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

    Post-White House, Obamas to Rent Washington Mansion

    Nine-bedroom home is 3 kilometers from Oval Office, near capital's Embassy Row; rent estimated at around $22,000 a month

    Red Planet? Not so much!

    New research suggest that Mars is in a warm period between cyclical ice ages, and that during Ice Age Maximum over 500,000 years ago, the red planet was decidedly ice, and much whiter to the naked eye.

    Taj Mahal Battles New Threat from Insects

    Swarms of insects are proliferating in the heavily contaminated waters of the Yamuna River, which flows behind the 17th century monument

    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.
    Vietnamese-American Youth Optimistic About Obama's Visit to Vietnami
    X
    Elizabeth Lee
    May 22, 2016 6:04 AM
    U.S. President Barack Obama's visit to Vietnam later this month comes at a time when Vietnam is seeking stronger ties with the United States. Many Vietnamese Americans, especially the younger generation, are optimistic Obama’s trip will help further reconciliation between the two former foes. Elizabeth Lee has more from the community called "Little Saigon" located south of Los Angeles.
    Video

    Video Vietnamese-American Youth Optimistic About Obama's Visit to Vietnam

    U.S. President Barack Obama's visit to Vietnam later this month comes at a time when Vietnam is seeking stronger ties with the United States. Many Vietnamese Americans, especially the younger generation, are optimistic Obama’s trip will help further reconciliation between the two former foes. Elizabeth Lee has more from the community called "Little Saigon" located south of Los Angeles.
    Video

    Video First-generation, Afghan-American Student Sets Sights on Basketball Glory

    Their parents are immigrants to the United States. They are kids who live between two worlds -- their parents' homeland and the U.S. For many of them, they feel most "American" at school. It can be tricky balancing both worlds. In this report, produced by Beth Mendelson, Arash Arabasadi tells us about one Afghan-American student who seems to be coping -- one shot at a time.
    Video

    Video Newest US Citizens, Writing the Next Great Chapter

    While universities across the United States honor their newest graduates this Friday, many immigrants in downtown Manhattan are celebrating, too. One hundred of them, representing 31 countries across four continents, graduated as U.S. citizens, joining the ranks of 680,000 others every year in New York and cities around the country.
    Video

    Video Vietnam Sees Strong Economic Growth Despite Incomplete Reforms

    Vietnam has transformed its communist economy to become one of the world's fastest-growing nations. While the reforms are incomplete, multinational corporations see a profitable future in Vietnam and have made major investments -- as VOA's Jim Randle reports.
    Video

    Video Qatar Denies World Cup Corruption

    The head of Qatar’s organizing committee for the 2022 World Cup insists his country's bid to host the soccer tournament was completely clean, despite the corruption scandals that have rocked the sport’s governing body, FIFA. Hassan Al-Thawadi also said new laws would offer protection to migrants working on World Cup construction projects. VOA's Henry Ridgwell reports.
    Video

    Video Infrastructure Funding Puts Cambodia on Front Line of International Politics

    When leaders of the world’s seven most developed economies meet in Japan next week, demands for infrastructure investment world wide will be high on the agenda. Japanese Prime Minister Shinzo Abe’s push for “quality infrastructure investment” throughout Asia has been widely viewed as a counter to the rise of Chinese investment flooding into region.
    Video

    Video Democrats Fear Party Unity a Casualty in Clinton-Sanders Battle

    Democratic presidential front-runner Hillary Clinton claimed a narrow victory in Tuesday's Kentucky primary even as rival Bernie Sanders won in Oregon. Tensions between the two campaigns are rising, prompting fears that the party will have a difficult time unifying to face the presumptive Republican nominee, Donald Trump. VOA national correspondent Jim Malone has more from Washington.
    Video

    Video Portrait of a Transgender Marriage: Husband and Wife Navigate New Roles

    As controversy continues in North Carolina over the use of public bathrooms by transgender individuals, personal struggles with gender identity that were once secret are now coming to light. VOA’s Tina Trinh explored the ramifications for one couple as part of trans.formation, a series of stories on transgender issues.
    Video

    Video Amerikan Hero Flips Stereotype of Middle Eastern Character

    An Iranian American comedian is hoping to connect with American audiences through a film that inverts some of Hollywood's stereotypes about Middle Eastern characters. Sama Dizayee reports.
    Video

    Video Budding Young Inventors Tackle City's Problems with 3-D Printing

    Every city has problems, and local officials and politicians are often frustrated by their inability to solve them. But surprising solutions can come from unexpected places. Students in Baltimore. Maryland, took up the challenge to solve problems they identified in their city, and came up with projects and products to make a difference. VOA's June Soh has more on a digital fabrication competition primarily focused on 3-D design and printing. Carol Pearson narrates.

    Special Report

    Adrift The Invisible African Diaspora