I recently read an article regarding the capital investment that Brimstone Energy raised to support the development of their ‘carbon negative’ cement. Link to the article:
Having a look through the information I can find online, they grind up calcium silicate from rocks and extract lime (calcium oxide) using a leaching agent to form OPC. They consider it ‘carbon negative’ as magnesium is a byproduct of the production that can be reacted with carbon dioxide to form magnesium carbonate.
It seems like quite a simple process so I am trying to understand the potential drawbacks. Does anyone have any additional information regarding this method of producing OPC? Is the calcium silicate they require globally abundant in the purity required?
The Brimstone CEO Cody Finke gave a presentation to CLF late last year, it looks like a pretty great option. Their process produces OPC and SCMs from calcium silicates, which don’t appear to have any supply issues, while also producing magnesium oxide that can ‘sequester’ CO2 to form magnesium carbonates. There are two possible drawbacks that I can think of:
They are using fossil fuels to heat their furnaces, and until renewable electricity prices come down they probably have around the same energy emissions as OPC.
It is not clear that they can be cost competitive with OPC and SCMs, this is yet to be seen once they scale - also right now their production volumes are quite low.
Otherwise this is a potential game changer in that they have a feasible path to produce zero emissions OPC and SCMs while complying with existing concrete standards, specifications and design methodologies.
About Will’s comment on heat energy required, it is my understanding that the Brimstone process has a lower MJ/mol requirement than OPC. There is a public record of the patent application available from the U.S. patent office that goes into the invention in great detail but it would take a PhD in chemistry to really understand it. It would be great if Cody Finke would help answer the relative heat energy requirements question.