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Concrete Mfring Processes Win CO2 Conversion Challenge

Gaurav Sant

Gaurav Sant (UCLA School of Engineering)

20 Apr. 2021. Two companies with alternative techniques for manufacturing concrete won a challenge competition to convert carbon dioxide into useful products. UCLA and CarbonBuilt in Los Angeles and CarbonCure Technologies in Halifax, Nova Scotia each earn $7.5 million as first-place winners in the NRG Cosia Carbon XPrize, conducted by XPrize, an organization that holds technology challenge competitions.

The NRG Cosia Carbon XPrize sought new techniques and processes for converting high volumes of greenhouse gas emissions from coal and natural gas production into valuable products. The challenge began in 2015, sponsored by U.S. electric power production company NRG Energy and Canada Oil Sands Innovation Alliance, or Cosia, an organization of crude oil producers from Canada’s oil sands in Alberta. The five-year competition was interrupted last year due to the Covid-19 pandemic that delayed judging and awarding of prizes.

The challenge offered participants a choice of two existing sites for demonstrating their technologies to convert carbon dioxide emissions. One site was the Wyoming Integrated Test Center in Gillette, Wyoming providing testing facilities for carbon capture, use, and sequestration, with emissions generated by a nearby coal-fired power plant. The second location was the Alberta Carbon Conversion Technology Centre in Calgary, for conversion of emissions from a natural gas power plant next door. XPrize awarded first prizes in the challenge for each track.

The Wyoming site winner is UCLA and CarbonBuilt in Los Angeles, a spin-off company from UCLA’s engineering school. CarbonBuilt licenses a process from the lab of Gaurav Sant, an engineering and materials science professor and director of UCLA’s Institute for Carbon Management, and the company’s founder. Sant and colleagues study the chemistry and structural properties of cement-like materials in construction.

Their research led to a process that injects carbon dioxide from flue gases into cement, the binding agent in concrete, where it’s absorbed and cured into calcium carbonate, or common limestone. That process, say its developers, reduces CO2 emissions by half compared to conventional concrete production methods. The process also needs 60 to 90 percent less cement to make concrete, further reducing its carbon footprint.

Injecting CO2 into reclaimed wastewater

“Seashells are made of calcium carbonate, which is nature’s original cementation agent,” says Sant in a university statement. “We were really motivated by the idea of how seashells were held together. And that’s how we really set about to turn carbon dioxide into concrete.”

CarbonCure, the Alberta track winner, offers a concrete production process that injects carbon dioxide into reclaimed then recycled wastewater for making concrete. The CO2 interacts with calcium in wet cement to produce calcium carbonate, or limestone, strengthening the concrete like the CarbonBuilt process. The company says its process saves on water as well as reduces the carbon footprint from manufacturing.

CarbonCure President Jennifer Wagner notes in a company statement that the Xprize competition shows the problem of climate change “is surmountable and that we have the solutions available today to create meaningful change.” Wagner adds, “The prize money will be used to accelerate our path to our mission of reducing 500 million tonnes of carbon emissions annually by 2030.” In addition, the company plans to invest part of the prize funds into social equity initiatives.

“The production of portland cement, the key ingredient that binds concrete and gives it its strength, accounts for approximately seven percent of global CO2 emissions,” says XPrize vice president of climate and energy Marcius Extavour in an organization statement. “Concrete is also a material that can be readily made using CO2 as an input, which the winning teams have demonstrated really clearly.”

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