Cement is a very popular building material for a lot of good reasons, the problem though is that the process of making it requires a ton of energy. This problem has led to a growing number of people looking into ways to make cement less damaging to the planet. We’ve covered cement on here before.
The Smithsonian has a good round-up of the current world of greening the cement industry. In some ways these solutions can work together.
Though still refining its procedures, Novacem is racing with at least five other companies and university centers to come up with a greener cement. “Given all the attention to carbon these days, a lot of entrepreneurs have popped up,” said MIT’s Jennings. “They see the opportunity side.” With cement a $170 billion-a-year industry, investment money is pouring in.
A California company called Calera has perhaps the most unusual approach: It harnesses carbon dioxide emitted from a power plant and mixes it with seawater or brine to create carbonates that are used to make cement. They can be added to Portland cement to replace some or all of the limestone. Calera is backed by a $50 million investment from Vinod Khosla, a computer engineer who is perhaps Silicon Valley’s most respected and deep-pocketed investor in green technologies. “We are actually making our cement out of CO2,” said company founder Brent Constantz. “We are taking CO2 that would have gone into the atmosphere and turning it into cement.” The technology is still in development, with a demonstration plant in Moss Landing, California, and a partnership with a Chinese group to build a plant next to a coal mine in Inner Mongolia, where they plan to use carbon dioxide emissions to make cement.
Calix, an Australian company, makes cement using superheated steam, which modifies the cement particles and makes them purer and more chemically reactive. The process also separates out carbon dioxide, making it easier to capture the gas and keep it out of the atmosphere.
Louisiana Tech University, like Novacem and Calera, is doing away with limestone altogether; it’s using a paste called geopolymer, which is made of fly ash, sodium hydroxide and potassium hydroxide.