CarbonRun’s first limestone silo in Pictou County, Nova Scotia. The company is building a machine to help slow global warming by transforming Earth’s rivers and oceans into giant sponges that absorb carbon dioxide from the air. — ©2024 The New York Times Company
IN a quiet forest in Nova Scotia, a start-up called CarbonRun is testing a new way to combat climate change by turning rivers into carbon-absorbing sponges.
Using a machine that grinds limestone and releases it into rivers, CarbonRun aims to trap carbon dioxide and prevent it from escaping into the atmosphere, ultimately reducing global warming.
“When the machine is turned on later this year, the limestone will mix into the West River Pictou, creating a chalky plume that dissolves within minutes,” explains Eddie Halfyard, freshwater ecologist and co-founder of CarbonRun.
The limestone reacts with the carbon dioxide in the water, converting it into a stable molecule that remains trapped in the water, eventually flowing into the ocean where it can be stored for millennia. Halfyard is excited about the simplicity of the method, saying: We let the water do most of the work.”
The company’s US$400,000 (RM1.6mil) limestone machine is the first of what they hope will be many, designed to harness nature to fight climate change.
A worker preparing for seawater sampling in Halifax Harbour, Nova Scotia. — ©2024 The New York Times Company
Rising need for carbon removal
As greenhouse gas emissions continue to soar, many scientists argue that it is no longer enough just to reduce fossil fuel usage. To prevent catastrophic warming, some of the excess carbon in the atmosphere must be removed.
Nan Ransohoff, head of Frontier, a US$1bil (RM4.1bil) fund backing carbon removal technologies, sees huge potential in ocean-based solutions.
“Oceans have naturally absorbed about one-third of the 1.7 trillion tonnes of carbon dioxide we’ve emitted since the industrial age,” she explains.
“We believe that accelerating this process could remove even more carbon.”
Frontier has already pledged US$25mil (RM103mil) to CarbonRun to help scale up their operations, with plans to remove 55,000 tonnes of carbon dioxide from the atmosphere, equivalent to the emissions of 13,000 cars.
The challenges ahead
While CarbonRun’s method has shown promising results in rivers, scaling it up to work in oceans, which are far more complex, presents significant hurdles.
David Ho, an ocean scientist at the University of Hawaii, warns that achieving this on a global scale would require a massive industry.
“It has to go from something most people have never heard of to the largest industry the world has ever seen, in a very short time,” he says.
Additionally, altering ocean chemistry is risky. Environmental groups are concerned about the potential harm to marine life, particularly as companies race to profit from these technologies.
Ken Buesseler from the Woods Hole Oceanographic Institution says the risks must be carefully weighed.
“Every method has its consequences, but doing nothing is catastrophic.”
Learning from the past
CarbonRun hopes to avoid the backlash experienced by earlier efforts in ocean geoengineering.
In the 1980s, controversial proposals to sprinkle iron into the ocean to fertilise plankton – so they would absorb more carbon – met with fierce opposition.
Halfyard and his team are treading carefully, ensuring that their limestone method is effective and environmentally safe.Their approach builds on lessons from the 1970s and ’80s, when countries like Canada and Norway used limestone to counteract acid rain, successfully restoring the pH balance of waterways and revitalising fish populations.
Halfyard and his co-founder, Shannon Sterling, discovered that this same process could also trap carbon in rivers, leading to the founding of CarbonRun.
Researchers bringing up a seafaring drone, which measures the exchange of carbon dioxide between the air and sea, in Halifax Harbour. — ©2024 The New York Times Company
A business opportunity?
For businesses eager to profit from carbon removal, these technologies represent a growing market.
CarbonRun needs about two tonnes of limestone to remove one ton of carbon, a calculation that presents logistical challenges in terms of mining and transportation. However, rivers worldwide could potentially trap millions of tons of carbon dioxide annually, offering significant opportunities.
CarbonRun has been working closely with local communities in Nova Scotia, where limestone restoration has already helped revive devastated fisheries.
For some, the benefits are deeply personal.
“I can go fishing with my grandson again,” says Donald Rutledge, a 79-year-old resident who witnessed salmon disappear from rivers in the 1980s, only to see them return after river liming.
Oceans: the next frontier
Despite the potential for rivers, the real prize lies in the oceans, which hold far more carbon-storing capacity. However, oceans are vast and turbulent, making it much harder to control the spread of limestone or other alkaline substances.
“The biggest challenge right now is proving that ocean alkalinity enhancement works,” says Jaime Palter, an oceanographer from the University of Rhode Island.In Halifax Harbour, a company called Planetary Technologies is adding magnesium oxide to the water to increase alkalinity. Researchers from Dalhousie University, including Dariia Atamanchuk, are working to verify the results, measuring water samples and assessing carbon dioxide levels.“As a scientist, I’m sceptical, but I’m also optimistic,” Atamanchuk says.
Navigating regulatory waters
The regulatory landscape for ocean-based carbon removal is still in its infancy.
While some projects, like Planetary’s work in Halifax, operate under local clean water laws, the lack of a unified global framework complicates large-scale efforts. International waters, in particular, remain a legal grey area, raising concerns about potential disputes between countries.
At Woods Hole Oceanographic Institution, Adam Subhas and his team plan to test ocean alkalinity enhancement by releasing thousands of gallons of alkaline solution into the Atlantic. But approval has been slow, and community opposition strong.“Leave the ocean alone,” wrote one critic in response to the project’s proposal.
Subhas is aware of the risks but believes it is crucial to study these technologies thoroughly, adding: “The danger is that for-profit companies might not be as careful about getting the science right. That’s what keeps me up at night.”
The future of carbon removal
As the world confronts the realities of climate change, these early efforts to use natural systems to trap carbon may be essential for ensuring a livable future. But the path forward is fraught with uncertainty, both in terms of technological feasibility and public acceptance.
The balance between risk and reward is clear for scientists like Buesseler: “The consequences of doing nothing are catastrophic.” — ©2024 The New York Times Company
