News / USA

California Company's 'Green' Cement Captures CO2

California Company's 'Green' Cement Captures CO2
California Company's 'Green' Cement Captures CO2
Shelley Schlender

Cement is a major component of concrete, the world's most widely used man-made material, an integral part of roads, bridges and buildings. But making cement requires heating limestone and other materials to very high temperatures, a process that releases into the atmosphere large amount of carbon dioxide, or CO2, a leading cause of global warming.

Brent Constantz is working to fix that problem with an environmentally-friendly cement that actually captures CO2 and locks it away.

A clean approach to making a dirty product

Calera's aggregate product is made in a variety of sizes
Calera's aggregate product is made in a variety of sizes

At his California company, Calera, scientists mix air and water to create the cement powder and aggregate pebbles that are the basic ingredients of concrete. But while traditional cement, called Portland cement, adds CO2 to the atmosphere, Calera's green cement takes the greenhouse gas out of the air - a lot of it. For every unit of carbon that Portland cement adds to the air, Brent Constantz says his green cement removes three units. "The more concrete you pour, the more CO2 you take out of the environment. So the way to mitigate the carbon problem is to pour more concrete!" But only, Constantz adds, if it's his concrete.

Conventional cement is the world's third-largest industrial contributor of CO2, mainly due to the high-temperature kilns required to make traditional cement pastes. Calera produces cement without high heat. Constantz explains the patented process mimics the way that nature grows the hard, durable materials in teeth, bone and sea shells. "It's a complicated, interesting, beautiful biologic process," he says, "that produces fantastic structures like a chambered nautilus shell or the human hip and the greater trochanter in the top of our femur, which are elaborate biologic structures made out of mineral."

Minerals in briny water attach to CO2 molecules in the air to create a limestone-like material
Minerals in briny water attach to CO2 molecules in the air to create a limestone-like material

Calera's technology targets the CO2 in the smoky air that's belched from the smokestacks of large industrial sites, such as coal-fired power plants. To capture the gas, Calera mixes the air with briny, brackish seawater, oil field wastewater or other salty waters. This causes minerals in the water to bond with CO2 and then rain out as particles of synthetic limestone. As a bonus, the briny water becomes easier to turn into drinkable water.

Proving its process in the real world

Calera's been doing all this in its labs. Now, it's gearing up to do it on a grander scale, near California's largest power plant, at Moss Landing, on the Pacific coast near San Francisco. Giant turbines at the Dynegy company's gas-fired plant generate electric power for roughly 2 million people.

The first segment of the 3 meter wide pipe that will pull CO2-rich air from Dynegy's smokestack and deliver it 2.5 kilometers away to Calera's plant
The first segment of the 3 meter wide pipe that will pull CO2-rich air from Dynegy's smokestack and deliver it 2.5 kilometers away to Calera's plant

In January, Calera began drawing one percent of the Dynegy stack gas through a massive pipe, across the street to its green cement plant. Calera hopes to capture 80 percent of the smokestack CO2, and sequester it in its patented cement mixture. If it works, says Moss Landing Power Plant manager Jim Dodson, the technology could be a game-changer for carbon sequestration efforts. He calls the Calera process "probably one of the best carbon-capture processes out there that we know of today."
 
Conventional carbon-capture technologies, such as chemical scrubbing, can capture as much as 90 percent of the CO2 from smokestack gas. However, they also use a lot of the energy generated by the plant, almost doubling the cost of the power for consumers.

The U.S. Department of Energy is looking for new carbon-capture technologies that can reduce this so-called parasitic load on power production below 30 percent. Calera's Brent Constantz says his company's relatively low-cost cement-making process can surpass that, cutting a plant's energy drain in half, to less than 15 percent. And he says adding in the potential profits from Calera's green cement would completely offset the financial loss of reduced power plant output. "Our costs of goods are lower than Portland cement because we don't have to burn coal or build a quarry and quarry limestone," he explains, "so our capital costs are quite a bit lower." He estimates using Calera's technology would effectively cut the parasitic load to zero.

Next step: convincing the concrete industry

But many experts in the traditional concrete industry - like Steve Regis of Cal-Portland Cement - are skeptical that Calera can make an affordable cement. "I simply don't believe it, and I've seen no evidence otherwise," he says.

Calera's cement product separates from the water in large holding tanks
Calera's cement product separates from the water in large holding tanks

While he doubts many of Calera's claims, Regis says he wants more carbon capture, and the concrete industry is eager to inspect Calera's products. "We can run tests that look at how hard it is, how durable it is, we can look at all that then run several tests out in less than 6 months." Brent Constantz says his products have already passed those tests, and he promises that the company will share that information when the time is right.

Constantz hopes that traditional concrete makers will team up, first, by blending Calera's green cement product with traditional Portland cement. The goal will be to fight global warming by capturing carbon in concrete . . . so much that it would help reverse man-made climate change.

"We can actively sequester about 16 billion tons of CO2 a year in a profitable, sustainable, ongoing way for our children, our great grandchildren, for centuries to come and deal literally with most of the carbon problem," he insists. The key, he says, is to start tackling that problem – right now.

You May Like

Islamic State Survivor: A Yazidi Girl's Tale

Sarah Said Haydar, captured a year ago while fleeing Islamic State onslaught in northern Iraq, was so traumatized by militants, she sought to end her own life More

EU, US Applaud Kosovo Law on Special Court

Joint statement says lawmakers' decision to address allegations of war crimes 'demonstrated their commitment to the rule of law and to honor international agreements' More

ASEAN Ministers to Push for S. China Sea Agreements

According to documents obtained by VOA Khmer, ministers will stand up for 'freedom of navigation, unimpeded lawful maritime commerce, trade and over flight' More

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Cambodia Makes Progress Curbing Bear Tradei
X
Robert Carmichael
August 04, 2015 3:07 PM
Cambodia’s wild bears are under unprecedented pressure. Their native forests are being cut down at record rates, and China's huge demand for traditional medicine has made them targets. But experts say Cambodia's conservation efforts are setting an example that has put it well ahead of its neighbors in protecting bears. Robert Carmichael reports for VOA from Phnom Penh.
Video

Video Cambodia Makes Progress Curbing Bear Trade

Cambodia’s wild bears are under unprecedented pressure. Their native forests are being cut down at record rates, and China's huge demand for traditional medicine has made them targets. But experts say Cambodia's conservation efforts are setting an example that has put it well ahead of its neighbors in protecting bears. Robert Carmichael reports for VOA from Phnom Penh.
Video

Video Growing Number of E. Jerusalem Palestinians Seek Israeli Citizenship

Most Palestinians living in East Jerusalem have long rejected the option of full Israeli citizenship, seeing it as a betrayal to their political cause - the formation of a Palestinian state with East Jerusalem as its capital. But as that dream remains elusive, more and more Palestinians are applying for Israeli citizenship. Zlatica Hoke reports the decision is hard for many Palestinians who say they have to be pragmatic about it.
Video

Video With No Money, More Students, African Universities Struggle

Academics from around the African continent converged in Johannesburg last week for the African Universities Summit, a chance to tackle some of the major issues facing higher education in Africa today. VOA's Anita Powell reports from Johannesburg.
Video

Video Iraqi Yazidis Fear Death of Their Community

A year ago on August 3, Islamic State militants stormed the homelands of Iraq’s Yazidi minority, killing hundreds of men and enslaving thousands of women. The scenes of desperate Yazidi families crowding on the top of Sinjar mountain without food or water spurred Kurdish fighters into action, an emergency airlift and the start of the U.S. airstrike campaign against the Islamic State Sunni extremists. VOA's Sharon Benh reports from northern Iraq.
Video

Video Bangkok Warned It Soon Could Be Submerged

Italy's Venice and America's New Orleans are not the only cities gradually submerging. The nearly ten million residents of the Bangkok urban area now must confront warnings the city could become uninhabitable in a few decades. VOA Correspondent Steve Herman reports from the Thai capital.
Video

Video Inclusive Gym Gets People With Disabilities in Fitness Spirit

Individuals with special needs are 58 percent more likely to be obese than the general population. According to the U.S. Centers for Disease Control, they also have an increased likelihood of anxiety, depression and social isolation. But a sports club outside Washington wants to make a difference in these people's lives. With Carol Pearson narrating, VOA's June Soh reports.
Video

Video Wisconsin's Voter ID Law Still Mired In Controversy

Voter ID laws have sparked controversy across the US. More than 30 states enacted laws requiring citizens to show identification before they vote. Against fierce opposition, the state of Wisconsin recently enacted one the most restrictive voter ID laws in country. As Jeff Swicord reports, no one can predict its impact as the 2016 election nears.
Video

Video Astronauts Train Underwater for Deep Space Missions

Manned deep space missions are still a long way off, but space agencies are already testing procedures, equipment and human stamina for operations in extreme environment conditions. Small groups of astronauts take turns in spending days in an underwater lab, off Florida’s southern coast, simulating future missions to some remote world. VOA’s George Putic reports.
Video

Video Ebola Vaccine Hailed as Highly Effective

At last, there's a way to end the suffering from the Ebola epidemic that has ravaged West Africa for more than a year. Researchers say the vaccine is so effective, there may never be a major outbreak of Ebola again. VOA's Carol Pearson reports.
Video

Video Special Olympics Show Competitors' Skill, Determination

Special Olympics competitions will wrap up Saturday in Los Angeles, and the closing ceremony for athletes with intellectual disabilities will be held Sunday night. In a week of competition, athletes have shown what they can do through skill and determination. VOA's Mike O'Sullivan reports.
Video

Video Civil Rights Leaders Struggled to Achieve Voting Rights Act

Fifty years ago, lawmakers approved, and U.S. President Lyndon Johnson signed, the Voting Rights Act of 1965. The measure outlawed racial discrimination in voting, giving millions of blacks in many parts of the southern United States federal enforcement of the right to vote. Correspondent Chris Simkins introduces us to some civil rights leaders who were on the front lines in the struggle for voting rights.
Video

Video Shooter’s Grill: Serving Food with a Touch of the Second Amendment

Shooter's Grill, a restaurant in Rifle, Colorado, attracts visitors from all over the world as well as local patrons. The reason? Waitresses openly carry loaded firearms as they serve food, and customers are welcome to carry them, too. VOA's Enming Liu and Lin Yang paid a visit to Shooter's Grill, and heard different opinions about this unique establishment.
Video

Video Despite Controversy, Business Owner Continues Sale of Confederate Flags

At Cooter’s, a store in rural Sperryville, Virginia, about 120 kilometers west of Washington, D.C., Confederate flags are flying off the shelves. The red, white and blue battle flag, with 13 white stars representing the Confederate states, was carried by southern forces during the U.S. Civil War in the 1860s. The South had seceded from the Union over several key issues of disagreement, including slavery. VOA’s Deborah Block has the story.
Video

Video Booming London Property a ‘Haven for Dirty Money’

Billions of dollars of so-called ‘dirty money’ from the proceeds of crime - especially from Russia - are being laundered through the London property market, according to anti-corruption activists. As Henry Ridgwell reports from the British capital, the government has pledged to crack down on the practice.
Video

Video Hometown of Boy Scouts of America Founder Reacts to Gay Leader Decision

Ottawa, Illinois, is the hometown of W.D. Boyce, who founded the Boy Scouts of America in 1910. In Ottawa, where Scouting remains an important part of the legacy of the community, the end of the organization's ban on openly gay adult leaders was seen as inevitable. VOA's Kane Farabaugh reports.

VOA Blogs