Most people, when they think about global warming, and the sources of carbon dioxide in the atmosphere, which, by the way, just hit 392 ppm last month, think about coal-fired power plants, or cars and trucks rolling down the highway. Few, if any, think about the highway itself, or the concrete bridges and overpasses that negotiate the many roads and rivers that it encounters along the way.
And yet concrete, which is used widely in highways, buildings, sewers and many other structures, is responsible for more than 5% of all carbon dioxide pollution.
Not only do our major construction projects employ an awful lot of this material, but the production of cement, which is the key ingredient in concrete, produces an exceptionally large amount of CO2 for every pound of cement. Cement production creates CO2 emissions in two ways:
- The process requires extremely high temperatures and therefore consumes a large amount of fossil fuel for firing
- The conversion of limestone through a process called calcination releases large quantities of CO2 from the kilns during this process.
In fact, the second item actually produces quite a bit more CO2 than the first.
For a long time, it was generally agreed that CO2 emissions were an unfortunate but unavoidable consequence of cement production. In fact, not long ago, Dimitri Papalexopoulos, managing director of Titan Cement, an attendee of the Green Building Festival in Toronto, said: “No matter what you do, cement production will always release carbon dioxide. You can’t change the chemistry, so we can’t achieve spectacular cuts in emissions.”
Bad and getting worse. According to the Guardian,
Concrete is the second most used product on the planet, after water, and almost half of it is produced in China. The booming Chinese economy has created such a demand for building materials that cement production there last year released 540m tonnes of carbon dioxide – just short of Britain’s total output from all sources. Cement’s weight and low value mean it is almost always made close to where it is needed, and China’s demand helped it to overtake the US as the world’s leading polluter last year. Like the aviation industry, the expected rapid growth in cement production is at severe odds with calls to cut carbon emissions to tackle global warming.
Fortunately, there appears to be a solution to this juggernaut in the form of a new type of cement called Novacem, made by a British company of the same name. Novacem recently won the Material of the Year Award from Material ConneXion, which states that,
By replacing the calcium carbonates used in cement formulation with magnesium silicates, and by using a low-temperature production process that runs on biomass fuels, Novacem has developed a new class of cement that offers performance and cost parity with ordinary Portland Cement, but with a negative carbon footprint.
Presenting the award, George M. Beylerian, Founder & CEO of Material ConneXion said, “Our award for Material of the Year celebrates the power of material innovation to enhance the world in which we live—from our built environment to the designs that we interact with on a daily basis.”
Concrete constitutes the greatest amount of manmade material on this planet—one that is claimed to contribute to 5% of humanity’s carbon footprint. With a simple change of ingredient, Novacem has achieved what could be one of the single largest reductions in CO2 emissions in construction to date. This carbon negative cement reduces carbon emissions of poured concrete from 800Kg emitted per ton to 50kg absorbed per ton.
Pretty impressive, eh? Apparently, I’m not the only one that thinks so. When I visited Novacem’s website I saw that Novacem was also, “a World Economic Forum Technology Pioneer for 2011” and was featured on “MIT Technology Review’s list of the ten most important emerging technologies for 2010. It is also on the Global Cleantech 100, is a Wall Street Journal Technology Innovation winner and a Bloomberg New Energy Pioneer for 2010.”
So what are these magnesium silicates that they intend to use, you ask, some kind of exotic rare earth formulation? You might recognize them by their more common name: talc. Novacem, which has been developing this product for over twenty years, estimates that worldwide reserves are in excess of 10 billion tons.
Of course, no one expects makers of conventional Portland cement to simply roll over. They claim that magnesium based cements have been around for well over a century and are commonly known as Sorel cements. They acknowledge that Novacem represents a new formulation, but speculate that it will likely be far more expensive. Or maybe they are just hoping so.
Novacem is not yet commercially available, and there are no independent test reports available as yet either. So some caution is warranted here. Yet if this company comes anywhere close to meeting its claims, this would be very good news indeed. China, are you listening?
RP Siegel is the co-author of the eco-thriller Vapor Trails, the first in a series covering the human side of various sustainability issues including energy, food, and water. Like airplanes, we all leave behind a vapor trail. And though we can easily see others’, we rarely see our own.
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