Can 'green cement' make carbon capture and storage obsolete?

The conventional wisdom among utilities, the Obama administration, many scientists and some major environmental groups is that the future of coal-fired electricity under an eventual cap on carbon dioxide emissions will require an overhaul that will be technologically complicated, politically difficult and financially expensive.

Policy experts say that to "decarbonize" the future power system, we will need a new generation of power plants that can separate CO2 from their emissions. They must be connected to a large network of pipelines and injection facilities that can transport the odorless, transparent gas and pump it deep underground. Finally, it will require a regime of new state and federal laws and regulations, probably backed up by insurance policies, to protect against long-term damage from leakage.

There are a growing number of companies and investors that are betting this conventional wisdom is wrong. They are supporting technologies that will separate and then trap carbon emissions in a series of "beneficial products" that can be shipped to markets and sold at a profit. That, they assert, will avoid the need for much of the carbon capture and storage (CCS) infrastructure now on energy planners' drawing boards.

The most outspoken salesman for this approach is Brent Constantz, who has spent much of his career studying, patenting and marketing new ways to make cement. He believes that what he calls "green cement," which starts as a milky precipitate made from injecting carbon dioxide from power plant emissions into seawater, can be made and sold at a profit.

In the Constantz scenario, his "green" cement and "green" aggregate that is used to make concrete would begin to take market share from conventional cement makers, which are the nation's third-largest source of CO2 emissions behind the utility and transportation sectors.

That is because normal cement is made by heating limestone to high temperatures in kilns. The limestone gives off CO2 in the process, and so do the kilns, which are usually coal-fired.

Rather than adding emissions to the atmosphere, green cement and cement aggregates are made by subtracting CO2 emissions and then locking them permanently in construction materials. A price on carbon emissions imposed by states or the federal government would help it replace conventional cement, asserts Constantz, a consulting professor at Stanford University's School of Earth Sciences.

Helping China and India clean up

What he is really counting on, though, is that the product, by itself, will turn a profit -- a message that would resonate in China and India. Their economies are heavily dependent upon coal-fired electricity and also feature soaring demands for concrete. Neither country will be swayed by U.S. legislative moves to require CCS, Constantz believes. "The only way you're going to clean up the environment in China and India is to make it profitable," he adds. "If it's profitable, the Chinese are going to get there before we are."

Constantz's company, Calera Corp., of Los Gatos, Calif., recently appeared on a list of six winners of $106 million in federal stimulus grants awarded by the Department of Energy to demonstrate the "beneficial use" of CO2. The competition was not open to foreign companies. Steven Chu, secretary of Energy, described it as part of a "broad commitment to unleash the American innovation machine."

Elaine Everitt, a project manager for the National Energy Technology Laboratory, which selected the winners, said DOE still believes carbon capture and storage "is the best way to go." But officials have continuing concerns that not all areas of the United States have the right geology to store CO2 underground permanently.

Ten years ago, her agency began exploring the potential of "beneficial use" of CO2. It found few companies interested then. Last year, 115 companies applied for grants. She said her office is preparing to track the six winners to see whether their technology is feasible and "what it would take to scale up to larger commercial use."

In a 233-page CCS report issued by a 14-agency task force of the Obama administration yesterday, it appears that the innovators have failed to convince government policymakers that there is an alternative to CCS. Buried in the back of the report are three pages on "CO2 Reuse" that conclude that none of the alternative ideas will be commercially viable by 2016, when the government is preparing to "roll out" its CCS strategy on a national basis (see related story).

Among the winners of the DOE awards, Constantz, a tall, confident inventor given to professorial lectures as well as sweeping statements, found himself in interesting company. Alcoa Inc. and Eastman Kodak Co. were among the winning teams, as well as Joe Jones, whose company, Skyonic Corp., will use its $25 million grant to build a demonstration plant that turns CO2 emissions from a San Antonio cement plant into bicarbonate of soda for animal feed and other industrial products.


None of the winners has made the case for an alternative approach as doggedly as Constantz. He built a small but solid base for himself in the concrete business by inventing a super-strong cement that orthopedic surgeons use to cement broken bones back together. It sells for $200 a gram.

Addressing 'the entire problem'

As Constantz describes his green cement, the process that makes it mimics the way corals, shellfish and other deep-sea creatures create their shells and skeletons out of calcium and magnesium in seawater. In the late 1980s, he decided it could be scaled up to produce the equivalent of portland cement, the binding ingredient of most concrete.

In 2007 he invited Vinod Khosla, the Silicon Valley investor, to his laboratory at Los Gatos, where he was beginning to make concrete from seawater.

Constantz, who knew relatively little about global warming then, noted that success was limited by the relatively small amount of CO2 dissolved in seawater. He said he turned to Khosla and asked: "Where can we get large quantities of carbon dioxide?"

Three years and about $50 million of Khosla's money later, Calera has a pilot plant operating on at Moss Landing on California's Monterey Bay. It bubbles some of the emissions from a natural gas-fired Dynegy power plant next door through seawater.

The additional CO2 and a patented low-energy electrochemical process increased the production of the chalk-like precursor to synthetic concrete and aggregate by about eight times, according to Calera. The plant makes the equivalent of about a ton of concrete a day, Constantz says.

Testifying last year before a House committee, Constantz asserted that his process could be scaled up at multiple facilities to produce 12.5 billion tons of concrete a year -- roughly as much as world markets consume. If it locked that much CO2 in concrete, the process could begin to cut global CO2 emissions by itself. Or, as he put it more bluntly during a lecture at Stanford: "We can address the entire problem."

He envisions selling "carbon-negative building materials" -- products such as cement, sand and aggregate -- under a regulatory regime that would give credit for products that contained CO2 removed from the atmosphere. One ton of green cement would reduce a building's carbon footprint by almost half a ton, he calculates. Part of the credit could come from providing builders with materials that avoided the emissions from mining and transporting the ingredients of traditional concrete, he adds.

Confronting the 'World of Concrete'

In an interview, Constantz called the Department of Energy's current preoccupation with CCS projects that inject and store carbon underground a "big scam" created by lobbyists from the oil industry. "For every dollar set aside for CCS, you will need to set aside $2 to take care of liability issues."

In his lectures, he has also lashed out at the concrete industry for having a "Phillip Morris problem" with regard to its emissions and climate change, reminiscent of the tobacco company, which spent years fighting charges that cigarettes caused cancer.

In February of 2009, Constantz showcased his idea at a seminar held for cement experts at the annual "World of Concrete" convention in Las Vegas. "There was a lot of interest. It was a packed room," recalled Steven Kosmatka, vice president of research for the Portland Cement Association, sponsor of the convention.

"People are waiting to see what products will be developed and how they will perform," said Kosmatka, who explained that experts do not fully understand Calera's process because some of the critical details were not revealed. "They [Calera] have some proprietary issues they need to protect."

Clay Perry, a spokesman for the Electric Power Research Institute, the nonprofit research arm of the nation's private utilities, said it is examining Calera's technology but cannot comment on it because it has signed a nondisclosure agreement with Constantz's company.

Ken Caldeira, a climate scientist and fellow professor at Stanford University's Department of Environmental Earth System Sciences, said he regarded some of Constantz's earlier claims as "chemical fantasy without any real bounding in reality." Since then, he says, Calera has modified its approach. "There is a whole family of strategies that they are intending to pursue."

"The question is whether they can do this at a scale that's interesting and at a price that's interesting," he said.

Over the past two years, Calera has attracted some potent allies. Peabody Energy, a global leader in the coal industry, bought a $15 million equity position in the company in March. Beth Sutton, a spokeswoman for Peabody, said her company has invested in at least a dozen promising carbon sequestration projects around the world. "This is our philosophy of pursing the ultimate goal of near zero emissions from coal."

(Constantz may have fanned the flames of the industry's interest by asserting to the House committee that his process will help existing coal-fired plants continue operating under government regulations on carbon emissions. "This will save jobs at coal plants, mining sites and in transportation," he said.)

In December, Calera signed an agreement with Bechtel Corp., one of the world's largest engineering and construction firms, to develop carbon capture facilities around the world. Ian Copeland, president of a Bechtel subsidiary, said "the fundamental chemistry and physics of the Calera process are based on sound scientific principles." Its cement-making process can be integrated with power plants, Copeland added.

Aiming too low?

Calera has received $7 million from Australian authorities to build a pilot plant to make building materials out of emissions from a power plant that uses some of the world's dirtiest coal. In April, a federal minister, Martin Ferguson, called the venture "very exciting" and said if the project proves feasible, Australia will contribute up to $40 million more.

One person whom Constantz hasn't been able to sell on the idea is Jones, president and founder of Skyonic. A chemical engineer who spent most of his career in the semiconductor business, Jones founded his company in Austin, Texas, in 2005. Jones thinks Constantz is aiming too low. Entering the concrete market, he says, is "like competing with dirt."

Jones says his invention, called the "SkyMine Process," will use the CO2 emissions from a San Antonio cement plant to make carbonates and bicarbonates, solids and liquids that capture the CO2 molecule. The end result, he says, will be an array of more valuable industrial chemicals including sodium bicarbonate, calcium carbonate, hydrochloric acid, hydrogen and chlorine gases.

While Constantz has Khosla backing him, Jones has another Silicon Valley investor, Carl Berg, helping to bankroll his venture. Jones said he has already proved his products can be sold at a profit, using emissions from a coal-fired powered plant along with salt, electricity and water as basic ingredients. "There has been considerable interest from utilities," he added.

His new plant, to be located next to Capitol Aggregates Ltd., a cement plant in San Antonio, will be in production by mid-2012. That, he said, will give his products access to a potential $3.5 billion market of chemicals "mined" from an invisible gas that what would otherwise have been wafted into the atmosphere.

Making "green cement," he says, is way down his list of product possibilities from "sky mining." "You want to do the lucrative stuff first and have it power your R&D," he said.

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