McDonald their geochemical simulations suggest the technology, called Solid Carbon, would not only be more efficient than current systems, but it also wouldn't require vast amounts of water. Nor would have to be done in anyone's backyard. 

This visualization schematically shows the process by which highly-pressurized supercritical CO2 is converted to solid carbonate minerals by interaction with porous basalt. (Benjamin Tutolo)

He said they're working to implement this technology by the middle of the century, so he stressed this would not replace the need to decarbonize our economy, but would be used to augment our decarbonization efforts. 

Produced and written by Sonya Buyting. Click on the link at the top of the page to hear the interview with Prof. Ben Tutolo.