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Dr. Sean Monkman, senior vice president of technology development at CarbonCure Technologies Inc., at the company's headquarters in Halifax on Jan. 22, 2021.Darren Calabrese/The Globe and Mail

As Inc. (AMZN-Q) builds its massive second headquarters in Virginia, the company is using concrete strengthened by one of the most quietly successful startups from Canada’s East Coast.

CarbonCure Technologies Inc. has honed its techniques for injecting carbon dioxide into concrete for more than a dozen years. The process adds enough strength to the building material to cut the amount needed for a project by about 5 per cent. Doing so also significantly reduces the environmental impact of using concrete: For every tonne of carbon dioxide injected, the Halifax company says it can save about 40 tonnes of emissions.

Since 2016, CarbonCure says its clients have diverted more than 105,000 tonnes of carbon dioxide from entering the atmosphere thanks to its technology. At the same time, the company itself has been strengthening its brand and budget with investments from some of the world’s most well-known executives.

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Assembly technician Jordan Porter blasts CO2 while testing injection technology.Darren Calabrese/The Globe and Mail

Bill Gates’s cleantech fund Breakthrough Energy Ventures (BEV) first bought into CarbonCure in 2018, and the company has since secured both an investment and building partnership from Amazon. And on Thursday, the company will announce additional financing from both Mitsubishi Corp. and the carbon-reduction advisory firm Carbon Direct.

The building industry has raced in recent years to reduce emissions from its materials. This month, Lafarge Canada Inc. said it had finished installing a carbon-capture unit made by Svante Inc. at its cement plant in Richmond, B.C. And both Montreal’s Carbicrete and Calgary’s Carbon Upcycling Technologies work to make concrete using industrial byproducts to assist with carbon absorption.

CarbonCure says it can save money for clients by reducing the amount of concrete used while recycling carbon dioxide purchased from other industrial producers. Concrete is one of the world’s most widely used materials, but cement, a component in concrete, is responsible for somewhere between 6 per cent and 8 per cent of global carbon emissions caused by humans.

“People generally aren’t just going to be more sustainable because they feel like it,” said Sean Monkman, CarbonCure’s senior vice-president of technology, in an interview at the company’s Halifax head office and manufacturing facility.

CarbonCure’s secret weapon is what Dr. Monkman colloquially calls the “box,” which helps clients inject the right amount of carbon dioxide to strengthen the concrete. It’s a small attachment housing the company’s proprietary technology that bridges a CO2 supply tank with a mixer filled with concrete. It’s a small, easy retrofit: Since the pandemic began, CarbonCure staff have begun sending the box to clients remotely, and can help as many as three customers install it in a single morning.

The carbon is usually bought from industrial producers – a byproduct of the creation of chemicals such as ethanol and ammonia, though CarbonCure is looking to expand its group of suppliers. The injection is done early in the mixing process, often at a concrete plant or on a truck. In a solution with water, carbon dioxide can create carbonate ions that connect with calcium ions from the cement within the concrete. These bind to make calcium carbonate – little particles of limestone ­– which can help strengthen the concrete.

Solid concrete can absorb carbon dioxide, potentially shrinking the material and corroding any steel embedded inside, which is a problem that plagues many highway underpasses. But CarbonCure executives say that treating concrete with carbon early in the process can minimize this issue.

A growing number of customers are using CarbonCure’s technology across North America: Dr. Monkman says that its 300-plus customers used the material in 1.2 per cent of concrete made in the United States last October.

Indiana-based Irving Materials Inc. uses CarbonCure’s technology in nearly 80 plants. Senior vice-president Bob Haldrup said it’s delivered 1.4 million cubic yards of concrete using the tech, saving more than 13,500 tonnes of carbon dioxide.

Mr. Haldrup said that working with CarbonCure aided sales amid growing demand for sustainable building materials. “It creates a tremendous marketing opportunity, morale in the work force, and loyalty in the customer base,” he said by phone.

Both Dr. Monkman and Robert Niven, CarbonCure’s chief executive officer, studied concrete and carbonization during graduate work at McGill University in the 2000s. Mr. Niven said by phone from Victoria that as Canada pushes to reach net zero carbon emissions by 2050, carbon removal technologies could help close that gap.

“The reality is that there is just not enough capital to replace the vast infrastructure investments in the concrete industry – and probably, more importantly, not enough time,” Mr. Niven said. “We wanted a retrofit solution that could cost, really, pennies.”

So CarbonCure has set a goal to reduce carbon dioxide emissions by 500 million tonnes by 2030. Amazon took interest in 2020 after announcing its US$2-billion Climate Pledge Fund, a cross-industry investment program to reduce greenhouse gas emissions. It revealed an investment of undisclosed value into CarbonCure last September, and says it has already been using its technology in new buildings, including its second headquarters in Virginia near Washington.

“Lower carbon building materials reduce a building’s embodied carbon emissions, an integral strategy in the shift towards net-zero carbon buildings,” said Matt Peterson, director of Amazon’s Climate Pledge Fund, in an e-mailed statement. (Though no one would reveal the size of CarbonCure’s recent investment rounds, Mr. Niven said that, “These companies don’t cut small cheques.”)

Houston-based Rouzbeh Shahsavari, president of C-Crete Technologies LLC and an adjunct professor at Rice University, said in an e-mail that as carbon-injection technologies develop, “we can unleash the true potential of concrete” as a material to store carbon dioxide.

But among the handful of companies developing and academics studying concrete carbonization, there is some discussion over the most efficient approach to the process. Speaking in general terms about carbon injection, and not about CarbonCure, which competes with C-Crete, Prof. Shahsavari said that injecting the CO2 in a traditional plant or truck can wind up storing much less carbon than a dedicated facility making precast concrete where the environment can be controlled.

He said the difference could be as wide as storing just 0.1 per cent of the carbon when the concrete is cast in place to double-digit percentage-point storage for controlled, precast concrete. But he added that the conditions for making precast concrete can make the process more expensive, at least until economies of scale drive the price down.

This can give a cost advantage to companies such as CarbonCure, which a growing number of big-name boosters are buying into. That financing includes BEV, which first invested in CarbonCure in 2018. Founded by Mr. Gates, its investors include Michael Bloomberg, Amazon’s Jeff Bezos, Alibaba Group’s Jack Ma and Softbank Group Corp.’s Masayoshi Son.

Eric Toone, BEV’s science lead, said that he believes CarbonCure has the potential to be adopted widely worldwide because of its low costs and easy setup, giving it the potential to augment other carbon-reducing technologies in the building process. “It’s a solution that doesn’t really cost anything,” he said in an interview.

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