THE SNAPSHOT
While working to restore Nova Scotia鈥檚 salmon habitats, H漫画 hydrologist Dr. Shannon Sterling and Dal alum Dr. Edmund Halfyard uncovered a groundbreaking approach to carbon dioxide removal. Their discovery not only advanced climate science but also positioned them to meet the growing market demand for CO鈧� removal, sparking a promising startup that has secured a $25 million investment.
THE CHALLENGE
Drs. Sterling and Halfyard had been working for years trying to save what remains of Nova Scotia鈥檚 wild salmon stocks by studying a process that combats the acidification of the province鈥檚 rivers.
Following restoration techniques established in Scandinavia to counteract the impacts of acid rain, the聽聽has pursued a program of adding crushed limestone to rivers and the forests that drain into them. Dr. Sterling collaborated with the charitable organization and its former lead scientist Dr. Halfyard to study the process and how its introduction of alkalinity to the waterways can help fish flourish.
A noble pursuit, but Dr. Sterling discovered that there was as much good happening above the waterline as there was for fish in the river. The a-ha moment came in 2018, when she started reading scientific papers focused on the urgent need to remove CO2 from the atmosphere.聽
H漫画 hydrologist Dr. Shannon Sterling
鈥淚t was the IPCC Paris Agreement where the world community got together and collectively said 鈥極kay, we鈥檝e really screwed up. Even if we meet all our聽CO2聽emissions reduction targets, we're still going to overshoot by 1.5 degrees of warming. We have to draw down carbon from the atmosphere,鈥欌�� says Dr. Sterling.
Emerging studies showed that adding聽alkaline materials such as limestone to the Earth鈥檚 surface had the potential to enhance the absorption of聽CO2聽from the air.聽
鈥淲e鈥檝e been doing that in watersheds for years,鈥� thought Dr. Sterling, who felt slightly dizzied by the realization that her ecosystem research might serendipitously make her a player in the emerging global movement to remove atmospheric CO2.
THE SOLUTION
鈥淭he scariest thing we faced was building a whole new pathway,鈥� she says. 鈥淲e were making quite a large claim. There was ocean alkalinity enhancement as a CO2聽removal strategy. And enhanced weathering on land. But we were proposing this whole new class of CO2听removal for rivers.鈥�
H漫画 graduate student tests river water.
To start getting the idea on the radar of the global climate mitigation community, she reached out to one of the leaders in the space, Dr. David Beerling at the University of Sheffield. The founder and director of the聽, had received a large grant following the Paris Agreement to study how spreading crushed rocks on soils could 鈥渉ack鈥� the long-term carbon cycle.
鈥淪o, I called David and said, 鈥榊ou know, we're already putting crushed rock on soils and in rivers in our work with salmon. Maybe there is a CO2聽removal component to what we are doing you鈥檇 like to consider,鈥欌�� she says.聽
Excited by the opportunity to see similar work in action, he came to observe Dr. Sterling and her colleagues鈥� field studies spreading limestone on forest floors via helicopter. While she was encouraged by Dr. Beerling鈥檚 interest in their land-based work, she couldn鈥檛 help her attention flowing back to the potential of river-based methods.
鈥淚 was thinking rivers could actually give us similar result with the added advantage of increased control and speed,鈥� she says. 鈥淲e've been monitoring the effects of adding limestone to land and you don鈥檛 get results for a few years, so there鈥檚 potentially years delay in the impact. With rivers, you can quickly test if you don't have the right dose and can change it.鈥�
THE WORK
She set out to investigate her theory with Dr. Halfyard. But to move the science forward, the pair needed monitor reactions at the water鈥檚 surface to observe if CO2聽was being absorbed. It would take complex and expensive fieldwork.
A lab on the side of the riverbank.
That鈥檚 when Dr. Sterling got a lifeline from a Toronto philanthropist turned on to her work by Dr. Beerling who, in yet another fortunate twist of fate, had just returned from his visit to Nova Scotia.
鈥淭hey funded our monitoring, and we started measuring changes to the carbonate system in rivers where limestone dosers were being employed.鈥� The results were impressive, she says, 鈥淚t was like, wow, this is actually working really well.鈥�
When Dr. Sterling looked out into the world, she couldn鈥檛 find anyone else doing what she was doing.聽CO2 removal researchers were focused on the ocean and land, but not rivers. She realized that her discovery could comprise intellectual property for a new carbon credits business venture while also advancing her goals to restore acidified river habitats. And so, with Dr. Halfyard and Luke Connell, who is now CEO, as her cofounders, CarbonRun was born.
H漫画 alumnus Dr. Edmund Halfyard, CarbonRun鈥檚 Chief Tech Officer. (Photo provided)
Using standards defined by聽 to identify successful carbon removal startups, Dr. Sterling validated the impact of her approach. 鈥淭hey established criteria, and we started ticking them off one by one 鈥� cost, community engagement, feedstock, CO2聽uptake 鈥� tick, tick, tick,鈥� she says.
And, because there are more than 50 years of research focused on adding limestone to rivers for habitat restoration, she says there is significant data demonstrating safety and ecosystem benefits.
THE IMPACT
In September, CarbonRun struck a $25.4 million deal through Frontier Climate, agreeing to pull 55,442 tons of聽CO2 from the atmosphere over four years. The agreement is a watershed moment, signaling that river alkalinity enhancement could scale into a formidable climate tool. The breakthrough deal sent reverberations throughout the emerging carbon dioxide removal sector landed the company on the front page of the New York Times.
In October, CarbonRun launched their pilot project in West River Pictou Nova Scotia. With local community members, government officials, and industry leaders in attendance, the event showcased the ingenuity behind the tower on the riverbank which releases a steady dose of crushed limestone into the water 鈥� a system designed to transform rivers into active agents of climate mitigation while improving ecosystems along the way.
Using solar and wind power, the doser passively takes in river water, mixes it with limestone and then returns it to the river. Currents then weather the mineral, creating the reaction that allows it to capture聽CO2 from the air above and convert it to a stable bicarbonate. Then it鈥檚 off to the ocean for permanent storage.
As CarbonRun moves forward, Dr. Sterling says partnerships are paramount, noting that community collaboration and comfort are essential. The company鈥檚 projects will bring ecosystem restoration, employment and other economic benefits she says, all of which will be important to communicate to communities that surround potential dosing sites.
The hunt is now on to find other ideal locations. It鈥檚 important that sites are close to limestone deposits to lessen fossil fuels used to deliver the minerals to the site 鈥� a key variable to consider when CO2听removal is the essence of your enterprise. Factors like river size, velocity, chemistry, and proximity to the ocean are also important, but most important are the considerations of the aquatic ecosystems and the communities around each river.
鈥淚t's a Goldilocks approach,鈥� she says. 鈥淲e need to find communities to partner with and rivers that are just right."