Decarbonizing Industries

The California based startup Brimstone plans to make cement low carbon. What is its concept?


Please make a selection

Correct Answer
Use Calcium Silicate instead of limestone (calcium carbonate) as the starting material

And here's something for you to take back

The startup is planning to make cement using calcium silicate as the starting material, and claims this will result in a carbon-negative cement

According to the startup's CEO Cody Finke, the calcium silicate rocks are about 200 times more abundant than limestone, which is traditionally used to make cement.

The emissions from the use limestone to make cement is because limestone contains carbon dioxide in the form of carbonate (limestone is CaCO3), which when superheated in a kiln releases CO2. The business case is that by using the silicate instead of the carbonate of calcium, the startup can prevent CO2 emissions release from the process.

That still leaves CO2 emissions from the use of heat energy needed for the kiln, but I presume they have some plans for that as well - electrification of heating of the kiln through the use of solar power perhaps?

Interestingly, their web site also says that their process is carbon negative (not just neutral) because they also use the magnesium present in the calcium silicate rock to capture CO2 - and convert it into MgCO3? - "Our process removes CO2 from the air, resulting in truly carbon negative cement. How? In addition to the calcium, silicon, iron and aluminum used to make cement, our rock also contains magnesium. We use this magnesium to permanently remove atmospheric CO2."

Pretty exciting stuff, for sure.