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Comment by filleokus | Hacker News Reader

Really cool! Looking forward to follow your journey.

I understand that you might not be ready to share numbers, but you mention both hydrogen and desalinated water as byproducts, which both are quite energy intensive to produce. Any chance to give a hint along the lines of:

    X kWh of power + sea water + sorbent (consumable?) => Y% CaCO3 + Z% H2 + W% H2O

When at scale, will your synthetic limestone be much more expensive than mined limestone or roughly the same?

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Our synthetic limestone will be on par with mined limestone. At scale when accounting for the higher calcium content per tonne and value of carbon we expect to be cheaper even than mined limestone.

You hit the nail on the head there. The most important cost factor is energy. We're looking at <3MWh/tonne of CO2 removed. Somewhat higher than some competing DAC companies that claim 1.5-2.5MWh. But these guys have the added cost of finding permanent storage of their gaseous CO2. Cost estimates for this, at scale, are as high as $100/tonne

Is it that expensive to pump the c02 back down an old oil or gas well so that it is stored underground again?

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