A team of scientists believes it has a “rock-solid” way to combat the climate crisis by sucking carbon out of the atmosphere and storing it deep below the ocean floor.

The proposed Solid Carbon project aims to scrub vast amounts of carbon dioxide (CO2) from the air and inject it nearly three kilometres beneath the ocean’s surface into basalt aquifers where it will eventually transform into rock.

The initiative will use direct air capture (DAC), a type of carbon capture technology, powered by renewable energy on a floating platform or ship to collect and pump concentrated CO2 about 300 metres beneath the seabed, said Kate Moran, CEO of Ocean Networks Canada (ONC), the University of Victoria research group leading the international scientists on the project.

The CO2 is injected into porous basalt, which is covered by a deep impermeable cap of sediment on the ocean floor, where it dissolves in water. Then it binds with dissolved basalt minerals such as calcium, magnesium and iron silicates to transform into carbonate rock that can’t escape the seabed reservoir, Moran said.

The potential scale of the project as a climate solution is “gigantic,” said Solid Carbon researcher Benjamin Tutolo, a geoscientist with the University of Calgary who recently led a study indicating basalt could capture up to a gigaton — a billion tonnes — of CO2 annually.

There is enough sub-ocean basalt worldwide to potentially sequester 250 gigatons of CO2, said Tutolo. That’s approximately 10 times the amount needed should we burn all the fossil fuels on the planet, he said.

The project’s potential sounds almost unbelievable, Tutolo conceded.

“Although it sounds crazy and expensive, there are plenty of reasons to be optimistic about this technology,” he said. “The capacity is so enormous.”

Carbon capture as a climate solution is controversial with critics who believe the technology is too nascent and expensive and offers policymakers and fossil fuel industries an excuse to prolong the use of oil and gas

While the project is certainly feasible, said Phillip Jessop, Queen’s University research chair in green chemistry, there are always challenges to be overcome with wide-scale deployment.

“I have no doubt that given enough time and money, they could achieve this,” said Jessop, who is not involved in the project, but believes some version of carbon capture is necessary to meet the global warming threshold of 1.5 C set out by the UN Paris Agreement.

“But the question is … is this a good idea environmentally speaking, and is somebody willing to pay?”

A life-cycle assessment to calculate the environmental footprint for all stages or aspects of the project would be necessary to answer the question, he said.

Presumably, the project will rely on money collected from carbon taxes, or carbon offsets bought by companies to reduce their greenhouse gas emissions, he said.

But the current energy costs of direct air capture are still prohibitively high, Jessop said.

“So for every dollar invested for every kilowatt-hour they get from sunlight, or other (renewable) energy sources, how much CO2 can they sequester?” asked Jessop.

“That’s going to be one issue the skeptics will want to know.”

Price of polluting is growing

Moran agreed the cost of DAC technology is a challenge but notes the price of carbon pollution is rising rapidly, and Canada has promised emissions will cost $170 per tonne by 2030.

Early estimates suggested the project’s carbon cost would be a bit more than US$180 per tonne, Moran said.

But similar to renewables such as solar or wind energy, the initial costs should drop over time as the technology continues to develop.

“It’s no more expensive than the technology that’s being developed or in use right now with the offshore oil extractive industry,” Moran said.

No one should view carbon capture as a total solution, Moran added. It should be paired with dramatic reductions in greenhouse gas emissions, she said.

Scalable carbon capture and storage projects, such as Solid Carbon, are urgently needed to meet mid-century net-zero climate targets that can’t be met by reducing emissions alone, Moran said. And the project’s component technology — such as DAC, ocean platforms, solar or wind power, CO2 injection systems, and offshore drilling — is already in use elsewhere, Moran said.

“It’s not pie in the sky,” she said. The next goal is to launch a small-scale demonstration in 2024 in the Cascadia Basin, 200 kilometres west of Vancouver Island, where ONC maintains an underwater observatory.

The proof-of-concept demonstration will likely cost $20 million and allow researchers to better understand the extent and speed of CO2 mineralization, she said.

Work is also underway to determine the regulatory processes for the project.

“We have all the pieces, so from a systems engineering perspective, it’s eminently doable.”

Launch of biggest carbon capture project will drive improvements

The recent launch of the world’s biggest carbon capture plant in Iceland has been particularly inspiring for the ONC team, Tutolo said.

The Orca project, which also uses DAC technology and injects CO2 into basalt where it forms rock, will demonstrate the process is achievable at a larger scale and pave the way for efficiencies, he said.

One of Solid Carbon’s advantages over the Iceland project is it doesn’t require lots of water to get the CO2 into the ground, Tutolo said.

The trade-off is it will likely take longer than the two years demonstrated in previous Icelandic research projects for CO2 mineralization to occur, but as the emissions are permanently sequestered, that shouldn’t be a problem.

“Basically, the earth will give it time to react, and that’s all we really need to happen.”

The demo project expects to inject a minimum of 10,000 tonnes of CO2 into the Cascadia Basin basalt and monitor it for two years, he said.

But ultimately, the plan is to be storing a gigaton of emissions annually by 2040 — an amount equalling all emissions from transportation in Canada over a six-year period.

Senior levels of government also need to foster and fund carbon capture projects to get them to the stage they need to be to help achieve net-zero targets, Tutolo said.

“We really need to be moving forward on these technologies to help us deal with the action that we haven’t taken over the last 20 years.”