Turning carbon into concrete is your formula to combat climate change

Gabe Falzone and his teammates had been awake since 5 a.m., anticipating the arrival of the concrete mixer. When the truck stopped in the alley behind UCLA Boelter Hall, hundreds of narrow red cylinders were ready. The engineers rushed to fill the containers with approximately 8 tons of wet mud before putting them in giant ovens in the basement.

They had only 24 hours to complete the following task: to bathe the concrete in carbon dioxide to enclose the gas in the most used construction material in the world. This was the critical step in the semifinal challenge of a contest with a payment of $ 6.5 million.

“It was until the end,” said Falzone, a project scientist on the Westwood campus.

the UCLA team It is one of the 10 competing for the NRG COSIA Carbon XPrize, an international competition to see who can convert more COtwo in valuable products.

The idea is gaining momentum as a promising climate solution. Called carbon utilization or carbon conversion, involves taking COtwo emitted by power plants, steel factories, breweries and other industrial facilities and making it practical, and profitable, instead of letting the greenhouse gas escape into the atmosphere.

“It is very difficult to encourage people to do things by altruism,” said Emily Carter, an expert in sustainable energy technologies at UCLA. But “if people can earn money,” he said, “it will happen without government intervention.”

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

(Jason Armond / Los Angeles Times)

Studies suggest that, at best, the conversion of carbon into useful goods could mitigate from 1% to 15% of global emissions, and a 2019 report The National Academies of Science, Engineering and Medicine said it could help fight climate change by converting a pollutant into profits.

“It almost sounds too good to be true,” he said. Marcio Extavour, executive director of the Carbon XPrize contest.

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Researchers have spent decades studying how to capture COtwo from sources such as coal plants so that they could pump it to deep geological formations, where, hopefully, it would remain there for centuries or more. Extavour said there is only one problem: “It doesn’t make money to anyone.”

Then scientists began exploring ways to convert COtwo in things that people were willing to pay.

Some are channeling it in greenhouses to nourish the plants, or using it to grow algae for biofuels and animal feed. COtwo It 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. COtwo It is the main driver of climate change caused by man and the culprit of ocean acidification.

To stop these trends, society will have to drastically reduce its production of greenhouse gases. But in the meantime, the use of carbon could put some of that COtwo to work.

“There is the opportunity to realize the circular economy,” he said Jennifer Dunn, a chemical engineer at Northwestern University who contributed to the report of the National Academies. With each of these new approaches, “we are making a usable product.”

Gabe Falzone has a concrete brick with CO2.

Gabe Falzone holds a concrete brick that contains trapped carbon.

(Jason Armond / Los Angeles Times)

Like concrete

The use of recycled coal was obvious to Gaurav Sant, the civil engineer who directs the UCLA team. The key bonding ingredient in concrete is cement, which has a massive carbon footprint. The cement industry represents approximately 8% of the global CO.two emissions, and if it were a country, it would be the third largest emitter in the world.

Cement is made by heating limestone with other elements. About half of the cement-related emissions come from the energy needed to run ovens at scorching temperatures, and these emissions could be avoided by switching to renewable energy. But the other half is emitted during chemical reactions that involve limestone and cannot simply be removed.

So Sant and his team set to work on a greener approach that begins with a compound called portlandite instead of traditional Portland cement.

Portlandite production also releases COtwo. But its unique chemistry allows it to absorb COtwo later in the process, when the concrete is cured and hardened into prefabricated blocks and other shapes. Sant says the method releases 75% less carbon than conventional techniques and can store CO wastetwo too.

At first, the researchers worked with small amounts of green concrete in the laboratory. “We literally produce a thimble of things,” Sant said.

The challenge was a recipe that escalated. They had to find the right mixture of ingredients, the correct curing temperature and the correct CO flowtwo. Sant compared it with baking a souffle.

For now, team members have cooked more than 100 tons of things. They have even split a company, CO2Concrete, to market the technology to the construction industry, which consumes 20 billion tons of concrete every year.

“There is no other material that we produce or use in greater quantity,” Sant said.

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There is, of course, one thing we do more: COtwo. Each year, the company emits approximately 40 billion tons of gas.

“As human beings, CO could be saidtwo it’s almost like our number one product, “said Extavour.

If all the concrete in the world was made of CO2Concreto, it could store around one billion tons of COtwo per year, Sant esteem.

Several other types of carbon utilization could theoretically absorb a similar amount, according to a recent analysis in the journal Nature. But few seem like a bet as safe as the concrete one.

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

The UCLA project scientist, Iman Mehdipour, opens the doors to a machine used to make CO2Concrete.

The UCLA project scientist, Iman Mehdipour, opens the doors to a machine used to make CO2Concrete.

(Jason Armond / Los Angeles Times)

Turning COtwo Fuel requires a lot of energy, and ensuring a clean supply means increasing renewable sources that could be better utilized offset fossil fuels directly, said Ed Rubin, who studies engineering and public policy at Carnegie Mellon University.

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

Such forms of carbon utilization are not a good use of the limited time we have to address climate change. Niall Mac Dowell, who studies energy systems at Imperial College London, warns that they could be a “costly distraction”Of the real task of reducing emissions.

“You really haven’t done anything, you just think you’ve done something,” he said.

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Some researchers say that short-lived products still offer climate benefits as long as they have a smaller carbon footprint than their conventional counterparts, or if they reduce the need to extract new fossil fuels. “That can still be a victory,” Dunn said.

And although products like vodka and feathers made of captured COtwo It will not greatly affect global emissions, they help raise awareness about the potential to reuse carbon waste, he said.

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

Sant believes that the use of carbon could be especially valuable for sectors such as manufacturing, where it will be difficult to eliminate emissions altogether.

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

At least everyone agrees to put COtwo specifically it makes sense. The product lasts a long time and it is projected that demand will skyrocket as cities grow. In fact, the UCLA team has several competitors in the field, including Carbicrete Y Carbon cure, another Carbon XPrize contender.

The trick is not just storing COtwo, but do it profitably. “It’s not about what’s possible, it’s about what’s affordable,” Sant said.

His group can already make concrete 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 earned their place with their red cylinder demonstration. Then, in March, Falzone and the project scientist Iman Mehdipour will move to Gillette, Wyo., For most of the three months to test their methods at a coal-fired power station. They will be judged by the amount of carbon stored and the value of the products created.

Two concrete bricks made with recycled carbon dioxide.

A pair of CO2 concrete bricks in a laboratory of the Department of Civil and Environmental Engineering at UCLA.

(Jason Armond / Los Angeles Times)

Instead of cylinders, they will make standard masonry blocks. Each 33-pound brick contains approximately 400 grams of COtwo, and its goal is to produce 800 a day. That would kidnap more COtwo He would issue a car driving from Los Angeles to Salt Lake City.

The team will discover in September how they fared against the other finalists. The XPrize Foundation, based in Culver City, will crown a coal plant winner and another among a group of teams competing in a natural gas plant in Alberta, Canada.

For Sant, it’s about both demonstrating a point and winning a prize. And the point is that we need to start taking solutions to the climate challenge seriously.

“We have a tendency to look at everything in terms of their problems first instead of their opportunities,” he said. “We have to reverse that thought.”

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