What are the plants supposed to breathe, then?

At $600 per ton, that's about $240 trillion for all the carbon we put into the atmosphere. But total world GDP is only about $100 trillion. So unless we can get carbon-reduction costs under about $200/ton it's clear that from a purely accounting point of view the only profitable decision is to let civilization fall.
(What you would do with any profits once civilization had fallen is left as an exercise for the reader.)

Humans are so stupid. Except for these guys, who have found a scam to make money of all those stupid humans who can't grasp the idea that planting trees, rather than clearing more forests to make way for "solar farms" would do that - not that either will have any noticeable effect on the climate...

How long does it take this plant to break even ,removing more tonnes of CO2 than it took to build and power itself.
I would have thought planting and harvesting trees would be a lot simpler and more efficient.

There is yet an alternative to bind CO2 : olivine , see:
https://www.greensand.nl/en/about-greensand/greensand-explained

see also : https://www.olino.org/articles/2009/12/24/co2-vreter-olivijn-nader-onderzocht/ and :
" 9)Het wegstoppen in de grond kost ca. € 50,- per ton CO2, afhankelijk van de toepassing olivijn is dit vanaf ca. €10,- ton CO2 "
translated to bring CO2 into the ground cost will be E 50 / per ton for olivin about E 10 .....






:
"

The solution is simple. Put all the cost of it, pollution FFs make in them at the source and rebate as a dividend to the lower 80% of income people.

Why is planting trees not feasible? Better yet, what about other cellulosic plant materials like switchgrass? Turning dead plant matter into a charcoal like material is not that technically difficult. It could probably be done right in the field - and if done right, could be "sequestered" right into the topsoil. Problem is farmers don't have much political clout, so that solution is ignored. Plus, until we adopt a system of carbon credits, nothing but grandstanding will be done.

Once the blue-green algae appeared on Earth some billions of years ago, the problem of too much atmospheric CO2 began to be relieved. The result of just plain old photosynthesis has made life on Earth possible. Geologically speaking, concentrations of atmospheric CO2 are unusually low (even at .04%). The process will continue to sequester CO2 into the ocean and into rocks, or coal, or crude oil and natural gas. In the meantime, the old photosynthesis will continue to provide food and oxygen, which is essential for most of today's forms of life. I wish the young developers well in their endeavors in the private sector. But please don't tout my government. They have been gullible to too many stupid schemes and don't need any more distractions. Bo Hoye

So they need 750k plants @ $4m apiece ($3T) and capture cost is $600/T x 225 million T ($150M), and you add 675 Terawatts of energy to make it happen. That's, um, very, very ambitious...and GDMF EXPENSIVE. It seems that the KoolAid has been spiked even more this year. Where are they going to get the carbon-free energy?