You may not realize it since the material is heavy, and sits still, but the production of concrete accounts for ~3x the amount of carbon emissions as aviation.
That figure is especially concerning with the world’s building stock on track to double by 2060.
Fortunately, in a climate tech first, companies say they’ve not only removed CO2 from the atmosphere, but trapped it in concrete, and used that concrete to construct new things.
As part of a small-scale demonstration, Heirloom — a startup claiming to run America’s only operational Direct Air Capture facility — began the process by capturing CO2 at their headquarters in Brisbane, California.
Next, CarbonCure Technologies, which has produced CO2-captured concrete for Amazon’s second headquarters in Virginia, injected the captured CO2 into wastewater. CarbonCure has raised $12.4m and is also backed by Gates.
Finally, Central Concrete Supply Co. used the processed wastewater to make new concrete, which was used for various construction projects around the Bay Area.
Scaling up is key. The experiment used just ~38 kilograms of captured CO2. According to the EPA’s calculator, that’s what a gas-powered car emits every ~94 miles.
It’ll also be important for these companies to analyze whether other parts of the process have a negative impact on its benefits.
In the meantime, momentum across climate policies, tax credits, and federal funding — including $3.5B toward carbon removal — is moving the space forward.
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I think Bill Gates is pushing a false narrative related to putting CO2 into concrete to reduce global warming. I’ve done a little research and simple math:
1. Water makes up about 9% of concrete.
2. The energy used to create cement, the basic strength component of concrete, comes primarily from natural gas power generation plants (38% of all electricity produced in USA). Another 19% comes from coal fired plants, thus 57% comes from fossil fuels.
3. 1 ton of concrete requires 110 kwh of electrical energy. If 57% of the electrical energy comes from fossil fuels then 62.7 kwh of fossil fuels electrical energy is required to produce 1 ton of concrete.
4. In 2022 the US produced 80 million tons of concrete, while the world produced 4.1 billion tons, therefore the US produced less than 2% of the total amount of global concrete, and an equal amount of total CO2 emissions.
5. 4-8% of total CO2 global emissions comes from the production of concrete, therefore only 6.4 million tons of CO2 were released in the US from concrete production versus 73.6 tons released into the atmosphere from other sources, many not human related. Why then are we so consumed with putting CO2 into concrete to reduce global warming? Seems like another political red herring.
6. The article’s picture indicates that CO2 from concrete is released as a vapor. While this is true it gives the impression, along with the headline, that the vapor is 100% CO2 which is not the case. Normal surface water only contains 10 parts per million CO2, therefore the amount of CO2 released by vaporization from 1 ton of concrete would be about 0.0002 pounds of CO2.
7. Finally, putting CO2 back into the water for concrete production is not going to reduce the amount of energy required to produce a ton of concrete, in fact it will require MORE energy to introduce additional CO2 into the concrete. How much more CO2 introduced into the concrete mix will affect its strength?
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