Arthur DanskinReading about concrete chemistry today. Concrete is about 1:6:1 cement to sand/gravel to water. Cement is made from limestone (Calcium Carbonate) by burning off the carbon in a big rotary kiln. Making a tonne of cement liberates about a tonne of CO2. Just glancing around at how much concrete is used in the city gives a real visceral indication of the scale of the problem.
Oscar@manylegged I remember reading that concrete production contributes up to 10% of greenhouse gas emissions. It's insane.
@ofrbg It is. I hadn’t realized until recently that about half the carbon released was from rocks, not just petroleum or coal used for energy, so you can’t reduce emissions too much by using solar or wind power. We need to find a new building material. Concrete is at least 2000 years old, it’s kind of an intimidating problem. If only we could build things out of reified co2.