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

New England Bears Brunt of US Blizzard

Boston, surrounding region grapple with as much as 3 feet of snow, coastal flooding; leaders in New York, spared most severe weather, criticized for being overly cautious More

China Lifts Lid on Sale of Fake Goods Online

A recent survey found nearly 60 percent of a random sample of items bought from Taobao were fake More

Upward Aims to Create Old-girls Network in Silicon Valley

Lisa Lambert, an executive with Intel Corp.'s venture-capital unit, responds to the gender-disparity debate by creating a new social organization 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.
NASA Monitors Earth’s Vital Signs From Spacei
X
Rosanne Skirble
January 27, 2015 5:05 PM
The U.S. space agency, NASA, is wrapping up its busiest 12-month period in more than a decade, with three missions launched in 2014 and two this month, one in early January and the fifth scheduled for January 29. As VOA’s Rosanne Skirble reports, the instruments being lifted into orbit are focused on Earth’s vital life support systems and how they are responding to a warmer planet.
Video

Video NASA Monitors Earth’s Vital Signs From Space

The U.S. space agency, NASA, is wrapping up its busiest 12-month period in more than a decade, with three missions launched in 2014 and two this month, one in early January and the fifth scheduled for January 29. As VOA’s Rosanne Skirble reports, the instruments being lifted into orbit are focused on Earth’s vital life support systems and how they are responding to a warmer planet.
Video

Video Saved By a Mistake - an Auschwitz Survivor's Story

Dagmar Lieblova was 14 when she arrived at Auschwitz in December 1943, along with her entire Czech Jewish family. All of them were to die there, but she was able to leave after several months due to a bureaucratic mix-up which saved her life. Now 85, with three children and six grandchildren, she says she has a feeling of victory. This report by Ahmad Wadiei and Farin Assemi, of RFE/RL's Radio Farda is narrated by RFE’s Raymond Furlong.
Video

Video Weekly Protests in Korea Keep Japanese WWII Atrocities Alive

Every week in Seoul protesters gather in front of the Japanese Embassy to demand an apology and reparations from Tokyo for the thousands of South Korean women who were forced into prostitution during World War II. Although this year marks the 70th anniversary of the end of the war, these protestors have helped keep the issue of comfort women alive and made it difficult for Japan to move beyond its past wartime atrocities. VOA's Brian Padden reports from Seoul.
Video

Video Exercise: New Prescription for Parkinsons Disease

Exercise could be the new prescription for Parkinson's Disease, a progressive disorder of the nervous system that affects movement. More than six million people worldwide suffer from Parkinsons and they're traditionally treated with medication and surgery. Shelley Schlender has more.
Video

Video Brussels Shaken as New Greek Leader Challenges Europe’s Austerity Drive

Greece’s youngest-ever prime minister, 40-year-old Alexis Tsipras, was sworn in Monday after his victorious far-left Syriza party entered a coalition with far right rivals. Tsipras says he will restore dignity to Greece by ending spending cuts. So begins a new chapter for the country at the epicenter of Europe’s economic crisis - a change that has sent tremors across the continent, as Henry Ridgwell reports from London.
Video

Video Obama Urges Closer Economic Ties During Historic India Visit

U.S. President Barack Obama says the United States and India must do better to capitalize on untapped potential in their economic relationship - by removing some of the roadblocks to greater trade and investment. As VOA correspondent Aru Pande reports from New Delhi, Obama spoke after participating in India’s Republic Day celebration.
Video

Video White House Grapples With Yemen Counterterrorism Strategy

Reports say the U.S. has carried out a drone strike on suspected militants in Yemen, the first after President Barack Obama offered reassurances the U.S. is continuing its counterterrorism operations in the country. The future of those operations has been in question following the collapse last week of Yemen’s government. VOA White House correspondent Luis Ramirez reports.
Video

Video Worldwide Photo Workshops Empower Youth

Last September, 20 young adults from South Sudan took part in a National Geographic Photo Camp. They are among hundreds of students from around the world who have learned how to use a camera to tell the stories of the people in their communities through the powerful medium of photography. Three camp participants talked about their experiences recently on a visit to Washington. VOA’s Julie Taboh reports.
Video

Video US, Japan Offer Lessons as Eurozone Launches Huge Stimulus

The Euro currency has fallen sharply after the European Central Bank announced a bigger-than-expected $67 billion-a-month quantitative easing program Thursday - commonly seen as a form of printing new money. Henry Ridgwell reports for VOA from London on whether the move might rescue the eurozone economy -- and what lessons have been learned from similar programs around the world.
Video

Video Oil Price Drop Troubles Texas Producers

As oil prices have fallen over the past several months, drilling operations have slowed in some parts of the United States - including Texas, the state that surpasses all others in energy production. The Lone Star State’s energy output has been boosted in recent years by development of resources trapped deep below ground in the Eagle Ford shale deposit, which stretches across south central Texas. As VOA’s Greg Flakus reports from Karnes City, Texas, the drop in oil prices has created concerns,
Video

Video Nigerian Elections Pose Concern of Potential Conflict in 'Middle Belt'

Nigeria’s north-central state of Kaduna has long been the site of fighting between Muslims and Christians as well as between people of different ethnic groups. As the February elections approach, community and religious leaders are making plans they hope will keep the streets calm after results are announced. Chris Stein reports from the state capital, Kaduna.
Video

Video As Viewership Drops, Obama Puts His Message on YouTube

Ratings reports show President Obama’s State of the Union address this week drew the lowest number of viewers for this annual speech in 15 years. White House officials anticipated this, and the president has decided to take a non-traditional approach to getting his message out. VOA White House correspondent Luis Ramirez reports.

Circumventing Censorship

An Internet Primer for Healthy Web Habits

As surveillance and censoring technologies advance, so, too, do new tools for your computer or mobile device that help protect your privacy and break through Internet censorship.
More

All About America

AppleAndroid