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

    Top US General: Turkish Media Report ‘Absurd'

    General Dunford rejects ‘irresponsible' claims of coup involvement by former four-star Army General Campbell, who led NATO forces in Afghanistan before retiring earlier this year

    Video Saving Ethiopian Children Thought to Be Cursed

    'Omo Child' looks at efforts of one African man to stop killings of ‘mingi’ children

    Protests Over Western Troops Threaten Libyan 'Unity' Government

    Fears mount that Islamist foes of ‘unity' government plan to declare a revolutionaries' council in Tripoli

    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.
    London’s Financial Crown at Risk as Rivals Eye Brexit Opportunitiesi
    X
    VOA News
    July 25, 2016 5:09 PM
    By most measures, London rivals New York as the only true global financial center. But Britain’s vote to leave the European Union – so-called ‘Brexit’ – means the city could lose its right to sell services tariff-free across the bloc, risking its position as Europe’s financial headquarters. Already some banks have said they may shift operations to the mainland. Henry Ridgwell reports from London.
    Video

    Video London’s Financial Crown at Risk as Rivals Eye Brexit Opportunities

    By most measures, London rivals New York as the only true global financial center. But Britain’s vote to leave the European Union – so-called ‘Brexit’ – means the city could lose its right to sell services tariff-free across the bloc, risking its position as Europe’s financial headquarters. Already some banks have said they may shift operations to the mainland. Henry Ridgwell reports from London.
    Video

    Video Recycling Lifeline for Lebanon’s Last Glassblowers

    In a small Lebanese coastal town, one family is preserving a craft that stretches back millennia. The art of glass blowing was developed by Phoenicians in the region, and the Khalifehs say they are the only ones keeping the skill alive in Lebanon. But despite teaming up with an eco-entrepreneur and receiving an unexpected boost from the country’s recent trash crisis the future remains uncertain. John Owens reports from Sarafand.
    Video

    Video Migrants Continue to Risk Lives Crossing US Border from Mexico

    In his speech Thursday before the Republican National Convention, the party’s presidential candidate, Donald Trump, reiterated his proposal to build a wall along the U.S.-Mexico border if elected. Polls show a large percentage of Americans support better control of the nation's southwestern border, but as VOA’s Greg Flakus reports from the border town of Nogales in the Mexican state of Sonora, the situation faced by people trying to cross the border is already daunting.
    Video

    Video In State of Emergency, Turkey’s Erdogan Focuses on Spiritual Movement

    The state of emergency that Turkish President Recep Tayyip Erdogan has declared is giving him even more power to expand a purge that has seen an estimated 60,000 people either arrested or suspended from their jobs. VOA Europe correspondent Luis Ramirez reports from Istanbul.
    Video

    Video Calm the Waters: US Doubles Down Diplomatic Efforts in ASEAN Meetings

    The United States is redoubling diplomatic efforts and looking to upcoming regional meetings to calm the waters after an international tribunal invalidated the legal basis of Beijing's extensive claims in the South China Sea. VOA State Department correspondent Nike Ching has the story.
    Video

    Video Four Brother Goats Arrive in Brooklyn on a Mission

    While it's unusual to see farm animals in cities, it's become familiar for residents of Brooklyn, New York, to see a little herd of goats. Unlike gas-powered mowing equipment, goats remove invasive weeds quietly and without adding more pollution to the air. As Faiza Elmasry tells us, this is a pilot program and if it proves to be successful, the goat gardener program will be extended to other areas of New York. Faith Lapidus narrates.
    Video

    Video Scientists in Poland Race to Save Honeybees

    Honeybees are in danger worldwide. Causes of what's known as colony collapse disorder range from pesticides and loss of habitat to infections. But scientists in Poland say they are on track to finding a cure for one of the diseases. VOA’s George Putic reports.
    Video

    Video Wall Already Runs Along Parts of US-Mexico Border

    The Republican Party’s presidential nominee, Donald Trump, gained the support of many voters by saying he would build a wall to keep undocumented immigrants and drugs from coming across the border from Mexico. Critics have called his idea impractical and offensive to Mexico, while supporters say such a bold approach is needed to control the border. VOA’s Greg Flakus has more from the border town of Nogales, Arizona.
    Video

    Video New HIV Tests Emphasize Rapid Results

    As the global fight against AIDS intensifies, activists have placed increasing importance on getting people to know their HIV status. Some companies are developing new HIV testing methods designed to be quick, easy and accurate. Thuso Khumalo looks at the latest methods, presented at the International AIDS conference in Durban, South Africa.
    Video

    Video African Youth with HIV Urge More Support

    HIV, the virus that causes AIDS, is the top killer of teens in sub-Saharan Africa. But many youths say their experience with the virus is unique and needs to be addressed differently than the adult epidemic. VOA South African Correspondent Anita Powell reports.
    Video

    Video Pop-Up Art Comes to Your Living Room, Backyard and Elsewhere

    Around the world, independent artists and musicians wrestle with a common problem: where to exhibit or perform? Traditional spaces such as museums and galleries are reserved for bigger names, and renting a space is not feasible for many. Enter ArtsUp, which connects artists with venue owners. Whether it’s a living room, restaurant, office or even a boat, pop-up events are bringing music and art to unexpected places. Tina Trinh has more.
    Video

    Video Scotland’s Booming Whisky Industry Fears Brexit Hangover

    After Britain’s vote to leave the European Union, Scotland’s government wants to break away from the United Kingdom – fearing the nation’s exports are at risk. Among the biggest of these is whisky. Henry Ridgwell reports on a time of turmoil for those involved in the ancient art of distilling Scotland’s most famous product.

    Special Report

    Adrift The Invisible African Diaspora