Clean coal: just add water?

Cleantech startup Calera mixes carbon dioxide with seawater to produce cement. Is this marine-inspired technology the future of clean coal?
Written by Melissa Mahony, Contributor

On land, coal and fire make carbon dioxide (CO2).

Under the sea, coral and water turn CO2 into calcium carbonate, or CaCO3. The hard, white CaCO3 is a key building block for these living marine structures.

Calera has taken a lesson from coral. At its pilot plant in Moss Landing, California, this cleantech start-up has devised a process to treat CO2 emissions with seawater to form CaCO3, with which they make cement, a component of concrete.

On their website, Calera equates the amount of concrete comprising the Grand Coulee Dam to 7 million tons of CO2.

If feasible on a large scale, the company sees an opportunity for 100-percent-clean coal power (clean except for issues surrounding coal extraction, of course). In his column on Sunday, Thomas Friedman wrote that the large coal company Peabody is expected to announce an investment in Calera this week.

With help from Bechtel Renewables and New Technology, Calera is hoping to build more plants.

In a statement last December, Bechtel's President Ian Copeland says:

“The fundamental chemistry and physics of the Calera process are based on sound scientific principles, and its core technology and equipment can be integrated with base power plants very effectively...While there are challenges to bringing the Calera process to commercial scale, they are not as great as those facing other carbon sequestration approaches."

So far, the best bet for burning coal with little CO2 emissions is sequestering, liquefying, and injecting CO2 into underground wells. But this type of carbon sequestration, also not proven commercially, could come with a hefty price tag—and no cement to sell afterward.

Calera CEO Brent Constantz, shown in this video on Fox Business, explains that the existing relationship between cement and coal companies could support the infrastructure needed for his idea to work.

Scientific American

This post was originally published on Smartplanet.com

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