#04 Carbon-Neutral Cement
Decarbonizing the main building material to eliminate 8% of global CO2 emissions
Read time: 4.5 minutes
In this week’s issue you will learn why cement is so polluting and how to decarbonize it: Carbon-Neutral Cement
“In the time it takes you to read this sentence, the global building industry will have poured more than 19,000 bathtubs of concrete.” -The Guardian
Top Carbon-Neutral Cement News 🗞️
Obel Award 2022 for carbon-neutral concrete: It’s a very prestigious international prize for architecture. The co-founders of Seratech won this year for making carbon-neutral concrete.
The biggest players have a roadmap: In 2021 the Global Cement and Concrete Association launched its 2050 Cement and Concrete Industry Roadmap for Net Zero Concrete. Some parts are questionable but it’s better than nothing.
Funding is coming in: Bill Gates’ Breakthrough Energy Ventures $2 billion fund has invested in 3 cement startups. Many more climate tech funds are also investing in this sector.
Let’s dive in 🧠
We produce over 4 billion tonnes of cement a year, responsible for almost 8% of global CO2 emissions.
Cement is one of the elements that make up concrete (the second most used resource in the world after water).
10% cement, 20% air and water, 30% sand, and 40% gravel = concrete
While there are some environmental issues with the other elements as well, cement is by far the most polluting one.
Here’s how cement is made:
Grind up limestone aka (CaCO3), mix it with other elements in a rotating kiln at 1500ºC.
1 tonne of cement = 1 tonne of CO2
Here’s where the emissions come from:
50% from the chemical reaction. CaCO3 → CaO + CO2
40% from burning fuel to create the reaction.
10% other elements in the supply chain
The last two can be dealt with by making the supply chain more efficient and by using renewables and clean fuels to power the process.
The big problem is the chemical reaction.
The good news is that now we have a bunch of companies working on ways to avoid or compensate for the emissions from that reaction. Here are some really cool ones:
Using other rocks instead of limestone: We use limestone because it has calcium but other rocks like basalt also have calcium and don’t produce CO2 when they react. Such rocks are know as calcium silicates. They are 100x more abundant than limestone.
Inject CO2 into concrete: Inject CO2 into concrete while it's mixing, which enables a 4-6% reduction in the carbon footprint while maintaining the concrete's strength and performance.
Source: CarbonCure Don’t use cement to make concrete: Instead of using cement, some companies are using “steel slag” which is a leftover byproduct of making steel. It is mixed with the other materials and binds perfectly to create concrete.
Use nature: Some companies are taking advantage of biological options to make cement. For example using limestone that was grown by algae through photosynthesis, rather than limestone that was mined from the earth.
Source: University of Colorado Capture emissions: Another very popular option is to capture the emissions that come from making cement and storing them underground/using them somewhere else. If done right it’s great but there’s room for bad practices and it does not solve the root issue, the chemical reaction.
Source: Financial Times
The technology is there. Many companies are coming up with great solutions and scaling them.
So why aren’t they everywhere?
Cons
Money: Both governments and big companies need to to start seriously investing in carbon neutral cement to make it more economically attractive.
Tradition: Construction is a very conservative and safety conscious sector and thus getting it to change materials and suppliers is not easy.
Friends with benefits: Fly ash, a byproduct of coal burning that’s used in the concrete industry has kept these two industries in a very good and stable relationship.
Top Carbon-Neutral Cement Companies💰
Brimstone: Instead of using limestone, they use carbon-free rocks and their process produces magnesium, which captures CO2. From California, 3 years old and they have raised $55 million from Bill Gates’ Breakthrough Energy Ventures fund.
CarbonCure: They have already saved 250000 tonnes of CO2 by injecting captured CO2 into concrete. From Canada, 10 years old and they have raised $30 million from Bill Gates’ Breakthrough Energy Ventures fund and others.
Also check out the different cool approaches made by Ecocem, Carbicrete, Chement, and Solidia.
❗Extreme knowledge area❗
If you think this wasn’t enough here are a few more links to dig deeper.
Some cool data visualizations: A great way to see the evolution of cement production by country in different types of visualizations made by “Our World in Data”.
For you video lovers: This video explains the cement making process as well as some solutions really well. The channel is awesome to learn about climate tech.
That’s it for today, 1 climate tech topic in under 5 minutes.
Next week… Methane! 🤯
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