Calera Cement Process Details and Operational Pilot Plant and Competitors

Carbon capture and storage (CCS) is one of the main approaches that have been put forward for mitigating climate change.

Norway’s Statoil saves hundreds of millions of euro in avoided carbon taxes by using CCS. Since 1996, the Sleipner gas field has stored about one million tonnes CO2 a year. A second project in the Snøhvit gas field in the Barents Sea stores 700,000 tonnes per year.

The production of Portland cement is the third largest source of the world’s carbon dioxide. People generate 27 billion tons of carbon dioxide each year There was 2.35 billion tons of cement used in 2007 and demand is increasing at 130 million tons per year. 1.4 billion tons of cement produced and used in China is 2007. The production of cement generates 1 to 1.2 tons of CO2 per ton of cement or about 2.5 billion tons of CO2.

Calera cement is a startup funded by Vinod Khosla, technology billionaire. Calera’s process takes the idea of carbon capture and storage a step forward by storing the CO2 in a useful product. For every ton of Calera cement that is made, they are sequestering half a ton of CO2. Note: this is less than original reports of sequestering one ton of CO2 per ton of Calera Cement. Still this is 75% as good. 50% is from not generating the 1 to 1.2 tons of CO2 to begin with.

Calera Cement Process

Flue gas from coal plants/steel plants or natural gas plants + seawater for calcium & Magnesium = Cement + Clean water + Cleaner Air

The Calera process essentially mimics marine cement, which is produced by coral when making their shells and reefs, taking the calcium and magnesium in seawater and using it to form carbonates at normal temperatures and pressures. “We are turning CO2 into carbonic acid and then making carbonate,” Constantz says. “All we need is water and pollution.”

The company employs spray dryers that utilize the heat in the flue gas to dry the slurry that results from mixing the water and pollution. “A gas-fired power plant is basically like attaching a jet engine to the ground,” Constantz notes. “We use the waste heat of the flue gas. They’re just shooting it up into the atmosphere anyway.”

In essence, the company is making chalk, and that’s the color of the resulting cement: snow white. Once dried, the Calera cement can be used as a replacement for the Portland cement that is typically blended with rock and other material to make the concrete in everything from roads to buildings. “We think since we’re making the cement out of CO2, the more you use, the better,” says Constantz, who formerly made medical cements. “Make that wall five feet thick, sequester CO2, and be cooler in summer, warmer in winter and more seismically stable. Or make a road twice as thick.”

Calera Corporation to use the Monterey Moss landing power plant’s emissions to produce carbon-sequestering cement. Photo by Nic Coury from Monterey County Weekly.

Calera has set up a pilot plant at Moss Landing because California is soon to adopt regulations limiting the amount of CO2 power plants and other sources can emit, and natural gas is the primary fuel of power plants in that state. Calera cement is already using emissions from gas-fired generation as their CO2 source at the pilot plant where we are making up to 10 tons a day.

This site previously covered Calera Cement as having one of the best technologies for dealing with excess carbon dioxide on a large scale while simultaneously enabling more and higher economic growth.

Calera leased a part of the commercial park and began test operations. For now, they’re using simulated flue gas to produce test batches of cement, according to Bose.

Engineers are also designing a pipe to transport waste heat from the power plant. Constantz hopes to tap emissions from 5 megawatts of Dynegy’s production (one-half of 1 percent of the plant’s 1,000-megawatt capacity) before expanding to full production.

Many of the refractory’s leftovers– windowless steel buildings, empty silos, round thickener tanks and 40 acres of dolomite and magnesium hydroxide waste– can be converted to Calera’s use, Bose says. He points out a pipe connecting to nine pumps on the ocean side of Highway 1, each of which can intake 4,000 gallons of seawater per minute. The pumps could provide much of Calera’s required 60 million gallons per day, supplemented by wastewater from the Dynegy plant.

Calera’s own wastewater might come in handy for the planned desalination facility next to the Dynegy plant. “Because we take the calcium and magnesium carbonates out of the water, it’s going to increase the efficiency of desalination by about 70 percent,” Constantz says.

“The construction industry is very conservative,” he adds. “It took Portland Cement Association (PCA) about 25 years to get the standards changed to allow 5 percent limestone [in the Portland cement mix]. So things move kind of slowly.”

Calera hopes to get over that hurdle quickly by first offering a blend of its carbon-storing cement and Portland cement, which would not initially store any extra greenhouse gases but would at least balance out the emissions from making the traditional mortar.


Hendrik van Oss, a cement comodity specialist with the U.S. Geologic Society, is skeptical. After a few impromptu calculations based on media reports of Calera’s process, van Oss figures the cement would be carbon-neutral at best– neither emitting nor sequestering net CO2.

The chemistry strikes van Oss as improbable. He doubts Calera could harvest enough seawater or waste heat to drive the manufacturing process. And even if it does work, he doubts the resulting mortar would be strong enough for roads or bridges.

“It’s an intriguing flow sheet. The devil might be in the details of how he does it well,” he says. “He will have to ride that chemical line carefully.”

There could be issues getting the necessary permitting in the United States because concern for local marine life. The global environment would not be considered in current US environmental impact studies. China would likely be more accepting and China has ten times more cement demand than the US and will have more coal power.


Carbon Sciences plans to use flue gas and the water leftover after mining operations, so-called mine slime, which is often rich in magnesium and calcium, to create similar cements. They are working on CO2 to fuel as well as CO2 to carbonate.

Halifax, Nova Scotia–based Carbon Sense Solutions plans to accelerate the natural process of cement absorbing CO2 by exposing a fresh batch to flue gas. And a number of companies are working on reducing the energy needs of Portland cement making. The key will be ensuring that such specialty cements have the same properties and the same or lower cost than Portland cement, says Carbon Sciences president and CEO Derek McLeish.

University of Calgary climate change scientist has developed a machine capable of removing CO2 from the air.

Directly extracting CO2 from regular air not from smoke stack polluted air. The custom-built tower captures CO2 directly from the air while requiring less than 100 kilowatt-hours of electricity per tonne of carbon dioxide.

The proposed air capture system differs from existing carbon capture and storage (CCS) technology, which is already a contributing factor in the strategy of federal governments as they strive to reduce greenhouse gas emissions.

For example, while CCS involves installing equipment at, say, a coal-fired power plant to capture CO2 produced during the coal-burning process before then piping the emissions for permanent underground storage in a geological reservoir, air capture machines will be able to literally remove the CO2 present in ambient air everywhere.

In applying the technology, Keith offers that: “A company could, in principle, contract with an oilsands plant near Fort McMurray to remove CO2 from the air and could build its air capture plant wherever it’s cheapest — China, for example — and the same amount of CO2 would be removed.”

In demonstrating the technology in practice, Keith and his team used a custom-built tower to capture CO2 directly from the air while requiring less than 100 kilowatt-hours of electricity per tonne of carbon dioxide. The tower unit was able to capture the equivalent of approximately 20 tonnes per year of CO2 on a single square metre of scrubbing material — which amounts to the average level of emissions produced by one person each year in North America.

Peswiki entry on Calera Corporation

Peswiki entry on CO2 Sequestration.