Quest for “green” cement draws big name investors to $300B industry

"Europe is an exception, where cement companies have to buy allowances to cover their CO2 emissions and can save money if they produce less. But in many other countries, such as the US, policies are not in place yet to encourage cement makers to pay for greener alternatives."

That seems like a no-brainer, to build the externalities into the cost of goods.

> CarbonCure, a start-up based in Canada, has developed an add-on machine that injects CO2 at the point of mixing the cement with water and sand to create concrete. This permanently stores the CO2 and makes the concrete stronger.

I'm very sceptical of this. If you add CO2 to concrete, the extra strength comes from calcium carbonate, which accelerates concrete aging, and generally reduces its useful life. It's never a good thing.

I readup on what they do, and there is nowhere this is addressed.

Their official stance (https://www.carboncure.com/concrete-corner/key-differences-b...) simply restates the facts without addressing the ultimate fact that this concrete will have much lesser pH reserve for the corrosion to eat through, more porosity, and that this will reduce its useful life in the end no matter what.

cement scientist here, two postdocs in the field for 4 years.

while this co2 curing seems interesting some points should be noted:

1) polluting industries greenwash with no shame, further inspection of claims most of the time reveals that either the technology is impossible to scale up, or is simple PR with of scientific value.

2) i had the opportunity to work with some of the best cement scientists on earth. cement is so complex that it's basically not understood at all. we typically know more of a neutron star a billion light years away than a piece of concrete. this is arguably the most complex material known to man. we don't even know how various phases cristallise individually.

3) any effort to understand the fundamentals of the material in a scientific context will result in little to no funding. writing a proposal for "nano-smart-bs-concrete" you'll get millions of funding and make the front page of Nature/Science with your fancy article.

4) co2 isn't the only issue, by far. resources extraction is a massive problem, search "Holcim Eclepens" to see the scares it leaves. sand is even worst since desert sand doesn't work, and many places are running out of it.

5) yet another issue is comminution, namely the process of grinding clinker to dust, it is a process (ball mills) that has less than 1% efficiency. it's estimated that humanity spends 10% of electricity to make powders. there are other techniques but usually it's very hard to get a particle size distribution (PSD) with good properties.

6) it's in the end a cultural thing mostly. you can build most of the building with crude soil + straw + wood. slightly more expensive but materials readily available on site most of the time and have much better thermal properties.

7) why not using material that Life developed during 4 billion years. mushrooms are promising for instance.

Timber buildings sequester carbon naturally. Transitioning from cement and steel to timber could take hundreds of millions of tons of CO2 out of the atmosphere.

https://www.sciencedaily.com/releases/2020/01/200127134828.h...

It alredy exists and has been used from beginning of humanity til today. its called adobe. I just built a brand new kitchen with it.

There's also the Bill Gates-backed solar-concentrator tech that came out of stealth mode a couple of years back...

https://edition.cnn.com/2019/11/19/business/heliogen-solar-e...

I know it's not the same thing as conventional concrete but hempcrete is "green cement" in spirit.