Carbon Negative Cement

According to the EPA, the cement industry was responsible for 829 million metric tons of CO2 emissions, or approximately 3.4% of global emissions in 2000. Today, that number is reported to be as high as 5%.

The cement industry is also a major contributor to industrial process-related emissions and a product used in nearly all construction. In fact, annually, we use about 2.5 billion tons of the stuff.

Now, several companies are developing cement that is CO2 absorbing. That’s right, this cement is not just carbon neutral, it’s carbon negative.

California’s Calera Corporation is one of them, as is British start-up, Novacem, which just raised $1.7 million.

How are these companies creating environmentally friendly cement?

According to Scientific American, Calera states it can use the fumes from a natural gas power plant to make cement.  The company says that it can use more than 90% of the flue gas, which contains 30,000 parts per million of CO2, mix it with some sea water, which has natural calcium and magnesium, and produce cement. Calera’s founder says that for every ton of cement they make, they can sequester half a ton of CO2.

In the case of Novacem, instead of using limestone (calcium carbonate) to make the cement, as is done with conventional Portland cement, they are using magnesium silicates for their cement. Not only does the silicate not emit CO2, it actually absorbs it as it ages developers say, according to Reuters.

Novacem says that their product “combines the sustainability of timber and the recyclability of metal with the technical properties and high thermal mass of concrete.”  These are the types of innovations that the construction industry needs to minimize its environmental impact:

Novacem estimates that for every ton of Portland cement replaced by its product, around three-quarters of a tonne of CO2 is saved, turning the cement industry from a big emitter to a big absorber of carbon. - Reuters

Novacem plans to have a manufacturing plant online in 2011. Calera is working on getting regulator approval. And if you check the events page on their website, they are also hitting the green and traditional building circuit to work on getting acceptance from the building trade. It should all happen just in time for the economic recovery and the ensuing building boom that is sure to follow!