New research shows that carbon dioxide captured from the atmosphere and pumped deep below the ocean floor could turn into solid rock in 25 years.  

The research is part of a UVic-led project, Solid Carbon, which began in 2019 to determine whether storing carbon dioxide deep below the ocean’s surface could be an effective, more permanent solution to decrease the concentration of the major greenhouse gas in the atmosphere.

The project’s most recent study shows that 95% of carbon dioxide pumped into basalt rock—a porous, volcanic rock predominantly found at the ocean floor—would mineralize within a quarter of a century.

“What we have shown in this study is that carbon dioxide can transform to rock within 25 years as opposed to cases where mineralization takes many millennia,” says Adedapo Awolayo, the research paper’s principal author, in a statement. 

Even in less likely scenarios, where the CO2 interacts less with the basalt rock, mineralization would still be expected within 100 years. 

“The findings from this modelling of ocean basalt lay an incredibly strong foundation for our next steps,” says Kate Moran, Ocean Networks Canada president and chief executive officer. She added that planning is underway to demonstratie Solid Carbon’s project in the Cascadia Basin off the coast of Vancouver Island. 

How it works

Canada has been capturing and sequestering carbon underground for decades at its biggest sources, such as natural gas power plants. But using this method, CO2 remains in a gaseous form, maintaining the possibility that it could leak out of the ground. 

Other methods of storing carbon are also in use, such as storing CO2 in concrete. Last year, Langford mandated the use of carbon capture technology in concrete buildings. Several Langford concrete manufacturers are already using the technology. 

Solid Carbon is planning to create a floating platform, powered by renewable energy such as wind, over an area where basalts occur—the Cascadia Basin is one such area. There, direct air capture technology will be used to extract CO2 from the atmosphere. Using offshore drilling technology, the CO2 will be injected directly into the ocean basalt, where it interacts with different minerals to create carbonate rock.  (Capital Daily previously wrote about the plan to sequester carbon under the ocean floor in 2019 when the pilot program was first announced.) 

Similar studies have been conducted elsewhere with positive results. In Iceland, researchers have been testing injecting dissolved carbon dioxide into shallow basalt, where it has been shown to mineralize within two years. 

However, researcher Benjamin Tutolo of the Solid Carbon team has previously said that this faster approach is water-intensive, costly, and difficult to scale up. 

“The reaction needn’t be completed in days or even months as long as the CO2 doesn’t escape before the process is complete, even if it takes centuries,” he said.

Carbon dioxide that is injected into the basalt rock would be trapped there by a natural layer of up to 800m of sedimentary rock. The gas would be forced to react with the rock instead of escaping. 

How much carbon are we talking about? 

Human activity adds around 50 gigatons of greenhouse gases to the atmosphere each year, according to Solid Carbon. Carbon dioxide makes up the majority of those greenhouse gases. 

Last year, Solid Carbon researchers released a study that showed the project could capture a gigaton of carbon dioxide per year using this method. Moran said in a release earlier this month that each sequestration site could potentially inject half a million tons of CO2 into basalt per year to start, though that could be scaled up to more than 20 gigatons per year by 2100 if successful. 

However, Tutolo points out that this technology does not decrease the need to reduce global carbon emissions. 

“This is not a ‘get out of jail free’ card,” Tutolo said in a statement. “All pathways to remain under 1.5 degrees of global warming require the use of negative emissions technologies such as this, but we also need to decarbonize the economy to get there. We need both.”