The best way H2Orbit has seen for pulling carbon dioxide from the atmosphere is through the work of Dr. Klaus Lackner, a Columbia University geophysicist, and Alan Wright, an engineer formerly with the Biosphere 2 project.  The two are working an atmospheric carbon dioxide extraction machine that has been dubbed a "synthetic tree".  Their calculations show that a synthetic tree could remove 1,000 times more CO2 than a living tree and given the volume needing removal - that might be a good thing.

• The device itself looks like a large American Football goal post with Venetian Blinds.  Liquid sodium hydroxide, pumped through the machine is then converted chemically by the wind stream to sodium carbonate as it interacts with carbon dioxide in the air.

• The numbers we have seen show a unit with a collection area of 50 x 60 meters, could gather around 90,000 tons of carbon dioxide annually.  That means one synthetic tree could handle an amount of carbon dioxide equivalent to the annual emissions of 15,000 automobiles.

• The real answer to this question is "it depends".  Why?  Because currently there are many issues at stake.  We need to understand the complete picture of carbon dioxide in our biosphere.  Take careful notice that we used the word biosphere and not atmosphere.   The point is that our oceans have been a carbon dioxide sink since mankind lit that first camp fire.
  
  The oceans have absorbed billions, if not trillions, of tons of carbon dioxide.  Then we need to look at what's in the atmosphere.  We need to understand the interaction between the atmosphere and the oceans better - when the carbon dioxide might move from the oceans to the atmosphere (and what rare circumstances would be required for that to happen).  Then we need a complete picture of how much CO2 is being dumped by anthropogenic activity.
  
  H2Orbit has seen CO2 numbers as low as 22 billion tons annually to orders of magnitude higher than that.  So our answer at the moment is we don't know.  In any case, having said that, the number of synthetic trees is going to number in the hundreds of thousands if not millions.
• It is important to remember the strategic vision is not to perpetuate the hydrocarbon paradigm.  The strategic objective is a healthy sustainable biosphere.   If you didn't read the second worst case scenario we suggest you do.

• You percolate the liquid sodium carbonate over solid calcium hydroxide, and the calcium catches the carbon.   So the you have taken the carbon out of the sodium hydroxide, and you can use it again.  But then you have to take the carbon out of the calcium so that you can repeat the process at the site of this unit.  You do that by heating the calcium carbonate.  The carbon dioxide is then in a concentrated stream, with which we can do whatever we want.
• An alternative to the scenario immediately above would be to consider the calcium hydroxide "a consumable item" and the end product would be the raw calcium carbonate.

H2Orbit would prefer to industrialize these processes and manufacture calcium carbonate in usable form.  Especially in Coral Reef Restoration projects and commercial  construction projects. 

Especially if in doing so will help correct problems or situations in other areas.  We already know that calcium carbonate can help with water acidity problems and our oceans have that problem in abundance.