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Comment by dheera | Hacker News Reader

> Our device captures the carbon emissions from a semi truck. We sell the captured carbon dioxide to concrete producers

> Adding our device to one truck is equivalent to planting 6,200 trees.

Honest question here, I'm not a chemistry expert here but could you please explain how you selling it to concrete producers and also remain carbon negative? What do the concrete producers do with the carbon dioxide? If they need carbon dioxide input why couldn't get from e.g. capturing their own carbon dioxide (I thought concrete construction was one of the bigger CO2 emitters ...)

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Many concrete producers are using technology invented by CarbonCure and Solidia to inject CO2 into concrete, which makes it stronger. It's one of the most permanent forms of sequestration, so it takes the CO2 out of circulation forever. Right now, these concrete plants don't have the capability to capture their own CO2, which would be a very elegant solution. In the medium term, as that gets built out, we're going to be switching to permanently sequestering our CO2 in depleted oil wells and saline aquifers, rather than selling it to concrete producers. And in the long term, we hope to turn it back into fuel right at the truck stop. So selling to concrete producers is only the first step of our roadmap for CO2 sequestration!

Thanks for the explanation!

Follow up -- Considering that at some point we'll reach saturation in the amount of buildings we need, and the world population will necessarily stabilize itself due to resource limits, are there other ways to take CO2 out of circulation besides concrete that don't come with the additional emissions of concrete?

For example I believe plants make sugars using CO2 and water? Can we make a ton of sugar (or other environmentally safe molecules) artificially using CO2 and bury it in the desert? (Sorry for my naivity, I'm not a chemist!)

Absolutely. The main answer is going to be permanent geologic storage in depleted oil wells or saline aquifers, which is widely agreed to be one of the most scalable form of carbon sequestration. We're also hoping to turn the CO2 back into fuel right at the truck stop, so we can put it right back into the trucks!

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