Remember the rocks that absorb CO2?Well, today the Guardian reports that British engineering firm Novacem has developed a new cement that does the same-and produces far less CO2 in production than traditional cement. If this technology can find scalability it would be a truly huge innovation, as cement making is presently one of the single largest sources of global carbon-dioxide emissions (the Guardian cites it as 5% of of all CO2-more than the entire aviation industry).Here's the Guardian's simple description of how Novacem's new concrete is different from our regular concrete: Standard cement, also known as Portland cement, is made by heating limestone or clay to around 1,500C. The processing of the ingredients releases 0.8 tonnes of CO2 per tonne of cement. When it is eventually mixed with water for use in a building, each tonne of cement can absorb up to 0.4 tonnes of CO2, but that still leaves an overall carbon footprint per tonne of 0.4 tonnes.Novacem's cement, which has a patent pending on it, uses magnesium silicates which emit no CO2 when heated. Its production process also runs at much lower temperatures - around 650C. This leads to total CO2 emissions of up to 0.5 tonnes of CO2 per tonne of cement produced. But the Novacem cement formula absorb far more CO2 as it hardens - about 1.1 tonnes. So the overall carbon footprint is negative - i.e. the cement removes 0.6 tonnes of CO2 per tonne used.Click here for the full article.(Image above shows The Portland Cement Factory in Aalborg, Denmark)