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Scientist Discover How to Convert CO2 into Powder That Can Be Stored for Decades
(www.scientificamerican.com)
This is a most excellent place for technology news and articles.
The big problem with physical carbon storage is that we emit way too much to ever have enough land to store it all as powder. All of these technologies work great at the demonstration scale, but when you do the math for any sort of scale that would make a dent in our emissions, it's just way too many carbon atoms.
Granulated as roadbase for roads and footpaths? Lightweight agregate additive in concrete? Bricks?