You store it as graphite.
DAC isn't useful for short term, but could be useful as a very long term cleanup project.
Assuming world wide solar panel production continues to rapidly grow, wait until it reaches a point where we could set aside a number of solar panels for DAC each year equal to the current annual production of solar panels. Let's call this an arseload of solar panels.
Each year use those panels to build a solar farm in a subtropical desert dedicated solely to powering a DAC facility using current commercial DAC technology.
When we've expanded solar panel production enough raise the set aside to two arseloads a year. Keep increasing it when we can.
By the time we have 180 arseloads worth of panels (at current panel efficiency) powering DAC (at current DAC efficiency), we'd be removing each year about 10% more CO2 than we currently emit per year. We'd be using about 1/15th of the area of the 5 largest subtropical deserts.
If we ever got to 1600 arseloads we'd be removing CO2 fast enough to take the atmosphere from 450 ppm CO2 to 280 ppm in 6 years.
All that carbon removed, if stored as graphite and spread out evenly under 1600 aresloads of solar panels would form a layer about 1 cm deep.
Note that I'm not hypothesizing any breakthroughs in solar power or in DAC. The only thing speculative here is that it is possible to build hundreds of arseloads of solar panels over the next several hundred years. I have no idea if there is some consumable needed that is sufficiently limited to make this impossible.
DAC isn't useful for short term, but could be useful as a very long term cleanup project.
Assuming world wide solar panel production continues to rapidly grow, wait until it reaches a point where we could set aside a number of solar panels for DAC each year equal to the current annual production of solar panels. Let's call this an arseload of solar panels.
Each year use those panels to build a solar farm in a subtropical desert dedicated solely to powering a DAC facility using current commercial DAC technology.
When we've expanded solar panel production enough raise the set aside to two arseloads a year. Keep increasing it when we can.
By the time we have 180 arseloads worth of panels (at current panel efficiency) powering DAC (at current DAC efficiency), we'd be removing each year about 10% more CO2 than we currently emit per year. We'd be using about 1/15th of the area of the 5 largest subtropical deserts.
If we ever got to 1600 arseloads we'd be removing CO2 fast enough to take the atmosphere from 450 ppm CO2 to 280 ppm in 6 years.
All that carbon removed, if stored as graphite and spread out evenly under 1600 aresloads of solar panels would form a layer about 1 cm deep.
Note that I'm not hypothesizing any breakthroughs in solar power or in DAC. The only thing speculative here is that it is possible to build hundreds of arseloads of solar panels over the next several hundred years. I have no idea if there is some consumable needed that is sufficiently limited to make this impossible.