Concrete is among the most common building materials in the world, and it has a massive carbon footprint. The 15% of concrete that is cement is behind five to six percent of all man made CO2, producing nine kilograms of carbon dioxide for every ten kilograms of cement. A new solar process may put a big dent in those numbers.
Researchers at The George Washington University have developed a process called Solar Thermal Electrochemical Production (STEP) of CaO without CO2, reported Green Car Congress. As the name implies, it's a way to produce the lime that goes into cement without yielding CO2.As Lloyd noted a few years ago: "The chemical reaction that creates cement releases large amounts of CO2 in and of itself. Sixty percent of emissions caused by making cement are from this chemical process alone."
The GWU team, led by Dr. Stuart Licht, goes after that chemical reaction and that 60 percent:
The majority of CO2 emissions occurs during the decarbonation of limestone (CaCO3) to lime (CaO)...and the remainder (30 to 40%) from burning fossil fuels, such as coal, to heat the kiln reactors to ~900°C.
The "new thermal chemistry" relies on "anomalies in oxide solubilites" to cut out the production of CO2 in the making of cement. It remains to be seen how STEP can be translated to the industrial model, if it will be practical and cost-effective. If all goes well, concrete could bump off bamboo as the new green building material du jour.
Thanks to Michael Crumpton for the story tip.