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

Thousands of Ethiopian Israelis Rally Against Racism

PM Netanyahu says he will meet Damas Pakada, the Ethiopia-born Israeli soldier who was filmed being beaten by two policemen More

Multimedia Ten Migrants Drown in Mediterranean, 4,800 Rescued

All of those rescued are being ferried to Italian ports, with some arriving on Italy's southernmost island, Lampedusa, and others taken to Sicily and Calabria More

HRW: Saudis Using US Cluster Bombs in Yemen

Human Rights Watch says photographs, video and other evidence have emerged indicating cluster munitions have been used in 'recent weeks' in airstrikes in Houthi stronghold in northern Yemen 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.
From Aleppo To Berlin: Band of Brothers Escapes Civil Wari
X
Henry Ridgwell
May 03, 2015 1:12 AM
Hundreds of thousands of Syrians have fled the civil war in their country and journeyed to Europe by boat across the Mediterranean. It is a terrifying ordeal with dangers at every turn. A group of Syrian brothers and their friends describe their ordeal as they try to reach Germany. VOA's Henry Ridgwell reports. ...
Video

Video From Aleppo To Berlin: Band of Brothers Escapes Civil War

Hundreds of thousands of Syrians have fled the civil war in their country and journeyed to Europe by boat across the Mediterranean. It is a terrifying ordeal with dangers at every turn. A group of Syrian brothers and their friends describe their ordeal as they try to reach Germany. VOA's Henry Ridgwell reports. ...
Video

Video Rural Nepal Suffers Brunt of Quake’s Devastation

Nepal is still coming to grips with the full extent of the devastation and misery caused by last Saturday’s magnitude 7.8 earthquake. Some of the hardest-hit communities have been cut off by landslides making it difficult to assess the precise toll. A VOA News crew has been among the first to reach a few of the smaller, remote communities. Correspondent Steve Herman reports from the Sindhupolchak district, east of Kathmandu, which suffered greatly in Nepal’s worst quake in more than 80 years.
Video

Video Black Families Use Baltimore Case to Revisit 'Police Talk'

Following Freddie Gray’s death in police custody this month, VOA interviewed black families throughout the eastern U.S. city of Baltimore about how they discuss the case. Over and over, parents pointed to a crucial talk they say every black mother or father has with their children. Victoria Macchi has more on how this conversation is passed down through generations.
Video

Video Middle East Atheist Channel Defies Taboo

In Egypt, a deeply religious country in a deeply religious region, atheism is not only taboo, it is dangerous. It is sometimes even criminal to publicly declare nonbelief. Despite the danger, one group of activists is pushing back with a new online channel that defends the right not to believe. VOA’s Heather Murdock reports.
Video

Video Nepal Quake Survivors Tell Their Stories

Against all hope, rescuers have found a few more survivors of the devastating earthquake that hit Nepal last Saturday. Mountain climbers and hikers trapped in remote places also have been airlifted to safety, and aid is finally reaching people in the areas closest to the quake's epicenter. Survivors and rescuers are now recounting their experience. Zlatica Hoke has this story.
Video

Video Lessons for Germany, Europe Remain on Anniversary of WWII's End

The 70th anniversary of the end of World War II will be marked May 8-9 in all European countries except Germany, which lost the war. How is the war viewed there, and what impact is it still having? From Berlin, VOA’s Al Pessin reports.
Video

Video 'Woman in Gold' Uses Artwork as Symbol of Cultural Identity

Simon Curtis’ legal drama, "Woman in Gold," is based on the true story of an American Jewish refugee from Austria who fights to reclaim a famous Gustav Klimt painting stolen from her family by the Nazis during World War II. It's a haunting film that speaks to the hearts of millions who have sought to reclaim their past, stripped from them 70 years ago. VOA's Penelope Poulou reports.
Video

Video Nepal Town Destroyed By Quake Counts Itself Lucky

Foreign search teams on Wednesday began reaching some of the communities outside Kathmandu that suffered worse damage than Nepal’s capital from last Saturday’s massive earthquake. VOA Correspondent Steve Herman is in Sankhu - a town of about 10,000 people - where there is relief the death toll is not higher despite widespread destruction.
Video

Video First Surgical Glue Approved for Use Inside Body

While medical adhesives are becoming more common, none had been approved for use inside the body until now. Earlier this year, the first ever biodegradable surgical glue won that approval from the U.S. Food and Drug Administration. VOA’s Rosanne Skirble reports on the innovation and its journey from academia to market.
Video

Video Somali Hotel Chain Owner Strives to Make a Difference

Many in the Somali diaspora are returning home to make a new life despite the continuing risks. Since 2011 when a military campaign against Al-Shabab militants began making progress, members of the diaspora community have come back to open hospitals, schools, hotels, restaurants and other businesses. Abdulaziz Billow in Mogadishu profiles the owner of a chain of hotels and restaurants who is helping to bring change to the once-deadly Somali capital.
Video

Video Study: One in Six Species Threatened with Extinction

Climate change is transforming the planet. Unless steps are taken to reduce global warming, scientists predict rising seas, stronger and more frequent storms, drought, fire and floods. As VOA’s Rosanne Skirble reports, a new study on species extinction underscores the need to take action to avoid the most catastrophic effects of rising temperatures.
Video

Video Taviani Brothers' 'Wondrous Boccaccio' Offers Tales of Love, Humor

The Italian duo of Paolo and Vittorio Taviani have been making movies for half a century: "The Night of the Shooting Stars," "Padre Padrone," "Good Morning, Babylon." Now in their 80s, the brothers have turned to one of the treasures of Italian culture for their latest film. VOA’s Carolyn Weaver reports.
Video

Video Child Migrants Cross Mediterranean Alone, Face Unknown Future

Among the thousands of migrants making the deadly journey by boat to Europe, there are unaccompanied girls and boys. Some have been sent by relatives to earn money; others are orphaned or fleeing war. From a shelter for young migrants in the Sicilian town of Caltagirone, VOA's Henry Ridgwell reports.
Video

Video Baltimore Riots Shed Light on City’s Troubled Past

National Guard troops took up positions Tuesday in Baltimore, Maryland, as authorities tried to restore order after rioting broke out a day earlier. It followed Monday's funeral of a 25-year-old black man who died while in police custody earlier this month. VOA's Chris Simkins reports.
Video

Video Challenges Await Aid Organizations on the Ground in Nepal

A major earthquake rocked Nepal on Saturday and killed thousands, injured thousands more and sent countless Nepalese outside to live in makeshift tent villages. The challenges to Nepal are enormous, with some reconstruction estimates at around $5 billion. Aid workers from around the world face challenges getting into Nepal, which likely makes for a difficult recovery. Arash Arabasadi has the story from Washington.

Poll: Baltimore Police Charged

Poll archive

VOA Blogs