I did some calculations on this a while back, using the energy requirements of direct air capture (DAC) CO2 removal that we currently know how to produce and deploy.
The results I got where that if we built a very large solar farm (500 000 km^2) operating at the efficiency of current commercial solar farms and used all its output to power DAC CO2 removal, that would be enough to remove about half as much CO2 as we currently emit each year. In effect it would be as if we had cut emissions back to 1970 levels.
Note that since the solar farm would just be used to power DAC, it would not need electrical infrastructure outside the farm itself. We just need a place where we can put in 500 000 km^2 of solar panels and a bunch of DAC facilities.
The atmosphere does a good job of distributing CO2 so the solar/DAC facility doesn't need to be near any heavy CO2 emitters either.
BTW, the output of a 500 000 km^2 solar farm per year is about equal to the total yearly energy use of humanity, which shows just how insane the amount of solar energy available is. Let's call this one Human Energy Unit (HEU).
Build two HEU's worth of solar/DAC and we are effectively carbon neutral.
Of course you wouldn't have to build these as 500 000 km^2 facilities. 500 facilities of 1000 km^2 would do, or any other combination that gives us 1 HEU total of energy that is all used for DAC.
How far could we take this?
The 5 largest subtropical deserts in the world have enough room to hold 30 HEUs worth of solar farms.
If we built all those and turned them all on at once it would take one year to remove enough CO2 to get us down to 320 ppm, which is around the levels we had in 1960. Two years would take us back to levels last seen around 1800. 6 years would get us down to pre-industrial levels.
That was all using technology that we have today. It would be a huge project, but it does not require any new science or new engineering. Just a lot of money, politics, manufacturing, and construction.
The results I got where that if we built a very large solar farm (500 000 km^2) operating at the efficiency of current commercial solar farms and used all its output to power DAC CO2 removal, that would be enough to remove about half as much CO2 as we currently emit each year. In effect it would be as if we had cut emissions back to 1970 levels.
Note that since the solar farm would just be used to power DAC, it would not need electrical infrastructure outside the farm itself. We just need a place where we can put in 500 000 km^2 of solar panels and a bunch of DAC facilities.
The atmosphere does a good job of distributing CO2 so the solar/DAC facility doesn't need to be near any heavy CO2 emitters either.
BTW, the output of a 500 000 km^2 solar farm per year is about equal to the total yearly energy use of humanity, which shows just how insane the amount of solar energy available is. Let's call this one Human Energy Unit (HEU).
Build two HEU's worth of solar/DAC and we are effectively carbon neutral.
Of course you wouldn't have to build these as 500 000 km^2 facilities. 500 facilities of 1000 km^2 would do, or any other combination that gives us 1 HEU total of energy that is all used for DAC.
How far could we take this?
The 5 largest subtropical deserts in the world have enough room to hold 30 HEUs worth of solar farms.
If we built all those and turned them all on at once it would take one year to remove enough CO2 to get us down to 320 ppm, which is around the levels we had in 1960. Two years would take us back to levels last seen around 1800. 6 years would get us down to pre-industrial levels.
That was all using technology that we have today. It would be a huge project, but it does not require any new science or new engineering. Just a lot of money, politics, manufacturing, and construction.