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The Holy Grail: Carbon-Capturing Cement

Richard Levangie | Friday May 8th, 2009 | 1 Comment

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Last January, Novacem, a spin-off from London’s Imperial College, won the coveted Rushlight Award for its novel CO2-capturing cement process that could turn one of the world’s most CO2-intensive industries into an important carbon sequestration solution. Cement production is a huge environmental problem, producing between six to eight percent of the world’s greenhouse gas emissions – and that makes the cement industry a much, much bigger headache than aviation.
Traditional Portland cement is made by heating limestone and clay in giant kilns which, according to the International Energy Agency, produces 0.83 (metric) tonnes of CO2 for every ton of cement. About half of this footprint is generated from the vast amounts of energy needed to heat the kilns (up to 1,500°C) and the other half is released by chemical reactions as the limestone decomposes.


Novacem’s cement process eschews limestone in favor of magnesium oxides. Nikolaos Vlasopoulos, the company’s chief scientist, is coy about the patent-pending process, but he does say that the magnesium oxides are created from magnesium silicates.
The Novacem process has two main benefits; creating magnesium oxide doesn’t release CO2, and turning it into cement requires less than half the energy required to create traditional Portland cement. Even better, when the cement hardens, it absorbs 1.1 metric tons of carbon dioxide, which means that the technique actually removes more than 0.7 metric tons of CO2 for every ton of cement produced. That offers enormous carbon capture and sequestration (CCS) potential.
Novacem is partnering with Rio Tinto Minerals to source the magnesium silcates, and Vlasopoulos believe the technology could be ready for commercialization in as little as three years.
Novacem is also working on a process that could recycle cement, so a good news story could get even better.


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