The inspiration for CarbonBuilt is derived from seashells, made from calcium carbonate: the original cement of nature. The researchers replaced the usual calcium silicate in cement with hydrated lime (calcium hydroxide) and allowed flue gases from industry to react with it, creating calcium carbonate that stores CO2. The cement is thus made ‘green.’ After curing, the CO2 is stored permanently.
In a demonstration project in Wyoming, 10,000 concrete blocks have now been produced with flue gases from a neighbouring coal-fired power plant. Per concrete block, about three quarters of a pound of CO2 has been stored. The absence of the need to capture CO2 makes the process cheaper. CarbonBuilt also claims that the green concrete is just as strong as traditional concrete.
The invention recently won the NRG COSIA Carbon XPRIZE prize. It provided $7.5 million for further development of the idea.