Home Sci-TechScience Turning carbon into concrete could win UCLA team a climate victory — and $7.5…


Turning carbon into concrete could win UCLA team a climate victory — and $7.5…

by Ace Damon
Turning carbon into concrete could win UCLA team a climate victory — and $7.5...

Gabe Falzone and his teammates had been awake since 5 am, anticipating the arrival of the concrete mixer. When the truck entered the alley behind UCLA's Boelter Hall, hundreds of narrow, red cylinders were ready. Engineers struggled to fill the containers with about 8 tons of wet sludge before pushing them into giant basement ovens.

They only had 24 hours to complete the next task: bathing the concrete in carbon dioxide to block the gas in the most widely used building material in the world. This was the critical step in the semifinal challenge of a $ 7.5 million contest.

9:59, January 16, 2020
An earlier version of this story said that winners of the Carbon XPrize competition would be paid $ 6.5 million. They will receive $ 7.5 million.

"It was all a thread," said Falzone, project scientist at the Westwood campus.

O UCLA team is one of 10 competing for NRG COSIA Carbon XPrize, an international competition to see who can turn maximum CO2 into valuable products.

The idea is gaining traction as a promising climate solution. Called carbon utilization or carbon conversion, it involves taking CO2 from power plants, steel mills, breweries and other industrial facilities and making it practical – and profitable – rather than allowing greenhouse gas to escape. into the atmosphere.

"It's very hard to encourage people to do things out of altruism," he said. Emily Carter, specialist in sustainable energy technologies at UCLA. But "if people can make money," she said, "it will happen without government intervention".

Team leader Gaurav Sant inspects the brick-curing machine in a UCLA laboratory. The researchers plan to capture carbon dioxide pollution from a coal-fired plant in concrete bricks.

(Jason Armond / Los Angeles Times)

Studies suggest that, at best, converting carbon into useful goods could mitigate 1% to 15% of global emissions and a Report 2019 The National Academies of Science, Engineering and Medicine have said that this could help combat climate change by turning a pollutant into profit.

"It sounds too good to be true," he said. Marcius Extavour, executive director of the Carbon XPrize contest.


Researchers spent decades studying how to capture CO2 from sources such as coal plants so that they could pump into deep geological formations where – hopefully – it would remain stationary for centuries or more. There is only one problem, Extavour said, "Make no money for anyone."

So scientists began exploring ways to turn CO2 into things that people were willing to pay for.

Some are putting it in greenhouses to nurture plants or using it to grow algae for biofuels and animal feed. CO2 already serves as a raw ingredient for many industrial processes, and researchers are developing techniques to incorporate recycled carbon into materials such as plastics, polymers, nanotubes – even vodka.

These uses provide an alternative destination for gas, which would otherwise heat the planet. CO2 is the main factor in man-made climate change and the culprit behind ocean acidification.

To stop these trends, society will have to drastically reduce its greenhouse gas production. Meanwhile, the use of carbon could put some of that CO2 into operation.

"There is an opportunity to really make the economy happen," he said. Jennifer Dunn, a chemical engineer at Northwestern University who contributed to the National Academies report. With each of these new approaches, "we are creating a usable product."

Gabe Falzone holds a CO2 concrete brick.

Gabe Falzone holds a concrete brick that contains trapped carbon.

(Jason Armond / Los Angeles Times)

Like concrete.

The use of recycled carbon was a no brainer for Gaurav Sant, the civil engineer who leads the UCLA team. The main binding ingredient in concrete is cement, which has a huge carbon footprint. O cement industry accounts for approximately 8% of global CO2 emissions and, if it were a country, would be the third largest emitter in the world.

Cement is made by heating limestone with other elements. About half of cement-related emissions come from the energy needed to operate furnaces at abrasive temperatures, and these emissions can be avoided by switching to renewable energy. But the other half is emitted during chemical reactions involving limestone and cannot simply be eliminated.

So Sant and his team started working on a greener approach that starts with a compound called portlandite instead of traditional Portland cement.

Portlandite production also releases CO2. But its unique chemistry allows it to absorb CO2 later in the process, when concrete cures and hardens in precast blocks and other shapes. Sant says the method releases 75% less carbon than conventional techniques and can also store CO2 waste.

At first, the researchers worked with small amounts of green concrete in the lab. "We literally produced a thimble of things," said Sant.

The challenge was to create a recipe that was scalable. They had to find the right mix of ingredients, the right cure temperature and the right flow of CO2. Sant likened it to baking a souffle.

So far, team members have prepared over 100 tons of material. They even broke up a company, CO2Concrete, commercialize the technology for the construction industry, which consumes 20 billion tons of concrete each year.

"There is no other material that we produce or use more," said Sant.


Obviously, there is one thing that we do more: CO2. Every year, the society emits approximately 40 billion tons of gas.

"As humans, you could say that CO2 is almost our number one product," said Extavour.

If all the concrete in the world were made of CO2Concrete, it could store around 1 billion tons of CO2 per year, estimates Sant.

Several other types of carbon use could theoretically absorb a similar amount according to a recent review in Nature magazine. But few seem as safe as a bet.

Take recycled fuels. Several research groups, including a Canadian team in the XPrize competition, are using the captured CO2 to produce fuels for cars and planes. So far, however, they cost much more than traditional fossil fuels – and that is not the only problem.

UCLA project scientist Iman Mehdipour opens the door to a machine used to make CO2Concrete.

UCLA project scientist Iman Mehdipour opens the door to a machine used to make CO2Concrete.

(Jason Armond / Los Angeles Times)

Transforming CO2 into fuel requires a lot of energy, and ensuring a clean supply means increasing renewable sources that can be better used directly offsetting fossil fuels, said Ed Rubin, who studies engineering and public policy at Carnegie Mellon University.

And there is another problem: storing CO2 in recycled fuels only delays emissions, since the gas ends up in the atmosphere when the fuel is burned.

Such forms of carbon use are not a good use of the limited time we have to deal with climate change. Niall Mac Dowell, who studies power systems at Imperial College London, warns that they may be a "expensive distraction”The real task of reducing emissions.

"You really didn't do anything, just think you did something," he said.


Some researchers claim that short-lived products still offer climatic benefits, as long as they have a smaller carbon footprint than their conventional equivalents or the need to extract new fossil fuels is reduced. "This could still be a victory," Dunn said.

And although products like vodka and pens made from captured CO2 do not have a major impact on global emissions, they help to raise awareness of the potential for reusing carbon waste, she said.

Proponents also argue that the use of carbon offers a way to capture emissions that cannot – or do not disappear – anytime soon. That is why fossil fuel companies and other carbon-intensive industries are some of their biggest supporters. (An example: Carbon XPrize is sponsored by the energy company NRG and COSIA, a coalition of Canadian oil sands producers.)

Sant thinks that the use of carbon can be especially valuable for sectors such as manufacturing, where it will be difficult to completely eliminate emissions.

“We know what to do with transportation. We know what to do with renewable energy and the grid, ”he said. But heavy industry? "Big question mark."

At least everyone agrees that putting CO2 in concrete makes sense. The product lasts a long time and demand is projected to skyrocket as cities grow. In fact, the UCLA team has several competitors in the field, including Carbicrete and CarbonCure, another competitor of Carbon XPrize.

The trick is not just to store CO2, but to do so profitably. "This is not a question of what is possible, it is a question of what is accessible," Sant said.

His group can already manufacture concrete at costs that compete with traditional prefabricated blocks, he said. Now, engineers need to increase production, which they will do this spring in the XPrize finals.

The Bruins conquered their place with the red drum demonstration. So in March, Falzone and his fellow project scientist, Iman Mehdipour, will move to Gillette, Wyo., For almost three months, to test their methods at a coal-fired power plant. They will be judged by the amount of carbon stored and the value of the products created.

Two concrete bricks made from recycled carbon dioxide.

A pair of CO2Concrete bricks in a laboratory at the UCLA Department of Civil and Environmental Engineering.

(Jason Armond / Los Angeles Times)

Instead of cylinders, they manufacture standard masonry blocks. Each 33-pound brick contains about 400 grams of CO2, and they aim to produce 800 a day. That would sequester more CO2 than a car would emit from Los Angeles to Salt Lake City.

The team will discover in September how it did against the other finalists. The Culver City-based XPrize Foundation will crown one coal plant winner and another among a group of teams competing at a natural gas plant in …



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